Flea control failure? Myths and realities.

PubMed

Halos, Lénaïg; Beugnet, Frédéric; Cardoso, Luís; Farkas, Robert; Franc, Michel; Guillot, Jacques; Pfister, Kurt; Wall, Richard

2014-05-01

Why is it that, despite the proliferation of research on their biology and control, fleas remain such a burden for companion animals and their owners? This review highlights a range of reasons for persistence and apparent treatment failures. It argues that a sustainable approach will require integrated pest management based upon a detailed understanding of the flea life cycle, targeting not only adult fleas but also the immature stages in the environment, combining several modes of control and limiting the risk of chemoresistance. Individual characteristics of the pet and its environment need to be considered. Control of fleas can be achieved, over a timescale of several months, if basic rules are respected. Copyright © 2014 Elsevier Ltd. All rights reserved.

Functional importance of short-range binding and long-range solvent interactions in helical antifreeze peptides.

PubMed

Ebbinghaus, Simon; Meister, Konrad; Prigozhin, Maxim B; Devries, Arthur L; Havenith, Martina; Dzubiella, Joachim; Gruebele, Martin

2012-07-18

Short-range ice binding and long-range solvent perturbation both have been implicated in the activity of antifreeze proteins and antifreeze glycoproteins. We study these two mechanisms for activity of winter flounder antifreeze peptide. Four mutants are characterized by freezing point hysteresis (activity), circular dichroism (secondary structure), Förster resonance energy transfer (end-to-end rigidity), molecular dynamics simulation (structure), and terahertz spectroscopy (long-range solvent perturbation). Our results show that the short-range model is sufficient to explain the activity of our mutants, but the long-range model provides a necessary condition for activity: the most active peptides in our data set all have an extended dynamical hydration shell. It appears that antifreeze proteins and antifreeze glycoproteins have reached different evolutionary solutions to the antifreeze problem, utilizing either a few precisely positioned OH groups or a large quantity of OH groups for ice binding, assisted by long-range solvent perturbation. Copyright © 2012 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Hey! A Flea Bit Me!

MedlinePlus

... Staying Safe Videos for Educators Search English Español Hey! A Flea Bit Me! KidsHealth / For Kids / Hey! A Flea Bit Me! Print en español ¡Ay! ¡ ... 30% DEET. More on this topic for: Kids Hey! A Gnat Bit Me! Hey! A Bedbug Bit ...

Cloning and expression of Tenebrio molitor antifreeze protein in Escherichia coli.

PubMed

Yue, Chang-Wu; Zhang, Yi-Zheng

2009-03-01

A novel antifreeze protein cDNA was cloned by RT-PCR from the larva of the yellow mealworm Tenebrio molitor. The coding fragment of 339 bp encodes a protein of 112 amino acid residues and was fused to the expression vectors pET32a and pTWIN1. The resulted expression plasmids were transformed into Escherischia coli strains BL21 (DE3), ER2566, and Origami B (DE3), respectively. Several strategies were used for expression of the highly disulfide-bonded beta-helix-contained protein with the activity of antifreeze in different expression systems. A protocol for production of refolded and active T. molitor antifreeze protein in bacteria was obtained.

Effect of antifreeze protein on heterogeneous ice nucleation based on a two-dimensional random-field Ising model

NASA Astrophysics Data System (ADS)

Dong, Zhen; Wang, Jianjun; Zhou, Xin

2017-05-01

Antifreeze proteins (AFPs) are the key biomolecules that protect many species from suffering the extreme conditions. Their unique properties of antifreezing provide the potential of a wide range of applications. Inspired by the present experimental approaches of creating an antifreeze surface by coating AFPs, here we present a two-dimensional random-field lattice Ising model to study the effect of AFPs on heterogeneous ice nucleation. The model shows that both the size and the free-energy effect of individual AFPs and their surface coverage dominate the antifreeze capacity of an AFP-coated surface. The simulation results are consistent with the recent experiments qualitatively, revealing the origin of the surprisingly low antifreeze capacity of an AFP-coated surface when the coverage is not particularly high as shown in experiment. These results will hopefully deepen our understanding of the antifreeze effects and thus be potentially useful for designing novel antifreeze coating materials based on biomolecules.

Blocking rapid ice crystal growth through nonbasal plane adsorption of antifreeze proteins

PubMed Central

Olijve, Luuk L. C.; Meister, Konrad; DeVries, Arthur L.; Duman, John G.; Guo, Shuaiqi; Bakker, Huib J.; Voets, Ilja K.

2016-01-01

Antifreeze proteins (AFPs) are a unique class of proteins that bind to growing ice crystal surfaces and arrest further ice growth. AFPs have gained a large interest for their use in antifreeze formulations for water-based materials, such as foods, waterborne paints, and organ transplants. Instead of commonly used colligative antifreezes such as salts and alcohols, the advantage of using AFPs as an additive is that they do not alter the physicochemical properties of the water-based material. Here, we report the first comprehensive evaluation of thermal hysteresis (TH) and ice recrystallization inhibition (IRI) activity of all major classes of AFPs using cryoscopy, sonocrystallization, and recrystallization assays. The results show that TH activities determined by cryoscopy and sonocrystallization differ markedly, and that TH and IRI activities are not correlated. The absence of a distinct correlation in antifreeze activity points to a mechanistic difference in ice growth inhibition by the different classes of AFPs: blocking fast ice growth requires rapid nonbasal plane adsorption, whereas basal plane adsorption is only relevant at long annealing times and at small undercooling. These findings clearly demonstrate that biomimetic analogs of antifreeze (glyco)proteins should be tailored to the specific requirements of the targeted application. PMID:26936953

Efficacy of a new spot-on formulation of selamectin plus sarolaner for cats against adult Ctenocephalides felis, flea egg production and adult flea emergence.

PubMed

Vatta, Adriano F; Everett, William R; Holzmer, Susan J; Cherni, Judith A; King, Vickie L; Rugg, Douglas; Geurden, Thomas

2017-04-01

A new spot-on formulation of selamectin plus sarolaner was evaluated against fleas for adulticidal efficacy, and for the effect on egg production and hatching when applied to flea-infested cats. Ten male and ten female adult domestic shorthair cats were randomly assigned to one of two treatment groups based on pre-treatment flea counts. Cats received topical treatment on Day 0 in a single spot to the dorsal scapular area with either a placebo formulation or with the combination formulation at the minimal dose of 6.0mg selamectin plus 1.0mg sarolaner per kg bodyweight. On Days -1, 5, 12, 19, 26 and 33, cats were infested with approximately 100 (±5) unfed Ctenocephalides felis fleas. At 24h after treatment or 48h after subsequent flea infestation, cats were housed for a 20-h period in a cage to allow collection of flea eggs. At the end of this period, flea eggs were collected from the cages and cats were combed to remove and count live fleas. Emerged viable larvae and emerged adult fleas were counted 3days and 35days, respectively, after egg collection. The new spot-on formulation of selamectin plus sarolaner provided 100% efficacy against adult fleas up to Day 36 following a single application. Fleas on placebo-treated cats produced large numbers of eggs throughout the study, with individual counts ranging from 110 to 1256 eggs. Following treatment, four flea eggs were collected from a single selamectin/sarolaner-treated cat on Day 29, but there were no eggs collected from any other selamectin/sarolaner-treated animal during the study. No larvae or adult fleas developed from these four eggs. From the eggs collected from the placebo-treated cats, the mean percentage of live larvae and adults that emerged ranged from 67.3% to 84.2% and from 50.7% to 81.8%, respectively. A single topical treatment with a new spot-on formulation of selamectin plus sarolaner at the minimum label dose thus controlled fleas on cats and was 100% effective in preventing flea reproduction

Non-equilibrium dog-flea model

NASA Astrophysics Data System (ADS)

Ackerson, Bruce J.

2017-11-01

We develop the open dog-flea model to serve as a check of proposed non-equilibrium theories of statistical mechanics. The model is developed in detail. Then it is applied to four recent models for non-equilibrium statistical mechanics. Comparison of the dog-flea solution with these different models allows checking claims and giving a concrete example of the theoretical models.

Rickettsia felis in fleas from Catalonia (Northeast Spain).

PubMed

Nogueras, María-Mercedes; Pons, Immaculada; Ortuño, Anna; Lario, Sergio; Segura, Ferran

2011-05-01

Rickettsia felis produces a syndrome indistinguishable from murine typhus, which has been described in Spain. R. felis is transmitted to humans by fleas. Although no clinical case has been described so far, serologic evidence of infections in humans, cats, and dogs has been obtained in our area. However, no study has been conducted regarding its presence in vectors. Recognition of routes of transmission is of great importance to prevent infection in humans. Taking into account these results, R. felis seems to be present in animals that are in contact with humans. The aim of this study was to determine the presence of R. felis in the fleas of cats and dogs from Northeast Spain, to show the presence of peridomestic cycle in our area. Between May 2006 and July 2008, 78 fleas were collected. Sixty-three fleas were recovered from kennels. Most of them were collected from cages and a few of them on dogs and cats living in kennels. Fifteen fleas were collected from dogs and cats attended at a veterinary clinic. Fleas were rinsed with ethanol, dried, identified, and stored at 4°C. DNA was extracted from each flea individually. Rickettsial DNA was determined by quantitative real-time polymerase chain reaction. OmpB-specific primers and molecular beacon probes targeting specifically R. felis were used. All 78 fleas were identified as Ctenocephalides felis. R. felis was detected in 34 (43.6%) fleas. No nucleic acids were amplified from negative controls and expected results were obtained from positive controls. Eight positive samples were also confirmed by sequencing. R. felis was found in a high percentage of Ct. felis from cats and dogs. It seems that there is a peridomestic cycle in Northeast Spain, which would allow contact of R. felis with humans.

Refolding of β-Stranded Class I Chitinases of Hippophae rhamnoides Enhances the Antifreeze Activity during Cold Acclimation

PubMed Central

Gupta, Ravi; Deswal, Renu

2014-01-01

Class I chitinases hydrolyse the β-1,4-linkage of chitin and also acquire antifreeze activity in some of the overwintering plants during cold stress. Two chitinases, HrCHT1a of 31 kDa and HrCHT1b of 34 kDa, were purified from cold acclimated and non-acclimated seabuckthorn seedlings using chitin affinity chromatography. 2-D gels of HrCHT1a and HrCHT1b showed single spots with pIs 7.0 and 4.6 respectively. N-terminal sequence of HrCHT1b matched with the class I chitinase of rice and antifreeze proteins while HrCHT1a could not be sequenced as it was N-terminally blocked. Unlike previous reports, where antifreeze activity of chitinase was cold inducible, our results showed that antifreeze activity is constitutive property of class I chitinase as both HrCHT1a and HrCHT1b isolated even from non-acclimated seedlings, exhibited antifreeze activity. Interestingly, HrCHT1a and HrCHT1b purified from cold acclimated seedlings, exhibited 4 and 2 times higher antifreeze activities than those purified from non-acclimated seedlings, suggesting that antifreeze activity increased during cold acclimation. HrCHT1b exhibited 23–33% higher hydrolytic activity and 2–4 times lower antifreeze activity than HrCHT1a did. HrCHT1b was found to be a glycoprotein; however, its antifreeze activity was independent of glycosylation as even deglycosylated HrCHT1b exhibited antifreeze activity. Circular dichroism (CD) analysis showed that both these chitinases were rich in unusual β-stranded conformation (36–43%) and the content of β-strand increased (∼11%) during cold acclimation. Surprisingly, calcium decreased both the activities of HrCHT1b while in case of HrCHT1a, a decrease in the hydrolytic activity and enhancement in its antifreeze activity was observed. CD results showed that addition of calcium also increased the β-stranded conformation of HrCHT1a and HrCHT1b. This is the first report, which shows that antifreeze activity is constitutive property of class I chitinase and cold

Refolding of β-stranded class I chitinases of Hippophae rhamnoides enhances the antifreeze activity during cold acclimation.

PubMed

Gupta, Ravi; Deswal, Renu

2014-01-01

Class I chitinases hydrolyse the β-1,4-linkage of chitin and also acquire antifreeze activity in some of the overwintering plants during cold stress. Two chitinases, HrCHT1a of 31 kDa and HrCHT1b of 34 kDa, were purified from cold acclimated and non-acclimated seabuckthorn seedlings using chitin affinity chromatography. 2-D gels of HrCHT1a and HrCHT1b showed single spots with pIs 7.0 and 4.6 respectively. N-terminal sequence of HrCHT1b matched with the class I chitinase of rice and antifreeze proteins while HrCHT1a could not be sequenced as it was N-terminally blocked. Unlike previous reports, where antifreeze activity of chitinase was cold inducible, our results showed that antifreeze activity is constitutive property of class I chitinase as both HrCHT1a and HrCHT1b isolated even from non-acclimated seedlings, exhibited antifreeze activity. Interestingly, HrCHT1a and HrCHT1b purified from cold acclimated seedlings, exhibited 4 and 2 times higher antifreeze activities than those purified from non-acclimated seedlings, suggesting that antifreeze activity increased during cold acclimation. HrCHT1b exhibited 23-33% higher hydrolytic activity and 2-4 times lower antifreeze activity than HrCHT1a did. HrCHT1b was found to be a glycoprotein; however, its antifreeze activity was independent of glycosylation as even deglycosylated HrCHT1b exhibited antifreeze activity. Circular dichroism (CD) analysis showed that both these chitinases were rich in unusual β-stranded conformation (36-43%) and the content of β-strand increased (∼11%) during cold acclimation. Surprisingly, calcium decreased both the activities of HrCHT1b while in case of HrCHT1a, a decrease in the hydrolytic activity and enhancement in its antifreeze activity was observed. CD results showed that addition of calcium also increased the β-stranded conformation of HrCHT1a and HrCHT1b. This is the first report, which shows that antifreeze activity is constitutive property of class I chitinase and cold

Basal Plane Affinity of an Insect Antifreeze Protein

NASA Astrophysics Data System (ADS)

Pertaya, N.; Gauthier, S. Y.; Davies, P. L.; Braslavsky, I.

2007-03-01

sbwAFP is a powerful antifreeze protein (AFP) with high thermal hysteresis activity that protects spruce budworm (sbw) from freezing during harsh winters in the spruce and fir forests of USA and Canada. Different types of antifreeze proteins have been found in many other species and have potential applications in cryomedicine and cryopreservation. When an ice crystal is cooled in the presence of AFP below the non-equilibrium freezing point the crystal will suddenly and rapidly grow in specific directions. Hyperactive antifreezes like sbwAFP expand perpendicular to the c-axis (in the plane of the a-axes), whereas moderately active AFPs, like type III from fish, grow in the direction parallel to the c-axis. It has been proposed that the basis for hyperactivity of certain AFPs is that they bind and accumulate on the basal plane to inhibit c-axial growth. By putting fluorescent tags on these two types of AFPs we have been able to directly visualize the binding of different types of AFPs to ice surfaces. We do indeed find that the insect AFP accumulates on the basal plane of an ice crystal while type III AFP does not. Supported by CIHR and BNTI.

[Lice, fleas and other beasts].

PubMed

Hufnagel, Markus; Berner, Reinhard

2007-07-01

Bedbugs, lice, fleas and mites are blood-sucking ectoparasites whose bites cause allergic skin reactions. Diagnosis of bites is based on the morphology of the skin eruptions and the pattern of involved skin areas. Confirmation of the diagnosis often requires detection of the causal parasite. The main reservoir for ectoparasites (e.g., bedbugs, fleas, lice and scabies mites) are humans, but animals are also known to harbor ectoparasites (e.g., certain fleas and mites). Fleas, body lice and certain mite larvae in the tropics can transmit infectious diseases, but bedbugs, headlice, pubic lice and scabies mites cannot. Therapy is primarily directed against itching and bacterial superinfections. Pediculosis and scabies are additionally treated with t0pical insecticides. In order to kill freshly hatched larvae, topical treatmentmust be repeated after one week. In the case of pediculosis, people who have come into contact with symptomatic individuals also need to be treated, whereas with scabies, all contact persons must undergo treatment in order toprevent further transmission. Topicalinsecticides, in combination with anti-itch treatment, is usually sufficientto immediately relieve the symptoms and promote permanent healing of the skin lesions.

The Fleas (Siphonaptera) in Iran: Diversity, Host Range, and Medical Importance.

PubMed

Maleki-Ravasan, Naseh; Solhjouy-Fard, Samaneh; Beaucournu, Jean-Claude; Laudisoit, Anne; Mostafavi, Ehsan

2017-01-01

Flea-borne diseases have a wide distribution in the world. Studies on the identity, abundance, distribution and seasonality of the potential vectors of pathogenic agents (e.g. Yersinia pestis, Francisella tularensis, and Rickettsia felis) are necessary tools for controlling and preventing such diseases outbreaks. The improvements of diagnostic tools are partly responsible for an easier detection of otherwise unnoticed agents in the ectoparasitic fauna and as such a good taxonomical knowledge of the potential vectors is crucial. The aims of this study were to make an exhaustive inventory of the literature on the fleas (Siphonaptera) and range of associated hosts in Iran, present their known distribution, and discuss their medical importance. The data were obtained by an extensive literature review related to medically significant fleas in Iran published before 31st August 2016. The flea-host specificity was then determined using a family and subfamily-oriented criteria to further realize and quantify the shared and exclusive vertebrate hosts of fleas among Iran fleas. The locations sampled and reported in the literature were primarily from human habitation, livestock farms, poultry, and rodents' burrows of the 31 provinces of the country. The flea fauna were dominated by seven families, namely the Ceratophyllidae, Leptopsyllidae, Pulicidae, Ctenophthalmidae, Coptopsyllidae, Ischnopsyllidae and Vermipsyllidae. The hosts associated with Iran fleas ranged from the small and large mammals to the birds. Pulicidae were associated with 73% (56/77) of identified host species. Flea-host association analysis indicates that rodents are the common hosts of 5 flea families but some sampling bias results in the reduced number of bird host sampled. Analyses of flea-host relationships at the subfamily level showed that most vertebrates hosted fleas belgonging to 3 subfamilies namely Xenopsyllinae (n = 43), Ctenophthalminae (n = 20) and Amphipsyllinae (n = 17). Meriones persicus was

The Fleas (Siphonaptera) in Iran: Diversity, Host Range, and Medical Importance

PubMed Central

Maleki-Ravasan, Naseh; Solhjouy-Fard, Samaneh; Beaucournu, Jean-Claude; Laudisoit, Anne

2017-01-01

Background Flea-borne diseases have a wide distribution in the world. Studies on the identity, abundance, distribution and seasonality of the potential vectors of pathogenic agents (e.g. Yersinia pestis, Francisella tularensis, and Rickettsia felis) are necessary tools for controlling and preventing such diseases outbreaks. The improvements of diagnostic tools are partly responsible for an easier detection of otherwise unnoticed agents in the ectoparasitic fauna and as such a good taxonomical knowledge of the potential vectors is crucial. The aims of this study were to make an exhaustive inventory of the literature on the fleas (Siphonaptera) and range of associated hosts in Iran, present their known distribution, and discuss their medical importance. Methodology/Principal Findings The data were obtained by an extensive literature review related to medically significant fleas in Iran published before 31st August 2016. The flea-host specificity was then determined using a family and subfamily-oriented criteria to further realize and quantify the shared and exclusive vertebrate hosts of fleas among Iran fleas. The locations sampled and reported in the literature were primarily from human habitation, livestock farms, poultry, and rodents’ burrows of the 31 provinces of the country. The flea fauna were dominated by seven families, namely the Ceratophyllidae, Leptopsyllidae, Pulicidae, Ctenophthalmidae, Coptopsyllidae, Ischnopsyllidae and Vermipsyllidae. The hosts associated with Iran fleas ranged from the small and large mammals to the birds. Pulicidae were associated with 73% (56/77) of identified host species. Flea-host association analysis indicates that rodents are the common hosts of 5 flea families but some sampling bias results in the reduced number of bird host sampled. Analyses of flea-host relationships at the subfamily level showed that most vertebrates hosted fleas belgonging to 3 subfamilies namely Xenopsyllinae (n = 43), Ctenophthalminae (n = 20) and

A serendipitous discovery of antifreeze protein-specific activity in C-linked antifreeze glycoprotein analogs.

PubMed

Eniade, Adewale; Purushotham, Madhusudhan; Ben, Robert N; Wang, J B; Horwath, Kathleen

2003-01-01

Structurally diverse carbon-linked (C-linked) analogs of antifreeze glycoprotein (AFGP) have been prepared via linear or convergent solid phase synthesis. These analogs range in molecular weight from approx 1.5-4.1 KDa and do not possess the beta-D-galactose-1,3-alpha-D-N-acetylgalactosamine carbohydrate moiety or the L-threonine-L-alanine-L-alanine polypeptide backbone native to the AFGP wild-type. Despite these dramatic structural modifications, the 2.7-KDa and 4.1-KDa analogs possess antifreeze protein-specific activity as determined by recrystallization-inhibition (RI) and thermal hysteresis (TH) assays. These analogs are weaker than the wild-type in their activity, but nanoliter osmometry indicates that these compounds are binding to ice and affecting a localized freezing point depression. This is the first example of a C-linked AFGP analog that possesses TH and RI activity and suggests that the rational design and synthesis of chemically and biologically stable AFGP analogs is a feasible and worthwhile endeavor. Given the low degree of TH activity, these compounds may prove useful for the protection of cells during freezing and thawing cycles.

Factors that affect parasitism of black-tailed prairie dogs by fleas

USGS Publications Warehouse

Eads, David A.; Hoogland, John L.

2016-01-01

Fleas (Insecta: Siphonaptera) are hematophagous ectoparasites that feed on vertebrate hosts. Fleas can reduce the fitness of hosts by interfering with immune responses, disrupting adaptive behaviors, and transmitting pathogens. The negative effects of fleas on hosts are usually most pronounced when fleas attain high densities. In lab studies, fleas desiccate and die under dry conditions, suggesting that populations of fleas will tend to decline when precipitation is scarce under natural conditions. To test this hypothesis, we compared precipitation vs. parasitism of black-tailed prairie dogs (Cynomys ludovicianus) by fleas at a single colony during May and June of 13 consecutive years (1976–1988) at Wind Cave National Park, South Dakota, USA. The number of fleas on prairie dogs decreased with increasing precipitation during both the prior growing season (April through August of the prior year) and the just-completed winter–spring (January through April of current year). Due to the reduction in available moisture and palatable forage in dry years, herbivorous prairie dogs might have been food-limited, with weakened behavioral and immunological defenses against fleas. In support of this hypothesis, adult prairie dogs of low mass harbored more fleas than heavier adults. Our results have implications for the spread of plague, an introduced bacterial disease, transmitted by fleas, that devastates prairie dog colonies and, in doing so, can transform grassland ecosystems.

Direct transmission of the cat flea (Ctenocephalides felis) between cats exhibiting social behaviour.

PubMed

Franc, Michel; Bouhsira, Émilie; Beugnet, Frédéric

2013-01-01

A study design was created to assess the potential for fleas to infest cats directly from other cats. In the first experiment, six cats were infested with 100 fleas each and then immediately put in contact with six flea-free cats for 24 h. After removal of all fleas the study was repeated and the contact between cats lasted 48 h. The total numbers of fleas recovered out of the 600 fleas deposited on the 6 donor cats after each infestation were 499 and 486 at 24 h and 48 h respectively. At 1 h post-contact, five fleas were found on the receiver cats, with three cats having one flea and one cat, two fleas. The number of fleas recovered on receiver cats increased towards the end of the study. At 24 h, 20% of the fleas were found on the receiver cats, and at 48 h, 23%. In a second experiment, the six flea-free cats were put in contact with the six donor cats which were each infested by 100 fleas 48 h before. Fewer fleas were found on the receiver cats (n = 15), representing 3.8% of all fleas recovered (n = 403). All the observed fleas had fed. The fleas collected on receiving cats comprised 10 males and 5 females, and 4 of the 5 females were engorged and contained eggs. The fleas collected on donor cats comprised 153 males and 235 females, they were all fed and all females contained eggs. This experiment demonstrated that gravid female fleas have a tendency to become permanently but not exclusively parasitic. Nevertheless, a few can change their cat host in as little as 1 h, which may play a role in the rapid introduction of a new flea population into a cat environment. © M. Franc et al., published by EDP Sciences, 2013.

[Fleas on small mammals in the surrounding area of Erhai Lake].

PubMed

Dong, Wen-Ge; Guo, Xian-Guo; Men, Xing-Yuan; Gong, Zheng-Da; Wu, Dian; Zhang, Zheng-Kun; Zhang, Li-Yun

2009-12-01

To investigate the distribution pattern, species diversity and community structure of fleas on small mammals in the surrounding area of Erhai Lake, and the relationship between fleas and their hosts. Different geographical areas surrounding the Erhai Lake in Yunnan were selected as investigated spots. Small mammals were captured with baited cages. The cage-traps were examined and re-baited each morning. All fleas on the hosts were collected and identified. The richness (S), evenness (J'), diversity index (H'), dominance index (C'), total ectoparasite infestation rate (Rpt), total ectoparasite infestation index (Ipt), and constituent ratio (Cr) were used to measure the community structure. Altogether, 3,303 small mammals and 3,243 fleas were collected. From the 21 species of small mammal hosts, 13 species of fleas were identified. In southern area of the Lake, the species richness (21 species of small mammals & 12 species of fleas) was highest among the three selected areas. Seventeen species of small mammals and 8 species of fleas were found in eastern area, and only 13 species of small mammals and 7 species of fleas found in the west. This implied the probable influences of ecological environments on the fleas and their corresponding hosts. The community structure of fleas on small mammals was complex. The species diversity, species composition, community structure and distribution pattern of fleas were simultaneously influenced by the hosts' body surface microenvironment and the macroenvironment (habitat). The fleas are commonly distributed in small mammals in the areas and their communities are related to host species and the habitats.

Human infestation by pigeon fleas (Ceratophyllus columbae) from feral pigeons.

PubMed

Haag-Wackernagel, Daniel; Spiewak, Radosław

2004-01-01

The report concerns a married couple who were repeatedly invaded by pigeon fleas (Ceratophyllus columbae) over a period of 2 months. The source of the fleas was a pair of breeding feral pigeons (Columba livia). The birds' nest was located in the attic immediately above the couple's apartment, and the fleas found their way along an unsealed heating pipe. The people encountered up to 40 bites per night. With invasions repeated almost every night, the man gradually developed an allergic urticarial reaction. The most traumatic experience for the couple, however, was to learn that they were invaded by fleas (initially, they had presumed they were bothered by mosquitoes). This information resulted in severe psychological distress with phobic reactions and insomnia. Despite the successful removal of the fleas and the pigeons that were source of the pest, parasitophobia of the man persisted over the following 4 months. This case is discussed from the broader aspect of health risks related to feral pigeons and animal fleas. Also summarised are previous observations on people invaded by pigeon fleas.

Antifreeze Protein Mimetic Metallohelices with Potent Ice Recrystallization Inhibition Activity.

PubMed

Mitchell, Daniel E; Clarkson, Guy; Fox, David J; Vipond, Rebecca A; Scott, Peter; Gibson, Matthew I

2017-07-26

Antifreeze proteins are produced by extremophile species to control ice formation and growth, and they have potential applications in many fields. There are few examples of synthetic materials which can reproduce their potent ice recrystallization inhibition property. We report that self-assembled enantiomerically pure, amphipathic metallohelicies inhibited ice growth at just 20 μM. Structure-property relationships and calculations support the hypothesis that amphipathicity is the key motif for activity. This opens up a new field of metallo-organic antifreeze protein mimetics and provides insight into the origins of ice-growth inhibition.

Flea species infesting dogs in Spain: updated spatial and seasonal distribution patterns.

PubMed

Gálvez, R; Montoya, A; Checa, R; Martín, O; Marino, V; Miró, G

2017-03-01

This entomological survey examines the spatial and seasonal distribution patterns of flea species infesting dogs in Spain. Bioclimatic zones covering broad climate and vegetation ranges were surveyed according to size. In a cross-sectional spatial survey carried out from late May 2013 to mid-July 2015, 1084 dogs from 42 different locations were examined. A total of 3032 fleas were collected and identified as belonging to the following species: Ctenocephalides felis (Siphonaptera: Pulicidae) (81.7%, 2476 fleas); Ctenocephalides canis (11.4%, 347 fleas); Pulex irritans (Siphonaptera: Pulicidae) (6.9%, 208 fleas), and Echidnophaga gallinacea (Siphonaptera: Pulicidae) (0.03%, one flea). Variables observed to have effects on flea abundance were animal weight, sex, length of hair and habitat. In the seasonal survey conducted from June 2014 to June 2015, 1014 fleas were collected from 239 dogs at 30 veterinary practices across Spain. Peaks in C. felis abundance were observed in early summer and late autumn, whereas high numbers of P. irritans and C. canis were recorded in autumn. Numbers of fleas detected in winter were low overall. Based on these findings, the present study updates the spatial and seasonal distributions of flea species in Spain and assesses the impacts of host and habitat variables on flea infestation. © 2016 The Royal Entomological Society.

Male-specific sesquiterpenes from Phyllotreta flea beetles

USDA-ARS?s Scientific Manuscript database

Flea beetles in several genera are known to possess male-specific sesquiterpenes, at least some of which serve as aggregation pheromones that attract both sexes. In continuing research on the chemical ecology of Phyllotreta flea beetles, six new male-specific sesquiterpenes were identified, one fro...

Quantitative competitive PCR as a technique for exploring flea-Yersina pestis dynamics.

PubMed

Engelthaler, D M; Hinnebusch, B J; Rittner, C M; Gage, K L

2000-05-01

We used a quantitative competitive polymerase chain reaction assay to quantify Yersinia pestis loads in fleas and bacteremia levels in mice that were used as sources of infectious blood meals for feeding the fleas. Xenopsylla cheopis, the Oriental rat flea, achieved higher infection rates, developed greater bacterial loads, and became infectious more rapidly than Oropsylla montana, a ground squirrel flea. Both flea species required about 10(6) Y. pestis cells per flea to be able to transmit to mice. Most fleas that achieved these levels, however, were incapable of transmitting. Our results suggest that at the time of flea feeding, host blood must contain > or = 10(6) bacteria/ml to result in detectable Y. pestis infections in these fleas, and > or = 10(7) bacteria/mL to cause infection levels sufficient for both species to eventually become capable of transmitting Y. pestis to uninfected mice. Yersinia pestis colonies primarily developed in the midguts of O. montana, whereas infections in X. cheopis often developed simultaneously in the proventriculus and the midgut. These findings were visually confirmed by infecting fleas with a strain of Y. pestis that had been transformed with the green fluorescent protein gene.

Modified Antifreeze Liquids for Use on Surfaces

NASA Technical Reports Server (NTRS)

Lynn, R. O.

1983-01-01

Report presents results of evaluation of two antifreeze liquids, dimethyl sulfoxide and ethylene glycol and five viscosity modifiers: gelatin, gum tragacanth, starch, agarose powder and citrus pectin. Purpose of evaluation to find best way of dealing with frost formation on Space Shuttle.

Rickettsia species in fleas collected from small mammals in Slovakia.

PubMed

Špitalská, Eva; Boldiš, Vojtech; Mošanský, Ladislav; Sparagano, Olivier; Stanko, Michal

2015-11-01

Epidemiological and epizootiological studies of Rickettsia felis and other Rickettsia spp. are very important, because their natural cycle has not yet been established completely. In total, 315 fleas (Siphonaptera) of 11 species of Ceratophyllidae, Hystrichopsyllidae and Leptopsyllidae families were tested for the presence of Rickettsia species and Coxiella burnetii with conventional and specific quantitative real-time PCR assays. Fleas were collected from five rodent hosts (Myodes glareolus, Apodemus flavicollis, Apodemus agrarius, Microtus subterraneus, Microtus arvalis) and three shrew species (Sorex araneus, Neomys fodiens, Crocidura suaveolens) captured in Eastern and Southern Slovakia. Overall, Rickettsia spp. was found in 10.8% (34/315) of the tested fleas of Ctenophthalmus agyrtes, Ctenophthalmus solutus, Ctenophthalmus uncinatus and Nosopsyllus fasciatus species. Infected fleas were coming from A. flavicollis, A. agrarius, and M. glareolus captured in Eastern Slovakia. C. burnetii was not found in any fleas. R. felis, Rickettsia helvetica, unidentified Rickettsia, and rickettsial endosymbionts were identified in fleas infesting small mammals in the Košice region, Eastern Slovakia. This study is the first report of R. felis infection in C. solutus male flea collected from A. agrarius in Slovakia.

Purification, composition, and physical properties of a thermal hysteresis "antifreeze" protein from larvae of the beetle, Tenebrio molitor.

PubMed

Tomchaney, A P; Morris, J P; Kang, S H; Duman, J G

1982-02-16

Proteins which produce a thermal hysteresis (difference between the freezing and melting points) in aqueous solution are well-known for their antifreeze activity in polar marine fishes. Much less is known about the biology and biochemistry of similar antifreeze proteins found in certain insects. A thermal hysteresis protein was purified from cold acclimated larvae of the beetle, Tenebrio molitor, by using ethanol fractionation, DEAE ion-exchange chromatography, gel filtration, and high-pressure liquid chromatography. The purified protein had a molecular mass of 17 000 daltons and its N terminus was lysine. The amino acid composition of the antifreeze protein contained more hydrophilic amino acids than the fish antifreezes. This is consistent with the compositions of previously purified insect thermal hysteresis proteins. However, the percentage of hydrophilic amino acids in this Tenebrio antifreeze protein was considerably less than that of other insect thermal hysteresis proteins. The freezing point depressing activity of the Tenebrio antifreeze was less than that of fish proteins and glycoproteins at low protein concentrations but was greater at high protein concentrations.

Diversity of Flea (Siphonaptera) Parasites on Red Foxes (Vulpes vulpes) in Romania.

PubMed

Foley, P; Foley, J; Sándor, A D; Ionica, A M; Matei, I A; D'Amico, G; Gherman, C M; Dom A, C; Mihalca, A D

2017-09-01

Red foxes (Vulpes vulpes (L.)) are widespread across Europe, tolerant of synanthropic ecosystems, and susceptible to diseases potentially shared with humans and other animals. We describe flea fauna on red foxes in Romania, a large, ecologically diverse country, in part because fleas may serve as an indicator of the risk of spillover of vector-borne disease. We found 912 individual fleas of seven species on the 305 foxes assessed, for an infestation prevalence of 49.5%. Mean flea load per fox was 5.8 (range 0-44 fleas), and flea detections were most abundant in fall and early spring. Fleas included generalists (Ctenocephalides canis (Curtis), 32.6% of all fleas), Ct. felis (Bouché, 0.1%), and Pulex irritans L. (29.9%), the fox specialist Chaetopsylla globiceps (Taschenberg, 32.5%), mesocarnivore fleas Paraceras melis Walker (3.2%) and Ch. trichosa Kohaut (1.5%), and the small mammal flea Ctenophthalmus assimilis (Taschenberg, 0.1%), which is rarely or never reported from carnivores. There were significantly more female than male Ch. globiceps, Ct. canis, and Pu. irritans, and these three species were the most broadly distributed geographically. Diversity indices suggested reduced diversity in mountainous areas above 700 m. When compared to other flea studies on foxes in Europe, Romania had flea diversity near the median of reports, which was unexpected given Romania's high ecological diversity. Notably absent prey specialists, compared to other studies, include Archaeopsylla erinacei (Bouché) and Spilopsyllus cuniculi (Dale). Further studies of possible disease agents in fox fleas could help elucidate possible risks of vector-borne disease in foxes, domestic animals, and humans as well. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Calcium interacts with antifreeze proteins and chitinase from cold-acclimated winter rye.

PubMed

Stressmann, Maja; Kitao, Satoshi; Griffith, Marilyn; Moresoli, Christine; Bravo, León A; Marangoni, Alejandro G

2004-05-01

During cold acclimation, winter rye (Secale cereale) plants accumulate pathogenesis-related proteins that are also antifreeze proteins (AFPs) because they adsorb onto ice and inhibit its growth. Although they promote winter survival in planta, these dual-function AFPs proteins lose activity when stored at subzero temperatures in vitro, so we examined their stability in solutions containing CaCl2, MgCl2, or NaCl. Antifreeze activity was unaffected by salts before freezing, but decreased after freezing and thawing in CaCl2 and was recovered by adding a chelator. Ca2+ enhanced chitinase activity 3- to 5-fold in unfrozen samples, although hydrolytic activity also decreased after freezing and thawing in CaCl2. Native PAGE, circular dichroism, and Trp fluorescence experiments showed that the AFPs partially unfold after freezing and thawing, but they fold more compactly or aggregate in CaCl2. Ruthenium red, which binds to Ca(2+)-binding sites, readily stained AFPs in the absence of Ca2+, but less stain was visible after freezing and thawing AFPs in CaCl2. We conclude that the structure of AFPs changes during freezing and thawing, creating new Ca(2+)-binding sites. Once Ca2+ binds to those sites, antifreeze activity, chitinase activity and ruthenium red binding are all inhibited. Because free Ca2+ concentrations are typically low in the apoplast, antifreeze activity is probably stable to freezing and thawing in planta. Ca2+ may regulate chitinase activity if concentrations are increased locally by release from pectin or interaction with Ca(2+)-binding proteins. Furthermore, antifreeze activity can be easily maintained in vitro by including a chelator during frozen storage.

Life-threatening methemoglobinemia after unintentional ingestion of antifreeze admixtures containing sodium nitrite in the construction sites.

PubMed

Sohn, C H; Seo, D W; Ryoo, S M; Lee, J H; Kim, W Y; Lim, K S; Oh, B J

2014-01-01

Construction workers are exposed to a wide variety of health hazards such as poisoning at the construction sites. Various forms of poisoning incidents in construction workers have been reported. However, studies on methemoglobinemia caused by unintentional ingestion of antifreeze admixtures containing sodium nitrite at the construction sites have not been reported yet. The aim of this study was to evaluate life-threatening methemoglobinemia after unintentional ingestion of antifreeze admixtures containing sodium nitrite at the construction sites and describe similar incidents involving ingestion of antifreeze admixtures in Korea. Retrospective observational case series study on patients with methemoglobinemia after unintentional ingestion of antifreeze admixtures containing sodium nitrite admitted to the emergency department (ED) from January 1, 2010 to December 31, 2012 and cases reported to the Korea Occupational Safety and Health Agency (KOSHA) was performed. Results. Six victims were admitted to our ED. They had methemoglobin levels ranging from 32.4% to 71.5% and all of them recovered after receiving one (2 mg/kg) or two doses infusion of methylene blue. From the data of the KOSHA, six incidents that caused 27 victims were identified. Of 27 victims, five were included in the ED cases. For all incidents, antifreeze admixtures were not contained in their original containers and all new containers did not have a new label. All workers mistook antifreeze admixtures for water. Among the 28 victims included in this study, four died. Unintentional ingestion of antifreeze admixtures containing sodium nitrite at the construction sites can cause life-threatening methemoglobinemia. There is a need to store and label potentially hazardous materials properly to avoid unintentional ingestion at the construction sites.

[Cloning, sequencing and prokaryotic expression of cDNAs for the antifreeze protein family from the beetle Tenebrio molitor].

PubMed

Liu, Zhong-Yuan; Wang, Yun; Lü, Guo-Dong; Wang, Xian-Lei; Zhang, Fu-Chun; Ma, Ji

2006-12-01

The partial cDNA sequence coding for the antifreeze proteins in the Tenebrio molitor was obtained by RT-PCR. Sequence analysis revealed nine putative cDNAs with a high degree of homology to Tenebrio molitor antifreeze proteins. The recombinant pGEX-4T-1-tmafp-XJ430 was introduced into E. coli BL21 to induce a GST fusion protein by IPTG. SDS-PAGE of the fusion protein demonstrated that the antifreeze protein migrated at a size of 38 kDa. The immunization was performed by intra-muscular injection of pCDNA3-tmafp-XJ430, and then antiserum was detected by ELISA. The titer of the antibody was 1:2,000. Western blotting analysis showed the antiserum was specific against the antifreeze protein. This finding could lead to further investigation of the properties and function of antifreeze proteins.

Flea abundance on black-tailed prairie dogs (Cynomys ludovicianus) increases during plague epizootics.

PubMed

Tripp, Daniel W; Gage, Kenneth L; Montenieri, John A; Antolin, Michael F

2009-06-01

Black-tailed prairie dogs (Cynomys ludovicianus) on the Great Plains of the United States are highly susceptible to plague, caused by the bacterium Yersinia pestis, with mortality on towns during plague epizootics often approaching 100%. The ability of flea-borne transmission to sustain disease spread has been questioned because of inefficiency of flea vectors. However, even with low individual efficiency, overall transmission can be increased if flea abundance (the number of fleas on hosts) increases. Changes in flea abundance on hosts during plague outbreaks were recorded during a large-scale study of plague outbreaks in prairie dogs in north central Colorado during 3 years (2004-2007). Fleas were collected from live-trapped black-tailed prairie dogs before and during plague epizootics and tested by PCR for the presence of Y. pestis. The predominant fleas were two prairie dog specialists (Oropsylla hirsuta and Oropsylla tuberculata cynomuris), and a generalist flea species (Pulex simulans) was also recorded from numerous mammals in the area. The three species differ in seasonal abundance, with greatest abundance in spring (February and March) and fall (September and October). Flea abundance and infestation intensity increased during epizootics and were highest on prairie dogs with Y. pestis-infected fleas. Seasonal occurrence of epizootics among black-tailed prairie dogs was found to coincide with seasonal peaks in flea abundance. Concentration of infected fleas on surviving animals may account for rapid spread of plague during epizootics. In particular, the role of the generalist flea P. simulans was previously underappreciated.

Diverse transitional giant fleas from the Mesozoic era of China.

PubMed

Huang, Diying; Engel, Michael S; Cai, Chenyang; Wu, Hao; Nel, André

2012-02-29

Fleas are one of the major lineages of ectoparasitic insects and are now highly specialized for feeding on the blood of birds or mammals. This has isolated them among holometabolan insect orders, although they derive from the Antliophora (scorpionflies and true flies). Like most ectoparasitic lineages, their fossil record is meagre and confined to Cenozoic-era representatives of modern families, so that we lack evidence of the origins of fleas in the Mesozoic era. The origins of the first recognized Cretaceous stem-group flea, Tarwinia, remains highly controversial. Here we report fossils of the oldest definitive fleas--giant forms from the Middle Jurassic and Early Cretaceous periods of China. They exhibit many defining features of fleas but retain primitive traits such as non-jumping hindlegs. More importantly, all have stout and elongate sucking siphons for piercing the hides of their hosts, implying that these fleas may be rooted among the pollinating 'long siphonate' scorpionflies of the Mesozoic. Their special morphology suggests that their earliest hosts were hairy or feathered 'reptilians', and that they radiated to mammalian and bird hosts later in the Cenozoic.

Integration of Nanofluids into Commercial Antifreeze Concentrates with ASTM D15 Corrosion Testing

DTIC Science & Technology

2013-05-01

are also proprietary. Blending and Milling A Fisher Scientific Model 550 Sonic Disembrator was used in making nano dispersions. A horizontal 2L...Commercial Antifreeze Zerex/Water Three Zerex antifreeze concentrates were chosen: Zerex G-05: Phosphate free, long life hybrid formulation, mostly used ...for passenger cars. Zerex 618: Fully formulated with organic acid, mostly used for heavy duty diesel engines. Zerex Dex-Cool: Phosphate and silicate

The immunopathogenesis of flea allergy dermatitis in dogs, an experimental study.

PubMed

Wilkerson, Melinda J; Bagladi-Swanson, Mary; Wheeler, David W; Floyd-Hawkins, Kim; Craig, Carol; Lee, Kenneth W; Dryden, Michael

2004-06-01

In this study, we investigated the development of clinical disease and immune responses in the development of an experimental model of flea allergy dermatitis. Dogs were randomly divided into four treatment groups and were infested with fleas on two different feeding schedules (continuous and episodic). Group 1 consisted of four non-exposed dogs (negative controls) and Group 2 consisted of six dogs exposed to fleas continually. Groups 3 and 4 consisted of 14 dogs each that were exposed to fleas on an episodic schedule (two consecutive days every other week for 12 weeks). Group 4 also received intraperitoneal injections of a low dose of lectin (ricin) with immunomodulatory properties. The purpose of Group 4 was to investigate the effects of ricin on enhancing the development of clinical signs, flea antigen-specific IgE levels and altering the number of CD4+ and CD8+ T cell subsets in peripheral blood. Clinical signs developed in all flea exposed dogs, however, the dermatology lesion scores were less and shorter in duration for continuously exposed dogs compared to episodic exposed dogs, independent of ricin treatment. Lesion development was concentrated in the flea triangle and consisted principally of erythema, followed by alopecia, excoriation, papules, and crusts. CD4+ and CD8+ lymphocyte subsets or IgE levels were not altered by ricin treatment. Flea antigen-specific IgE values were highest in dogs exposed to fleas on a continuous basis compared to those episodically exposed. A greater percentage of clinical responder dogs with negative flea-specific IgE titers or negative intradermal test (IDT) were present in the episodic exposure groups than in the continuous exposure group. IgE titers corresponded slightly better with clinical responders than the IDT. The agreement between the IgE titers and IDT was good (weighted K = 0.67). Histopathology of skin samples were consistent with a Type I hypersensitivity. In conclusion, we were able to develop a model of flea

Flea (Siphonaptera) species richness in the Great Basin Desert and island biogeography theory.

PubMed

Bossard, Robert L

2014-06-01

Numbers of flea (Siphonaptera) species (flea species richness) on individual mammals should be higher on large mammals, mammals with dense populations, and mammals with large geographic ranges, if mammals are islands for fleas. I tested the first two predictions with regressions of H. J. Egoscue's trapping data on flea species richness collected from individual mammals against mammal size and population density from the literature. Mammal size and population density did not correlate with flea species richness. Mammal geographic range did, in earlier studies. The intermediate-sized (31 g), moderately dense (0.004 individuals/m(2)) Peromyscus truei (Shufeldt) had the highest richness with eight flea species on one individual. Overall, island biogeography theory does not describe the distribution of flea species on mammals in the Great Basin Desert, based on H. J. Egoscue's collections. Alternatively, epidemiological or metapopulation theories may explain flea species richness. © 2014 The Society for Vector Ecology.

Imidacloprid treatment of marsupials for fleas (Pygiopsylla hoplia).

PubMed

Baker, R T; Beveridge, I

2001-09-01

Two eastern barred bandicoots (Perameles gunnii), two eastern quells (Dasyunrus viverrinus), four fat-tailed dunnarts (Sminthopsis crassicaudata), a Leadbeater's possum (Gymnobelideus leadbeateri), a yellow-bellied glider (Petaurus australis), and a ring-tailed possum (Pseudocheirus peregrinus) were treated with imidacloprid (10.7 +/- 0.6 mg/kg topically, minimum dose 0.5 mg) after observation of fleas (Pygiopsylla hoplia) on animals and in their nest boxes. No live fleas or adverse reactions to imidacloprid were observed for 27 days following treatment. The ease of application, absence of toxicity, and long residual effect makes imidacloprid a useful drug for treating flea infestations in these marsupials.

Synthesis and characterization of natural and modified antifreeze glycopeptides: glycosylated foldamers.

PubMed

Nagel, Lilly; Plattner, Carolin; Budke, Carsten; Majer, Zsuzsanna; DeVries, Arthur L; Berkemeier, Thomas; Koop, Thomas; Sewald, Norbert

2011-08-01

In Arctic and Antarctic marine regions, where the temperature declines below the colligative freezing point of physiological fluids, efficient biological antifreeze agents are crucial for the survival of polar fish. One group of such agents is classified as antifreeze glycoproteins (AFGP) that usually consist of a varying number (n = 4-55) of [AAT]( n )-repeating units. The threonine side chain of each unit is glycosidically linked to β-D: -galactosyl-(1 → 3)-α-N-acetyl-D: -galactosamine. These biopolymers can be considered as biological antifreeze foldamers. A preparative route for stepwise synthesis of AFGP allows for efficient synthesis. The diglycosylated threonine building block was introduced into the peptide using microwave-enhanced solid phase synthesis. By this versatile solid phase approach, glycosylated peptides of varying sequences and lengths could be obtained. Conformational studies of the synthetic AFGP analogs were performed by circular dichroism experiments (CD). Furthermore, the foldamers were analysed microphysically according to their inhibiting effect on ice recrystallization and influence on the crystal habit.

A new experimental correlation for non-Newtonian behavior of COOH-DWCNTs/antifreeze nanofluid

NASA Astrophysics Data System (ADS)

Izadi, Farhad; Ranjbarzadeh, Ramin; Kalbasi, Rasool; Afrand, Masoud

2018-04-01

In this paper, the rheological behavior of nano-antifreeze consisting of 50%vol. water, 50%vol. ethylene glycol and different quantities of functionalized double walled carbon nanotubes has been investigated experimentally. Initially, nano-antifreeze samples were prepared with solid volume fractions of 0.05, 0.1, 0.2, 0.4, 0.6, 0.8 and 1% using two-step method. Then, the dynamic viscosity of the nano-antifreeze samples was measured at different shear rates and temperatures. At this stage, the results showed that base fluid had the Newtonian behavior, while the behavior of all nano-antifreeze samples was non-Newtonian. Since the behavior of the samples was similar to power law model, it was attempted to find the constants of this model including consistency index and power law index. Therefore, using the measured viscosity and shear rates, consistency index and power law index were obtained by curve-fitting method. The obtained values showed that consistency index amplified with increasing volume fraction, while reduced with enhancing temperature. Besides, the obtained values for power law index were less than 1 for all samples which means shear thinning behavior. Lastly, new correlations were suggested to estimate the consistency index and power law index using curve-fitting.

Drivers of flea (Siphonaptera) community structure in sympatric wild carnivores in northwestern Mexico.

PubMed

López-Pérez, Andrés M; Gage, Kenneth; Rubio, Andre V; Montenieri, John; Orozco, Libertad; Suzan, Gerardo

2018-06-01

Host identity, habitat type, season, and interspecific interactions were investigated as determinants of the community structure of fleas on wild carnivores in northwestern Mexico. A total of 540 fleas belonging to seven species was collected from 64 wild carnivores belonging to eight species. We found that the abundances of some flea species are explained by season and host identity. Pulex irritans and Echidnophaga gallinacea abundances were significantly higher in spring than in fall season. Flea communities on carnivore hosts revealed three clusters with a high degree of similarity within each group that was explained by the flea dominance of E. gallinacea, P. simulans, and P. irritans across host identity. Flea abundances did not differ statistically among habitat types. Finally, we found a negative correlation between the abundances of three flea species within wild carnivore hosts. Individual hosts with high loads of P. simulans males usually had significantly lower loads of P. irritans males or tend to have lower loads of E. gallinacea fleas and vice-versa. Additionally, the logistic regression model showed that the presence of P. simulans males is more likely to occur in wild carnivore hosts in which P. irritans males are absent and vice-versa. These results suggest that there is an apparent competitive exclusion among fleas on wild carnivores. The study of flea community structure on wild carnivores is important to identify the potential flea vectors for infectious diseases and provide information needed to design programs for human health and wildlife conservation. © 2018 The Society for Vector Ecology.

Fleas of Small Mammals on Reunion Island: Diversity, Distribution and Epidemiological Consequences

PubMed Central

Guernier, Vanina; Lagadec, Erwan; LeMinter, Gildas; Licciardi, Séverine; Balleydier, Elsa; Pagès, Frédéric; Laudisoit, Anne; Dellagi, Koussay; Tortosa, Pablo

2014-01-01

The diversity and geographical distribution of fleas parasitizing small mammals have been poorly investigated on Indian Ocean islands with the exception of Madagascar where endemic plague has stimulated extensive research on these arthropod vectors. In the context of an emerging flea-borne murine typhus outbreak that occurred recently in Reunion Island, we explored fleas' diversity, distribution and host specificity on Reunion Island. Small mammal hosts belonging to five introduced species were trapped from November 2012 to November 2013 along two altitudinal transects, one on the windward eastern and one on the leeward western sides of the island. A total of 960 animals were trapped, and 286 fleas were morphologically and molecularly identified. Four species were reported: (i) two cosmopolitan Xenopsylla species which appeared by far as the prominent species, X. cheopis and X. brasiliensis; (ii) fewer fleas belonging to Echidnophaga gallinacea and Leptopsylla segnis. Rattus rattus was found to be the most abundant host species in our sample, and also the most parasitized host, predominantly by X. cheopis. A marked decrease in flea abundance was observed during the cool-dry season, which indicates seasonal fluctuation in infestation. Importantly, our data reveal that flea abundance was strongly biased on the island, with 81% of all collected fleas coming from the western dry side and no Xenopsylla flea collected on almost four hundred rodents trapped along the windward humid eastern side. The possible consequences of this sharp spatio-temporal pattern are discussed in terms of flea-borne disease risks in Reunion Island, particularly with regard to plague and the currently emerging murine typhus outbreak. PMID:25188026

Stable, high-level expression of a type I antifreeze protein in Escherichia coli.

PubMed

Solomon, R G; Appels, R

1999-06-01

The type I antifreeze proteins are simple amphipathic helical proteins found in abundance in polar fish species, where they act to prevent freezing of internal fluids by a mechanism of noncolligative freezing point depression. Large-scale production of these proteins for research and biotechnological purposes has been hampered by their apparent instability when expressed in heterologous host systems. This has necessitated their production as fusion proteins, in polymeric form, or as proproteins for secretion, with the concomitant necessity for postpurification processing to generate the mature form of the protein. We have successfully expressed a recombinant variant of type I antifreeze protein (rAFP) in Escherichia coli using the inducible T7 polymerase transcription expression system. The rAFP contains five copies of the 11 amino acid ice-binding repeat motif found in all type I antifreeze proteins. The protein accumulates to high levels intracellularly in the form of inclusion bodies, with no apparent degradation by the cellular proteolytic machinery. We have devised a simple and rapid purification protocol for this recombinant type I antifreeze protein which does not require cellular fractionation, purification of the inclusion bodies, or chromatographic steps. This protocol may be of general use for this class of protein. The protein displays all three activities common to these proteins: recrystallization inhibition, noncolligative freezing point depression, and modification of the morphology of single ice crystals in solution.

Fatal Flea-Borne Typhus in Texas: A Retrospective Case Series, 1985-2015.

PubMed

Pieracci, Emily G; Evert, Nicole; Drexler, Naomi A; Mayes, Bonny; Vilcins, Inger; Huang, Philip; Campbell, Jill; Behravesh, Casey Barton; Paddock, Christopher D

2017-05-01

AbstractFlea-borne (murine) typhus is a global rickettsiosis caused by Rickettsia typhi . Although flea-borne typhus is no longer nationally notifiable, cases are reported for surveillance purposes in a few U.S. states. The infection is typically self-limiting, but may be severe or life-threatening in some patients. We performed a retrospective review of confirmed or probable cases of fatal flea-borne typhus reported to the Texas Department of State Health Services during 1985-2015. When available, medical charts were also examined. Eleven cases of fatal flea-borne typhus were identified. The median patient age was 62 years (range, 36-84 years) and 8 (73%) were male. Patients presented most commonly with fever (100%), nausea and vomiting (55%), and rash (55%). Respiratory (55%) and neurologic (45%) manifestations were also identified frequently. Laboratory abnormalities included thrombocytopenia (82%) and elevated hepatic transaminases (63%). Flea or animal contact before illness onset was frequently reported (55%). The median time from hospitalization to administration of a tetracycline-class drug was 4 days (range, 0-5 days). The median time from symptom onset to death was 14 days (range, 1-34 days). Flea-borne typhus can be a life-threatening disease if not treated in a timely manner with appropriate tetracycline-class antibiotics. Flea-borne typhus should be considered in febrile patients with animal or flea exposure and respiratory or neurologic symptoms of unknown etiology.

Five-month comparative efficacy evaluation of three ectoparasiticides against adult cat fleas (Ctenocephalides felis), flea egg hatch and emergence, and adult brown dog ticks (Rhipicephalus sanguineus sensu lato) on dogs housed outdoors.

PubMed

Varloud, Marie; Hodgkins, Elizabeth

2015-03-01

This study was designed to compare the efficacy of three topical combinations on dogs in outdoor conditions against adult cat fleas (Ctenocephalides felis), flea egg hatch and emergence, and against adult brown dog ticks (Rhipicephalus sanguineus sensu lato). Treatment was performed on day 0 with a placebo; dinotefuran, pyriproxifen and permethrin (DPP); fipronil and (S)-methoprene (FM) or imidacloprid and permethrin (IP). Dogs (n = 32), housed outdoors for 7 months, were treated monthly for four consecutive months (on days 0, 30, 60 and 90) and infested with ~100 unfed adult fleas on days 14, 55, 74, 115 and 150 and with ~50 unfed adult ticks on days 28, 44, 88 and 104. Adult fleas were counted and removed 24 h after infestation. Immediately after flea removal, dogs were reinfested with ~100 new adult fleas 72 h prior to egg collection for up to 48 h. Flea eggs were incubated for 32 days, and newly emerged adults were counted. Ticks were counted and removed 48 h after each infestation. FM had >90 % efficacy against fleas at each time point and variable efficacy against ticks (38.0-99.6 %). Efficacy of IP was <90 % against fleas at day 64 and against ticks at day 30 of the first post-treatment. No flea eggs were laid in the treated groups until infestation was carried out >60 days after the last treatment. Despite challenging weather conditions, DPP was highly effective, providing >90 % efficacy against adult ticks as well as adult and immature fleas at every time point of the study.

Fleas (Siphonaptera) in the Nests of Dormice (Gliridae: Rodentia) in Lithuania.

PubMed

Lipatova, I; Stanko, M; Paulauskas, A; Spakovaite, S; Gedminas, V

2015-05-01

Negative effects of flea (Siphonaptera) parasitism on the host may be expressed in different ways. The aim of this study was to assess distribution of the flea fauna in nests of dormice in Lithuania. Nests of Glis glis (L.), Dryomys nitedula (Pallas), and Muscardinus avellanarius (L.) were collected from nest boxes in 2012 and 2013. Fleas were collected from nests in the laboratory and put into plastic tubes with 70% ethanol. Flea species were identified using morphological keys. From 400 nest boxes, 112 nests of dormice were collected from eight sites from mixed forests of central Lithuania. Twenty-three nests of G. glis were collected from nest boxes, with 16 of them containing 286 fleas belonging to four species: Ceratophyllus sciurorum (Schrank) (259), C. gallinae (Schrank) (23), Hystrichopsylla talpae (Curtis) (3), and Megabothris turbidus (Rothschild) (1). Fourteen nests of M. avellanarius were collected from nest boxes, 4 of which contained 224 fleas belonging to two species: C. sciurorum (221) and C. gallinae (3). Twenty-four nests of D. nitedula were collected from nest boxes, including 17 containing 207 fleas belonging to two species: C. sciurorum (205) and C. gallinae (2). Fifty-one nests of undetermined dormice species also were collected from nest boxes, 12 of them contained 395 fleas belonging to three species: C. sciurorum (374), Ctenophthalmus agyrtes (Heller) (19), and Ctenophthalmus assimilis (Taschenberg) (2). C. sciurorum was a predominant species in the nests of dormice. The occurrence of C. gallinae was documented in Lithuania for the first time. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Type-IV antifreeze proteins are essential for epiboly and convergence in gastrulation of zebrafish embryos.

PubMed

Xiao, Qing; Xia, Jian-Hong; Zhang, Xiao-Juan; Li, Zhi; Wang, Yang; Zhou, Li; Gui, Jian-Fang

2014-01-01

Many organisms in extremely cold environments such as the Antarctic Pole have evolved antifreeze molecules to prevent ice formation. There are four types of antifreeze proteins (AFPs). Type-IV antifreeze proteins (AFP4s) are present also in certain temperate and even tropical fish, which has raised a question as to whether these AFP4s have important functions in addition to antifreeze activity. Here we report the identification and functional analyses of AFP4s in cyprinid fish. Two genes, namely afp4a and afp4b coding for AFP4s, were identified in gibel carp (Carassius auratus gibelio) and zebrafish (Danio rerio). In both species, afp4a and afp4b display a head-to-tail tandem arrangement and share a common 4-exonic gene structure. In zebrafish, both afp4a and afp4b were found to express specifically in the yolk syncytial layer (YSL). Interestingly, afp4a expression continues in YSL and digestive system from early embryos to adults, whereas afp4b expression is restricted to embryogenesis. Importantly, we have shown by using afp4a-specific and afp4b-specifc morpholino knockdown and cell lineage tracing approaches that AFP4a participates in epiboly progression by stabilizing yolk cytoplasmic layer microtubules, and AFP4b is primarily related to convergence movement. Therefore, both AFP4 proteins are essential for gastrulation of zebrafish embryos. Our current results provide first evidence that AFP such as AFP4 has important roles in regulating developmental processes besides its well-known function as antifreeze factors.

Selective isolation of Yersinia pestis from plague-infected fleas

PubMed Central

Sarovich, Derek S.; Colman, Rebecca E.; Price, Erin P.; Chung, Wai Kwan; Lee, Judy; Schupp, James M.; Alexander, James; Keim, Paul; Wagner., David M.

2010-01-01

We evaluated Yersinia CIN agar for the isolation of Yersinia pestis from infected fleas. CIN media is effective for the differentiation of Y. pestis from flea commensal flora and is sufficiently inhibitory to other bacteria that typically outcompete Y. pestis after 48 hours of growth using less selective media. PMID:20385178

[The fleas of mammals from the Ucayali River basin (the Peruvian Amazonia)].

PubMed

Darskaia, N F; Malygin, V M

1996-01-01

The material collected from 57 specimens of 9 mammalian species in two localities of the Peruvian Amazonia includes 212 specimens of fleas belonging to four species (Polygenis klagesi, Ropalopsyllus lugubris, Rh. australis and Rothschildopsylla noctilionis). This is the first record of fleas in the Ucayali River basin. The majority of flea specimens were collected form three morphologically similar but karyotypically and electrophoretically distinct species of spiny rats of the genus Proechimys. These fleas belong to the species P. klagesi. The subspecies P. k. samuelis was collected from 32-chromosome spiny rats nearby Pucallpa (8 degrees 22' S, 74 degrees 43' W), whereas in the locality nearby the village Jenaro Errera (4 degrees 52' S, 73 degrees 39' W) only the nominative subspecies P. k. klagesi were collected from all three species of spiny rats. Other species of fleas have relatively less abundance. Six fleas Rh. l. lugubris were found on one specimen of Cuniculus paca; a single Rh. australis--on one specimen of Myoprocta pratti; and a single R. noctilionis--on one specimen of Eptesicus brasiliensis.

Antifreeze glycopeptide analogues: microwave-enhanced synthesis and functional studies.

PubMed

Heggemann, Carolin; Budke, Carsten; Schomburg, Benjamin; Majer, Zsuzsa; Wissbrock, Marco; Koop, Thomas; Sewald, Norbert

2010-01-01

Antifreeze glycoproteins enable life at temperatures below the freezing point of physiological solutions. They usually consist of the repetitive tripeptide unit (-Ala-Ala-Thr-) with the disaccharide alpha-D-galactosyl-(1-3)-beta-N-acetyl-D-galactosamine attached to each hydroxyl group of threonine. Monoglycosylated analogues have been synthesized from the corresponding monoglycosylated threonine building block by microwave-assisted solid phase peptide synthesis. This method allows the preparation of analogues containing sequence variations which are not accessible by other synthetic methods. As antifreeze glycoproteins consist of numerous isoforms they are difficult to obtain in pure form from natural sources. The synthetic peptides have been structurally analyzed by CD and NMR spectroscopy in proton exchange experiments revealing a structure as flexible as reported for the native peptides. Microphysical recrystallization tests show an ice structuring influence and ice growth inhibition depending on the concentration, chain length and sequence of the peptides.

FLEAS OF BLACK-FOOTED FERRETS (MUSTELA NIGRIPES) AND THEIR POTENTIAL ROLE IN THE MOVEMENT OF PLAGUE.

PubMed

Mize, Erica L; Grassel, Shaun M; Britten, Hugh B

2017-07-01

Sylvatic plague is one of the major impediments to the recovery of the black-footed ferret ( Mustela nigripes ) because it decimates their primary prey species, prairie dogs ( Cynomys spp.), and directly causes mortality in ferrets. Fleas are the primary vector of Yersinia pestis , the causative agent of sylvatic plague. The goal of this research was to better understand the flea fauna of ferrets and the factors that might influence flea abundance on ferrets. Fleas from ferrets were tested for Y. pestis in a post hoc assessment to investigate the plausibility that some ferrets could act as incidental transporter hosts of fleas infected with Y. pestis . Fleas were collected from ferrets captured on the Lower Brule Indian Reservation in central South Dakota, US from 2009 to 2012. A total of 528 fleas collected from 67 individual ferrets were identified and tested for the presence of Y. pestis with a nested PCR assay. The predominant flea recovered from ferrets was Oropsylla hirsuta , a species that comprises 70-100% of the fleas recovered from prairie dogs and their burrows in the study area. Yersinia pestis was detected at low levels in fleas collected from ferrets with prevalence ranging from 0% to 2.9%; male ferrets harbored significantly more fleas than female ferrets. Six of 67 ferrets vaccinated against plague carried fleas that tested positive for Y. pestis , which suggests ferrets vaccinated against plague could inadvertently act as incidental transporter hosts of Y. pestis -positive fleas.

International Program to Monitor Cat Flea Populations for Susceptibility to Imidacloprid.

PubMed

Rust, M K; Blagburn, B L; Denholm, I; Dryden, M W; Payne, P; Hinkle, N C; Kopp, S; Williamson, M

2018-06-20

An international team of scientists and veterinarians was assembled in 1999 to develop a monitoring program to determine the susceptibility of cat fleas, Ctenocephalides felis felis (Bouché) (Siphonaptera: Pulicidae), to imidacloprid. Cat flea eggs were collected, shipped to laboratories, and tested for their susceptibility to imidacloprid. Over 3,000 C. felis populations were collected from 2002 to 2017 from 10 different countries. Of these, 66.3% were collected from cats and 33.7% from dogs. C. f. felis populations (n = 2,200) were bioassayed by exposing cat flea eggs and the emerging larvae to a Diagnostic Dose (DD) of 3 ppm imidacloprid in larval rearing medium. Flea eggs hatched and developed in the untreated controls in 1,837 of the isolates (83.5%) bioassayed. Flea isolates (n = 61) that had ≥5% survival at the DD of 3 ppm were retested with a second DD of 3 ppm. None of them had ≥5% survival to the second dose of 3 ppm. Of the 1,837 valid C. felis isolates tested, there has been no evidence of a decreased susceptibility to imidacloprid over the past 17 yr. The methods outlined in this article should provide an acceptable protocol for testing many of the new active ingredients that have been registered for cat flea control.

Ticks and Fleas Infestation on East Hedgehogs (Erinaceus concolor) in Van Province, Eastern Region of Turkey

PubMed Central

Goz, Yaşar; Yilmaz, Ali Bilgin; Aydin, Abdulalim; Dicle, Yalçın

2016-01-01

Background: Ixodid ticks (Acari: İxodidae) and fleas (Siphonaptera) are the major vectors of pathogens threatening animals and human healths. The aim of our study was to detect the infestation rates of East Hedgehogs (Erinaceus concolor) with ticks and fleas in Van Province, eastern region of Turkey. Methods: We examined fleas and ticks infestation patterns in 21 hedgehogs, collected from three suburbs with the greater of number gardens. In order to estimate flea and tick infestation of hedgehogs, we immobilized the ectoparasites by treatment the body with a insecticide trichlorphon (Neguvon®-Bayer). Results: On the hedgehogs, 60 ixodid ticks and 125 fleas were detected. All of the ixodid ticks were Rhipicephalus turanicus and all of the fleas were Archaeopsylla erinacei. Infestation rate for ticks and fleas was detected 66.66 % and 100 %, respectively. Conclusion: We detected ticks (R. turanicus) and fleas (A. erinacei) in hedgehogs at fairly high rates. Since many ticks and fleas species may harbor on hedgehogs and transmit some tick-borne and flea-borne patogens, this results are the important in terms of veterinary and public health. PMID:27047971

Superheating of ice crystals in antifreeze protein solutions

PubMed Central

Celik, Yeliz; Graham, Laurie A.; Mok, Yee-Foong; Bar, Maya; Davies, Peter L.; Braslavsky, Ido

2010-01-01

It has been argued that for antifreeze proteins (AFPs) to stop ice crystal growth, they must irreversibly bind to the ice surface. Surface-adsorbed AFPs should also prevent ice from melting, but to date this has been demonstrated only in a qualitative manner. Here we present the first quantitative measurements of superheating of ice in AFP solutions. Superheated ice crystals were stable for hours above their equilibrium melting point, and the maximum superheating obtained was 0.44 °C. When melting commenced in this superheated regime, rapid melting of the crystals from a point on the surface was observed. This increase in melting temperature was more appreciable for hyperactive AFPs compared to the AFPs with moderate antifreeze activity. For each of the AFP solutions that exhibited superheating, the enhancement of the melting temperature was far smaller than the depression of the freezing temperature. The present findings clearly show that AFPs adsorb to ice surfaces as part of their mechanism of action, and this absorption leads to protection of ice against melting as well as freezing. PMID:20215465

RESISTANCE TO DELTAMETHRIN IN PRAIRIE DOG ( CYNOMYS LUDOVICIANUS) FLEAS IN THE FIELD AND IN THE LABORATORY.

PubMed

Eads, David A; Biggins, Dean E; Bowser, Jonathan; McAllister, Janet C; Griebel, Randall L; Childers, Eddie; Livieri, Travis M; Painter, Cristi; Krank, Lindsey Sterling; Bly, Kristy

2018-05-03

Sylvatic plague poses a substantial risk to black-tailed prairie dogs ( Cynomys ludovicianus) and their obligate predator, the black-footed ferret ( Mustela nigripes). The effects of plague on prairie dogs and ferrets are mitigated using a deltamethrin pulicide dust that reduces the spread of plague by killing fleas, the vector for the plague bacterium. In portions of Conata Basin, Buffalo Gap National Grasslands, and Badlands National Park, South Dakota, 0.05% deltamethrin has been infused into prairie dog burrows on an annual basis since 2005. We aimed to determine if fleas ( Oropsylla hirsuta) in portions of the Conata Basin and Badlands National Park have evolved resistance to deltamethrin. We assessed flea prevalence, obtained by combing prairie dogs for fleas, as an indirect measure of resistance. Dusting was ineffective in two colonies treated with deltamethrin for >8 yr; flea prevalence rebounded within 1 mo of dusting. We used a bioassay that exposed fleas to deltamethrin to directly evaluate resistance. Fleas from colonies with >8 yr of exposure to deltamethrin exhibited survival rates that were 15% to 83% higher than fleas from sites that had never been dusted. All fleas were paralyzed or dead after 55 min. After removal from deltamethrin, 30% of fleas from the dusted colonies recovered, compared with 1% of fleas from the not-dusted sites. Thus, deltamethrin paralyzed fleas from colonies with long-term exposure to deltamethrin, but a substantial number of those fleas was resistant and recovered. Flea collections from live-trapped prairie dogs in Thunder Basin National Grasslands, Wyoming suggest that, in some cases, fleas might begin to develop a moderate level of resistance to deltamethrin after 5-6 yr of annual treatments. Restoration of black-footed ferrets and prairie dogs will rely on an adaptive, integrative approach to plague management, for instance involving the use of vaccines and rotating applications of insecticidal products with different

Fatal Flea-Borne Typhus in Texas: A Retrospective Case Series, 1985–2015

PubMed Central

Pieracci, Emily G.; Evert, Nicole; Drexler, Naomi A.; Mayes, Bonny; Vilcins, Inger; Huang, Philip; Campbell, Jill; Behravesh, Casey Barton; Paddock, Christopher D.

2017-01-01

Flea-borne (murine) typhus is a global rickettsiosis caused by Rickettsia typhi. Although flea-borne typhus is no longer nationally notifiable, cases are reported for surveillance purposes in a few U.S. states. The infection is typically self-limiting, but may be severe or life-threatening in some patients. We performed a retrospective review of confirmed or probable cases of fatal flea-borne typhus reported to the Texas Department of State Health Services during 1985–2015. When available, medical charts were also examined. Eleven cases of fatal flea-borne typhus were identified. The median patient age was 62 years (range, 36–84 years) and 8 (73%) were male. Patients presented most commonly with fever (100%), nausea and vomiting (55%), and rash (55%). Respiratory (55%) and neurologic (45%) manifestations were also identified frequently. Laboratory abnormalities included thrombocytopenia (82%) and elevated hepatic transaminases (63%). Flea or animal contact before illness onset was frequently reported (55%). The median time from hospitalization to administration of a tetracycline-class drug was 4 days (range, 0–5 days). The median time from symptom onset to death was 14 days (range, 1–34 days). Flea-borne typhus can be a life-threatening disease if not treated in a timely manner with appropriate tetracycline-class antibiotics. Flea-borne typhus should be considered in febrile patients with animal or flea exposure and respiratory or neurologic symptoms of unknown etiology. PMID:28500797

An open, self-controlled study on the efficacy of topical indoxacarb for eliminating fleas and clinical signs of flea-allergy dermatitis in client-owned dogs in Queensland, Australia.

PubMed

Fisara, Petr; Sargent, Roger M; Shipstone, Michael; von Berky, Andrew; von Berky, Janet

2014-06-01

Canine flea-allergy dermatitis (FAD), a hypersensitivity response to antigenic material in the saliva of feeding fleas, occurs worldwide and remains a common presentation in companion animal veterinary practice despite widespread availability of effective systemic and topical flea-control products. To evaluate the clinical response in dogs with FAD treated topically with indoxacarb, a novel oxadiazine insecticide. Twenty-five client-owned dogs in Queensland, Australia diagnosed with pre-existing FAD on the basis of clinical signs, flea-antigen intradermal and serological tests. An open-label, noncontrolled study, in which all dogs were treated with topical indoxacarb at 4 week intervals, three times over 12 weeks. Twenty-four dogs completed the study. Complete resolution of clinical signs of FAD was observed in 21 cases (87.5%), with nearly complete resolution or marked improvement in the remaining three cases. Mean clinical scores (Canine Atopic Dermatitis Extent and Severity Index-03) were reduced by 93.3% at week 12. Mean owner-assessed pruritus scores were reduced by 88% by week 12. Mean flea counts reduced by 98.7 and 100% in weeks 8 and 12, respectively. Topical indoxacarb treatment applied every 4 weeks for 12 weeks, without concomitant antipruritic or ectoparasiticide therapy, completely alleviated flea infestations in all dogs and associated clinical signs of FAD in a high proportion of this population of dogs in a challenging flea-infestation environment. © 2014 The Authors. Veterinary Dermatology published by John Wiley & Sons Ltd on behalf of the ESVD and the ACVD.

HEAT INDUCIBLE EXPRESSION OF ANTIFREEZE PROTEIN GENES FROM THE BEETLES Tenebrio molitor AND Microdera punctipennis.

PubMed

Li, Jieqiong; Ma, Wenjing; Ma, Ji

2016-01-01

Antifreeze proteins (AFPs) play important roles in protecting poikilothermic organisms from cold damage. The expression of AFP genes (afps) is induced by low temperature. However, it is reported that heat can influence the expression of afps in the desert beetle Microdera punctipennis. To further detect whether heat also induce the expression of afps in other insects, and to determine the expression profiling of insect afps at different temperatures. The expression of antifreeze protein genes in the two beetles, Microdera punctipennis and Tenebrio molitor that have quite different living environment, under different temperatures were studied by using real-time quantitative PCR. Mild low temperatures (5~15 degree C), high temperature (38~47 degree C for M. punctipennis, or 37~42 degree C for T. molitor) and temperature difference (10~30 degree C) all stimulated strongly to the expression of AFP genes (Mpafps) in M. punctipennis which lives in the wild filed in desert. The mRNA level of Mpafps after M. punctipennis were exposed to these temperatures for 1h~5h was at least 30-fold of the control at 25 degree C. For T. molitor which is breeding in door with wheat bran all these temperatures stimulated significantly to the expression of Tmafps, while the extent and degree of the temperature stimulation on Tmafps expression were much lower than on Mpafps. After T. molitor were exposed to 5 degree C and 15 degree C for 1h~5h, the mRNA level of Tmafps was over 6-fold and 45-fold of the control at 25 degree C. High temperature (37~42 degree C) for 1h~3h treatments increased Tmafps mRNA level 4.8-fold of the control. Temperature difference of 10 degree C was effective in stimulating Tmafps expression. The expression of insect antifreeze protein genes both in M. punctipennis and T. molitor was induced by heat, suggesting that this phenomenon may be common in insects; the extent and degree of the influence differ in species that have different living conditions. The heat

Precipitation, Climate Change, and Parasitism of Prairie Dogs by Fleas that Transmit Plague.

PubMed

Eads, David A; Hoogland, John L

2017-08-01

Fleas (Insecta: Siphonaptera) are hematophagous ectoparasites that can reduce the fitness of vertebrate hosts. Laboratory populations of fleas decline under dry conditions, implying that populations of fleas will also decline when precipitation is scarce under natural conditions. If precipitation and hence vegetative production are reduced, however, then herbivorous hosts might suffer declines in body condition and have weakened defenses against fleas, so that fleas will increase in abundance. We tested these competing hypotheses using information from 23 yr of research on 3 species of colonial prairie dogs in the western United States: Gunnison's prairie dog (Cynomys gunnisoni, 1989-1994), Utah prairie dog (Cynomys parvidens, 1996-2005), and white-tailed prairie dog (Cynomys leucurus, 2006-2012). For all 3 species, flea-counts per individual varied inversely with the number of days in the prior growing season with >10 mm of precipitation, an index of the number of precipitation events that might have caused a substantial, prolonged increase in soil moisture and vegetative production. Flea-counts per Utah prairie dog also varied inversely with cumulative precipitation of the prior growing season. Furthermore, flea-counts per Gunnison's and white-tailed prairie dog varied inversely with cumulative precipitation of the just-completed January and February. These results complement research on black-tailed prairie dog (Cynomys ludovicianus) and might have important ramifications for plague, a bacterial disease transmitted by fleas that devastates populations of prairie dogs. In particular, our results might help to explain why, at some colonies, epizootics of plague, which can kill >95% of prairie dogs, are more likely to occur during or shortly after periods of reduced precipitation. Climate change is projected to increase the frequency of droughts in the grasslands of western North America. If so, then climate change might affect the occurrence of plague epizootics

Trypanosomes, fleas and field voles: ecological dynamics of a host-vector--parasite interaction.

PubMed

Smith, A; Telfer, S; Burthe, S; Bennett, M; Begon, M

2005-09-01

To investigate the prevalence of a flea-borne protozoan (Trypanosoma (Herpetosoma) microti) in its field vole (Microtus agrestis) host, we monitored over a 2-year period a range of intrinsic and extrinsic parameters pertaining to host demographics, infection status and vector (flea) prevalence. Generalized Linear Mixed Modelling was used to analyse patterns of both flea and trypanosome occurrence. Overall, males of all sizes and ages were more likely to be infested with fleas than their female counterparts. Flea prevalence also showed direct density dependence during the winter, but patterns of density dependence varied amongst body mass (age) classes during the summer. Trypanosome prevalence did not vary between the sexes but was positively related to past flea prevalence with a lag of 3 months, with the highest levels occurring during the autumn season. A convex age-prevalence distribution was observed, suggesting that individuals develop a degree of immunity to trypanosome infection with age and exposure. An interaction between age and whether the individual was new or recaptured suggested that infected animals are less likely to become territory holders than their uninfected counterparts.

Structure and application of antifreeze proteins from Antarctic bacteria.

PubMed

Muñoz, Patricio A; Márquez, Sebastián L; González-Nilo, Fernando D; Márquez-Miranda, Valeria; Blamey, Jenny M

2017-08-07

Antifreeze proteins (AFPs) production is a survival strategy of psychrophiles in ice. These proteins have potential in frozen food industry avoiding the damage in the structure of animal or vegetal foods. Moreover, there is not much information regarding the interaction of Antarctic bacterial AFPs with ice, and new determinations are needed to understand the behaviour of these proteins at the water/ice interface. Different Antarctic places were screened for antifreeze activity and microorganisms were selected for the presence of thermal hysteresis in their crude extracts. Isolates GU1.7.1, GU3.1.1, and AFP5.1 showed higher thermal hysteresis and were characterized using a polyphasic approach. Studies using cucumber and zucchini samples showed cellular protection when samples were treated with partially purified AFPs or a commercial AFP as was determined using toluidine blue O and neutral red staining. Additionally, genome analysis of these isolates revealed the presence of genes that encode for putative AFPs. Deduced amino acids sequences from GU3.1.1 (gu3A and gu3B) and AFP5.1 (afp5A) showed high similarity to reported AFPs which crystal structures are solved, allowing then generating homology models. Modelled proteins showed a triangular prism form similar to β-helix AFPs with a linear distribution of threonine residues at one side of the prism that could correspond to the putative ice binding side. The statistically best models were used to build a protein-water system. Molecular dynamics simulations were then performed to compare the antifreezing behaviour of these AFPs at the ice/water interface. Docking and molecular dynamics simulations revealed that gu3B could have the most efficient antifreezing behavior, but gu3A could have a higher affinity for ice. AFPs from Antarctic microorganisms GU1.7.1, GU3.1.1 and AFP5.1 protect cellular structures of frozen food showing a potential for frozen food industry. Modeled proteins possess a β-helix structure, and

Cat fleas (Ctenocephalides felis) carrying Rickettsia felis and Bartonella species in Hong Kong.

PubMed

Šlapeta, Jan; Lawrence, Andrea; Reichel, Michael P

2018-04-01

Fleas are commonly recorded on stray as well as domestic dogs and cats in Hong Kong. Fleas can be a major cause of pruritus in dogs and cats and also vectors of potentially zoonotic bacteria in the genera Rickettsia and Bartonella. Morphological examination of 174 fleas from dogs and cats living in Hong Kong revealed only cat fleas (Ctenocephalides felis). Cytochrome c oxidase subunit 1 gene (cox1) genotyping of 20 randomly selected specimens, revealed three cox1 haplotypes (HK-h1 to HK-h3). The most common haplotype was HK-h1 with 17 specimens (17/20, 85%). HK-h1 was identical to cox1 sequences of fleas in Thailand and Fiji. HK-h1 and HK-h2 form a distinct cat flea cox1 clade previously recognized as the Clade 3. HK-h3 forms a new Clade 6. A multiplex Bartonella and Rickettsia real-time PCR of DNA from 20 C. felis found Bartonella and Rickettsia DNA in three (15%) and ten (50%) C. felis, respectively. DNA sequencing confirmed the presence of R. felis, B. clarridgeiae and Bartonella henselae. This is the first reported study of that kind in Hong Kong, and further work is required to expand the survey of companion animals in the geographical region. The sampling of fleas on domestic cats and dogs in Hong Kong revealed them to be exclusively infested by the cat flea and to be harbouring pathogens of zoonotic potential. Copyright © 2017 Elsevier B.V. All rights reserved.

Effects of temperature on early-phase transmission of Yersina pestis by the flea, Xenopsylla cheopis.

PubMed

Schotthoefer, Anna M; Bearden, Scott W; Vetter, Sara M; Holmes, Jennifer; Montenieri, John A; Graham, Christine B; Woods, Michael E; Eisen, Rebecca J; Gage, Kenneth L

2011-03-01

Sharp declines in human and animal cases of plague, caused by the bacterium Yersinia pestis (Yersin), have been observed when outbreaks coincide with hot weather. Failure of biofilm production, or blockage, to occur in the flea, as temperatures reach 30 degrees C has been suggested as an explanation for these declines. Recent work demonstrating efficient flea transmission during the first few days after fleas have taken an infectious blood meal, in the absence of blockage (e.g., early-phase transmission), however, has called this hypothesis into question. To explore the potential effects of temperature on early-phase transmission, we infected colony-reared Xenopsylla cheopis (Rothchild) fleas with a wild-type strain of plague bacteria using an artificial feeding system, and held groups of fleas at 10, 23, 27, and 30 degrees C. Naive Swiss Webster mice were exposed to fleas from each of these temperatures on days 1-4 postinfection, and monitored for signs of infection for 21 d. Temperature did not significantly influence the rates of transmission observed for fleas held at 23, 27, and 30 degrees C. Estimated per flea transmission efficiencies for these higher temperatures ranged from 2.32 to 4.96% (95% confidence interval [CI]: 0.96-8.74). In contrast, no transmission was observed in mice challenged by fleas held at 10 degrees C (per flea transmission efficiency estimates, 0-1.68%). These results suggest that declines in human and animal cases during hot weather are not related to changes in the abilities of X. cheopis fleas to transmit Y. pestis infections during the early-phase period. By contrast, transmission may be delayed or inhibited at low temperatures, indicating that epizootic spread of Y. pestis by X. cheopis via early-phase transmission is unlikely during colder periods of the year.

[Fleas community in introduced Siberian chipmunks (Tamias sibiricus Laxmann) in Forest of Sénart, France].

PubMed

Pisanu, B; Marmet, J; Beaucournu, J C; Chapuis, J L

2008-03-01

We examined the fleas community in an introduced population of Siberian chipmunks, Tamias sibiricus, between 2005 and 2007, in the Forest of Sénart (Essonne, France). We collected and identified 383 fleas on 463 chipmunks (total: 1,891 captures on 471 chipmunks). In 2005, 120 fleas were also collected on 65 bank voles, Clethrionomys glareolus, and on 25 wood mice, Apodemus sylvaticus, trapped within the same area. Ceratophyllus sciurorum sciurorum formed 73.6% of the chipmunks' flea community, with an annual prevalence (P) ranging between 8 and 13% and a mean intensity (I) ranging between 1.1 and 1.6 fleas per individual. Among the six other species infecting this Sciurid, Ctenophthalmus agyrtes impavidus constituted 17.2% (P: 1.6-2.2%; I: 1.1-2.6), and Megabothris turbidus 8.1% (P: 0.8-1.9%; I: 1.0-1.4) of the flea community, respectively. These last two species represented respectively 60.8% and 36.6% of the flea community on the bank vole and the wood mouse. Originated from Asia, chipmunks did not import any flea species to Sénart, probably because they were used as pets before their release in the wild. Abundance in C. s. sciurorum increased with adult chipmunk density and with juvenile density in summer. On adult chipmunks C. s. sciurorum tented to decrease with increasing abundance of red squirrels (Sciurus vulgaris]. Moreover, the two other flea species mainly infected young chipmunks during the fall, and their number was not related to chipmunk density. However, the distribution of species within the flea community became more balanced with increase juvenile chipmunk density. Overall, these results indicate that the close phyletic relationship between chipmunks and red squirrels contributed in the acquisition and the spread of fleas by chipmunks. Primary and secondary hosts densities, their habitat use, and more specifically burrowing activities and tree canopy use, also played a role in the spread of fleas on chipmunks.

The role of sulfates on antifreeze protein activity.

PubMed

Meister, Konrad; Duman, John G; Xu, Yao; DeVries, Arthur L; Leitner, David M; Havenith, Martina

2014-07-17

In the present study, we have investigated the effect of sodium sulfate (Na2SO4) buffer on the antifreeze activity of DAFP-1, the primary AFP in the hemolymph of the beetle Dendroides canadensis. In contrast to previous studies, we found evidence that sodium sulfate does not suppress antifreeze activity of DAFP-1. Terahertz absorption spectroscopy (THz) studies were combined with molecular dynamics (MD) simulations to investigate the change in collective hydrogen bond dynamics in the vicinity of the AFP upon addition of sodium sulfate. The MD simulations revealed that the gradient of H-bond dynamics toward the ice-binding site is even more pronounced when adding sodium sulfate: The cosolute dramatically slows the hydrogen bond dynamics on the ice-binding plane of DAFP-1, whereas it has a more modest effect in the vicinity of other parts of the protein. These theoretical predictions are in agreement with the experimentally observed increase in THz absorption for solvated DAFP-1 upon addition of sodium sulfate. These studies support our previously postulated mechanism for AF activity, with a preferred ice binding by threonine on nanoice crystals which is supported by a long-range effect on hydrogen bond dynamics.

Responses of artificially reared cat fleas Ctenocephalides felis felis (Bouché, 1835) to different mammalian bloods.

PubMed

Kernif, T; Stafford, K; Coles, G C; Bitam, I; Papa, K; Chiaroni, J; Raoult, D; Parola, P

2015-06-01

The cat flea, Ctenocephalides felis felis (Bouche, 1835) (Siphonaptera: Pulicidae), which is found worldwide and which parasitizes many species of wild and domestic animal, is a vector and/or reservoir of bacteria, protozoa and helminths. To aid in the study of the physiology and behaviour of fleas and of their transmission of pathogens, it would be of value to improve the laboratory rearing of pathogen-free fleas. The conditions under which artificially reared fleas at the University of Bristol (U.K.) and the Rickettsial Diseases Institute (France) are maintained were studied, with different ratios of male to female fleas per chamber (25 : 50, 50 : 100, 100 : 100, 200 : 200). The fleas were fed with bovine, ovine, caprine, porcine or human blood containing the anticoagulants sodium citrate or EDTA. Egg production was highest when fleas were kept in chambers with a ratio of 25 males to 100 females. In addition, the use of EDTA as an anticoagulant rather than sodium citrate resulted in a large increase in the number of eggs produced per female; however, the low percentage of eggs developing through to adult fleas was lower with EDTA. The modifications described in our rearing methods will improve the rearing of cat fleas for research. © 2015 The Royal Entomological Society.

Control of flea populations in a simulated home environment model using lufenuron, imidacloprid or fipronil.

PubMed

Jacobs, D E; Hutchinson, M J; Ryan, W G

2001-03-01

Control strategies were evaluated over a 6-month period in a home simulation model comprising a series of similar carpeted pens, housing matched groups of six cats, in which the life-cycle of the flea Ctenocephalides felis felis Bouche (Siphonaptera: Pulicidae) had been established. Additional adult fleas were placed on the cats at intervals to mimic acquisition of extraneous fleas from outside the home. Treatment strategies included a single subcutaneous deposition of injectable lufenuron supported by initial treatments with a short-acting insecticidal spray, or monthly topical applications of imidacloprid or fipronil. An untreated control group indicated that conditions were suitable for flea replication and development. Controls had to be combed on 18 occasions to remove excessive flea burdens and two developed allergic reactions. Lufenuron cats were combed once and required two insecticidal treatments in the first month to achieve control. Even so, small flea burdens were constantly present thereafter. Imidacloprid and fipronil treatments appeared to give virtually complete control throughout. Single fleas were found on imidacloprid cats on two occasions, whereas none were recovered from fipronil cats at any time after the first treatment. Tracer cats were used to monitor re-infestation rates at the end of the trial period. Small numbers of host-seeking fleas were demonstrated in all treatment pens, indicating that total eradication had not been accomplished. It is concluded that the home environment simulation model incorporating tracer animals could provide a powerful tool for studying flea population dynamics under controlled conditions but improved techniques are needed for quantifying other off-host life-cycle stages.

Effects of temperature on the transmission of Yersinia Pestis by the flea, Xenopsylla Cheopis, in the late phase period

PubMed Central

2011-01-01

Background Traditionally, efficient flea-borne transmission of Yersinia pestis, the causative agent of plague, was thought to be dependent on a process referred to as blockage in which biofilm-mediated growth of the bacteria physically blocks the flea gut, leading to the regurgitation of contaminated blood into the host. This process was previously shown to be temperature-regulated, with blockage failing at temperatures approaching 30°C; however, the abilities of fleas to transmit infections at different temperatures had not been adequately assessed. We infected colony-reared fleas of Xenopsylla cheopis with a wild type strain of Y. pestis and maintained them at 10, 23, 27, or 30°C. Naïve mice were exposed to groups of infected fleas beginning on day 7 post-infection (p.i.), and every 3-4 days thereafter until day 14 p.i. for fleas held at 10°C, or 28 days p.i. for fleas held at 23-30°C. Transmission was confirmed using Y. pestis-specific antigen or antibody detection assays on mouse tissues. Results Although no statistically significant differences in per flea transmission efficiencies were detected between 23 and 30°C, efficiencies were highest for fleas maintained at 23°C and they began to decline at 27 and 30°C by day 21 p.i. These declines coincided with declining median bacterial loads in fleas at 27 and 30°C. Survival and feeding rates of fleas also varied by temperature to suggest fleas at 27 and 30°C would be less likely to sustain transmission than fleas maintained at 23°C. Fleas held at 10°C transmitted Y. pestis infections, although flea survival was significantly reduced compared to that of uninfected fleas at this temperature. Median bacterial loads were significantly higher at 10°C than at the other temperatures. Conclusions Our results suggest that temperature does not significantly effect the per flea efficiency of Y. pestis transmission by X. cheopis, but that temperature is likely to influence the dynamics of Y. pestis flea

Effects of temperature on the transmission of Yersinia Pestis by the flea, Xenopsylla Cheopis, in the late phase period.

PubMed

Schotthoefer, Anna M; Bearden, Scott W; Holmes, Jennifer L; Vetter, Sara M; Montenieri, John A; Williams, Shanna K; Graham, Christine B; Woods, Michael E; Eisen, Rebecca J; Gage, Kenneth L

2011-09-29

Traditionally, efficient flea-borne transmission of Yersinia pestis, the causative agent of plague, was thought to be dependent on a process referred to as blockage in which biofilm-mediated growth of the bacteria physically blocks the flea gut, leading to the regurgitation of contaminated blood into the host. This process was previously shown to be temperature-regulated, with blockage failing at temperatures approaching 30°C; however, the abilities of fleas to transmit infections at different temperatures had not been adequately assessed. We infected colony-reared fleas of Xenopsylla cheopis with a wild type strain of Y. pestis and maintained them at 10, 23, 27, or 30°C. Naïve mice were exposed to groups of infected fleas beginning on day 7 post-infection (p.i.), and every 3-4 days thereafter until day 14 p.i. for fleas held at 10°C, or 28 days p.i. for fleas held at 23-30°C. Transmission was confirmed using Y. pestis-specific antigen or antibody detection assays on mouse tissues. Although no statistically significant differences in per flea transmission efficiencies were detected between 23 and 30°C, efficiencies were highest for fleas maintained at 23°C and they began to decline at 27 and 30°C by day 21 p.i. These declines coincided with declining median bacterial loads in fleas at 27 and 30°C. Survival and feeding rates of fleas also varied by temperature to suggest fleas at 27 and 30°C would be less likely to sustain transmission than fleas maintained at 23°C. Fleas held at 10°C transmitted Y. pestis infections, although flea survival was significantly reduced compared to that of uninfected fleas at this temperature. Median bacterial loads were significantly higher at 10°C than at the other temperatures. Our results suggest that temperature does not significantly effect the per flea efficiency of Y. pestis transmission by X. cheopis, but that temperature is likely to influence the dynamics of Y. pestis flea-borne transmission, perhaps by affecting

Long-term dynamics of leafy spurge (Euphorbia esula) and its biocontrol agent, flea beetles in the genus Aphthona

USGS Publications Warehouse

Larson, Diane L.; Grace, James B.; Larson, Jennifer L.

2008-01-01

Three flea beetle species (Aphthona spp.), first introduced into North America in 1988, have come to be regarded as effective biological control organisms for leafy spurge (Euphorbia esula). The black flea beetles (Aphthona lacertosa and A. czwalinae) in particular have been shown to cause reductions in leafy spurge stem counts in the northern Great Plains, while the brown flea beetle (A. nigriscutis) has persisted and spread, but has not been found to be as effective at controlling leafy spurge. The ability of black flea beetles to control leafy spurge in any given year, however, has been found to vary. To better understand the long-term effects of flea beetle herbivory on leafy spurge, we monitored stem counts of leafy spurge and numbers of black and brown flea beetles at three sites on two National Wildlife Refuges in east-central North Dakota, USA, from 1998 to 2006. Brown flea beetle numbers were observed to be negligible on these sites. Over the 9 years of the study, black flea beetles were seen to spread over the three study sites and leafy spurge stem counts declined substantially on two of the three sites. Even at low densities of spurge, black flea beetle populations persisted, a necessary prerequisite for long-term control. We used structural equation models (SEM) to assess the yearly effects of black flea beetles, soil texture, and refuge site on leafy spurge stem counts over this time period. We then used equations developed from the SEM analysis to explore flea beetle–leafy spurge dynamics over time, after controlling for soil texture and refuge. Yearly effect strength of black flea beetles on leafy spurge was found to be modest, largely owing to substantial spatial variability in control. However, simulation results based on prediction coefficients revealed leafy spurge to be highly responsive to increases in flea beetle populations on average.

Long-term dynamics of leafy spurge (Euphorbia esula) and its biocontrol agent, flea beetles in the genus Aphthona

USGS Publications Warehouse

Larson, D.L.; Grace, J.B.; Larson, J.L.

2008-01-01

Three flea beetle species (Aphthona spp.), first introduced into North America in 1988, have come to be regarded as effective biological control organisms for leafy spurge (Euphorbia esula). The black flea beetles (Aphthona lacertosa and A. czwalinae) in particular have been shown to cause reductions in leafy spurge stem counts in the northern Great Plains, while the brown flea beetle (A. nigriscutis) has persisted and spread, but has not been found to be as effective at controlling leafy spurge. The ability of black flea beetles to control leafy spurge in any given year, however, has been found to vary. To better understand the long-term effects of flea beetle herbivory on leafy spurge, we monitored stem counts of leafy spurge and numbers of black and brown flea beetles at three sites on two National Wildlife Refuges in east-central North Dakota, USA, from 1998 to 2006. Brown flea beetle numbers were observed to be negligible on these sites. Over the 9 years of the study, black flea beetles were seen to spread over the three study sites and leafy spurge stem counts declined substantially on two of the three sites. Even at low densities of spurge, black flea beetle populations persisted, a necessary prerequisite for long-term control. We used structural equation models (SEM) to assess the yearly effects of black flea beetles, soil texture, and refuge site on leafy spurge stem counts over this time period. We then used equations developed from the SEM analysis to explore flea beetle-leafy spurge dynamics over time, after controlling for soil texture and refuge. Yearly effect strength of black flea beetles on leafy spurge was found to be modest, largely owing to substantial spatial variability in control. However, simulation results based on prediction coefficients revealed leafy spurge to be highly responsive to increases in flea beetle populations on average.

Evidence of an aggregation pheromone in the flea beetle,Phyllotreta Cruciferae (Goeze) (Coleoptera: Chrysomelidae).

PubMed

Peng, C; Weiss, M J

1992-06-01

Laboratory olfactometer bioassays and field trapping experiments showed that the flea beetle,Phyllotreta cruciferae (Goeze), was highly attracted by oilseed rape(Brassica napus L.) when flea beetles were on the plant. This attraction was mediated by a flea beetle-produced aggregation pheromone based upon: (1) Oilseed rape damaged mechanically, or byP. cruciferae, or by diamondback moth,Plutella xylostella (L.), did not attractP. cruciferae. (2) Contact with the plants or feeding was required for the production of aggregation pheromone because oilseed rape alone was not attractive when separated from flea beetles by a screen. (3) Equal numbers of males and females were attracted.

Systemic activity of the avermectins against the cat flea (Siphonaptera: Pulicidae).

PubMed

Zakson-Aiken, M; Gregory, L M; Meinke, P T; Shoop, W L

2001-07-01

Ivermectin has potent systemic activity against numerous species of nematodes and arthropods, but there are some important species in these two groups, such as the cat flea, Ctenocephalides felis (Bouché), that appear to be refractory to it. In an effort to determine if the lack of systemic activity against C. felis is specific to ivermectin, or if it is a class-wide phenomenon, 20 avermectin derivatives were tested in an artificial membrane flea feeding system at concentrations of 20, 10, and 1 microg/ml. Results showed that ivermectin had LC90 and LC50 values against fleas of 19.1 and 9.9 microg/ml, respectively. Only four of the other 19 compounds evaluated possessed both LC90 and LC50 values more potent than ivermectin and even then the advantage was modest. Among those four compounds was a two-fold increase in potency relative to ivermectin when the LC90 values were considered (range, 9.2-10.3 microg/ml) and a two- to eight-fold increase when the LC50 values were examined (range, 1.23-5.26 microg/ml). Neither the possession nor the number of oleandrosyl sugars on the macrocyclic backbone were relevant for additional flea activity because among these four compounds were two disaccharides, a monosaccharide and an aglycone. Also, bond disposition between C-22 and 23 did not contribute to increase in activity because these molecules comprise members with either single or double bonds. One of these avermectin analogs was scaled-up and tested subcutaneously in a dog at >100 times the commercial ivermectin dosage and zero efficacy was observed against the flea. We conclude that even the best in vitro avermectin does not have the in vivo potential to become a commercial oral or subcutaneous flea treatment for companion animals.

Biomechanics of jumping in the flea.

PubMed

Sutton, Gregory P; Burrows, Malcolm

2011-03-01

It has long been established that fleas jump by storing and releasing energy in a cuticular spring, but it is not known how forces from that spring are transmitted to the ground. One hypothesis is that the recoil of the spring pushes the trochanter onto the ground, thereby generating the jump. A second hypothesis is that the recoil of the spring acts through a lever system to push the tibia and tarsus onto the ground. To decide which of these two hypotheses is correct, we built a kinetic model to simulate the different possible velocities and accelerations produced by each proposed process and compared those simulations with the kinematics measured from high-speed images of natural jumping. The in vivo velocity and acceleration kinematics are consistent with the model that directs ground forces through the tibia and tarsus. Moreover, in some natural jumps there was no contact between the trochanter and the ground. There were also no observable differences between the kinematics of jumps that began with the trochanter on the ground and jumps that did not. Scanning electron microscopy showed that the tibia and tarsus have spines appropriate for applying forces to the ground, whereas no such structures were seen on the trochanter. Based on these observations, we discount the hypothesis that fleas use their trochantera to apply forces to the ground and conclude that fleas jump by applying forces to the ground through the end of the tibiae.

Feeding Behavior Modulates Biofilm-Mediated Transmission of Yersinia pestis by the Cat Flea, Ctenocephalides felis.

PubMed

Bland, David M; Hinnebusch, B Joseph

2016-02-01

The cat flea, Ctenocephalides felis, is prevalent worldwide, will parasitize animal reservoirs of plague, and is associated with human habitations in known plague foci. Despite its pervasiveness, limited information is available about the cat flea's competence as a vector for Yersinia pestis. It is generally considered to be a poor vector, based on studies examining early-phase transmission during the first week after infection, but transmission potential by the biofilm-dependent proventricular-blocking mechanism has never been systematically evaluated. In this study, we assessed the vector competence of cat fleas by both mechanisms. Because the feeding behavior of cat fleas differs markedly from important rat flea vectors, we also examined the influence of feeding behavior on transmission dynamics. Groups of cat fleas were infected with Y. pestis and subsequently provided access to sterile blood meals twice-weekly, 5 times per week, or daily for 4 weeks and monitored for infection, the development of proventricular biofilm and blockage, mortality, and the ability to transmit. In cat fleas allowed prolonged, daily access to blood meals, mimicking their natural feeding behavior, Y. pestis did not efficiently colonize the digestive tract and could only be transmitted during the first week after infection. In contrast, cat fleas that were fed intermittently, mimicking the feeding behavior of the efficient vector Xenopsylla cheopis, could become blocked and regularly transmitted Y. pestis for 3-4 weeks by the biofilm-mediated mechanism, but early-phase transmission was not detected. The normal feeding behavior of C. felis, more than an intrinsic resistance to infection or blockage by Y. pestis, limits its vector competence. Rapid turnover of midgut contents results in bacterial clearance and disruption of biofilm accumulation in the proventriculus. Anatomical features of the cat flea foregut may also restrict transmission by both early-phase and proventricular biofilm

The Biology and Ecology of Cat Fleas and Advancements in Their Pest Management: A Review.

PubMed

Rust, Michael K

2017-10-27

The cat flea Ctenocephalides felis felis (Bouché) is the most important ectoparasite of domestic cats and dogs worldwide. It has been two decades since the last comprehensive review concerning the biology and ecology of C. f. felis and its management. Since then there have been major advances in our understanding of the diseases associated with C. f. felis and their implications for humans and their pets. Two rickettsial diseases, flea-borne spotted fever and murine typhus, have been identified in domestic animal populations and cat fleas. Cat fleas are the primary vector of Bartonella henselae (cat scratch fever) with the spread of the bacteria when flea feces are scratched in to bites or wounds. Flea allergic dermatitis (FAD) common in dogs and cats has been successfully treated and tapeworm infestations prevented with a number of new products being used to control fleas. There has been a continuous development of new products with novel chemistries that have focused on increased convenience and the control of fleas and other arthropod ectoparasites. The possibility of feral animals serving as potential reservoirs for flea infestations has taken on additional importance because of the lack of effective environmental controls in recent years. Physiological insecticide resistance in C. f. felis continues to be of concern, especially because pyrethroid resistance now appears to be more widespread. In spite of their broad use since 1994, there is little evidence that resistance has developed to many of the on-animal or oral treatments such as fipronil, imidacloprid or lufenuron. Reports of the perceived lack of performance of some of the new on-animal therapies have been attributed to compliance issues and their misuse. Consequentially, there is a continuing need for consumer awareness of products registered for cats and dogs and their safety.

The Biology and Ecology of Cat Fleas and Advancements in Their Pest Management: A Review

PubMed Central

2017-01-01

The cat flea Ctenocephalides felis felis (Bouché) is the most important ectoparasite of domestic cats and dogs worldwide. It has been two decades since the last comprehensive review concerning the biology and ecology of C. f. felis and its management. Since then there have been major advances in our understanding of the diseases associated with C. f. felis and their implications for humans and their pets. Two rickettsial diseases, flea-borne spotted fever and murine typhus, have been identified in domestic animal populations and cat fleas. Cat fleas are the primary vector of Bartonella henselae (cat scratch fever) with the spread of the bacteria when flea feces are scratched in to bites or wounds. Flea allergic dermatitis (FAD) common in dogs and cats has been successfully treated and tapeworm infestations prevented with a number of new products being used to control fleas. There has been a continuous development of new products with novel chemistries that have focused on increased convenience and the control of fleas and other arthropod ectoparasites. The possibility of feral animals serving as potential reservoirs for flea infestations has taken on additional importance because of the lack of effective environmental controls in recent years. Physiological insecticide resistance in C. f. felis continues to be of concern, especially because pyrethroid resistance now appears to be more widespread. In spite of their broad use since 1994, there is little evidence that resistance has developed to many of the on-animal or oral treatments such as fipronil, imidacloprid or lufenuron. Reports of the perceived lack of performance of some of the new on-animal therapies have been attributed to compliance issues and their misuse. Consequentially, there is a continuing need for consumer awareness of products registered for cats and dogs and their safety. PMID:29077073

Effects of parasite pressure on parasite mortality and reproductive output in a rodent-flea system: inferring host defense trade-offs.

PubMed

Warburton, Elizabeth M; Kam, Michael; Bar-Shira, Enav; Friedman, Aharon; Khokhlova, Irina S; Koren, Lee; Asfur, Mustafa; Geffen, Eli; Kiefer, Daniel; Krasnov, Boris R; Degen, A Allan

2016-09-01

Evaluating host resistance via parasite fitness helps place host-parasite relationships within evolutionary and ecological contexts; however, few studies consider both these processes simultaneously. We investigated how different levels of parasite pressure affect parasite mortality and reproductive success in relationship to host defense efforts, using the rodent Gerbillus nanus and the flea Xenopsylla conformis as a host-parasite system. Fifteen immune-naïve male rodents were infested with 20, 50, or 100 fleas for four weeks. During this time number of new imagoes produced per adult flea (our flea reproductive output metric), flea mortality, and change in circulating anti-flea immunoglobulin G (our measure of adaptive immune defense) were monitored. Three hypotheses guided this work: (1) increasing parasite pressure would heighten host defenses; (2) parasite mortality would increase and parasite reproductive output would decrease with increasing investment in host defense; and (3) hosts under high parasite pressure could invest in behavioral and/or immune responses. We predicted that at high infestation levels (a) parasite mortality would increase; (b) flea reproductive output per individual would decrease; and (c) host circulating anti-flea antibody levels would increase. The hypotheses were partially supported. Flea mortality significantly increased and flea reproductive output significantly decreased as flea pressure increased. Host adaptive immune defense did not significantly change with increasing flea pressure. Therefore, we inferred that investment in host behavioral defense, either alone or in combination with density-dependent effects, may be more efficient at increasing flea mortality and decreasing flea reproductive output than antibody production during initial infestation in this system.

Rodent and flea abundance fail to predict a plague epizootic in black-tailed prairie dogs.

PubMed

Brinkerhoff, Robert Jory; Collinge, Sharon K; Ray, Chris; Gage, Ken L

2010-01-01

Small rodents are purported to be enzootic hosts of Yersinia pestis and may serve as sources of infection to prairie dogs or other epizootic hosts by direct or flea-mediated transmission. Recent research has shown that small rodent species composition and small rodent flea assemblages are influenced by the presence of prairie dogs, with higher relative abundance of both small rodents and fleas at prairie dog colony sites compared to grasslands without prairie dogs. However, it is unclear if increased rodent or flea abundance predisposes prairie dogs to infection with Y. pestis. We tracked rodent and flea occurrence for 3 years at a number of prairie dog colony sites in Boulder County, Colorado, before, during, and after a local plague epizootic to see if high rodent or flea abundance was associated with plague-affected colonies when compared to colonies that escaped infection. We found no difference in preepizootic rodent abundance or flea prevalence or abundance between plague-positive and plague-negative colonies. Further, we saw no significant before-plague/after-plague change in these metrics at either plague-positive or plague-negative sites. We did, however, find that small rodent species assemblages changed in the year following prairie dog die-offs at plague-affected colonies when compared to unaffected colonies. In light of previous research from this system that has shown that landscape features and proximity to recently plagued colonies are significant predictors of plague occurrence in prairie dogs, we suggest that landscape context is more important to local plague occurrence than are characteristics of rodent or flea species assemblages.

Myrmeconycha new genus: the first myrmecophilous flea beetle (Coleoptera: Chrysomelidae: Galerucinae: Alticini)

USDA-ARS?s Scientific Manuscript database

The first myrmecophilous flea beetle genus (Myrmeconycha) with four new species (M. erwini – Ecuador, M. gordoni - Brazil, M. pakaluki - Panama and M. pheidole - Costa Rica) is described and illustrated. It is compared with Disonychine flea beetles and may be easily differentiated based on the exte...

Efficacy of an imidacloprid/flumethrin collar against fleas, ticks, mites and lice on dogs

PubMed Central

2012-01-01

Background The studies reported here were conducted to ascertain the efficacy of imidacloprid/flumethrin incorporated in a slow-release matrix collar, against infestations of dogs by fleas, ticks, mites and lice. Efficacy was evaluated against the flea Ctenocephalides felis felis, the ticks Rhipicephalus sanguineus, Ixodes ricinus, Ixodes scapularis, Dermacentor reticulatus and Dermacentor variabilis, the mite Sarcoptes scabiei and the biting louse Trichodectes canis. Methods Groups of collar-treated dogs (n = 7–10) were infested with fleas and/or ticks at monthly intervals at least, over a period of up to 8 months. Efficacy against fleas was evaluated 24 to 48 h after treatment and 24 h after each re-infestation. Efficacy against ticks was evaluated at 48 h (acaricidal), 6 h (repellent) and 48 h (sustained) after infestation. The effect of regular shampooing or immersion in water on the efficacy of the collars was also tested. Efficacy against flea larvae was assessed by incubating blanket samples after dog contact with viable flea eggs. Effectiveness against lice and mites was evaluated after treatment of naturally infested animals. With the exception of the mites, efficacy was calculated by comparison with untreated negative control groups. Results Efficacy against fleas (24 h) generally exceeded 95%, and against flea larvae it exceeded 99% for 8 months. Sustained acaricidal (48 h) efficacy, covering a period of 8 months was 100% against I. ricinus, starting 2 days after treatment (in vivo), and 100% against I. scapularis (in vitro), above 97% against R. sanguineus, generally above 97% against D. reticulatus and above 90% for D. variabilis. Repellent (6 h) efficacy 2 days after treatment and continuing for 8 months was consistently 100% against I. ricinus, and above 90% against R. sanguineus. Regular shampooing affected efficacy against fleas and ticks to a lesser extent than regular immersion in water. The collars eliminated

Myxomatosis: some observations on breeding the European rabbit flea Spilopsyllus cuniculi (Dale) in an animal house

PubMed Central

Sobey, W. R.; Menzies, W.; Conolly, Dorothy

1974-01-01

Rabbit fleas for use in Myxomatosis investigations have been successfully bred on rabbits in an animal house. The timing of emergence appeared to be governed by a biological timing control interacting with different forms of disturbance. Yield was found to be related to litter size, the time the doe and her kittens were removed from the nest, the number of fleas put onto a doe before littering and the mean ambient temperature to which the doe was exposed in the week pre-partum. The survival rate of fleas in storage was affected by temperature, the degree of crowding, moisture content of the containers, whether fleas were fed or unfed and the source of fleas in terms of emergence times. PMID:4526409

Polyproline as a Minimal Antifreeze Protein Mimic That Enhances the Cryopreservation of Cell Monolayers.

PubMed

Graham, Ben; Bailey, Trisha L; Healey, Joseph R J; Marcellini, Moreno; Deville, Sylvain; Gibson, Matthew I

2017-12-11

Tissue engineering, gene therapy, drug screening, and emerging regenerative medicine therapies are fundamentally reliant on high-quality adherent cell culture, but current methods to cryopreserve cells in this format can give low cell yields and require large volumes of solvent "antifreezes". Herein, we report polyproline as a minimum (bio)synthetic mimic of antifreeze proteins that is accessible by solution, solid-phase, and recombinant methods. We demonstrate that polyproline has ice recrystallisation inhibition activity linked to its amphipathic helix and that it enhances the DMSO cryopreservation of adherent cell lines. Polyproline may be a versatile additive in the emerging field of macromolecular cryoprotectants. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Interaction of Tenebrio Molitor Antifreeze Protein with Ice Crystal: Insights from Molecular Dynamics Simulations.

PubMed

Ramya, L; Ramakrishnan, Vigneshwar

2016-07-01

Antifreeze proteins (AFP) observed in cold-adapting organisms bind to ice crystals and prevent further ice growth. However, the molecular mechanism of AFP-ice binding and AFP-inhibited ice growth remains unclear. Here we report the interaction of the insect antifreeze protein (Tenebrio molitor, TmAFP) with ice crystal by molecular dynamics simulation studies. Two sets of simulations were carried out at 263 K by placing the protein near the primary prism plane (PP) and basal plane (BL) of the ice crystal. To delineate the effect of temperatures, both the PP and BL simulations were carried out at 253 K as well. The analyses revealed that the protein interacts strongly with the ice crystal in BL simulation than in PP simulation both at 263 K and 253 K. Further, it was observed that the interactions are primarily mediated through the interface waters. We also observed that as the temperature decreases, the interaction between the protein and the ice increases which can be attributed to the decreased flexibility and the increased structuring of the protein at low temperature. In essence, our study has shed light on the interaction mechanism between the TmAFP antifreeze protein and the ice crystal. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Cloning and expression of a novel antifreeze protein AFP72 from the beetle Tenebrio molitor.

PubMed

Yan, Qing-Hua; Yang, Li; Wang, Qing; Zhang, Hui-Rong; Shao, Qiang

2012-01-01

A novel antifreeze protein AFP72 cDNA (GenBbank accession No. AY929389) was obtained by RT-PCR from Tenebrio molitor. The 216 bp fragment encodes a protein of 72 amino acid residues. Sequence analysis revealed that the cDNA displays a high degree of homology with T. molitor antifreeze proteins, ranging up to 90.78%. Recombinant plasmids pMAL-p2X-afp72 and pMAL-c2X-afp72 were transferred into E. coil TBI to induce a MBP fusion protein by IPTG. The target fusion protein was released from the periplasm and cytoplasm by the cold osmotic shock procedure and sonication respectively. The content of the fusion protein came up to 38.9 and 41.5% of the total dissolved protein, respectively. The fusion protein was purified through an amylose affinity column, and incised by factor Xa. Molecular sieve chromatography was used to achieve a high state of purity of the target protein. The purified target protein displayed a single band in SDS-PAGE. The fusion protein was shown to increase resistance to low temperatures in bacteria. This finding could help in further investigations of the properties and function of antifreeze proteins.

Differentiation of flea communities infesting small mammals across selected habitats of the Baltic coast, central lowlands, and southern mountains of Poland.

PubMed

Kowalski, Krzysztof; Eichert, Urszula; Bogdziewicz, Michał; Rychlik, Leszek

2014-05-01

Only a few studies comparing flea composition on the coast and in the mountains have been conducted. We investigated differences in flea communities infesting small mammals in selected habitats in northern, central, and southern Poland. We predicted (1) a greater number of flea species in the southeastern Poland and a lower number in the north, (2) a greater number of flea species in fertile and wet habitats than in poor and arid habitats, and (3) a low similarity of flea species between flea communities in western and eastern Poland. We found a negative effect of increasing latitude on flea species richness. We suppose that the mountains providing a variety of environments and the limits of the geographic ranges of several flea subspecies in southeastern Poland result in a higher number of flea species. There was a positive effect of increasing wetness of habitat on flea species richness. We found a high diversity in flea species composition between western and eastern Poland (beta diversity = 11) and between central and eastern Poland (beta diversity = 12). Re-colonization of Poland by small mammals and their ectoparasites from different (western and eastern) refugees can affect on this high diversity of flea species.

Marine Antifreeze Proteins: Structure, Function, and Application to Cryopreservation as a Potential Cryoprotectant

PubMed Central

Kim, Hak Jun; Lee, Jun Hyuck; Hur, Young Baek; Lee, Chang Woo; Park, Sun-Ha; Koo, Bon-Won

2017-01-01

Antifreeze proteins (AFPs) are biological antifreezes with unique properties, including thermal hysteresis (TH), ice recrystallization inhibition (IRI), and interaction with membranes and/or membrane proteins. These properties have been utilized in the preservation of biological samples at low temperatures. Here, we review the structure and function of marine-derived AFPs, including moderately active fish AFPs and hyperactive polar AFPs. We also survey previous and current reports of cryopreservation using AFPs. Cryopreserved biological samples are relatively diverse ranging from diatoms and reproductive cells to embryos and organs. Cryopreserved biological samples mainly originate from mammals. Most cryopreservation trials using marine-derived AFPs have demonstrated that addition of AFPs can improve post-thaw viability regardless of freezing method (slow-freezing or vitrification), storage temperature, and types of biological sample type. PMID:28134801

Targeting red-headed flea beetle larvae

USDA-ARS?s Scientific Manuscript database

Red-headed flea beetle (RHFB), Systena frontalis, is an emerging pest of cranberry that requires significant grower investment in monitoring and repeated applications of insecticides to reduce adult populations. The adult beetles are highly mobile and consume a broad range of host plants whereas t...

Gold Nanoparticle Aggregation as a Probe of Antifreeze (Glyco) Protein-Inspired Ice Recrystallization Inhibition and Identification of New IRI Active Macromolecules

NASA Astrophysics Data System (ADS)

Mitchell, Daniel E.; Congdon, Thomas; Rodger, Alison; Gibson, Matthew I.

2015-10-01

Antifreeze (glyco)proteins are found in polar fish species and act to slow the rate of growth of ice crystals; a property known as ice recrystallization inhibition. The ability to slow ice growth is of huge technological importance especially in the cryopreservation of donor cells and tissue, but native antifreeze proteins are often not suitable, nor easily available. Therefore, the search for new materials that mimic this function is important, but currently limited by the low-throughout assays associated with the antifreeze properties. Here 30 nm gold nanoparticles are demonstrated to be useful colorimetric probes for ice recrystallization inhibition, giving a visible optical response and is compatible with 96 well plates for high-throughout studies. This method is faster, requires less infrastructure, and has easier interpretation than the currently used ‘splat’ methods. Using this method, a series of serum proteins were identified to have weak, but specific ice recrystallization inhibition activity, which was removed upon denaturation. It is hoped that high-throughput tools such as this will accelerate the discovery of new antifreeze mimics.

Gold Nanoparticle Aggregation as a Probe of Antifreeze (Glyco) Protein-Inspired Ice Recrystallization Inhibition and Identification of New IRI Active Macromolecules

PubMed Central

Mitchell, Daniel E.; Congdon, Thomas; Rodger, Alison; Gibson, Matthew I.

2015-01-01

Antifreeze (glyco)proteins are found in polar fish species and act to slow the rate of growth of ice crystals; a property known as ice recrystallization inhibition. The ability to slow ice growth is of huge technological importance especially in the cryopreservation of donor cells and tissue, but native antifreeze proteins are often not suitable, nor easily available. Therefore, the search for new materials that mimic this function is important, but currently limited by the low-throughout assays associated with the antifreeze properties. Here 30 nm gold nanoparticles are demonstrated to be useful colorimetric probes for ice recrystallization inhibition, giving a visible optical response and is compatible with 96 well plates for high-throughout studies. This method is faster, requires less infrastructure, and has easier interpretation than the currently used ‘splat’ methods. Using this method, a series of serum proteins were identified to have weak, but specific ice recrystallization inhibition activity, which was removed upon denaturation. It is hoped that high-throughput tools such as this will accelerate the discovery of new antifreeze mimics. PMID:26499135

Gold Nanoparticle Aggregation as a Probe of Antifreeze (Glyco) Protein-Inspired Ice Recrystallization Inhibition and Identification of New IRI Active Macromolecules.

PubMed

Mitchell, Daniel E; Congdon, Thomas; Rodger, Alison; Gibson, Matthew I

2015-10-26

Antifreeze (glyco)proteins are found in polar fish species and act to slow the rate of growth of ice crystals; a property known as ice recrystallization inhibition. The ability to slow ice growth is of huge technological importance especially in the cryopreservation of donor cells and tissue, but native antifreeze proteins are often not suitable, nor easily available. Therefore, the search for new materials that mimic this function is important, but currently limited by the low-throughout assays associated with the antifreeze properties. Here 30 nm gold nanoparticles are demonstrated to be useful colorimetric probes for ice recrystallization inhibition, giving a visible optical response and is compatible with 96 well plates for high-throughout studies. This method is faster, requires less infrastructure, and has easier interpretation than the currently used 'splat' methods. Using this method, a series of serum proteins were identified to have weak, but specific ice recrystallization inhibition activity, which was removed upon denaturation. It is hoped that high-throughput tools such as this will accelerate the discovery of new antifreeze mimics.

Evaluation and modification of off-host flea collection techniques used in northwest Uganda: laboratory and field studies.

PubMed

Borchert, Jeff N; Eisen, Rebecca J; Holmes, Jennifer L; Atiku, Linda A; Mpanga, Joseph T; Brown, Heidi E; Graham, Christine B; Babi, Nackson; Montenieri, John A; Enscore, Russell E; Gage, Kenneth L

2012-01-01

Quantifying the abundance of host-seeking fleas is critical for assessing risk of human exposure to flea-borne disease agents, including Yersinia pestis, the etiological agent of plague. Yet, reliable measures of the efficacy of existing host-seeking flea collection methods are lacking. In this study, we compare the efficacy of passive and active methods for the collection of host-seeking fleas in both the laboratory and human habitations in a plague-endemic region of northwest Uganda. In the laboratory, lighted "Kilonzo" flea traps modified with either blinking lights, the creation of shadows or the generation of carbon dioxide were less efficient at collecting Xenopsylla cheopis Rothchild and Ctenocephalides felis Bouché fleas than an active collection method using white cotton socks or cotton flannel. Passive collection using Kilonzo light traps in the laboratory collected significantly more X. cheopis than C. felis and active collection, using white socks and flannel, collected significantly more C. felis than X. cheopis. In field studies conducted in Uganda, Kilonzo traps using a flashlight were similar in their collection efficacy to Kilonzo traps using kerosene lamps. However, in contrast to laboratory studies, Kilonzo flea traps using flashlights collected a greater number of fleas than swabbing. Within human habitations in Uganda, Kilonzo traps were especially useful for collecting C. felis, the dominant species found in human habitations in this area.

Molecular cloning, sequence analysis and homology modeling of the first caudata amphibian antifreeze-like protein in axolotl (Ambystoma mexicanum).

PubMed

Zhang, Songyan; Gao, Jiuxiang; Lu, Yiling; Cai, Shasha; Qiao, Xue; Wang, Yipeng; Yu, Haining

2013-08-01

Antifreeze proteins (AFPs) refer to a class of polypeptides that are produced by certain vertebrates, plants, fungi, and bacteria and which permit their survival in subzero environments. In this study, we report the molecular cloning, sequence analysis and three-dimensional structure of the axolotl antifreeze-like protein (AFLP) by homology modeling of the first caudate amphibian AFLP. We constructed a full-length spleen cDNA library of axolotl (Ambystoma mexicanum). An EST having highest similarity (∼42%) with freeze-responsive liver protein Li16 from Rana sylvatica was identified, and the full-length cDNA was subsequently obtained by RACE-PCR. The axolotl antifreeze-like protein sequence represents an open reading frame for a putative signal peptide and the mature protein composed of 93 amino acids. The calculated molecular mass and the theoretical isoelectric point (pl) of this mature protein were 10128.6 Da and 8.97, respectively. The molecular characterization of this gene and its deduced protein were further performed by detailed bioinformatics analysis. The three-dimensional structure of current AFLP was predicted by homology modeling, and the conserved residues required for functionality were identified. The homology model constructed could be of use for effective drug design. This is the first report of an antifreeze-like protein identified from a caudate amphibian.

Feeding Behavior Modulates Biofilm-Mediated Transmission of Yersinia pestis by the Cat Flea, Ctenocephalides felis

PubMed Central

Bland, David M.; Hinnebusch, B. Joseph

2016-01-01

Background The cat flea, Ctenocephalides felis, is prevalent worldwide, will parasitize animal reservoirs of plague, and is associated with human habitations in known plague foci. Despite its pervasiveness, limited information is available about the cat flea’s competence as a vector for Yersinia pestis. It is generally considered to be a poor vector, based on studies examining early-phase transmission during the first week after infection, but transmission potential by the biofilm-dependent proventricular-blocking mechanism has never been systematically evaluated. In this study, we assessed the vector competence of cat fleas by both mechanisms. Because the feeding behavior of cat fleas differs markedly from important rat flea vectors, we also examined the influence of feeding behavior on transmission dynamics. Methodology/Principal Findings Groups of cat fleas were infected with Y. pestis and subsequently provided access to sterile blood meals twice-weekly, 5 times per week, or daily for 4 weeks and monitored for infection, the development of proventricular biofilm and blockage, mortality, and the ability to transmit. In cat fleas allowed prolonged, daily access to blood meals, mimicking their natural feeding behavior, Y. pestis did not efficiently colonize the digestive tract and could only be transmitted during the first week after infection. In contrast, cat fleas that were fed intermittently, mimicking the feeding behavior of the efficient vector Xenopsylla cheopis, could become blocked and regularly transmitted Y. pestis for 3–4 weeks by the biofilm-mediated mechanism, but early-phase transmission was not detected. Conclusions The normal feeding behavior of C. felis, more than an intrinsic resistance to infection or blockage by Y. pestis, limits its vector competence. Rapid turnover of midgut contents results in bacterial clearance and disruption of biofilm accumulation in the proventriculus. Anatomical features of the cat flea foregut may also restrict

Transmission efficiency of two flea species (Oropsylla tuberculata cynomuris and Oropsylla hirsuta) involved in plague epizootics among prairie dogs.

PubMed

Wilder, Aryn P; Eisen, Rebecca J; Bearden, Scott W; Montenieri, John A; Tripp, Daniel W; Brinkerhoff, R Jory; Gage, Kenneth L; Antolin, Michael F

2008-06-01

Plague, caused by Yersinia pestis, is an exotic disease in North America circulating predominantly in wild populations of rodents and their fleas. Black-tailed prairie dogs (Cynomys ludovicianus) are highly susceptible to infection, often experiencing mortality of nearly all individuals in a town as a result of plague. The fleas of black-tailed prairie dogs are Oropsylla tuberculata cynomuris and Oropsylla hirsuta. We tested the efficiency of O. tuberculata cynomuris to transmit Y. pestis daily from 24 to 96 h postinfection and compared it to previously collected data for O. hirsuta. We found that O. tuberculata cynomuris has over threefold greater transmission efficiency (0.18 infected fleas transmit Y. pestis at 24 h postinfection) than O. hirsuta (0.05 fleas transmit). Using a simple model of flea-borne transmission, we combine these laboratory measurements with field data on monthly flea loads to compare the seasonal vectorial capacity of these two flea species. Coinciding with seasonal patterns of flea abundance, we find a peak in potential for flea-borne transmission in March, during high O. tuberculata cynomuris abundance, and in September-October when O. hirsuta is common. Our findings may be useful in determining the timing of insecticidal dusting to slow plague transmission in black-tailed prairie dogs.

Mimicking the properties of antifreeze glycoproteins: synthesis and characterization of a model system for ice nucleation and antifreeze studies.

PubMed

Hederos, Markus; Konradsson, Peter; Borgh, Annika; Liedberg, Bo

2005-08-25

Synthesis of beta-D-Gal-(1 --> 3)-beta-D-GalNAc coupled to HOC2H4NHCOC15H30SH is described. This compound was coadsorbed at various proportions with C2H5OC2H4NHCOC15H30SH to form statistically mixed self-assembled monolayers (SAMs) on gold in an attempt to mimic the properties of the active domain in antifreeze glycoproteins (AFGPs). The monolayers were characterized by null ellipsometry, contact angle goniometry, X-ray photoelectron spectroscopy, and infrared reflection-absorption spectroscopy. The disaccharide compound adsorbed preferentially, and SAMs prepared at a solution molar ratio >0.3 displayed total wetting. The mixed SAMs showed well-organized alkyl chains up to a disaccharide surface fraction of 0.8. The amount of gauche conformers in the alkyls increased rapidly above this point, and the monolayers became disordered and less densely packed. Furthermore, the generated mixed SAMs were subjected to water vapor at constant relative humidity and the subsequent ice crystallization on a cooled substrate was monitored via an optical microscope. Interestingly, rapid crystallization occurred within a narrow range of temperatures on mixed SAMs with a high disaccharide content, surface fraction >0.3. The reported crystallization temperatures and the ice layer topography were compared with results obtained for a much simpler reference system composed of -OH/-CH3 terminated n-alkanethiols in order to account for changes in topography of the water/ice layer with surface energy. Although preliminary, the obtained results can be useful in the search for the molecular mechanism behind the antifreeze activity of AFGPs.

Droughts may increase susceptibility of prairie dogs to fleas: Incongruity with hypothesized mechanisms of plague cycles in rodents

USGS Publications Warehouse

Eads, David A.; Biggins, Dean E.; Long, Dustin H.; Gage, Kenneth L.; Antolin, Michael F.

2016-01-01

Plague is a reemerging, rodent-associated zoonosis caused by the flea-borne bacterium Yersinia pestis. As a vector-borne disease, rates of plague transmission may increase when fleas are abundant. Fleas are highly susceptible to desiccation under hot-dry conditions; we posited that their densities decline during droughts. We evaluated this hypothesis with black-tailed prairie dogs (Cynomys ludovicianus) in New Mexico, June–August 2010–2012. Precipitation was relatively plentiful during 2010 and 2012 but scarce during 2011, the driest spring–summer on record for the northeastern grasslands of New Mexico. Unexpectedly, fleas were 200% more abundant in 2011 than in 2010 and 2012. Prairie dogs were in 27% better condition during 2010 and 2012, and they devoted 287% more time to grooming in 2012 than in 2011. During 2012, prairie dogs provided with supplemental food and water were in 23% better condition and carried 40% fewer fleas. Collectively, these results suggest that during dry years, prairie dogs are limited by food and water, and they exhibit weakened defenses against fleas. Long-term data are needed to evaluate the generality of whether droughts increase flea densities and how changes in flea abundance during sequences of dry and wet years might affect plague cycles in mammalian hosts.

Flea-Borne Rickettsioses in the North of Caldas Province, Colombia

PubMed Central

Montoya, Viviana; Martínez, Alejandra; Mercado, Marcela; De la Ossa, Alberto; Vélez, Carolina; Estrada, Gloria; Pérez, Jorge E.; Faccini-Martínez, Alvaro A.; Labruna, Marcelo B.; Valbuena, Gustavo

2013-01-01

Abstract Rickettsia typhi and R. felis are the etiological agents of murine typhus and flea-borne spotted fever, respectively. Both are emerging acute febrile zoonotic diseases for which fleas are vectors; they also have similar clinical characteristics and global distribution. In 2005, we identified the circulation of murine typhus in 6 towns within the mountainous coffee-growing area north of Caldas, Colombia. We now report the specific seroprevalence against R. typhi and R. felis, and associated risk factors in 7 towns of this province. The combined seroprevalence against the 2 flea-borne rickettsioses is the highest yet reported in the literature: 71.7% (17.8% for R. felis, 25.2% for R. typhi, and 28.7% for both). We also report a prospective analysis of 26 patients with a febrile illness compatible with rickettsioses, including murine typhus; 9 of these patients had a rickettsiosis. This supports our sero-epidemiological results and highlights the diagnostic complexity of febrile syndromes in this region. PMID:23473218

Retracing the Evolutionary Path that Led to Flea-borne Transmission of Yersinia pestis

PubMed Central

Sun, Yi-Cheng; Jarrett, Clayton O.; Bosio, Christopher F.; Hinnebusch, B. Joseph

2014-01-01

Summary Yersinia pestis is an arthropod-borne bacterial pathogen that evolved recently from Yersinia pseudotuberculosis, an enteric pathogen transmitted via the fecal-oral route. This radical ecological transition can be attributed to a few discrete genetic changes from a still-extant recent ancestor, thus providing a tractable case study in pathogen evolution and emergence. Here, we determined the precise genetic and mechanistic basis of the evolutionary adaptation of Y. pestis to flea-borne transmission. Remarkably, only four minor changes in the bacterial progenitor, representing one gene gain and three gene losses, enabled transmission by flea vectors. All three loss-of-function mutations enhanced c-di-GMP-mediated bacterial biofilm formation in the flea foregut that greatly increased transmissibility. Our results suggest a step-wise evolutionary model in which Y. pestis emerged as a flea-borne clone, with each genetic change incrementally reinforcing the transmission cycle. The model conforms well to the ecological theory of adaptive radiation. PMID:24832452

Retracing the evolutionary path that led to flea-borne transmission of Yersinia pestis.

PubMed

Sun, Yi-Cheng; Jarrett, Clayton O; Bosio, Christopher F; Hinnebusch, B Joseph

2014-05-14

Yersinia pestis is an arthropod-borne bacterial pathogen that evolved recently from Yersinia pseudotuberculosis, an enteric pathogen transmitted via the fecal-oral route. This radical ecological transition can be attributed to a few discrete genetic changes from a still-extant recent ancestor, thus providing a tractable case study in pathogen evolution and emergence. Here, we determined the genetic and mechanistic basis of the evolutionary adaptation of Y. pestis to flea-borne transmission. Remarkably, only four minor changes in the bacterial progenitor, representing one gene gain and three gene losses, enabled transmission by flea vectors. All three loss-of-function mutations enhanced cyclic-di-GMP-mediated bacterial biofilm formation in the flea foregut, which greatly increased transmissibility. Our results suggest a step-wise evolutionary model in which Y. pestis emerged as a flea-borne clone, with each genetic change incrementally reinforcing the transmission cycle. The model conforms well to the ecological theory of adaptive radiation. Copyright © 2014 Elsevier Inc. All rights reserved.

Sequencing and Expression Characterization of Antifreeze Protein Maxi-Like in Apis cerana cerana

PubMed Central

Xu, Kai; Niu, Qingsheng; Zhao, Huiting; Du, Yali; Guo, Lina; Jiang, Yusuo

2018-01-01

Abstract Antifreeze proteins (AFPs) are biological cryoprotectants with unique properties that play a crucial role in regulating the molecular mechanisms governing cold resistance in insects. To identify and characterize Apis cerana cerana AFP (AcerAFP), we cloned the full-length cDNA of AcerAFP and examined its expression patterns in A. cerana cerana. A nucleotide alignment analysis showed that the entire coding region of AcerAFP is 1095 bp and encodes a polypeptide of 365 amino acids. The amino acid sequence of this protein exhibits 63–96% homology with AFP homologs from other hymenopterans. α-helices form the main secondary and tertiary structures of AcerAFP, which is similar to the molecular structure of fish AFP type-I. The expression profiles of AcerAFP revealed that expression was tissue, sex, and developmentally specific. In response to cold stress, the mRNA and protein expression of AcerAFP were both induced by low temperatures, and were also related to the concentrations of several cryoprotectants, including glucose, glycerin, glutamic acid, cysteine, histidine, alanine, and methionine. In addition, we found that the knockdown of AcerAFP by RNA interference remarkably increased the total freezing temperature of hemolymph in A. cerana cerana, where levels of AcerAFP mRNA were correlated with the expression of most antifreeze-related proteins. Taken together, these results suggest that AcerAFP plays an essential role as a biological cryoprotectant in honeybees, and is in turn regulated by small cryoprotectants and antifreeze-related proteins.

Early-phase transmission of Yersinia pestis by unblocked fleas as a mechanism explaining rapidly spreading plague epizootics.

PubMed

Eisen, Rebecca J; Bearden, Scott W; Wilder, Aryn P; Montenieri, John A; Antolin, Michael F; Gage, Kenneth L

2006-10-17

Plague is a highly virulent disease believed to have killed millions during three historic human pandemics. Worldwide, it remains a threat to humans and is a potential agent of bioterrorism. Dissemination of Yersinia pestis, the etiological agent of plague, by blocked fleas has been the accepted paradigm for flea-borne transmission. However, this mechanism, which requires a lengthy extrinsic incubation period before a short infectious window often followed by death of the flea, cannot sufficiently explain the rapid rate of spread that typifies plague epidemics and epizootics. Inconsistencies between the expected rate of spread by blocked rat fleas and that observed during the Black Death has even caused speculation that plague was not the cause of this medieval pandemic. We used the primary vector to humans in North America, Oropsylla montana, which rarely becomes blocked, as a model for studying alternative flea-borne transmission mechanisms. Our data revealed that, in contrast to the classical blocked flea model, O. montana is immediately infectious, transmits efficiently for at least 4 d postinfection (early phase) and may remain infectious for a long time because the fleas do not suffer block-induced mortality. These factors match the criteria required to drive plague epizootics as defined by recently published mathematical models. The scenario of efficient early-phase transmission by unblocked fleas described in our study calls for a paradigm shift in concepts of how Y. pestis is transmitted during rapidly spreading epizootics and epidemics, including, perhaps, the Black Death.

Molecular Detection of Rickettsia felis in Humans, Cats, and Cat Fleas in Bangladesh, 2013-2014.

PubMed

Ahmed, Rajib; Paul, Shyamal Kumar; Hossain, Muhammad Akram; Ahmed, Salma; Mahmud, Muhammad Chand; Nasreen, Syeda Anjuman; Ferdouse, Faria; Sharmi, Rumana Hasan; Ahamed, Farid; Ghosh, Souvik; Urushibara, Noriko; Aung, Meiji Soe; Kobayashi, Nobumichi

2016-05-01

High prevalence of Rickettsia felis in patients with fever of unknown origin was revealed in the north-central Bangladesh from 2012 to 2013. Subsequently, in this study, prevalence of R. felis in cats and cat fleas (Ctenocephalides felis), together with febrile patients, was studied by PCR detection of 17 kDa antigen gene and DNA sequencing. R. felis was detected in 28% (28/100) and 21% (14/68) of cat blood and cat flea samples, respectively, whereas 42% (21/50) of patients were positive for R. felis. R. felis-positive cat fleas were detected at significantly higher rate on R. felis-positive cats. The results suggested a potential role of cats and cat fleas for transmission of R. felis to humans in Bangladesh.

Treatment of black-tailed prairie dog burrows with deltamethrin to control fleas (Insecta: Siphonaptera) and plague

USGS Publications Warehouse

Seery, D.B.; Biggins, D.E.; Montenieri, J.A.; Enscore, R.E.; Tanda, D.T.; Gage, K.L.

2003-01-01

Burrows within black-tailed prairie dog (Cynomys ludovicianus) colonies on the Rocky Mountain Arsenal National Wildlife Refuge, Colorado, were dusted with deltamethrin insecticide to reduce flea (Insecta: Siphonaptera) abundance. Flea populations were monitored pre- and posttreatment by combing prairie dogs and collecting fleas from burrows. A single application of deltamethrin significantly reduced populations of the plague vector Oropsylla hirsuta, and other flea species on prairie dogs and in prairie dog burrows for at least 84 d. A plague epizootic on the Rocky Mountain Arsenal National Wildlife Refuge caused high mortality of prairie dogs on some untreated colonies, but did not appear to affect nearby colonies dusted with deltamethrin.

Hfq Regulates Biofilm Gut Blockage That Facilitates Flea-Borne Transmission of Yersinia pestis

PubMed Central

Rempe, Katherine A.; Hinz, Angela K.

2012-01-01

The plague bacillus Yersinia pestis can achieve transmission by biofilm blockage of the foregut proventriculus of its flea vector. Hfq is revealed to be essential for biofilm blockage formation and acquisition and fitness of Y. pestis during flea gut infection, consistent with posttranscriptional regulatory mechanisms in plague transmission. PMID:22328669

Evolution of Antifreeze Protein Genes in the Diatom Genus Fragilariopsis: Evidence for Horizontal Gene Transfer, Gene Duplication and Episodic Diversifying Selection

PubMed Central

Sorhannus, Ulf

2011-01-01

Hypotheses about horizontal transfer of antifreeze protein genes to ice-living diatoms were addressed using two different statistical methods available in the program Prunier. The role of diversifying selection in driving the differentiation of a set of antifreeze protein genes in the diatom genus Fragilariopsis was also investigated. Four horizontal gene transfer events were identified. Two of these took place between two major eukaryote lineages, that is from the diatom Chaetoceros neogracile to the copepod Stephos longipes and from a basidiomycete clade to a monophyletic group, consisting of the diatom species Fragilariopsis curta and Fragilariopsis cylindrus. The remaining two events included transfers from an ascomycete lineage to the proteobacterium Stigmatella aurantiaca and from the proteobacterium Polaribacter irgensii to a group composed of 4 proteobacterium species. After the Fragilariopsis lineage acquired the antifreeze protein gene from the basidiomycetes, it duplicated and went through episodic evolution, characterized by strong positive selection acting on short segments of the branches in the tree. This selection pattern suggests that the paralogs differentiated functionally over relatively short time periods. Taken together, the results obtained here indicate that the group of antifreeze protein genes considered here have a complex evolutionary history. PMID:22253534

Comparative Ability of Oropsylla montana and Xenopsylla cheopis Fleas to Transmit Yersinia pestis by Two Different Mechanisms

PubMed Central

Bland, David M.; Bosio, Christopher F.; Jarrett, Clayton O.

2017-01-01

Background Transmission of Yersinia pestis by flea bite can occur by two mechanisms. After taking a blood meal from a bacteremic mammal, fleas have the potential to transmit the very next time they feed. This early-phase transmission resembles mechanical transmission in some respects, but the mechanism is unknown. Thereafter, transmission occurs after Yersinia pestis forms a biofilm in the proventricular valve in the flea foregut. The biofilm can impede and sometimes completely block the ingestion of blood, resulting in regurgitative transmission of bacteria into the bite site. In this study, we compared the relative efficiency of the two modes of transmission for Xenopsylla cheopis, a flea known to become completely blocked at a high rate, and Oropsylla montana, a flea that has been considered to rarely develop proventricular blockage. Methodology/Principal findings Fleas that took an infectious blood meal containing Y. pestis were maintained and monitored for four weeks for infection and proventricular blockage. The number of Y. pestis transmitted by groups of fleas by the two modes of transmission was also determined. O. montana readily developed complete proventricular blockage, and large numbers of Y. pestis were transmitted by that mechanism both by it and by X. cheopis, a flea known to block at a high rate. In contrast, few bacteria were transmitted in the early phase by either species. Conclusions A model system incorporating standardized experimental conditions and viability controls was developed to more reliably compare the infection, proventricular blockage and transmission dynamics of different flea vectors, and was used to resolve a long-standing uncertainty concerning the vector competence of O. montana. Both X. cheopis and O. montana are fully capable of transmitting Y. pestis by the proventricular biofilm-dependent mechanism. PMID:28081130

Antarctomyces pellizariae sp. nov., a new, endemic, blue, snow resident psychrophilic ascomycete fungus from Antarctica.

PubMed

de Menezes, Graciéle C A; Godinho, Valéria M; Porto, Bárbara A; Gonçalves, Vívian N; Rosa, Luiz H

2017-03-01

In the present study, we have identified and characterised a new snow resident ascomycete blue stain fungus from Antarctica named Antarctomyces pellizariae sp. nov. Menezes, Godinho, Porto, Gonçalves and Rosa, using polyphasic taxonomy techniques. This fungal species was recovered from the seasonal snow of the Antarctic Peninsula. Antarctomyces pellizariae displayed different macro- and micromorphology when compared with A. psychrotrophicus Stchigel and Guarro, the only other Antarctomyces species reported until date. Antarctomyces pellizariae showed psychrophilic behavior and very low growth rate at 22-25 °C, quite different from A. psychrotrophicus that has a higher growth rate at mesophilic temperatures. In addition, micromorphological characteristics and the analysis of the nuclear rDNA internal transcribed spacer, β-tubulin, and RNA polymerase II regions revealed that A. pellizariae is a new species that is related to A. psychrotrophicus and Thelebolus species. Since the Antarctic Peninsula is reported to be one of the main regions of the earth experiencing the effects of global change in climate, species, such as A. pellizariae, might provide information about these effects on the endemic Antarctic biota. In addition, A. pellizariae displayed psychrophilic behavior and might be a source of interesting anti-freeze compounds that might prove useful in biotechnological processes.

Ice Shaping Properties, Similar to That of Antifreeze Proteins, of a Zirconium Acetate Complex

PubMed Central

Deville, Sylvain; Viazzi, Céline; Leloup, Jérôme; Lasalle, Audrey; Guizard, Christian; Maire, Eric; Adrien, Jérôme; Gremillard, Laurent

2011-01-01

The control of the growth morphologies of ice crystals is a critical issue in fields as diverse as biomineralization, medicine, biology, civil or food engineering. Such control can be achieved through the ice-shaping properties of specific compounds. The development of synthetic ice-shaping compounds is inspired by the natural occurrence of such properties exhibited by antifreeze proteins. We reveal how a particular zirconium acetate complex is exhibiting ice-shaping properties very similar to that of antifreeze proteins, albeit being a radically different compound. We use these properties as a bioinspired approach to template unique faceted pores in cellular materials. These results suggest that ice-structuring properties are not exclusive to long organic molecules and should broaden the field of investigations and applications of such substances. PMID:22028886

Fleas (Siphonaptera) of the Allegheny woodrat (Neotoma magister) in West Virginia with comments on host specificity

USGS Publications Warehouse

Castleberry, S.B.; Castleberry, N.L.; Wood, P.B.; Ford, W.M.; Mengak, M.T.

2003-01-01

Previous research has indicated fewer host-specific ectoparasites on woodrats of the eastern United States as compared to western woodrat species. The Allegheny woodrat (Neotoma magister) is a species of conservation concern that is associated with rocky habitats in the Appalachian and Interior Highland regions in the eastern United States. We examined Allegheny woodrat flea parasites in the core of the distribution to further elucidate patterns of ectoparasite host specificity in woodrats of the eastern United States. Of 346 fleas collected from 62 Allegheny woodrats, all but 1 were identified as Orchopeas pennsylvanicus. The single exception was a male Epitedia cavernicola, which represents only the second collection of this species from West Virginia. Unlike the eastern woodrat (Neotoma floridana), which hosts a variety of generalist flea parasites, Allegheny woodrats in our study were host to only 2 flea species, both of which are host specific to woodrats. We suggest that flea host specificity may be related to the specific habitat requirements of this species.

Yersinia-flea interactions and the evolution of the arthropod-borne transmission route of plague

PubMed Central

Chouikha, Iman; Hinnebusch, B. Joseph

2012-01-01

Yersinia pestis, the causative agent of plague, is unique among the enteric group of Gram-negative bacteria in relying on a blood-feeding insect for transmission. The Yersinia-flea interactions that enable plague transmission cycles have had profound historical consequences as manifested by human plague pandemics. The arthropod-borne transmission route was a radical ecologic change from the food- and water-borne transmission route of Yersinia pseudotuberculosis, from which Y. pestis diverged only within the last 20,000 years. Thus, the interactions of Y. pestis with its flea vector that lead to colonization and successful transmission are the result of a recent evolutionary adaptation that required relatively few genetic changes. These changes from the Y. pseudotuberculosis progenitor included loss of insecticidal activity, increased resistance to antibacterial factors in the flea midgut, and extending Yersinia biofilm-forming ability to the flea host environment. PMID:22406208

Classic flea-borne transmission does not drive plague epizootics in prairie dogs.

PubMed

Webb, Colleen T; Brooks, Christopher P; Gage, Kenneth L; Antolin, Michael F

2006-04-18

We lack a clear understanding of the enzootic maintenance of the bacterium (Yersinia pestis) that causes plague and the sporadic epizootics that occur in its natural rodent hosts. A key to elucidating these epidemiological dynamics is determining the dominant transmission routes of plague. Plague can be acquired from the bites of infectious fleas (which is generally considered to occur via a blocked flea vector), inhalation of infectious respiratory droplets, or contact with a short-term infectious reservoir. We present results from a plague modeling approach that includes transmission from all three sources of infection simultaneously and uses sensitivity analysis to determine their relative importance. Our model is completely parameterized by using data from the literature and our own field studies of plague in the black-tailed prairie dog (Cynomys ludovicianus). Results of the model are qualitatively and quantitatively consistent with independent data from our field sites. Although infectious fleas might be an important source of infection and transmission via blocked fleas is a dominant paradigm in the literature, our model clearly predicts that this form of transmission cannot drive epizootics in prairie dogs. Rather, a short-term reservoir is required for epizootic dynamics. Several short-term reservoirs have the potential to affect the prairie dog system. Our model predictions of the residence time of the short-term reservoir suggest that other small mammals, infectious prairie dog carcasses, fleas that transmit plague without blockage of the digestive tract, or some combination of these three are the most likely of the candidate infectious reservoirs.

Occurrence of Dipylidium caninum in fleas from client-owned cats and dogs in Europe using a new PCR detection assay.

PubMed

Beugnet, Frédéric; Labuschagne, Michel; Fourie, Josephus; Jacques, Guillot; Farkas, Robert; Cozma, Vasile; Halos, Lénaïg; Hellmann, Klaus; Knaus, Martin; Rehbein, Steffen

2014-09-15

Ctenocephalides fleas are not only the most prevalent ectoparasites of dogs and cats but also the intermediate host of the cestode Dipylidium caninum. Due to the poor sensitivity of coproscopy to diagnose cat and dog infestation by Dipylidium, few epidemiological data are available on its prevalence among pet populations. A new PCR method was developed to specifically identify D. caninum rDNA inside single fleas. The PCR test was then applied to 5529 fleas of Ctenocephalides genus, 2701 Ctenocephalides felis fleas (1969 collected on 435 cats and 732 on 178 dogs) and 2828 Ctenocephalides canis fleas collected from 396 dogs. Precisely, 4.37% of cats were infested by a flea population infected with D. caninum. Out of the 1969 C. felis from cats, 2.23% were found to be infected with Dipylidium. From the 396 dogs infested with C. canis, 9.1%% were infested with the Dipylidium infected fleas, which is significantly higher than the observation made in cats (p=0.03). Moreover, 3.1% of the C. canis fleas were found to be infected with Dipylidium, which is not significantly different than in C. felis. Looking at the number of infected fleas in the positive samples (at least one PCR positive flea in a sample), the infestation rate in samples was varied from 3 to 100% with an average of 19.7% which is in favour of easy and regular Dipylidium reinfestations of both cats and dogs in households. For the first time, the spread of D. caninum between fleas and dogs and cats is confirmed throughout Europe. Copyright © 2014 Elsevier B.V. All rights reserved.

Effects of weather and plague-induced die-offs of prairie dogs on the fleas of northern grasshopper mice.

PubMed

Salkeld, Daniel J; Stapp, Paul

2009-05-01

Plague, the disease caused by the bacterium Yersinia pestis, can have devastating impacts on black-tailed prairie dogs (Cynomys ludovicianus Ord). Other mammal hosts living on prairie dog colonies may be important in the transmission and maintenance of plague. We examined the flea populations of northern grasshopper mice (Onychomys leucogaster Wied) before, during, and after plague epizootics in northern Colorado and studied the influence of host and environmental factors on flea abundance patterns. Grasshopper mice were frequently infested with high numbers of fleas, most commonly Pleochaetis exilis Jordan and Thrassis fotus Jordan. Flea loads changed in response to both environmental temperature and rainfall. After plague-induced prairie dog die-offs, flea loads and likelihood of infestation were unchanged for P. exilis, but T. fotus loads declined.

Flea-borne transmission model to evaluate vaccine efficacy against naturally acquired bubonic plague.

PubMed

Jarrett, Clayton O; Sebbane, Florent; Adamovicz, Jeffrey J; Andrews, Gerard P; Hinnebusch, B Joseph

2004-04-01

A flea-to-mouse transmission model was developed for use in testing new candidate vaccines for the ability to protect against flea-borne plague. The model was used to evaluate a recombinant fusion protein vaccine consisting of the Yersinia pestis F1 and V antigens. After one to three challenges with Y. pestis-infected fleas, 14 of 15 unvaccinated control mice developed plague, with an average septicemia level of 9.2 x 10(8) Y. pestis CFU/ml. None of 15 vaccinated mice developed the disease after similar challenges, and serological testing indicated that transmitted bacteria were eliminated by the immune system before extensive replication and systemic infection could occur. The transmission and development of disease in control mice correlated with the number of bites by blocked fleas but not with the total number of fleabites. The model provides a means to directly assess the efficacy of new vaccines to prevent naturally acquired bubonic plague and to study events at the vector-host interface that lead to dissemination and disease.

A Distributed Snow Evolution Modeling System (SnowModel)

NASA Astrophysics Data System (ADS)

Liston, G. E.; Elder, K.

2004-12-01

A spatially distributed snow-evolution modeling system (SnowModel) has been specifically designed to be applicable over a wide range of snow landscapes, climates, and conditions. To reach this goal, SnowModel is composed of four sub-models: MicroMet defines the meteorological forcing conditions, EnBal calculates surface energy exchanges, SnowMass simulates snow depth and water-equivalent evolution, and SnowTran-3D accounts for snow redistribution by wind. While other distributed snow models exist, SnowModel is unique in that it includes a well-tested blowing-snow sub-model (SnowTran-3D) for application in windy arctic, alpine, and prairie environments where snowdrifts are common. These environments comprise 68% of the seasonally snow-covered Northern Hemisphere land surface. SnowModel also accounts for snow processes occurring in forested environments (e.g., canopy interception related processes). SnowModel is designed to simulate snow-related physical processes occurring at spatial scales of 5-m and greater, and temporal scales of 1-hour and greater. These include: accumulation from precipitation; wind redistribution and sublimation; loading, unloading, and sublimation within forest canopies; snow-density evolution; and snowpack ripening and melt. To enhance its wide applicability, SnowModel includes the physical calculations required to simulate snow evolution within each of the global snow classes defined by Sturm et al. (1995), e.g., tundra, taiga, alpine, prairie, maritime, and ephemeral snow covers. The three, 25-km by 25-km, Cold Land Processes Experiment (CLPX) mesoscale study areas (MSAs: Fraser, North Park, and Rabbit Ears) are used as SnowModel simulation examples to highlight model strengths, weaknesses, and features in forested, semi-forested, alpine, and shrubland environments.

Successful immunotherapy of canine flea allergy with injected Actinomycetales preparations.

PubMed

Marro, Alicia; Pirles, Mónica; Schiaffino, Laura; Bin, Liliana; Dávila, Héctor; Bottasso, Oscar A; McIntyre, Graham; Ripley, Paul R; Stanford, Cynthia A; Stanford, John L

2011-08-01

Can heat-killed, borate-buffered suspensions of Gordonia bronchialis, Rhodococcus coprophilus or Tsukamurella inchonensis be used to treat canine flea allergy? Organisms cultured on Sauton's medium into stationary phase were autoclaved in borate-buffered saline and stored at 10 mg wet weight/ml. Intradermal injections of 0.1 ml containing 1 mg of bacilli were administered on the first and 20th days of the study. G. bronchialis and R. coprophilus were most effective in a pilot study of a small number of dogs with flea allergy. A larger number of affected dogs were then randomized to receive placebo or either of the two selected reagents. The extent and severity of allergic signs and symptoms were scored and blood samples were collected just before the first injection and 28 days after the second. Both selected reagents reduced the extent and severity of lesions (p < 0.001) and reduced scratching. Eosinophil numbers were reduced (p < 0.0001) between the first and second assessment. Injections of G. bronchialis or R. coprophilus effectively reduce the signs and symptoms of flea allergy in dogs.

Transmission efficiency of the plague pathogen (Y. pestis) by the flea, Xenopsylla skrjabini, to mice and great gerbils.

PubMed

Zhang, Yujiang; Dai, Xiang; Wang, Qiguo; Chen, Hongjian; Meng, Weiwei; Wu, Kemei; Luo, Tao; Wang, Xinhui; Rehemu, Azhati; Guo, Rong; Yu, Xiaotao; Yang, Ruifu; Cao, Hanli; Song, Yajun

2015-05-01

Plague, a zoonotic disease caused by Yersinia pestis, is characterized by its ability to persist in the plague natural foci. Junggar Basin plague focus was recently identified in China, with Rhombomys opimus (great gerbils) and Xenopsylla skrjabini as the main reservoir and vector for plague. No transmission efficiency data of X. skrjabini for Y. pestis is available till now. In this study, we estimated the median infectious dose (ID50) and the blockage rates of X. skrjabini with Y. pestis, by using artificial feeders. We then evaluated the flea transmission ability of Y. pestis to the mice and great gerbils via artificial bloodmeal feeding. Finally, we investigated the transmission of Y. pestis to mice with fleas fed by infected great gerbils. ID50 of Y. pestis to X. skrjabini was estimated as 2.04 × 10(5) CFU (95% CI, 1.45 × 10(5) - 3.18 × 10(5) CFU), around 40 times higher than that of X. cheopis. Although fleas fed by higher bacteremia bloodmeal had higher infection rates for Y. pestis, they lived significantly shorter than their counterparts. X. skrjabini could get fully blocked as early as day 3 post of infection (7.1%, 3/42 fleas), and the overall blockage rate of X. cheopis was estimated as 14.9% (82/550 fleas) during the 14 days of investigation. For the fleas infected by artificial feeders, they seemed to transmit plague more efficiently to great gerbils than mice. Our single flea transmission experiments also revealed that, the transmission capacity of naturally infected fleas (fed by infected great gerbils) was significantly higher than that of artificially infected ones (fed by artificial feeders). Our results indicated that ID50 of Y. pestis to X. skrjabini was higher than other fleas like X. cheopis, and its transmission efficiency to mice might be lower than other flea vectors in the artificial feeding modes. We also found different transmission potentials in the artificially infected fleas and the naturally infected ones. Further studies are

Effect of Rickettsia felis Strain Variation on Infection, Transmission, and Fitness in the Cat Flea (Siphonaptera: Pulicidae).

PubMed

Healy, Sean P; Brown, Lisa D; Hagstrom, Melena R; Foil, Lane D; Macaluso, Kevin R

2017-07-01

Rickettsia felis is a human pathogen transmitted by the cat flea, Ctenocephalides felis (Bouché) (str. LSU), as well as an obligate symbiont of the parthenogenic booklouse Liposcelis bostrychophila (Badonnel) (str. LSU-Lb). The influence of genetic variability in these two strains of R. felis on host specialization and fitness and possible resulting differences on infection and transmission kinetics in C. felis is unknown. Utilizing an artificial host system, cat fleas were exposed to a R. felis str. LSU-Lb-infected bloodmeal and monitored for infection at 7-d intervals for 28 d. Quantitative real-time PCR was used to determine rickettsial load and infection density in newly exposed cat fleas, and transmission frequency between cat fleas. The effect of persistent R. felis infection on cat flea F1 progeny was also assessed. At 7 d postexposure 76.7% of the cat fleas successfully acquired R. felis str. LSU-Lb. In R. felis str. LSU-Lb-exposed cat fleas, the mean infection load (6.15 × 106), infection density (0.76), and infection prevalence (91/114) were significantly greater than R. felis str. LSU infection load (3.09 × 106), infection density (0.68), and infection prevalence (76/113). A persistent R. felis str. LSU-Lb infection was detected for 28 d in adult cat fleas but neither female:male ratio distortion nor vertical transmission was observed in F1 progeny. While infection kinetics differed, with higher intensity associated with R. felis str. LSU-Lb, no distinct phenotype was observed in the F1 progeny. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America.

First molecular detection and characterization of zoonotic Bartonella species in fleas infesting domestic animals in Tunisia.

PubMed

Zouari, Saba; Khrouf, Fatma; M'ghirbi, Youmna; Bouattour, Ali

2017-09-19

Bartonellosis is an emerging vector-borne disease caused by different intracellular bacteria of the genus Bartonella (Rhizobiales: Bartonellaceae) that is transmitted primarily by blood-sucking arthropods such as sandflies, ticks and fleas. In Tunisia, there are no data available identifying the vectors of Bartonella spp. In our research, we used molecular methods to detect and characterize Bartonella species circulating in fleas collected from domestic animals in several of the country's bioclimatic areas. A total of 2178 fleas were collected from 5 cats, 27 dogs, 34 sheep, and 41 goats at 22 sites located in Tunisia's five bioclimatic zones. The fleas were identified as: 1803 Ctenocephalides felis (83%) (Siphonaptera: Pulicidae), 266 C. canis (12%) and 109 Pulex irritans (5%) (Siphonaptera: Pulicidae). Using conventional PCR, we screened the fleas for the presence of Bartonella spp., targeting the citrate synthase gene (gltA). Bartonella DNA was detected in 14% (121/866) of the tested flea pools [estimated infection rate (EIR) per 2 specimens: 0.072, 95% confidence interval (CI): 0.060-0.086]. The Bartonella infection rate per pool was broken down as follows: 55% (65/118; EIR per 2 specimens: 0.329, 95% CI: 0.262-0.402) in C. canis; 23.5% (8/34; EIR per 2 specimens: 0.125, 95% CI: 0.055-0.233) in P. irritans and 6.7% (48/714; EIR per 2 specimens: 0.032, 95% CI: 0.025-0.045) in C. felis. Infection rates, which varied significantly by bioclimatic zone (P < 0.0001), were highest in the humid areas. By sequencing, targeting the gltA gene and the 16S-23S rRNA Intergenic Spacer Regions (ITS), we identified three Bartonella zoonotic species: B. elizabethae, B. henselae, B. clarridgeiae, as well as uncharacterized Bartonella genotypes. To the best of our knowledge, this is the first time that fleas in Tunisia have been shown to carry zoonotic species of Bartonella. The dog flea, Ctenocephalides canis, should be considered the main potential vector of Bartonella. Our

Influence of Block Copolymerization on the Antifreeze Protein Mimetic Ice Recrystallization Inhibition Activity of Poly(vinyl alcohol).

PubMed

Congdon, Thomas R; Notman, Rebecca; Gibson, Matthew I

2016-09-12

Antifreeze (glyco) proteins are produced by many cold-acclimatized species to enable them to survive subzero temperatures. These proteins have multiple macroscopic effects on ice crystal growth which makes them appealing for low-temperature applications-from cellular cryopreservation to food storage. Poly(vinyl alcohol) has remarkable ice recrystallization inhibition activity, but its mode of action is uncertain as is the extent at which it can be incorporated into other high-order structures. Here the synthesis and characterization of well-defined block copolymers containing poly(vinyl alcohol) and poly(vinylpyrrolidone) by RAFT/MADIX polymerization is reported, as new antifreeze protein mimetics. The effect of adding a large second hydrophilic block is studied across a range of compositions, and it is found to be a passive component in ice recrystallization inhibition assays, enabling retention of all activity. In the extreme case, a block copolymer with only 10% poly(vinyl alcohol) was found to retain all activity, where statistical copolymers of PVA lose all activity with very minor changes to composition. These findings present a new method to increase the complexity of antifreeze protein mimetic materials, while retaining activity, and also to help understand the underlying mechanisms of action.

Influence of Block Copolymerization on the Antifreeze Protein Mimetic Ice Recrystallization Inhibition Activity of Poly(vinyl alcohol)

PubMed Central

2016-01-01

Antifreeze (glyco) proteins are produced by many cold-acclimatized species to enable them to survive subzero temperatures. These proteins have multiple macroscopic effects on ice crystal growth which makes them appealing for low-temperature applications—from cellular cryopreservation to food storage. Poly(vinyl alcohol) has remarkable ice recrystallization inhibition activity, but its mode of action is uncertain as is the extent at which it can be incorporated into other high-order structures. Here the synthesis and characterization of well-defined block copolymers containing poly(vinyl alcohol) and poly(vinylpyrrolidone) by RAFT/MADIX polymerization is reported, as new antifreeze protein mimetics. The effect of adding a large second hydrophilic block is studied across a range of compositions, and it is found to be a passive component in ice recrystallization inhibition assays, enabling retention of all activity. In the extreme case, a block copolymer with only 10% poly(vinyl alcohol) was found to retain all activity, where statistical copolymers of PVA lose all activity with very minor changes to composition. These findings present a new method to increase the complexity of antifreeze protein mimetic materials, while retaining activity, and also to help understand the underlying mechanisms of action. PMID:27476873

Louse- and flea-borne rickettsioses: biological and genomic analyses

PubMed Central

Gillespie, Joseph J.; Ammerman, Nicole C.; Beier-Sexton, Magda; Sobral, Bruno S.; Azad, Abdu F.

2009-01-01

In contrast to 15 or more validated and/or proposed tick-borne spotted fever group species, only three named medically important rickettsial species are associated with insects. These insect-borne rickettsiae are comprised of two highly pathogenic species, Rickettsia prowazekii (the agent of epidemic typhus) and R. typhi (the agent of murine typhus), as well as R. felis, a species with unconfirmed pathogenicity. Rickettsial association with obligate hematophagous insects such as the human body louse (R. prowazekii transmitted by Pediculus h. humanus) and several flea species (R. typhi and R. felis, as well as R. prowazekii in sylvatic form) provides rickettsiae the potential for further multiplications, longer transmission cycles and rapid spread among susceptible human populations. Both human body lice and fleas are intermittent feeders capable of multiple blood meals per generation, facilitating the efficient transmission of rickettsiae to several disparate hosts within urban/rural ecosystems. While taking into consideration the existing knowledge of rickettsial biology and genomic attributes, we have analyzed and summarized the interacting features that are unique to both the rickettsiae and their vector fleas and lice. Furthermore, factors that underlie rickettsial changing ecology, where native mammalian populations are involved in the maintenance of rickettsial cycle and transmission, are discussed. PMID:19036234

Antifreeze and cryoprotective activities of ice-binding collagen peptides from pig skin.

PubMed

Cao, Hui; Zhao, Ying; Zhu, Yu Bing; Xu, Fei; Yu, Jing Song; Yuan, Min

2016-03-01

A novel "hyperactive" ice-binding peptide from porcine collagen was prepared by alkaline protease hydrolysis and a series of column chromatography separations, and then its antifreeze and cryoprotective properties were reported. Using differential scanning calorimetry (DSC), the thermal hysteresis (TH) of ice-binding collagen peptides was closely related to their concentration and crystal fraction. Collagen hydrolysates with maximal TH were obtained by hydrolysis at pH 8.0, DH 15.0%, and 5% alkaline protease at 55°C. After purification by column chromatography, the AP-3 ice-binding collagen peptide (GLLGPLGPRGLL) with 1162.8Da molecular weights exhibited the highest TH (5.28°C), which can be classified as "hyperactive". Recrystallisation and melt-resistance of ice cream were improved by AP-3 ice-binding collagen peptide at 0.2% (w/v) in a similar manner to natural antifreeze proteins. Moreover, the addition of AP-3 collagen peptides in ice cream greatly elevated the glass transition temperature (Tg) to -17.64°C. Copyright © 2015 Elsevier Ltd. All rights reserved.

ASSESSING LEVELS OF INTERMITTENT EXPOSURES OF CHILDRENTO FLEA CONTROL INSECTICIDES FROM THE FUR OF DOGS

EPA Science Inventory

There are reported insecticide residues present in food, water, and surfaces such as carpets treated for flea control. However, no studies (except those we currently have in place) have quantified the transferable flea control insecticide residues which occur on pets (the majo...

Population genetic structure of the prairie dog flea and plague vector, Oropsylla hirsuta.

PubMed

Brinkerhoff, R Jory; Martin, Andrew P; Jones, Ryan T; Collinge, Sharon K

2011-01-01

Oropsylla hirsuta is the primary flea of the black-tailed prairie dog and is a vector of the plague bacterium, Yersinia pestis. We examined the population genetic structure of O. hirsuta fleas collected from 11 prairie dog colonies, 7 of which had experienced a plague-associated die-off in 1994. In a sample of 332 O. hirsuta collected from 226 host individuals, we detected 24 unique haplotype sequences in a 480 nucleotide segment of the cytochrome oxidase II gene. We found significant overall population structure but we did not detect a signal of isolation by distance, suggesting that O. hirsuta may be able to disperse relatively quickly at the scale of this study. All 7 colonies that were recently decimated by plague showed signs of recent population expansion, whereas 3 of the 4 plague-negative colonies showed haplotype patterns consistent with stable populations. These results suggest that O. hirsuta populations are affected by plague-induced prairie dog die-offs and that flea dispersal among prairie dog colonies may not be dependent exclusively on dispersal of prairie dogs. Re-colonization following plague events from plague-free refugia may allow for rapid flea population expansion following plague epizootics.

Preventive efficacy of NexGard Spectra® against Dipylidium caninum infection in dogs using a natural flea (Ctenocephalides felis) infestation model

PubMed Central

Beugnet, Frédéric; Meyer, Leon; Fourie, Josephus; Larsen, Diane

2017-01-01

The efficacy of a monthly oral endectocide product, NexGard Spectra® (Merial), a combination of afoxolaner and milbemycin oxime, was evaluated in a flea (Ctenocephalides felis) challenge model for the prevention of Dipylidium caninum tapeworm infection in dogs. The efficacy of treatment with NexGard Spectra® was assessed in 10 dogs following weekly flea infestation with metacestode naturally infected fleas and compared with that in 10 untreated control dogs. The 100 fleas deposited weekly on each dog were not removed until Day 35, allowing enough time for their ingestion. The microscopical analysis of 30 fleas from the flea batches before each weekly challenge demonstrated that 10–33% of the fleas were infected by D. caninum cysticercoid larvae. The arithmetic mean flea count recorded was 47.7 for the 10 untreated dogs and 0 for the 10 treated dogs at Day 35. Based on the daily collection of expelled D. caninum proglottids by dogs during the 70 days of the study, 70% (7/10) of the control dogs and 0% (0/10) of the treated dogs were infected with D. caninum (p < 0.0031). Through its efficacy against fleas, NexGard Spectra® treatment provided indirect prevention of D. caninum infestation. No treatment-related adverse events were observed in dogs during this study. PMID:28497745

Preventive efficacy of NexGard Spectra® against Dipylidium caninum infection in dogs using a natural flea (Ctenocephalides felis) infestation model.

PubMed

Beugnet, Frédéric; Meyer, Leon; Fourie, Josephus; Larsen, Diane

2017-01-01

The efficacy of a monthly oral endectocide product, NexGard Spectra ® (Merial), a combination of afoxolaner and milbemycin oxime, was evaluated in a flea (Ctenocephalides felis) challenge model for the prevention of Dipylidium caninum tapeworm infection in dogs. The efficacy of treatment with NexGard Spectra ® was assessed in 10 dogs following weekly flea infestation with metacestode naturally infected fleas and compared with that in 10 untreated control dogs. The 100 fleas deposited weekly on each dog were not removed until Day 35, allowing enough time for their ingestion. The microscopical analysis of 30 fleas from the flea batches before each weekly challenge demonstrated that 10-33% of the fleas were infected by D. caninum cysticercoid larvae. The arithmetic mean flea count recorded was 47.7 for the 10 untreated dogs and 0 for the 10 treated dogs at Day 35. Based on the daily collection of expelled D. caninum proglottids by dogs during the 70 days of the study, 70% (7/10) of the control dogs and 0% (0/10) of the treated dogs were infected with D. caninum (p < 0.0031). Through its efficacy against fleas, NexGard Spectra ® treatment provided indirect prevention of D. caninum infestation. No treatment-related adverse events were observed in dogs during this study. © F. Beugnet et al., published by EDP Sciences, 2017.

Prevalence of Fleas and Gastrointestinal Parasites in Free-Roaming Cats in Central Mexico

PubMed Central

Cantó, Germinal J.; Guerrero, Roberto I.; Olvera-Ramírez, Andrea M.; Milián, Feliciano; Mosqueda, Juan; Aguilar-Tipacamú, Gabriela

2013-01-01

The prevalence of fleas and gastrointestinal parasites in free-roaming and domestic cats in central Mexico was evaluated. Three hundred and fifty eight cats captured in the street or brought in by owners to the Animal Control Center Unit, a unit of State Government, from June 2010 to May 2011, were included in the study. All cats were examined for the presence of fleas and gastrointestinal worms. One-hundred and ninety (53%) cats were infested with at least one flea species. Single infestations were observed in 106 (30%) cats and mixed infestations in 84 (23%) cats. Four species of fleas were recovered: Ctenocephalides felis in 53% of the cats, C. canis in 18%, Echidnophaga gallinacea in 7% and Pulex irritans in 1%. One-hundred and sixty three (45%) cats were infected with one or more species of gastrointestinal parasites: 48 (13%) with nematodes, 145 (40%) with cestodes, and one animal presented Moniliformis moniliformis. Prevalences and mean intensity of infection were: Physaloptera praeputialis 7 and 18; T. cati 3 and 2; Ancylostoma tubaeforme 2.5 and 2; Toxascaris leonina 0.5 and 2; Dipylidium caninum 36 and 32; Taenia taeniformis 4 and 3 and Moniliformis moniliformis 0.3 and 106, respectively. There was significant association (P<0.01), between season and ectoparasites load, more fleas were obtained in the summer and autumn than in the winter and spring; however, no statistical difference was observed for endoparasites load (P>0.05). The correlation between the total number of ectoparasites and endoparasites was not significant (r = 0.089, P = 0.094). PMID:23573282

Contribution of land use to rodent flea load distribution in the plague endemic area of Lushoto District, Tanzania.

PubMed

Hieronimo, Proches; Kihupi, Nganga I; Kimaro, Didas N; Gulinck, Hubert; Mulungu, Loth S; Msanya, Balthazar M; Leirs, Herwig; Deckers, Jozef A

2014-07-01

Fleas associated with different rodent species are considered as the major vectors of bubonic plague, which is still rampant in different parts of the world. The objective of this study was to investigate the contribution of land use to rodent flea load distribution at fine scale in the plague endemic area of north-eastern Tanzania. Data was collected in three case areas namely, Shume, Lukozi and Mwangoi, differing in plague incidence levels. Data collection was carried out during both wet and dry seasons of 2012. Analysis of Variance and Boosted Regression Tree (BRT) statistical methods were used to clarify the relationships between fleas and specific land use characteristics. There was a significant variation (P ≤ 0.05) of flea indices in different land use types. Fallow and natural forest had higher flea indices whereas plantation forest mono-crop and mixed annual crops had the lowest flea indices among the aggregated land use types. The influence of individual land use types on flea indices was variable with fallow having a positive effect and land tillage showing a negative effect. The results also demonstrated a seasonal effect, part of which can be attributed to different land use practices such as application of pesticides, or the presence of grass strips around fields. These findings suggest that land use factors have a major influence on rodent flea abundance which can be taken as a proxy for plague infection risk. The results further point to the need for a comprehensive package that includes land tillage and crop type considerations on one hand and the associated human activities on the other, in planning and implementation of plague control interventions.

A distributed snow-evolution modeling system (SnowModel)

Treesearch

Glen E. Liston; Kelly Elder

2006-01-01

SnowModel is a spatially distributed snow-evolution modeling system designed for application in landscapes, climates, and conditions where snow occurs. It is an aggregation of four submodels: MicroMet defines meteorological forcing conditions, EnBal calculates surface energy exchanges, SnowPack simulates snow depth and water-equivalent evolution, and SnowTran-3D...

A new species of Cangshanaltica Konstantinov et al., a moss-inhabiting flea beetle from Thailand (Coleoptera: Chrysomelidae: Galerucinae: Alticini).

PubMed

Damaška, Albert; Konstantinov, Alexander

2016-04-29

Moss cushions represent an interesting, but poorly understood habitat, which hosts many species of flea beetles (Coleoptera: Chrysomelidae: Galerucinae: Alticini). However, the diversity of moss-inhabiting flea beetles is not well studied, and collecting in tropical and subtropical locations that were not sampled in the past led to the discovery of many new species (Konstantinov et al. 2013). Here, a new species of a moss-inhabiting flea beetle from the genus Cangshanaltica Konstantinov et al. 2013 is described and illustrated. This genus is one of the recently described moss-inhabiting flea beetle genera and before this study, only one species was known (Konstantinov et al., 2013). This publication raises the number of flea beetle species that are known to occur in moss cushions around the world to 30, distributed among 15 genera.

Using occupancy models to investigate the prevalence of ectoparasitic vectors on hosts: an example with fleas on prairie dogs

USGS Publications Warehouse

Eads, David A.; Biggins, Dean E.; Doherty, Paul F.; Gage, Kenneth L.; Huyvaert, Kathryn P.; Long, Dustin H.; Antolin, Michael F.

2013-01-01

Ectoparasites are often difficult to detect in the field. We developed a method that can be used with occupancy models to estimate the prevalence of ectoparasites on hosts, and to investigate factors that influence rates of ectoparasite occupancy while accounting for imperfect detection. We describe the approach using a study of fleas (Siphonaptera) on black-tailed prairie dogs (Cynomys ludovicianus). During each primary occasion (monthly trapping events), we combed a prairie dog three consecutive times to detect fleas (15 s/combing). We used robust design occupancy modeling to evaluate hypotheses for factors that might correlate with the occurrence of fleas on prairie dogs, and factors that might influence the rate at which prairie dogs are colonized by fleas. Our combing method was highly effective; dislodged fleas fell into a tub of water and could not escape, and there was an estimated 99.3% probability of detecting a flea on an occupied host when using three combings. While overall detection was high, the probability of detection was always <1.00 during each primary combing occasion, highlighting the importance of considering imperfect detection. The combing method (removal of fleas) caused a decline in detection during primary occasions, and we accounted for that decline to avoid inflated estimates of occupancy. Regarding prairie dogs, flea occupancy was heightened in old/natural colonies of prairie dogs, and on hosts that were in poor condition. Occupancy was initially low in plots with high densities of prairie dogs, but, as the study progressed, the rate of flea colonization increased in plots with high densities of prairie dogs in particular. Our methodology can be used to improve studies of ectoparasites, especially when the probability of detection is low. Moreover, the method can be modified to investigate the co-occurrence of ectoparasite species, and community level factors such as species richness and interspecific interactions.

Phylogenetic Analysis of Entomoparasitic Nematodes, Potential Control Agents of Flea Populations in Natural Foci of Plague

PubMed Central

Koshel, E. I.; Aleshin, V. V.; Eroshenko, G. A.; Kutyrev, V. V.

2014-01-01

Entomoparasitic nematodes are natural control agents for many insect pests, including fleas that transmit Yersinia pestis, a causative agent of plague, in the natural foci of this extremely dangerous zoonosis. We examined the flea samples from the Volga-Ural natural focus of plague for their infestation with nematodes. Among the six flea species feeding on different rodent hosts (Citellus pygmaeus, Microtus socialis, and Allactaga major), the rate of infestation varied from 0 to 21%. The propagation rate of parasitic nematodes in the haemocoel of infected fleas was very high; in some cases, we observed up to 1,000 juveniles per flea specimen. Our study of morphology, life cycle, and rDNA sequences of these parasites revealed that they belong to three distinct species differing in the host specificity. On SSU and LSU rRNA phylogenies, these species representing three genera (Rubzovinema, Psyllotylenchus, and Spilotylenchus), constitute a monophyletic group close to Allantonema and Parasitylenchus, the type genera of the families Allantonematidae and Parasitylenchidae (Nematoda: Tylenchida). We discuss the SSU-ITS1-5.8S-LSU rDNA phylogeny of the Tylenchida with a special emphasis on the suborder Hexatylina. PMID:24804197

Flea abundance, diversity, and plague in Gunnison's prairie dogs (Cynomys gunnisoni) and their burrows in montane grasslands in northern New Mexico.

PubMed

Friggens, Megan M; Parmenter, Robert R; Boyden, Michael; Ford, Paulette L; Gage, Kenneth; Keim, Paul

2010-04-01

Plague, a flea-transmitted infectious disease caused by the bacterium Yersinia pestis, is a primary threat to the persistence of prairie dog populations (Cynomys spp.). We conducted a 3-yr survey (2004-2006) of fleas from Gunnison's prairie dogs (Cynomys gunnisoni) and their burrows in montane grasslands in Valles Caldera National Preserve in New Mexico. Our objectives were to describe flea communities and identify flea and rodent species important to the maintenance of plague. We live-trapped prairie dogs and conducted burrow sweeps at three colonies in spring and summer of each year. One hundred thirty prairie dogs and 51 golden-mantled ground squirrels (Spermophilus lateralis) were captured over 3,640 trap nights and 320 burrows were swabbed for fleas. Five flea species were identified from prairie dogs and ground squirrels and four were identified from burrow samples. Oropsylla hirsuta was the most abundant species found on prairie dogs and in burrows. Oropsylla idahoensis was most common on ground squirrels. Two colonies experienced plague epizootics in fall 2004. Plague-positive fleas were recovered from burrows (O. hirsuta and Oropsylla tuberculata tuberculata) and a prairie dog (O. hirsuta) in spring 2005 and summer 2006. Three prairie dogs collected in summer 2005 and 2006 had plague antibody. We found a significant surge in flea abundance and prevalence, particularly within burrows, following plague exposure. We noted an increased tendency for flea exchange opportunities in the spring before O. hirsuta reached its peak population. We hypothesize that the role of burrows as a site of flea exchange, particularly between prairie dogs and ground squirrels, may be as important as summer conditions that lead to buildup in O. hirsuta populations for determining plague outbreaks.

Antifreeze (glyco)protein mimetic behavior of poly(vinyl alcohol): detailed structure ice recrystallization inhibition activity study.

PubMed

Congdon, Thomas; Notman, Rebecca; Gibson, Matthew I

2013-05-13

This manuscript reports a detailed study on the ability of poly(vinyl alcohol) to act as a biomimetic surrogate for antifreeze(glyco)proteins, with a focus on the specific property of ice-recrystallization inhibition (IRI). Despite over 40 years of study, the underlying mechanisms that govern the action of biological antifreezes are still poorly understood, which is in part due to their limited availability and challenging synthesis. Poly(vinyl alcohol) (PVA) has been shown to display remarkable ice recrystallization inhibition activity despite its major structural differences to native antifreeze proteins. Here, controlled radical polymerization is used to synthesize well-defined PVA, which has enabled us to obtain the first quantitative structure-activity relationships, to probe the role of molecular weight and comonomers on IRI activity. Crucially, it was found that IRI activity is "switched on" when the polymer chain length increases from 10 and 20 repeat units. Substitution of the polymer side chains with hydrophilic or hydrophobic units was found to diminish activity. Hydrophobic modifications to the backbone were slightly more tolerated than side chain modifications, which implies an unbroken sequence of hydroxyl units is necessary for activity. These results highlight that, although hydrophobic domains are key components of IRI activity, the random inclusion of addition hydrophobic units does not guarantee an increase in activity and that the actual polymer conformation is important.

Molecular and serological evidence of flea-associated typhus group and spotted fever group rickettsial infections in Madagascar.

PubMed

Rakotonanahary, Rado J L; Harrison, Alan; Maina, Alice N; Jiang, Ju; Richards, Allen L; Rajerison, Minoarisoa; Telfer, Sandra

2017-03-04

Rickettsiae are obligate intracellular bacteria responsible for many febrile syndromes around the world, including in sub-Saharan Africa. Vectors of these pathogens include ticks, lice, mites and fleas. In order to assess exposure to flea-associated Rickettsia species in Madagascar, human and small mammal samples from an urban and a rural area, and their associated fleas were tested. Anti-typhus group (TGR)- and anti-spotted fever group rickettsiae (SFGR)-specific IgG were detected in 24 (39%) and 21 (34%) of 62 human serum samples, respectively, using indirect ELISAs, with six individuals seropositive for both. Only two (2%) Rattus rattus out of 86 small mammals presented antibodies against TGR. Out of 117 fleas collected from small mammals, Rickettsia typhi, a TGR, was detected in 26 Xenopsylla cheopis (24%) collected from rodents of an urban area (n = 107), while two of these urban X. cheopis (2%) were positive for Rickettsia felis, a SFGR. R. felis DNA was also detected in eight (31%) out of 26 Pulex irritans fleas. The general population in Madagascar are exposed to rickettsiae, and two flea-associated Rickettsia pathogens, R. typhi and R. felis, are present near or in homes. Although our results are from a single district, they demonstrate that rickettsiae should be considered as potential agents of undifferentiated fever in Madagascar.

The inhibition of tetrahydrofuran clathrate-hydrate formation with antifreeze protein

NASA Astrophysics Data System (ADS)

Zeng, H.; Wilson, L. D.; Walker, V. K.; Ripmeester, J. A.

2003-01-01

The effect of Type I fish antifreeze protein (AFP) from the winter flounder, Pleuronectes americanus (Walbaum), (WfAFP) on the formation of tetrahydrofuran (THF) clathrate hydrate was studied by observing changes in THF crystal morphology and determining the induction time for nucleation. AFP retarded THF clathrate-hydrate growth at the tested temperatures and modified the THF clathrate-hydrate crystal morphology from octahedral to plate-like. AFP appears to be even more effective than the kinetic inhibitor, polyvinylpyrrolidone (PVP). Recombinant AFP from an insect, a spruce budworm, Choristoneura fumiferana (Clem.), moth, (Cf) was also tested for inhibition activity by observation of the THF-hydrate-crystal-growth habit. Like WfAFP, CfAFP appeared to show adsorption on multiple THF-hydrate-crystal faces. A protein with no antifreeze activity, cytochrome C, was used as a control and it neither changed the morphology of the THF clathrate-hydrate crystals, nor retarded the formation of the hydrate. Preliminary experiments on the inhibition activity of WfAFP on a natural gas hydrate assessed induction time and the amount of propane gas consumed. Similar to the observations for THF, the data indicated that WfAFP inhibited propane-hydrate growth. Taken together, these results support our hypothesis that AFPs can inhibit clathrate-hydrate growth and as well, offer promise for the understanding of the inhibition mechanism.

Molecular Detection of Rickettsia felis in Different Flea Species from Caldas, Colombia

PubMed Central

Ramírez-Hernández, Alejandro; Montoya, Viviana; Martínez, Alejandra; Pérez, Jorge E.; Mercado, Marcela; de la Ossa, Alberto; Vélez, Carolina; Estrada, Gloria; Correa, Maria I.; Duque, Laura; Ariza, Juan S.; Henao, Cesar; Valbuena, Gustavo; Hidalgo, Marylin

2013-01-01

Rickettsioses caused by Rickettsia felis are an emergent global threat. Historically, the northern region of the province of Caldas in Colombia has reported murine typhus cases, and recently, serological studies confirmed high seroprevalence for both R. felis and R. typhi. In the present study, fleas from seven municipalities were collected from dogs, cats, and mice. DNA was extracted and amplified by polymerase chain reaction (PCR) to identify gltA, ompB, and 17kD genes. Positive samples were sequenced to identify the species of Rickettsia. Of 1,341 fleas, Ctenocephalides felis was the most prevalent (76.7%). Positive PCR results in the three genes were evidenced in C. felis (minimum infection rates; 5.3%), C. canis (9.2%), and Pulex irritans (10.0%). Basic Local Alignment Search Tool (BLAST) analyses of sequences showed high identity values (> 98%) with R. felis, and all were highly related by phylogenetic analyses. This work shows the first detection of R. felis in fleas collected from animals in Colombia. PMID:23878183

Prophylactic treatment of flea-infested cats with an imidacloprid/flumethrin collar to forestall infection with Dipylidium caninum

PubMed Central

2012-01-01

Background The objective of the study was to determine the sustained effectiveness of 10% imidacloprid (w/w) and 4.5% flumethrin (w/w) incorporated in a slow-release matrix collar in preventing Dipylidium caninum infection in cats following repeated laboratory-infestations with fleas infected with metacestodes. Methods Efficacy against infection with D. caninum was evaluated by infesting 16 cats with the flea Ctenocephalides felis felis infected with metacestodes of the tapeworm. Medicated collars were fitted to 8 of the cats and infestation of each cat with 200 fleas from a suitably infected batch commenced 7 days later and continued at weekly intervals until Day 28. Efficacy against fleas was evaluated 24 h after each infestation. Infection of the cats with D. caninum was verified by daily examination of the cats’ faeces and immediate surroundings for proglottids from Day 21 to Day 60. Calculation of the prophylactic effectiveness of the collars in preventing infection of the cats with D. caninum was based on the difference in the geometric mean number of scoleces recovered from the gastrointestinal tracts of collared compared to untreated cats at necropsy on Day 61. Results Efficacy of the collars against infestation of the cats with fleas was 99.9% on Day 7 and 100% at each subsequent weekly assessment. Infection of the fleas with metacestodes was ≥40% in 7 to 13 day old fleas, but progressively decreased thereafter. At necropsy all the control cats were infected with D. caninum and harboured between 19 and 346 scoleces with a geometric mean of 58.3. A single treated cat was infected and harboured 2 scoleces. Effective prevention of infection with D. caninum, based on a comparison of the geometric mean numbers of scoleces recovered from control and treated cats, was 99.7%. Conclusion The insecticidal components of the medicated collars are capable of rapidly eliminating newly-acquired infestations of fleas that are infected with the metacestodes of D

Prophylactic treatment of flea-infested cats with an imidacloprid/flumethrin collar to forestall infection with Dipylidium caninum.

PubMed

Fourie, Josephus J; Crafford, Dionne; Horak, Ivan G; Stanneck, Dorothee

2012-07-27

The objective of the study was to determine the sustained effectiveness of 10% imidacloprid (w/w) and 4.5% flumethrin (w/w) incorporated in a slow-release matrix collar in preventing Dipylidium caninum infection in cats following repeated laboratory-infestations with fleas infected with metacestodes. Efficacy against infection with D. caninum was evaluated by infesting 16 cats with the flea Ctenocephalides felis felis infected with metacestodes of the tapeworm. Medicated collars were fitted to 8 of the cats and infestation of each cat with 200 fleas from a suitably infected batch commenced 7 days later and continued at weekly intervals until Day 28. Efficacy against fleas was evaluated 24 h after each infestation. Infection of the cats with D. caninum was verified by daily examination of the cats' faeces and immediate surroundings for proglottids from Day 21 to Day 60. Calculation of the prophylactic effectiveness of the collars in preventing infection of the cats with D. caninum was based on the difference in the geometric mean number of scoleces recovered from the gastrointestinal tracts of collared compared to untreated cats at necropsy on Day 61. Efficacy of the collars against infestation of the cats with fleas was 99.9% on Day 7 and 100% at each subsequent weekly assessment. Infection of the fleas with metacestodes was ≥40% in 7 to 13 day old fleas, but progressively decreased thereafter. At necropsy all the control cats were infected with D. caninum and harboured between 19 and 346 scoleces with a geometric mean of 58.3. A single treated cat was infected and harboured 2 scoleces. Effective prevention of infection with D. caninum, based on a comparison of the geometric mean numbers of scoleces recovered from control and treated cats, was 99.7%. The insecticidal components of the medicated collars are capable of rapidly eliminating newly-acquired infestations of fleas that are infected with the metacestodes of D. caninum, thus preventing infection with the

Yersinia pestis Biofilm in the Flea Vector and Its Role in the Transmission of Plague

PubMed Central

Erickson, D. L.

2013-01-01

Transmission by fleabite is a relatively recent evolutionary adaptation of Yersinia pestis, the bacterial agent of bubonic plague. To produce a transmissible infection, Y. pestis grows as an attached biofilm in the foregut of the flea vector. Biofilm formation both in the flea foregut and in vitro is dependent on an extracellular matrix (ECM) synthesized by the Yersinia hms gene products. The hms genes are similar to the pga and ica genes of Escherichia coli and Staphylococcus epidermidis, respectively, that act to synthesize a poly-β-1,6-N-acetyl-d-glucosamine ECM required for biofilm formation. As with extracellular polysaccharide production in many other bacteria, synthesis of the Hms-dependent ECM is controlled by intracellular levels of cyclic-di-GMP. Yersinia pseudotuberculosis, the food- and water-borne enteric pathogen from which Y. pestis evolved recently, possesses identical hms genes and can form biofilm in vitro but not in the flea. The genetic changes in Y. pestis that resulted in adapting biofilm-forming capability to the flea gut environment, a critical step in the evolution of vector-borne transmission, have yet to be identified. During a flea bite, Y. pestis is regurgitated into the dermis in a unique biofilm phenotype, and this has implications for the initial interaction with the mammalian innate immune response. PMID:18453279

Role of the Yersinia pestis yersiniabactin iron acquisition system in the incidence of flea-borne plague.

PubMed

Sebbane, Florent; Jarrett, Clayton; Gardner, Donald; Long, Daniel; Hinnebusch, B Joseph

2010-12-17

Plague is a flea-borne zoonosis caused by the bacterium Yersinia pestis. Y. pestis mutants lacking the yersiniabactin (Ybt) siderophore-based iron transport system are avirulent when inoculated intradermally but fully virulent when inoculated intravenously in mice. Presumably, Ybt is required to provide sufficient iron at the peripheral injection site, suggesting that Ybt would be an essential virulence factor for flea-borne plague. Here, using a flea-to-mouse transmission model, we show that a Y. pestis strain lacking the Ybt system causes fatal plague at low incidence when transmitted by fleas. Bacteriology and histology analyses revealed that a Ybt-negative strain caused only primary septicemic plague and atypical bubonic plague instead of the typical bubonic form of disease. The results provide new evidence that primary septicemic plague is a distinct clinical entity and suggest that unusual forms of plague may be caused by atypical Y. pestis strains.

Cat fleas (Ctenocephalides felis) from cats and dogs in New Zealand: Molecular characterisation, presence of Rickettsia felis and Bartonella clarridgeiae and comparison with Australia.

PubMed

Chandra, Shona; Forsyth, Maureen; Lawrence, Andrea L; Emery, David; Šlapeta, Jan

2017-01-30

The cat flea (Ctenocephalides felis) is the most common flea species parasitising both domestic cats and dogs globally. Fleas are known vectors of zoonotic pathogens such as vector borne Rickettsia and Bartonella. This study compared cat fleas from domestic cats and dogs in New Zealand's North and South Islands to Australian cat fleas, using the mitochondrial DNA (mtDNA) marker, cytochrome c oxidase subunit I and II (cox1, cox2). We assessed the prevalence of Rickettsia and Bartonella using genus specific multiplexed real-time PCR assays. Morphological identification confirmed that the cat flea (C. felis) is the most common flea in New Zealand. The examined fleas (n=43) at cox1 locus revealed six closely related C. felis haplotypes (inter-haplotype distance 1.1%) across New Zealand. The New Zealand C. felis haplotypes were identical or near identical with haplotypes from southern Australia demonstrating common dispersal of haplotype lineage across both the geographical (Tasman Sea) and climate scale. New Zealand cat fleas carried Rickettsia felis (5.3%) and Bartonella clarridgeiae (18.4%). To understand the capability of C. felis to vector zoonotic pathogens, we determined flea cox1 and cox2 haplotype diversity with the tandem multiplexed real-time PCR and sequencing for Bartonella and Rickettsia. This enabled us to demonstrate highly similar cat fleas on cat and dog populations across Australia and New Zealand. Copyright © 2016 Elsevier B.V. All rights reserved.

Prophylactic treatment of flea-infested dogs with an imidacloprid / flumethrin collar (Seresto®, Bayer) to preempt infection with Dipylidium caninum.

PubMed

Fourie, Josephus J; Crafford, Dionne; Horak, Ivan G; Stanneck, Dorothee

2013-08-01

The objective of the study was to determine the sustained effectiveness of 10 % imidacloprid and 4.5 % flumethrin, incorporated in a slow-release matrix collar, in preventing Dipylidium caninum infection in dogs after repeated laboratory infestations with fleas infected with metacestodes of this tapeworm. Efficacy against infection with D. caninum was evaluated by infesting 16 dogs with cat fleas (Ctenocephalides felis) on study days 7, 14, 21, 28, 35 and 42, from batches suitably infected with D. caninum metacestodes. Prior to each post-treatment infestation the D. caninum infection rate for the fleas was determined by microscopically examining 100 fleas for D. caninum metacestodes. The D. caninum prevalence in the fleas used for infestations ranged from 23 % to 52 %. Medicated collars were fitted to 8 of the dogs on study day 0. The weight of the IVP collars varied between 35.48 g and 38.48 g (average 37.16 g), whilst animal weight varied between 12.20 kg and 17.98 kg (treated group, n = 8, average 14.79 kg). Seven days later infestation of each of the 16 dogs with 250 fleas commenced. Infestations continued at weekly intervals until Day 42 with efficacy against fleas evaluated 24 hours after each infestation. From Days 21 to 74, infection of the dogs with D. caninum was verified (daily examination of faeces and cages for the presence of expelled proglottids). Calculation of prophylactic effectiveness of the collars in preventing infection with D. caninum was based on the difference in geometric mean numbers of scoleces between groups at necropsy on Day 75. Effective prevention of infection with D. caninum was found to be 96.6 %. Efficacy of the collars against fleas was ≥ 99.9 % for the duration of the assessment period. Newly acquired infestations of fleas are rapidly eliminated by the insecticidal components of the medicated collars over a period of several months. In the event of fleas being infected with metacestodes, with D. caninum can be prevented in

Th1/Th2 immune responses and oxidative stress in caprine flea allergy dermatitis.

PubMed

Ajith, Y; Dimri, U; Gopalakrishnan, A; Madhesh, E; Jhambh, R; Joshi, V; Devi, G

2017-12-01

Flea allergy dermatitis (FAD) is the common, often neglected skin disease of goats caused mainly by Ctenocephalides felis. This study aimed to evaluate the immuno-oxidative pathobiology of FAD in goats. Twelve goats from the same herd were divided into two groups of six animals each. The group I (FAD) included animals with natural flea infestation and severe dermatitis lesions. The group II (Healthy control) animals were free from any parasitic infestation. To assess the pathological changes, the markers of oxidative stress (lipid peroxidation, reduced glutathione and total antioxidant capacity), and immune status (Tumour necrosis factor alpha, Interleukin 10, Transforming growth factor beta 1 and Th1/Th2 cytokine ratio) were evaluated from the blood and the serum samples. Remarkable oxidative stress and severe inflammatory response with Th2 cytokine dominance were observed in flea infested animals. Highly antigenic agents of fleas, either secretory or excretory or structural, induced severe inflammatory responses and significant oxidative stress in caprine FAD. Massive release of cytokines may be responsible for severe skin inflammation and lesions in FAD in contrast to other Th2 dominant ectoparasitic skin conditions of goats'. © 2017 John Wiley & Sons Ltd.

Ice-surface adsorption enhanced colligative effect of antifreeze proteins in ice growth inhibition

NASA Astrophysics Data System (ADS)

Mao, Yougang; Ba, Yong

2006-09-01

This Communication describes a mechanism to explain antifreeze protein's function to inhibit the growth of ice crystals. We propose that the adsorption of antifreeze protein (AFP) molecules on an ice surface induces a dense AFP-water layer, which can significantly decrease the mole fraction of the interfacial water and, thus, lower the temperature for a seed ice crystal to grow in a super-cooled AFP solution. This mechanism can also explain the nearly unchanged melting point for the ice crystal due to the AFP's ice-surface adsorption. A mathematical model combining the Langmuir theory of adsorption and the colligative effect of thermodynamics has been proposed to find the equilibrium constants of the ice-surface adsorptions, and the interfacial concentrations of AFPs through fitting the theoretical curves to the experimental thermal hysteresis data. This model has been demonstrated by using the experimental data of serial size-mutated beetle Tenebrio molitor (Tm) AFPs. It was found that the AFP's ice-surface adsorptions could increase the interfacial AFP's concentrations by 3 to 4 orders compared with those in the bulk AFP solutions.

Evaluation of anti-freeze viscosity modifier for potential external tank applications

NASA Technical Reports Server (NTRS)

Lynn, R. O. L.

1981-01-01

Viscosity modifiers and gelling agents were evaluated in combination with ethylene glycol and dimethyl sulfoxide water eutectics. Pectin and agarose are found to gel these eutectics effectively in low concentration, but the anti-freeze protection afforded by these compositions is found to be marginal in simulations of the intended applications. Oxygen vent shutters and vertical metallic surfaces were simulated, with water supplied as a spray, dropwise, and by condensation from the air.

Molecular survey of ITS1 spacer and Rickettsia infection in human flea, Pulex irritans.

PubMed

Ghavami, Mohammad Bagher; Mirzadeh, Habibeh; Mohammadi, Jamshid; Fazaeli, Asghar

2018-05-01

The human flea is an important ectoparasite causing serious public health problems worldwide. Planning and monitoring the control programs against this vector require the knowledge of population structure and vector competence. This study was carried out to identify molecular structure of internal transcribed spacer 1 (ITS1) of ribosomal gene and its capability in the survey of Pulex irritans populations as well as to investigate Rickettsia infection in these populations. Flea samples were collected via human baits from animal farms in two districts of Zanjan Province, northwest of Iran. The ITS1 region and the partial Rickettsia gltA gene were amplified from the samples of human flea, and 30 amplicons were sequenced. The 1136 collected fleas consisted of 1079 (94.98%) P. irritans, 36 (3.17%) Ctenocephalides canis, and 21 (1.85%) Ctenocephalides felis. Molecular investigation of 182 human fleas detected the infection of Rickettsia sp. in 4.9%. The ITS1 region covered 957 bp and contained three tandem units of 98-99 bp, starting at positions 145, 245, and 331. Multiple alignments of ITS1 sequences showed single-nucleotide polymorphism at position 798, which caused the substitution of cytosine for adenine in the novel haplotype. High frequency of P. irritans and its Rickettsia infection requires the application of vector control measures, and full characterization of Rickettsia sp. and its potential to cause disease in humans. Regarding the consistency of ITS1 region and its ability to differentiate insect communities, further investigations are recommended to identify the role of selective factors in maintenance of this spacer.

Flea and Small Mammal Species Composition in Mixed-Grass Prairies: Implications for the Maintenance of Yersinia pestis.

PubMed

Maestas, Lauren P; Britten, Hugh B

2017-07-01

Maintenance of sylvatic plague in prairie dogs (Cynomis spp.) was once thought unlikely due to high mortality rates; yet more recent findings indicate that low-level enzootic plague may be maintained in susceptible prairie dog populations. Another hypothesis for the maintenance of sylvatic plague involves small mammals, other than prairie dogs, as an alternative reservoir in the sylvatic plague system. These hypotheses, however, are not mutually exclusive, as both prairie dogs and small mammals could together be driving sylvatic cycles of plague. The concept of a bridging vector has been used to explain the transmission of pathogens from one host species to another. In the case of sylvatic plague, this would require overlap in fleas between small mammals and prairie dogs, and potentially other species such as carnivores. Our goal was to evaluate the level of flea sharing between black-tailed prairie dogs (Cynomis ludovicianus) and other small mammals in a mixed-grass prairie in South Dakota. We investigated the species richness of small mammals and small-mammal fleas in a mixed-grass prairie system and compared findings with previous studies from a short-grass ecosystem in Colorado. Over the summer field seasons 2014-2016 we live-trapped small mammals, collected fleas, and showed differences between both the flea and small mammal composition of the two systems. We also recorded higher densities of deer mice and lower densities of northern grasshopper mice in mixed versus shortgrass prairies. We confirmed, as is the case in shortgrass prairies, a lack of substantial flea species overlap on small mammal hosts and fleas from prairie dogs and their burrows. Moreover this study demonstrates that although small mammals may not play a large part in interepizootic plague cycling in shortgrass prairie ecosystems, their role in mixed-grass prairies requires further evaluation.

Animal ice-binding (antifreeze) proteins and glycolipids: an overview with emphasis on physiological function.

PubMed

Duman, John G

2015-06-01

Ice-binding proteins (IBPs) assist in subzero tolerance of multiple cold-tolerant organisms: animals, plants, fungi, bacteria etc. IBPs include: (1) antifreeze proteins (AFPs) with high thermal hysteresis antifreeze activity; (2) low thermal hysteresis IBPs; and (3) ice-nucleating proteins (INPs). Several structurally different IBPs have evolved, even within related taxa. Proteins that produce thermal hysteresis inhibit freezing by a non-colligative mechanism, whereby they adsorb onto ice crystals or ice-nucleating surfaces and prevent further growth. This lowers the so-called hysteretic freezing point below the normal equilibrium freezing/melting point, producing a difference between the two, termed thermal hysteresis. True AFPs with high thermal hysteresis are found in freeze-avoiding animals (those that must prevent freezing, as they die if frozen) especially marine fish, insects and other terrestrial arthropods where they function to prevent freezing at temperatures below those commonly experienced by the organism. Low thermal hysteresis IBPs are found in freeze-tolerant organisms (those able to survive extracellular freezing), and function to inhibit recrystallization - a potentially damaging process whereby larger ice crystals grow at the expense of smaller ones - and in some cases, prevent lethal propagation of extracellular ice into the cytoplasm. Ice-nucleator proteins inhibit supercooling and induce freezing in the extracellular fluid at high subzero temperatures in many freeze-tolerant species, thereby allowing them to control the location and temperature of ice nucleation, and the rate of ice growth. Numerous nuances to these functions have evolved. Antifreeze glycolipids with significant thermal hysteresis activity were recently identified in insects, frogs and plants. © 2015. Published by The Company of Biologists Ltd.

Assessing Cat Flea Microbiomes in Northern and Southern California by 16S rRNA Next-Generation Sequencing.

PubMed

Vasconcelos, Elton J R; Billeter, Sarah A; Jett, Lindsey A; Meinersmann, Richard J; Barr, Margaret C; Diniz, Pedro P V P; Oakley, Brian B

2018-06-12

Flea-borne diseases (FBDs) impact both human and animal health worldwide. Because adult fleas are obligately hematophagous and can harbor potential pathogens, fleas act as ectoparasites of vertebrates, as well as zoonotic disease vectors. Cat fleas (Ctenocephalides felis) are important vectors of two zoonotic bacterial genera listed as priority pathogens by the National Institute of Allergy and Infectious Diseases (NIAID-USA): Bartonella spp. and Rickettsia spp., causative agents of bartonelloses and rickettsioses, respectively. In this study, we introduce the first microbiome analysis of C. felis samples from California, determining the presence and abundance of relevant pathogenic genera by characterizing the cat flea microbiome through 16S rRNA next-generation sequencing (16S-NGS). Samples from both northern (NoCal) and southern (SoCal) California were assessed to expand current knowledge regarding FBDs in the state. We identified Rickettsia and Bartonella, as well as the endosymbiont Wolbachia, as the most abundant genera, followed by less abundant taxa. In comparison to our previous study screening Californian cat fleas for rickettsiae using PCR/digestion/sequencing of the ompB gene, the 16S-NGS approach applied herein showed a 95% level of agreement in detecting Rickettsia spp. There was no overall difference in microbiome diversity between NoCal and SoCal samples. Bacterial taxa identified by 16S-NGS in this study may help to improve epidemiological investigations, pathogen surveillance efforts, and clinical diagnostics of FBDs in California and elsewhere.

Blood Meal Identification in Off-Host Cat Fleas (Ctenocephalides felis) from a Plague-Endemic Region of Uganda

PubMed Central

Graham, Christine B.; Borchert, Jeff N.; Black, William C.; Atiku, Linda A.; Mpanga, Joseph T.; Boegler, Karen A.; Moore, Sean M.; Gage, Kenneth L.; Eisen, Rebecca J.

2013-01-01

The cat flea, Ctenocephalides felis, is an inefficient vector of the plague bacterium (Yersinia pestis) and is the predominant off-host flea species in human habitations in the West Nile region, an established plague focus in northwest Uganda. To determine if C. felis might serve as a Y. pestis bridging vector in the West Nile region, we collected on- and off-host fleas from human habitations and used a real-time polymerase chain reaction-based assay to estimate the proportion of off-host C. felis that had fed on humans and the proportion that had fed on potentially infectious rodents or shrews. Our findings indicate that cat fleas in human habitations in the West Nile region feed primarily on domesticated species. We conclude that C. felis is unlikely to serve as a Y. pestis bridging vector in this region. PMID:23208882

Blood meal identification in off-host cat fleas (Ctenocephalides felis) from a plague-endemic region of Uganda.

PubMed

Graham, Christine B; Borchert, Jeff N; Black, William C; Atiku, Linda A; Mpanga, Joseph T; Boegler, Karen A; Moore, Sean M; Gage, Kenneth L; Eisen, Rebecca J

2013-02-01

The cat flea, Ctenocephalides felis, is an inefficient vector of the plague bacterium (Yersinia pestis) and is the predominant off-host flea species in human habitations in the West Nile region, an established plague focus in northwest Uganda. To determine if C. felis might serve as a Y. pestis bridging vector in the West Nile region, we collected on- and off-host fleas from human habitations and used a real-time polymerase chain reaction-based assay to estimate the proportion of off-host C. felis that had fed on humans and the proportion that had fed on potentially infectious rodents or shrews. Our findings indicate that cat fleas in human habitations in the West Nile region feed primarily on domesticated species. We conclude that C. felis is unlikely to serve as a Y. pestis bridging vector in this region.

Influence of Adsorption Orientation on the Statistical Mechanics Model of Type I Antifreeze Protein: The Thermal Hysteresis Temperature.

PubMed

Li, Li-Fen; Liang, Xi-Xia

2017-10-19

The antifreeze activity of type I antifreeze proteins (AFPIs) is studied on the basis of the statistical mechanics theory, by taking the AFP's adsorption orientation into account. The thermal hysteresis temperatures are calculated by determining the system Gibbs function as well as the AFP molecule coverage rate on the ice-crystal surface. The numerical results for the thermal hysteresis temperatures of AFP9, HPLC-6, and AAAA2kE are obtained for both of the cases with and without inclusion of the adsorption orientation. The results show that the influence of the adsorption orientation on the thermal hysteresis temperature cannot be neglected. The theoretical results are coincidental preferably with the experimental data.

Detection of Rickettsia felis, Rickettsia typhi, Bartonella Species and Yersinia pestis in Fleas (Siphonaptera) from Africa.

PubMed

Leulmi, Hamza; Socolovschi, Cristina; Laudisoit, Anne; Houemenou, Gualbert; Davoust, Bernard; Bitam, Idir; Raoult, Didier; Parola, Philippe

2014-10-01

Little is known about the presence/absence and prevalence of Rickettsia spp, Bartonella spp. and Yersinia pestis in domestic and urban flea populations in tropical and subtropical African countries. Fleas collected in Benin, the United Republic of Tanzania and the Democratic Republic of the Congo were investigated for the presence and identity of Rickettsia spp., Bartonella spp. and Yersinia pestis using two qPCR systems or qPCR and standard PCR. In Xenopsylla cheopis fleas collected from Cotonou (Benin), Rickettsia typhi was detected in 1% (2/199), and an uncultured Bartonella sp. was detected in 34.7% (69/199). In the Lushoto district (United Republic of Tanzania), R. typhi DNA was detected in 10% (2/20) of Xenopsylla brasiliensis, and Rickettsia felis was detected in 65% (13/20) of Ctenocephalides felis strongylus, 71.4% (5/7) of Ctenocephalides canis and 25% (5/20) of Ctenophthalmus calceatus calceatus. In the Democratic Republic of the Congo, R. felis was detected in 56.5% (13/23) of Ct. f. felis from Kinshasa, in 26.3% (10/38) of Ct. f. felis and 9% (1/11) of Leptopsylla aethiopica aethiopica from Ituri district and in 19.2% (5/26) of Ct. f. strongylus and 4.7% (1/21) of Echidnophaga gallinacea. Bartonella sp. was also detected in 36.3% (4/11) of L. a. aethiopica. Finally, in Ituri, Y. pestis DNA was detected in 3.8% (1/26) of Ct. f. strongylus and 10% (3/30) of Pulex irritans from the villages of Wanyale and Zaa. Most flea-borne infections are neglected diseases which should be monitored systematically in domestic rural and urban human populations to assess their epidemiological and clinical relevance. Finally, the presence of Y. pestis DNA in fleas captured in households was unexpected and raises a series of questions regarding the role of free fleas in the transmission of plague in rural Africa, especially in remote areas where the flea density in houses is high.

Improved Snow Mapping Accuracy with Revised MODIS Snow Algorithm

NASA Technical Reports Server (NTRS)

Riggs, George; Hall, Dorothy K.

2012-01-01

The MODIS snow cover products have been used in over 225 published studies. From those reports, and our ongoing analysis, we have learned about the accuracy and errors in the snow products. Revisions have been made in the algorithms to improve the accuracy of snow cover detection in Collection 6 (C6), the next processing/reprocessing of the MODIS data archive planned to start in September 2012. Our objective in the C6 revision of the MODIS snow-cover algorithms and products is to maximize the capability to detect snow cover while minimizing snow detection errors of commission and omission. While the basic snow detection algorithm will not change, new screens will be applied to alleviate snow detection commission and omission errors, and only the fractional snow cover (FSC) will be output (the binary snow cover area (SCA) map will no longer be included).

Prevalence and abundance of fleas in black-tailed prairie dog burrows: implications for the transmission of plague (Yersinia pestis).

PubMed

Salkeld, Dan J; Stapp, Paul

2008-06-01

Plague, the disease caused by the bacterium Yersinia pestis, can have devastating impacts on North American wildlife. Epizootics, or die-offs, in prairie dogs (Cynomys ludovicianus) occur sporadically and fleas (Siphonaptera) are probably important in the disease's transmission and possibly as maintenance hosts of Y. pestis between epizootics. We monitored changes in flea abundance in prairie dog burrows in response to precipitation, temperature, and plague activity in shortgrass steppe in northern Colorado. Oropsylla hirsuta was the most commonly found flea, and it increased in abundance with temperature. In contrast, Oropsylla tuberculata cynomuris declined with rising temperature. During plague epizootics, flea abundance in burrows increased and then subsequently declined after the extirpation of their prairie dog hosts.

Effects on the development of Dipylidium caninum and on the host reaction to this parasite in the adult flea (Ctenocephalides felis felis).

PubMed

Pugh, R E

1987-01-01

Temperature was found to be a major factor affecting the development of Dipylidium caninum and the presence of a host reaction of adult Ctenocephalides felis felis to D. caninum. Adult fleas reared at 30-32 degrees C contained fully developed metacestodes when they emerged from their cocoons. However at lower temperatures, D. caninum could not complete development until the flea hosts had spent some time on their mammalian hosts. It was the surface temperature of the mammals (31-36 degrees C) and not the fleas' blood meals which resulted in the metacestodes completing their development. This development of D. caninum was therefore independent of the flea development. At 20 degrees C, a larger and more prolonged host reaction was mounted than at higher temperatures. The larval flea diet had a small effect on the subsequent cestode development and the adult fleas' reaction to it.

Efficacy of a fipronil bait in reducing the number of fleas (Oropsylla spp.) infesting wild black-tailed prairie dogs.

PubMed

Poché, David M; Hartman, Daniel; Polyakova, Larisa; Poché, Richard M

2017-06-01

Bubonic plague (Yersinia pestis) is a deadly zoonosis with black-tailed prairie dogs (Cynomys ludovicianus) as a reservoir host in the United States. Systemic insecticides are a promising means of controlling the vectors, Oropsylla spp. fleas, infesting these prairie dogs, subsequently disrupting the Y. pestis cycle. The objective of this study was to conduct a field trial evaluating the efficacy of a grain rodent bait containing fipronil (0.005%) against fleas infesting prairie dogs. The study was performed in Larimer County, CO, where bait was applied to a treatment area containing a dense prairie dog population, three times over a three-week period. Prairie dogs were captured and combed for fleas during four study periods (pre-, mid-, 1 st post-, and 2 nd post-treatment). Results indicated the use of bait containing fipronil significantly reduced flea burden. The bait containing fipronil was determined to reduce the mean number of fleas per prairie dog >95% for a minimum of 52 days post-initial treatment application and 31 days post-final treatment application. These results suggest the potential for this form of treatment to reduce flea population density on prairie dogs, and subsequently plague transmission, among mammalian hosts across the United States and beyond. © 2017 The Society for Vector Ecology.

A primary animal health care approach to treatment and control of flea (Ctenocephalides felis) infestation in indigenous goats kept on communal grazing.

PubMed

McCrindle, C M; Green, E D; Bryson, N R

1999-03-01

This paper describes a primary health care approach to an infestation of indigenous goats by the common cat flea, Ctenocephalides felis. The flea species was identified using scanning electron microscopy. The infested goats were kept on communal grazing at Winterveld in the North-West Province. They were penned at night in housing made of wire and corrugated iron. The owner complained that the goats were lethargic. Fleas were found on the goats and flea larvae were found in the kraal. Haematology and blood biochemistry performed on the infested goats revealed no abnormalities; however, infestation caused irritation that made the animals lethargic. Available flea control methods for domestic animals were appraised in terms of cost, availability and ease of administration at a primary animal health care level using participatory extension methods. It was found that a carbamate powder was available, affordable and effective for flea control in this small flock of goats kept under communal grazing conditions. Although the authors had observed fleas on goats kept under similar conditions elsewhere in Mpumalanga and the North-West Province, this was the 1st time that the species had been identified.

MODIS Snow Cover Mapping Decision Tree Technique: Snow and Cloud Discrimination

NASA Technical Reports Server (NTRS)

Riggs, George A.; Hall, Dorothy K.

2010-01-01

Accurate mapping of snow cover continues to challenge cryospheric scientists and modelers. The Moderate-Resolution Imaging Spectroradiometer (MODIS) snow data products have been used since 2000 by many investigators to map and monitor snow cover extent for various applications. Users have reported on the utility of the products and also on problems encountered. Three problems or hindrances in the use of the MODIS snow data products that have been reported in the literature are: cloud obscuration, snow/cloud confusion, and snow omission errors in thin or sparse snow cover conditions. Implementation of the MODIS snow algorithm in a decision tree technique using surface reflectance input to mitigate those problems is being investigated. The objective of this work is to use a decision tree structure for the snow algorithm. This should alleviate snow/cloud confusion and omission errors and provide a snow map with classes that convey information on how snow was detected, e.g. snow under clear sky, snow tinder cloud, to enable users' flexibility in interpreting and deriving a snow map. Results of a snow cover decision tree algorithm are compared to the standard MODIS snow map and found to exhibit improved ability to alleviate snow/cloud confusion in some situations allowing up to about 5% increase in mapped snow cover extent, thus accuracy, in some scenes.

Remote Sensing of Snow Cover. Section; Snow Extent

NASA Technical Reports Server (NTRS)

Hall, Dorothy K.; Frei, Allan; Drey, Stephen J.

2012-01-01

Snow was easily identified in the first image obtained from the Television Infrared Operational Satellite-1 (TIROS-1) weather satellite in 1960 because the high albedo of snow presents a good contrast with most other natural surfaces. Subsequently, the National Oceanic and Atmospheric Administration (NOAA) began to map snow using satellite-borne instruments in 1966. Snow plays an important role in the Earth s energy balance, causing more solar radiation to be reflected back into space as compared to most snow-free surfaces. Seasonal snow cover also provides a critical water resource through meltwater emanating from rivers that originate from high-mountain areas such as the Tibetan Plateau. Meltwater from mountain snow packs flows to some of the world s most densely-populated areas such as Southeast Asia, benefiting over 1 billion people (Immerzeel et al., 2010). In this section, we provide a brief overview of the remote sensing of snow cover using visible and near-infrared (VNIR) and passive-microwave (PM) data. Snow can be mapped using the microwave part of the electromagnetic spectrum, even in darkness and through cloud cover, but at a coarser spatial resolution than when using VNIR data. Fusing VNIR and PM algorithms to produce a blended product offers synergistic benefits. Snow-water equivalent (SWE), snow extent, and melt onset are important parameters for climate models and for the initialization of atmospheric forecasts at daily and seasonal time scales. Snowmelt data are also needed as input to hydrological models to improve flood control and irrigation management.

Sticktight fleas associated with fowl pox in a backyard chicken flock in California.

PubMed

Gustafson, C R; Bickford, A A; Cooper, G L; Charlton, B R

1997-01-01

A mixed breed rooster, from a backyard flock of 13 chickens, was received at California Veterinary Diagnostic Laboratory System-Turlock Branch for postmortem examination. The bird presented with thickened, featherless, scab-encrusted skin around the head region. Numerous sticktight fleas were found attached to the encrusted skin. Microscopic evaluation of the skin revealed a lymphoplasmacytic reaction in the dermis with visible embedded flea mouthparts. Also noted histologically in this region were epidermal hyperplasia and ballooned epidermal cells containing intracytoplasmic inclusions indicative of fowl poxvirus.

Unusual dynamic properties of water near the ice-binding plane of hyperactive antifreeze protein

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuffel, Anna; Czapiewski, Dariusz; Zielkiewicz, Jan, E-mail: jaz@chem.pg.gda.pl

2015-10-07

The dynamical properties of solvation water of hyperactive antifreeze protein from Choristoneura fumiferana (CfAFP) are analyzed and discussed in context of its antifreeze activity. The protein comprises of three well-defined planes and one of them binds to the surface of ice. The dynamical properties of solvation water around each of these planes were analyzed separately; the results are compared with the dynamical properties of solvation water of ice around its two crystallographic planes: basal and prism. Three main conclusions are inferred from our investigations. The first one is that the solvation shell of CfAFP does not seem to be particularlymore » far-ranged, at least not beyond what is usually observed for proteins that do not interact with ice. Therefore, it does not appear to us that the antifreeze activity is enhanced by a long-ranged retardation of water mobility. Also the correlation between the collective mobility of water and the collective mobility of protein atoms highly resembles the one measured for the protein that does not interact with ice. Our second conclusion is that the dynamical properties of solvation water of CfAFP are non-uniform. The dynamics of solvation water of ice-binding plane is, in some respects, different from the dynamics of solvation water of the two remaining planes. The feature that distinguishes the dynamics of solvation water of the three planes is the activation energy of diffusion process. The third conclusion is that—from the three analyzed solvation shells of CfAFP—the dynamical properties of solvation water of the ice-binding plane resemble the most the properties of solvation water of ice; note, however, that these properties still clearly differ from the dynamic properties of solvation water of ice.« less

Hyperactive antifreeze protein from an Antarctic sea ice bacterium Colwellia sp. has a compound ice-binding site without repetitive sequences.

PubMed

Hanada, Yuichi; Nishimiya, Yoshiyuki; Miura, Ai; Tsuda, Sakae; Kondo, Hidemasa

2014-08-01

Antifreeze proteins (AFPs) are structurally diverse macromolecules that bind to ice crystals and inhibit their growth to protect the organism from injuries caused by freezing. An AFP identified from the Antarctic bacterium Colwellia sp. strain SLW05 (ColAFP) is homologous to AFPs from a wide variety of psychrophilic microorganisms. To understand the antifreeze function of ColAFP, we have characterized its antifreeze activity and determined the crystal structure of this protein. The recombinant ColAFP exhibited thermal hysteresis activity of approximately 4 °C at a concentration of 0.14 mm, and induced rapid growth of ice crystals in the hexagonal direction. Fluorescence-based ice plane affinity analysis showed that ColAFP binds to multiple planes of ice, including the basal plane. These observations show that ColAFP is a hyperactive AFP. The crystal structure of ColAFP determined at 1.6 Å resolution revealed an irregular β-helical structure, similar to known homologs. Mutational and molecular docking studies showed that ColAFP binds to ice through a compound ice-binding site (IBS) located at a flat surface of the β-helix and the adjoining loop region. The IBS of ColAFP lacks the repetitive sequences that are characteristic of hyperactive AFPs. These results suggest that ColAFP exerts antifreeze activity through a compound IBS that differs from the characteristic IBSs shared by other hyperactive AFPs. This study demonstrates a novel method for protection from freezing by AFPs in psychrophilic microorganisms. Structural data for ColAFP have been submitted to the Protein Data Bank (PDB) under accession number 3WP9. © 2014 FEBS.

Fleas and lice of mammals in New Mexico

Treesearch

Paulette L. Ford; Richard A. Fagerlund; Donald W. Duszynski; Paul J. Polechla

2004-01-01

All available records are compiled for three orders of ectoparasites of mammals in New Mexico: fleas (Siphonaptera), sucking lice (Anoplura), and chewing lice (Mallophaga). We have drawn from records at the University of New Mexico's Museum of Southwestern Biology, the Vector Control Program of the New Mexico Environment Department, the Environmental Health...

Evaluation of sarolaner and spinosad oral treatments to eliminate fleas, reduce dermatologic lesions and minimize pruritus in naturally infested dogs in west Central Florida, USA.

PubMed

Dryden, Michael W; Canfield, Michael S; Niedfeldt, Emily; Kinnon, Amanda; Kalosy, Kimberly; Smith, Amber; Foley, Kaitlin M; Smith, Vicki; Bress, Todd S; Smith, Nicole; Endrizzi, Mike; Login, Joyce

2017-08-17

An in-home investigation of naturally flea infested dogs was conducted in West Central Florida, USA to evaluate and compare the effectiveness of two different oral flea adulticides to control flea infestations, minimize dermatologic lesions and reduce pruritus over an 8-week period. Twenty-nine dogs living in 19 homes and another 26 dogs residing in 16 different homes were orally administered either a sarolaner or spinosad chewable, respectively on day 0 and once between days 28-30. Products were administered by study personnel according to label directions. Flea populations on dogs were estimated using visual area counts and flea infestations in the indoor premises were assessed using intermittent-light flea traps on days 0, 7, 14, 21 and once between days 28-30, 40-45, and 56-60. Assessments of dermatologic lesions were conducted monthly during the study and severity of pruritus was evaluated throughout the study on the same schedule as flea counts were conducted. Concurrent treatments for existing skin disease were not allowed. The administration of sarolaner or spinosad reduced flea populations on dogs by 99.0% and 97.3%, respectively within 7 days. Flea infestations on the sarolaner- and spinosad-treated dogs were reduced by > 99% at every counting period from day 14 post-treatment through the end of the 8-week study. At the end of the study 96.4 and 92.0% of the dogs treated with sarolaner and spinosad, respectively were flea-free. Flea populations in the indoor premises were also markedly reduced the end of the study, with 100 and 99.8% reductions in flea trap counts in the sarolaner and spinosad treatment groups, respectively. FAD lesion scores, atopic dermatitis lesions scores (CADESI-4) and pruritus severity scores were also markedly improved with both formulations. An in-home clinical field study conducted during the summer of 2016 in subtropical Florida demonstrated that two-monthly administrations of either sarolaner or spinosad chewables almost

Coexistence of Bartonella henselae and B. clarridgeiae in populations of cats and their fleas in Guatemala.

PubMed

Bai, Ying; Rizzo, Maria Fernanda; Alvarez, Danilo; Moran, David; Peruski, Leonard F; Kosoy, Michael

2015-12-01

Cats and their fleas collected in Guatemala were investigated for the presence of Bartonella infections. Bartonella bacteria were cultured from 8.2% (13/159) of cats, and all cultures were identified as B. henselae. Molecular analysis allowed detection of Bartonella DNA in 33.8% (48/142) of cats and in 22.4% (34/152) of cat fleas using gltA, nuoG, and 16S-23S internal transcribed spacer targets. Two Bartonella species, B. henselae and B. clarridgeiae, were identified in cats and cat fleas by molecular analysis, with B. henselae being more common than B. clarridgeiae in the cats (68.1%; 32/47 vs 31.9%; 15/47). The nuoG was found to be less sensitive for detecting B. clarridgeiae compared with other molecular targets and could detect only two of the 15 B. clarridgeiae-infected cats. No significant differences were observed for prevalence between male and female cats and between different age groups. No evident association was observed between the presence of Bartonella species in cats and in their fleas. © 2015 The Society for Vector Ecology.

Evaluation of the speed of kill, effects on reproduction, and effectiveness in a simulated infested-home environment of sarolaner (Simparica™) against fleas on dogs.

PubMed

Six, Robert H; Becskei, Csilla; Carter, Lori; Gale, Boyd; Young, David R; Mahabir, Sean P; Chapin, Sara; Myers, Melanie R

2016-05-30

Four studies were conducted to evaluate the speed of kill, effect on egg production, and efficacy in a simulated infested-home environment of a novel isoxazoline, sarolaner (Simparica™, Zoetis), against fleas on dogs. Individually identified and housed, purpose-bred Beagles were used in each study and were allocated randomly to groups based on pretreatment parasite counts. In two speed of kill studies, groups of dogs infested with 100 fleas prior to treatment were treated orally with placebo or sarolaner tablets providing the minimum dose of 2mg/kg and then re-infested with fleas weekly for five weeks post-treatment. Comb counts were conducted to determine the numbers of viable fleas at one to three, four, eight and 12h after treatment and each subsequent infestation. In the egg production study, sarolaner- and placebo-treated dogs were similarly challenged with fleas and at 48h after each infestation the dogs were housed for 20h in cages allowing the collection and counting of all flea eggs produced during this period. Collected eggs were incubated to evaluate hatch and development to adults. The last study used dogs housed in a flea-infested simulated-home environment. Dogs were allocated to treatment with either placebo or sarolaner tablets providing a dose of 2mg/kg once a month for three treatments. Flea infestations were assessed by comb counts (fleas were replaced on the dogs) on Days 14, 30, 44, 60, 74 and 90. The speed of kill studies demonstrated that a single 2mg/kg oral dose of sarolaner started killing fleas within three to four hours after treatment or subsequent re-infestations for up to a month, and achieved ≥98% control of fleas by eight hours after treatment or re-infestation for 28 days. In the study to assess effects on flea reproduction, a single oral treatment of sarolaner resulted in the complete cessation of egg-laying for 35 days. This rapid kill of fleas and inhibition of reproduction were confirmed in a simulated-home environment

Transport of intercepted snow from trees during snow storms

Treesearch

David H. Miller

1966-01-01

Five principal processes by which intercepted snow in trees is removed during snow storms are described and evaluated as far as data permit: vapor flux from melt water, vapor flux from bodies of snow, stem flow and dripping of melt water, sliding of bodies of intercepted snow from branches, and wind erosion and transport of intercepted snow. Further research is...

Antifreeze Proteins Modify the Freezing Process In Planta12

PubMed Central

Griffith, Marilyn; Lumb, Chelsey; Wiseman, Steven B.; Wisniewski, Michael; Johnson, Robert W.; Marangoni, Alejandro G.

2005-01-01

During cold acclimation, winter rye (Secale cereale L. cv Musketeer) plants accumulate antifreeze proteins (AFPs) in the apoplast of leaves and crowns. The goal of this study was to determine whether these AFPs influence survival at subzero temperatures by modifying the freezing process or by acting as cryoprotectants. In order to inhibit the growth of ice, AFPs must be mobile so that they can bind to specific sites on the ice crystal lattice. Guttate obtained from cold-acclimated winter rye leaves exhibited antifreeze activity, indicating that the AFPs are free in solution. Infrared video thermography was used to observe freezing in winter rye leaves. In the absence of an ice nucleator, AFPs had no effect on the supercooling temperature of the leaves. However, in the presence of an ice nucleator, AFPs lowered the temperature at which the leaves froze by 0.3°C to 1.2°C. In vitro studies showed that apoplastic proteins extracted from cold-acclimated winter rye leaves inhibited the recrystallization of ice and also slowed the rate of migration of ice through solution-saturated filter paper. When we examined the possible role of winter rye AFPs in cryoprotection, we found that lactate dehydrogenase activity was higher after freezing in the presence of AFPs compared with buffer, but the same effect was obtained by adding bovine serum albumin. AFPs had no effect on unstacked thylakoid volume after freezing, but did inhibit stacking of the thylakoids, thus indicating a loss of thylakoid function. We conclude that rye AFPs have no specific cryoprotective activity; rather, they interact directly with ice in planta and reduce freezing injury by slowing the growth and recrystallization of ice. PMID:15805474

An Effective Antifreeze Protein Predictor with Ensemble Classifiers and Comprehensive Sequence Descriptors.

PubMed

Yang, Runtao; Zhang, Chengjin; Gao, Rui; Zhang, Lina

2015-09-07

Antifreeze proteins (AFPs) play a pivotal role in the antifreeze effect of overwintering organisms. They have a wide range of applications in numerous fields, such as improving the production of crops and the quality of frozen foods. Accurate identification of AFPs may provide important clues to decipher the underlying mechanisms of AFPs in ice-binding and to facilitate the selection of the most appropriate AFPs for several applications. Based on an ensemble learning technique, this study proposes an AFP identification system called AFP-Ensemble. In this system, random forest classifiers are trained by different training subsets and then aggregated into a consensus classifier by majority voting. The resulting predictor yields a sensitivity of 0.892, a specificity of 0.940, an accuracy of 0.938 and a balanced accuracy of 0.916 on an independent dataset, which are far better than the results obtained by previous methods. These results reveal that AFP-Ensemble is an effective and promising predictor for large-scale determination of AFPs. The detailed feature analysis in this study may give useful insights into the molecular mechanisms of AFP-ice interactions and provide guidance for the related experimental validation. A web server has been designed to implement the proposed method.

Snow depth evolution on sea ice from Snow Buoy measurement

NASA Astrophysics Data System (ADS)

Nicolaus, M.; Arndt, S.; Hendricks, S.; Hoppmann, M.; Katlein, C.; König-Langlo, G.; Nicolaus, A.; Rossmann, H. L.; Schiller, M.; Schwegmann, S.; Langevin, D.

2016-12-01

Snow cover is an Essential Climate Variable. On sea ice, snow dominates the energy and momentum exchanges across the atmosphere-ice-ocean interfaces, and actively contributes to sea ice mass balance. Yet, snow depth on sea ice is one of the least known and most difficult to observe parameters of the Arctic and Antarctic; mainly due to its exceptionally high spatial and temporal variability. In this study; we present a unique time series dataset of snow depth and air temperature evolution on Arctic and Antarctic sea ice recorded by autonomous instruments. Snow Buoys record snow depth with four independent ultrasonic sensors, increasing the reliability of the measurements and allowing for additional analyses. Auxiliary measurements include surface and air temperature, barometric pressure and GPS position. 39 deployments of such Snow Buoys were achieved over the last three years either on drifting pack ice, on landfast sea ice or on an ice shelf. Here we highlight results from two pairs of Snow Buoys installed on drifting pack ice in the Weddell Sea. The data reveals large regional differences in the annual cycle of snow depth. Almost no reduction in snow depth (snow melt) was observed in the inner and southern part of the Weddell Sea, allowing a net snow accumulation of 0.2 to 0.9 m per year. In contrast, summer snow melt close to the ice edge resulted in a decrease of about 0.5 m during the summer 2015/16. Another array of eight Snow Buoys was installed on central Arctic sea ice in September 2015. Their air temperature record revealed exceptionally high air temperatures in the subsequent winter, even exceeding the melting point but with almost no impact on snow depth at that time. Future applications of Snow Buoys on Arctic and Antarctic sea ice will allow additional inter-annual studies of snow depth and snow processes, e.g. to support the development of snow depth data products from airborne and satellite data or though assimilation in numerical models.

First detection of Candidatus Rickettsia barbariae in the flea Vermipsylla alakurt from north-western China.

PubMed

Zhao, Shan-Shan; Li, Hong-Yu; Yin, Xiao-Ping; Liu, Zhi-Qiang; Chen, Chuang-Fu; Wang, Yuan-Zhi

2016-06-07

Vermipsylla is a genus of the family Vermipsyllidae within the order Siphonaptera of fleas. Vermipsylla alakurt is mainly distributed in alpine pastoral areas of Kazakhstan, Mongolia, China and Nepal, and infests sheep, yaks and horses, causing irritation, poor condition, anaemia and even death. However, to date, no rickettsial agents have been reported in V. alakurt. A total of 133 fleas were collected directly from the tails of three sheep flocks (n = 335) in Minfeng County, Xinjiang Uygur Autonomous Region, north-western China. Of these, 55 fleas were identified by morphological examination and molecular analysis of four loci (the ribosomal 18S and 28S rDNA genes and the mitochondrial genes cytochrome  c oxidase subunit II and elongation factor 1-alpha). Eight Rickettsia-specific gene fragments originated from seven genes: the 17-kilodalton antigen gene (17-kDa), citrate synthase gene (gltA), 16S rRNA gene (rrs), outer membrane protein A gene (ompA), surface cell antigen 1 gene (sca1), PS120 protein gene (gene D), and outer membrane protein B gene (ompB, two fragments), were used to identify the species of Rickettsia in 53 fleas. The amplified products were sequenced and included in a phylogenetic analysis to verify the taxonomic identification of the rickettsial agents. Based on morphological and molecular evidence, the flea was identified as Vermipsylla alakurt. Nine samples were positive (16.98 %, 9/53) for Rickettsia spp. The phylogenetic tree revealed that the rickettsial agents found in V. alakurt cluster with Candidatus Rickettsia barbariae. Our study suggests that: (i) V. alakurt may serve as a carrier for Candidatus R. barbariae; and (ii) Candidatus R. barbariae, previously reported in Israel, is the eighth newly discovered validated Rickettsia species in China. This finding extends our knowledge of the distribution of Candidatus R. barbariae and the profile of carriers, which not only comprise ticks but also fleas.

Systematic size study of an insect antifreeze protein and its interaction with ice.

PubMed

Liu, Kai; Jia, Zongchao; Chen, Guangju; Tung, Chenho; Liu, Ruozhuang

2005-02-01

Because of their remarkable ability to depress the freezing point of aqueous solutions, antifreeze proteins (AFPs) play a critical role in helping many organisms survive subzero temperatures. The beta-helical insect AFP structures solved to date, consisting of multiple repeating circular loops or coils, are perhaps the most regular protein structures discovered thus far. Taking an exceptional advantage of the unusually high structural regularity of insect AFPs, we have employed both semiempirical and quantum mechanics computational approaches to systematically investigate the relationship between the number of AFP coils and the AFP-ice interaction energy, an indicator of antifreeze activity. We generated a series of AFP models with varying numbers of 12-residue coils (sequence TCTxSxxCxxAx) and calculated their interaction energies with ice. Using several independent computational methods, we found that the AFP-ice interaction energy increased as the number of coils increased, until an upper bound was reached. The increase of interaction energy was significant for each of the first five coils, and there was a clear synergism that gradually diminished and even decreased with further increase of the number of coils. Our results are in excellent agreement with the recently reported experimental observations.

Systematic Size Study of an Insect Antifreeze Protein and Its Interaction with Ice

PubMed Central

Liu, Kai; Jia, Zongchao; Chen, Guangju; Tung, Chenho; Liu, Ruozhuang

2005-01-01

Because of their remarkable ability to depress the freezing point of aqueous solutions, antifreeze proteins (AFPs) play a critical role in helping many organisms survive subzero temperatures. The β-helical insect AFP structures solved to date, consisting of multiple repeating circular loops or coils, are perhaps the most regular protein structures discovered thus far. Taking an exceptional advantage of the unusually high structural regularity of insect AFPs, we have employed both semiempirical and quantum mechanics computational approaches to systematically investigate the relationship between the number of AFP coils and the AFP-ice interaction energy, an indicator of antifreeze activity. We generated a series of AFP models with varying numbers of 12-residue coils (sequence TCTxSxxCxxAx) and calculated their interaction energies with ice. Using several independent computational methods, we found that the AFP-ice interaction energy increased as the number of coils increased, until an upper bound was reached. The increase of interaction energy was significant for each of the first five coils, and there was a clear synergism that gradually diminished and even decreased with further increase of the number of coils. Our results are in excellent agreement with the recently reported experimental observations. PMID:15713600

[Fleas from the nests of Passer domesticus and Passer montanus].

PubMed

Kaczmarek, S

1991-01-01

In the years 1986-1988 102 nests of Passer domesticus and 113 nests of P. montanus were collected from Słupsk, Warszawa and its surrounding. Ceratophyllus gallinae was found in 55 nests of P. domesticus and in 74 nests of P. montanus: C. fringillae in 13 nests of P. domesticus. The highest mean number of C. gallinae per nest was recorded in nest of P. domesticus (11.9), lower in nest of P. montanus (5.9). The highest percentage of nests with fleas and the highest mean number of fleas per nest were recorded in September in P. domesticus and in June, July and September in P. montanus. The highest (111) nests to be inhabited by 1-10 specimens. Number of specimens in nests was not depending on the weight nests.

Fleas, hosts and habitat: What can we predict about the spread of vector-borne zoonotic diseases?

Treesearch

Megan M. Friggens

2010-01-01

Vector-borne diseases of humans and wildlife are experiencing resurgence across the globe. I examine the dynamics of flea borne diseases through a comparative analysis of flea literature and analyses of field data collected from three sites in New Mexico: The Sevilleta National Wildlife Refuge, the Sandia Mountains and the Valles Caldera National Preserve (VCNP). My...

Efficacy of a Novel Topical Combination of Fipronil 9.8% and (S)-Methoprene 8.8% against Ticks and Fleas in Naturally Infested Dogs.

PubMed

Nambi, Ayyanampakkam Pandurangan; Rathi, Badal; S, Kavitha; Dudhatra, Ghanshyam; Yamini, Hamsa S; Ali Bhat, Abid

2016-01-01

The efficacy of a novel topical combination of fipronil 9.8% (w/v) and (S)-methoprene 8.8% (w/v) (Fiprofort® Plus) was tested against ticks and fleas in naturally infested dogs. A total of fifty dogs were allocated in the study with ticks infestation (n = 35) and fleas infestation (n = 15). On day 0, thirty-five tick and fifteen flea infested dogs received the test formulation, a combination of fipronil 9.8% (w/v) and (S)-methoprene 8.8% (w/v) spot-on solution. Ticks and flea counts were taken on days 0 (pretreatment) and 3, 7, 14, 21, 28, and 35 after treatment. Blood samples were collected for evaluation of haematological parameters on days 0 (pretreatment) and 7, 21, and 35 after treatment. All the adult ticks and fleas collected were identified as Rhipicephalus sanguineus and Ctenocephalides felis, respectively. The efficacy of spot-on formulation against ticks was 34.00% (day 3), 53.14% (day 7), 62.71% (day 14), 65.48% (day 21), 59.80% (day 28), and 58.82% (day 35), whereas against fleas it was 38.00% (day 3), 64.34% (day 7), 89.67% (day 14), 95.40% (day 21), 100.00% (day 28), and 100.00% (day 35). Haematological parameters for ticks and fleas infested dogs were statistically nonsignificant as compared to control. The combination of fipronil and (S)-methoprene eliminated the existing ticks and fleas infestation and prevented the dogs from flea and tick infestation for four weeks.

First report of a Rickettsia asembonensis related infecting fleas in Brazil.

PubMed

Silva, Arannadia Barbosa; Vizzoni, Vinicius Figueiredo; Costa, Andréa Pereira; Costa, Francisco Borges; Moraes-Filho, Jonas; Labruna, Marcelo Bahia; Gazêta, Gilberto Salles; de Maria Seabra Nogueira, Rita

2017-08-01

The present study was performed in a non-endemic area for spotted fever (SF) in Imperatriz microregion, state of Maranhão, Brazil. Blood samples and ectoparasites were collected from 300 dogs of the Imperatriz microregion. Canine serum samples were tested individually by indirect immunofluorescence assay (IFA), using five Rickettsia isolates from Brazil. Antibodies reactive to at least one of the five species of Rickettsia were detected in 1.6% of the dogs (5/300). These sera were considered reactive to Rickettsia rickettsii and Rickettsia amblyommatis or very closely related species. The ticks (Acari: Ixodidae), identified as Rhipicephalus sanguineus sensu lato (Latreille), and the fleas, identified as Ctenocephalides felis, were tested by polymerase chain reaction (PCR) for detection of rickettsial DNA. More than 78% (83/106) of the C. felis fleas were found to be infected with Rickettsia species using gltA as rickettsial PCR targets, whereas no evidence of Rickettsia spp. was found in R. sanguineus s. l. Genetic analysis based on genes gltA, htrA and ompB showed that the detected strain, is most closely related to Rickettsia asembonensis (formerly Candidatus Rickettsia asemboensis). The present study is the first report of a R. asembonensis related infecting C. felis fleas in Brazil. Copyright © 2017 Elsevier B.V. All rights reserved.

A small-scale open-label study of the treatment of canine flea allergy dermatitis with fluralaner.

PubMed

Fisara, Petr; Shipstone, Michael; von Berky, Andrew; von Berky, Janet

2015-12-01

Fluralaner is an isoxazoline systemic insecticide and acaricide that provides persistent flea-killing activity on dogs for 12 weeks. European and US field studies have shown that fluralaner treatment alleviates the signs of flea allergy dermatitis (FAD) in client-owned dogs. To assess the clinical response in FAD affected dogs over the 12-week period following a single oral fluralaner treatment. Twenty client-owned dogs were diagnosed with FAD on the basis of compatible clinical signs and a positive response in flea antigen tests, using intradermal and or serological methods. An open-label small-scale study with all dogs receiving a single oral fluralaner treatment. All enrolled dogs were diagnosed with FAD and then clinically monitored at 4-week intervals for 12 weeks. Twenty dogs completed the study. All dogs were flea-free at all post-treatment assessments except for one dog that had a single flea at the first post-enrollment assessment at 4 weeks. At the 4-week post-treatment assessment active FAD signs had resolved in all dogs; at 8 weeks post-treatment, two dogs showed mild signs. All clinical signs of FAD had resolved at the final assessment of 12 weeks after treatment. A single administration of fluralaner alleviated or resolved signs associated with FAD in all treated dogs over the recommended 12-week treatment period. © 2015 The Authors. Veterinary Dermatology published by John Wiley & Sons Ltd on behalf of Intervet Australia Pty Ltd.

Influence of sequential modifications and carbohydrate variations in synthetic AFGP analogues on conformation and antifreeze activity.

PubMed

Nagel, Lilly; Budke, Carsten; Erdmann, Roman S; Dreyer, Axel; Wennemers, Helma; Koop, Thomas; Sewald, Norbert

2012-10-01

Certain Arctic and Antarctic ectotherm species have developed strategies for survival under low temperature conditions that, among others, consist of antifreeze glycopeptides (AFGP). AFGP form a class of biological antifreeze agents that exhibit the ability to inhibit ice growth in vitro and in vivo and, hence, enable life at temperatures below the freezing point. AFGP usually consist of a varying number of (Ala-Ala-Thr)(n) units (n=4-55) with the disaccharide β-D-galactosyl-(1→3)-α-N-acetyl-D-galactosamine glycosidically attached to every threonine side chain hydroxyl group. AFGP have been shown to adopt polyproline II helical conformation. Although this pattern is highly conserved among different species, microheterogeneity concerning the amino acid composition usually occurs; for example, alanine is occasionally replaced by proline in smaller AFGP. The influence of minor and major sequence mutations on conformation and antifreeze activity of AFGP analogues was investigated by replacement of alanine by proline and glycosylated threonine by glycosylated hydroxyproline. The target compounds were prepared by using microwave-enhanced solid phase peptide synthesis. Furthermore, artificial analogues were obtained by copper-catalyzed azide-alkyne cycloaddition (CuAAC): propargyl glycosides were treated with polyproline helix II-forming peptides comprising (Pro-Azp-Pro)(n) units (n=2-4) that contained 4-azidoproline (Azp). The conformations of all analogues were examined by circular dichroism (CD). In addition, microphysical analysis was performed to provide information on their inhibitory effect on ice recrystallization. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Comprehensive Snow Density Model for Integrating Lidar-Derived Snow Depth Data into Spatial Snow Modeling

NASA Astrophysics Data System (ADS)

Marks, D. G.; Kormos, P.; Johnson, M.; Bormann, K. J.; Hedrick, A. R.; Havens, S.; Robertson, M.; Painter, T. H.

2017-12-01

Lidar-derived snow depths when combined with modeled or estimated snow density can provide reliable estimates of the distribution of SWE over large mountain areas. Application of this approach is transforming western snow hydrology. We present a comprehensive approach toward modeling bulk snow density that is reliable over a vast range of weather and snow conditions. The method is applied and evaluated over mountainous regions of California, Idaho, Oregon and Colorado in the western US. Simulated and measured snow density are compared at fourteen validation sites across the western US where measurements of snow mass (SWE) and depth are co-located. Fitting statistics for ten sites from three mountain catchments (two in Idaho, one in California) show an average Nash-Sutcliff model efficiency coefficient of 0.83, and mean bias of 4 kg m-3. Results illustrate issues associated with monitoring snow depth and SWE and show the effectiveness of the model, with a small mean bias across a range of snow and climate conditions in the west.

Snow Ecology

NASA Astrophysics Data System (ADS)

Jones, H. G.; Pomeroy, J. W.; Walker, D. A.; Hoham, R. W.

2001-01-01

In this volume, a multidisciplinary group of acknowledged experts fully intergrate the physical, chemical, and biological sciences to provide a complete understanding of the interrelationships between snow structure and life. This volume opens a new perspecitve on snow cover as a habitat for organisms under extreme environmental conditions and as a key factor in the ecology of much of the Earth's surface. The contributors describe the fundamental physical and small-scale chemical processes that characterize the evolution of snow and their influence on the life cycles of true snow organisms and the biota of cold regions with extended snow cover. The book further expands on the role of snow in the biosphere by the study of the relationship between snow and climate and the paleo-ecological evidence for the influence of past snow regimes on plant communities. Snow Ecology will form a main textbook on advanced courses in biology, ecology, geography, environmental science, and earth science where an important component is devoted to the study of the cryosphere. It will also be useful as a reference text for graduate students, researchers, and professionals at academic institutions and in government and nongovernmental agencies with environmental concerns.

Snow farming: conserving snow over the summer season

NASA Astrophysics Data System (ADS)

Grünewald, Thomas; Wolfsperger, Fabian; Lehning, Michael

2018-01-01

Summer storage of snow for tourism has seen an increasing interest in the last years. Covering large snow piles with materials such as sawdust enables more than two-thirds of the initial snow volume to be conserved. We present detailed mass balance measurements of two sawdust-covered snow piles obtained by terrestrial laser scanning during summer 2015. Results indicate that 74 and 63 % of the snow volume remained over the summer for piles in Davos, Switzerland and Martell, Italy. If snow mass is considered instead of volume, the values increase to 83 and 72 %. The difference is attributed to settling and densification of the snow. Additionally, we adapted the one-dimensional, physically based snow cover model SNOWPACK to perform simulations of the sawdust-covered snow piles. Model results and measurements agreed extremely well at the point scale. Moreover, we analysed the contribution of the different terms of the surface energy balance to snow ablation for a pile covered with a 40 cm thick sawdust layer and a pile without insulation. Short-wave radiation was the dominant source of energy for both scenarios, but the moist sawdust caused strong cooling by long-wave emission and negative sensible and latent heat fluxes. This cooling effect reduces the energy available for melt by up to a factor of 12. As a result only 9 % of the net short-wave energy remained available for melt. Finally, sensitivity studies of the parameters thickness of the sawdust layer, air temperature, precipitation and wind speed were performed. We show that sawdust thickness has a tremendous effect on snow loss. Higher air temperatures and wind speeds increase snow ablation but less significantly. No significant effect of additional precipitation could be found as the sawdust remained wet during the entire summer with the measured quantity of rain. Setting precipitation amounts to zero, however, strongly increased melt. Overall, the 40 cm sawdust provides sufficient

Modelling the current distribution and predicted spread of the flea species Ctenocephalides felis infesting outdoor dogs in Spain.

PubMed

Gálvez, Rosa; Musella, Vicenzo; Descalzo, Miguel A; Montoya, Ana; Checa, Rocío; Marino, Valentina; Martín, Oihane; Cringoli, Giuseppe; Rinaldi, Laura; Miró, Guadalupe

2017-09-19

The cat flea, Ctenocephalides felis, is the most prevalent flea species detected on dogs and cats in Europe and other world regions. The status of flea infestation today is an evident public health concern because of their cosmopolitan distribution and the flea-borne diseases transmission. This study determines the spatial distribution of the cat flea C. felis infesting dogs in Spain. Using geospatial tools, models were constructed based on entomological data collected from dogs during the period 2013-2015. Bioclimatic zones, covering broad climate and vegetation ranges, were surveyed in relation to their size. The models builded were obtained by negative binomial regression of several environmental variables to show impacts on C. felis infestation prevalence: land cover, bioclimatic zone, mean summer and autumn temperature, mean summer rainfall, distance to urban settlement and normalized difference vegetation index. In the face of climate change, we also simulated the future distributions of C. felis for the global climate model (GCM) "GFDL-CM3" and for the representative concentration pathway RCP45, which predicts their spread in the country. Predictive models for current climate conditions indicated the widespread distribution of C. felis throughout Spain, mainly across the central northernmost zone of the mainland. Under predicted conditions of climate change, the risk of spread was slightly greater, especially in the north and central peninsula, than for the current situation. The data provided will be useful for local veterinarians to design effective strategies against flea infestation and the pathogens transmitted by these arthropods.

Seasonal and among-site variation in the occurrence and abundance of fleas on California ground squirrels (Otospermophilus beecheyi).

PubMed

Hubbart, Jason A; Jachowski, David S; Eads, David A

2011-06-01

An improved understanding of the ecology of fleas on California ground squirrels, Otospermophilus beecheyi, is warranted given the role of fleas in the transmission, and perhaps persistence, of the plague-causing bacterium Yersinia pestis. We sampled O. beecheyi on a seasonal basis from three study sites, each representing a different land use type (preserve, pasture, and agriculture) in the San Joaquin Valley, CA. Overall, the abundance of fleas on squirrels was greatest in spring at the preserve site, in summer at the agriculture and pasture sites, and in winter at the pasture site. Hoplopsyllus anomalus, the species most frequently found on squirrels, was most abundant in spring at the preserve site and in summer at the agriculture and pasture sites. Oropsylla montana was most abundant in winter at the pasture site and on adult squirrels. Echidnophaga gallinacea was most abundant in fall on juvenile squirrels at the preserve site. All three flea species we encountered are known to be potential vectors of Y. pestis. Future efforts to predict flea species occurrence and abundance (and plague risk) at sites of concern should consider seasonal microclimatic conditions and the potential influence of human land use practices. © 2011 The Society for Vector Ecology.

Ectoparasites in urban stray cats in Jerusalem, Israel: differences in infestation patterns of fleas, ticks and permanent ectoparasites.

PubMed

Salant, H; Mumcuoglu, K Y; Baneth, G

2014-09-01

In a period cross-sectional study performed to examine ectoparasites on 340 stray cats in Jerusalem, Israel, 186 (54.7%) were infested with the cat flea, Ctenocephalides felis (Siphonaptera: Pulicidae), 49 (14.4%) with the cat louse, Felicola subrostratus (Phthiraptera: Trichodectidae), 41 (12.0%) with the ear mite, Otodectes cynotis (Astigmata: Psoroptidae), three (0.9%) with the fur mite, Cheyletiella blakei (Trobidiformes: Cheyletidae), two (0.6%) with the itch mite Notoedres cati (Astigmata: Sarcoptidae), and 25 (7.3%) with ticks of the species Rhipicephalus sanguineus sensu lato (Ixodida: Ixodidae), Rhipicephalus turanicus or Haemaphysalis adleri (Ixodida: Ixodidae). A higher number of flea infestations was observed in apparently sick cats (P < 0.05) and in cats aged < 6 months (P < 0.05). The proportion of flea-infested cats (P < 0.01), as well as the number of fleas per infested cat (P < 0.01), was higher in autumn than in other seasons. By contrast with findings in cats with flea infestations, rates of infestation with ticks were higher amongst cats with clinical signs (P < 0.01) and cats aged ≥ 6 months (P < 0.05). The high rates of ectoparasite infestation in the cats studied constitute a risk for the spread of vector-borne infections of zoonotic and veterinary importance. © 2013 The Royal Entomological Society.

A review of plague persistence with special emphasis on fleas

USGS Publications Warehouse

Wimsatt, Jeffrey; Biggins, Dean E.

2009-01-01

Here, we note a potentially pivotal role for fleas. These epizootic plague vectors should be closely studied with newer more exacting methods to determine their potential to serve as participants in or accomplices to a plague persistence reservoir.

Molecular Recognition of Methyl α-d-Mannopyranoside by Antifreeze (Glyco)Proteins

PubMed Central

2015-01-01

Antifreeze proteins and glycoproteins [AF(G)Ps] have been well-known for more than three decades for their ability to inhibit the growth and recrystallization of ice through binding to specific ice crystal faces, and they show remarkable structural compatibility with specific ice crystal faces. Here, we show that the crystal growth faces of methyl α-d-mannopyranoside (MDM), a representative pyranose sugar, also show noteworthy structural compatibility with the known periodicities of AF(G)Ps. We selected fish AFGPs (AFGP8, AFGP1–5), and a beetle AFP (DAFP1) with increasing antifreeze activity as potential additives for controlling MDM crystal growth. Similar to their effects on ice growth, the AF(G)Ps can inhibit MDM crystal growth and recrystallization, and more significantly, the effectiveness for the AF(G)Ps are well correlated with their antifreeze activity. MDM crystals grown in the presence of AF(G)Ps are smaller and have better defined shapes and are of higher quality as indicated by single crystal X-ray diffraction and polarized microscopy than control crystals, but no new polymorphs of MDM were identified by single crystal X-ray diffraction, solid-state NMR, and attenuated total reflectance infrared spectroscopy. The observed changes in the average sizes of the MDM crystals can be related to the changes in the number of the MDM nuclei in the presence of the AF(G)Ps. The critical free energy change differences of the MDM nucleation in the absence and presence of the additives were calculated. These values are close to those of the ice nucleation in the presence of AF(G)Ps suggesting similar interactions are involved in the molecular recognition of MDM by the AF(G)Ps. To our knowledge this is the first report where AF(G)Ps have been used to control crystal growth of carbohydrates and on AFGPs controlling non-ice-like crystals. Our finding suggests MDM might be a possible alternative to ice for studying the detailed mechanism of AF

Observed Differences between North American Snow Extent and Snow Depth Variability

NASA Astrophysics Data System (ADS)

Ge, Y.; Gong, G.

2006-12-01

Snow extent and snow depth are two related characteristics of a snowpack, but they need not be mutually consistent. Differences between these two variables at local scales are readily apparent. However at larger scales which interact with atmospheric circulation and climate, snow extent is typically the variable used, while snow depth is often assumed to be minor and/or mutually consistent compared to snow extent, though this is rarely verified. In this study, a new regional/continental-scale gridded dataset derived from field observations is utilized to quantitatively evaluate the relationship between snow extent and snow depth over North America. Various statistical methods are applied to assess the mutual consistency of monthly snow depth vs. snow extent, including correlations, composites and principal components. Results indicate that snow depth variations are significant in their own rights, and that depth and extent anomalies are largely unrelated, especially over broad high latitude regions north of the snowline. In the vicinity of the snowline, where precipitation and ablation can affect both snow extent and snow depth, the two variables vary concurrently, especially in autumn and spring. It is also found that deeper winter snow translates into larger snow-covered area in the subsequent spring/summer season, which suggests a possible influence of winter snow depth on summer climate. The observed lack of mutual consistency at continental/regional scales suggests that snowpack depth variations may be of sufficiently large magnitude, spatial scope and temporal duration to influence regional-hemispheric climate, in a manner unrelated to the more extensively studied snow extent variations.

Predicting small mammal and flea abundance using landform and soil properties in a plague endemic area in Lushoto District, Tanzania.

PubMed

Meliyo, Joel L; Kimaro, Didas N; Msanya, Balthazar M; Mulungu, Loth S; Hieronimo, Proches; Kihupi, Nganga I; Gulinck, Hubert; Deckers, Jozef A

2014-07-01

Small mammals particularly rodents, are considered the primary natural hosts of plague. Literature suggests that plague persistence in natural foci has a root cause in soils. The objective of this study was to investigate the relationship between on the one hand landforms and associated soil properties, and on the other hand small mammals and fleas in West Usambara Mountains in Tanzania, a plague endemic area. Standard field survey methods coupled with Geographical Information System (GIS) technique were used to examine landform and soils characteristics. Soil samples were analysed in the laboratory for physico-chemical properties. Small mammals were trapped on pre-established landform positions and identified to genus/species level. Fleas were removed from the trapped small mammals and counted. Exploration of landform and soil data was done using ArcGIS Toolbox functions and descriptive statistical analysis. The relationships between landforms, soils, small mammals and fleas were established by generalised linear regression model (GLM) operated in R statistics software. Results show that landforms and soils influence the abundance of small mammals and fleas and their spatial distribution. The abundance of small mammals and fleas increased with increase in elevation. Small mammal species richness also increases with elevation. A landform-soil model shows that available phosphorus, slope aspect and elevation were statistically significant predictors explaining richness and abundance of small mammals. Fleas' abundance and spatial distribution were influenced by hill-shade, available phosphorus and base saturation. The study suggests that landforms and soils have a strong influence on the richness and evenness of small mammals and their fleas' abundance hence could be used to explain plague dynamics in the area.

Efficacy of fluralaner flavored chews (Bravecto) administered to dogs against the adult cat flea, Ctenocephalides felis felis and egg production.

PubMed

Dryden, Michael W; Smith, Vicki; Bennett, Tashina; Math, Lisa; Kallman, James; Heaney, Kathleen; Sun, Fangshi

2015-07-11

Fluralaner is a potent insecticide and acaricide with rapid and persistent efficacy. This study measured the efficacy of fluralaner flavored chews (Bravecto®, Merck Animal Health) administered to dogs against adult Ctenocephalides felis felis and egg production. Twelve purpose-bred dogs were randomly allocated to two groups of six dogs each. Dogs in treatment group 1 were administered a single fluralaner flavored chew to achieve a minimum dose of at least 25 mg/kg while treatment group 2 served as untreated controls. On Days -2, 28, 56, 84, 91, 98, 105, 112, and 120 post-treatment, each dog was infested with approximately 200 unfed cat fleas, C. felis felis (KS1 strain). Forty-eight hours after treatment and 48 h after each infestation, eggs were collected over a 3-h period, counted and viability determined. Dogs were combed to remove any remaining fleas. Treatment of dogs with oral fluralaner provided a 100% reduction in flea counts 48 h after treatment and within 48 h of every post-treatment infestation through Day122. Egg production from fluralaner treated dogs was reduced by 99.9% (two eggs from one dog) within 48 h after treatment and not a single egg (100% efficacy) was thereafter collected from treated dogs. Adult flea counts and egg production from the fluralaner-treated dogs were significantly lower than for non-treated controls at all post-treatment evaluations (P < 0.001). The two eggs collected from the single treated dog 48 h after treatment did not produce any adult fleas. As no additional eggs were collected from treated dogs, no viability assessment was performed. A single oral dose of fluralaner flavored chews provided 100% efficacy against repeated flea infestations on dogs for 4 months. Fluralaner reduced egg production of activity reproducing female fleas by 99.9% and then killed every single female flea before any eggs could be produced following each subsequent re-infestation for the entire 122-day evaluation period.

Snow cover and snow goose Anser caerulescens caerulescens distribution during spring migration

USGS Publications Warehouse

Hupp, Jerry W.; Zacheis, Amy B.; Anthony, R. Michael; Robertson, Donna G.; Erickson, Wallace P.; Palacios, Kelly C.

2001-01-01

Arctic geese often use spring migration stopover areas when feeding habitats are partially snow covered. Melting of snow during the stopover period causes spatial and temporal variability in distribution and abundance of feeding habitat. We recorded changes in snow cover and lesser snow goose Anser caerulescens caerulescens distribution on a spring migration stopover area in south-central Alaska during aerial surveys in 1993-1994. Our objectives were to determine whether geese selected among areas with different amounts of snow cover and to assess how temporal changes in snow cover affected goose distribution. We also measured temporal changes in chemical composition of forage species after snow melt. We divided an Arc/Info coverage of the approximately 210 km2 coastal stopover area into 2-km2 cells, and measured snow cover and snow goose use of cells. Cells that had 10-49.9% snow cover were selected by snow geese, whereas cells that lacked snow cover were avoided. In both years, snow cover diminished along the coast between mid-April and early May. Flock distribution changed as snow geese abandoned snow-free areas in favour of cells where snow patches were interspersed with bare ground. Snow-free areas may have been less attractive to geese because available forage had been quickly exploited as bare ground was exposed, and because soils became drier making extraction of underground forage more difficult. Fiber content of two forage species increased whereas non-structural carbohydrate concentrations of forage plants appeared to diminish after snow melt, but changes in nutrient concentrations likely occurred too slowly to account for abandonment of snow-free areas by snow geese.

NOHRSC Interactive Snow Information

Science.gov Websites

-present) RFC Basin Other (non-RFC) Basin State NSA region (Discussion) NSA subregion (Disc.) Basins by None Snow Water Equivalent Snow Depth Shallow SWE Shallow Snow Depth Snow Temperature Snow Density Snow Melt Snow Precipitation Non-Snow Precipitation Air Temperature Solar Radiation Relative Humidity

Identification of the Rdl mutation in laboratory and field strains of the cat flea, Ctenocephalides felis (Siphonaptera: Pulicidae).

PubMed

Bass, Chris; Schroeder, Iris; Turberg, Andreas; Field, Linda M; Williamson, Martin S

2004-12-01

In many insect species, resistance to cyclodiene insecticides is caused by amino acid substitutions at a single residue (A302) within the M2 transmembrane region of the gamma-aminobutyric acid (GABA) receptor sub-unit termed Rdl (resistance to dieldrin). These mutations (A302S and A302G) have also been shown to confer varying levels of cross-resistance to fipronil, a phenylpyrazole insecticide with a similar mode of action to cyclodienes. To investigate the possible occurrence of these mutations in the cat flea, Ctenocephalides felis (Bouché), a 176-bp fragment of the cat flea Rdl gene, encompassing the mutation site, was PCR amplified and sequenced from nine laboratory flea strains. The A302S mutation was found in eight of the nine strains analysed, although the relative frequency of the mutant allele varied between strains. Only one strain (R6) was found to be homozygous for the S302 allele in all the individuals tested, and this correlated with previous reports of low-level fipronil resistance in this strain. A PCR-based diagnostic assay, capable of screening individual fleas for this mutation, was developed and used to survey a range of fleas collected at random from veterinary clinics in the UK and USA. The A302S mutation was present at a high frequency in these domestic pet populations. 2004 Society of Chemical Industry.

Calculation of new snow densities from sub-daily automated snow measurements

NASA Astrophysics Data System (ADS)

Helfricht, Kay; Hartl, Lea; Koch, Roland; Marty, Christoph; Lehning, Michael; Olefs, Marc

2017-04-01

In mountain regions there is an increasing demand for high-quality analysis, nowcasting and short-range forecasts of the spatial distribution of snowfall. Operational services, such as for avalanche warning, road maintenance and hydrology, as well as hydropower companies and ski resorts need reliable information on the depth of new snow (HN) and the corresponding water equivalent (HNW). However, the ratio of HNW to HN can vary from 1:3 to 1:30 because of the high variability of new snow density with respect to meteorological conditions. In the past, attempts were made to calculate new snow densities from meteorological parameters mainly using daily values of temperature and wind. Further complex statistical relationships have been used to calculate new snow densities on hourly to sub-hourly time intervals to drive multi-layer snow cover models. However, only a few long-term in-situ measurements of new snow density exist for sub-daily time intervals. Settling processes within the new snow due to loading and metamorphism need to be considered when computing new snow density. As the effect of these processes is more pronounced for long time intervals, a high temporal resolution of measurements is desirable. Within the pluSnow project data of several automatic weather stations with simultaneous measurements of precipitation (pluviometers), snow water equivalent (SWE) using snow pillows and snow depth (HS) measurements using ultrasonic rangers were analysed. New snow densities were calculated for a set of data filtered on the basis of meteorological thresholds. The calculated new snow densities were compared to results from existing new snow density parameterizations. To account for effects of settling of the snow cover, a case study based on a multi-year data set using the snow cover model SNOWPACK at Weissfluhjoch was performed. Measured median values of hourly new snow densities at the different stations range from 54 to 83 kgm-3. This is considerably lower than a 1

Snow Water Equivalent Pressure Sensor Performance in a Deep Snow Cover

NASA Astrophysics Data System (ADS)

Johnson, J. B.; Gelvin, A. B.; Schaefer, G. L.

2006-12-01

Accurate measurements of snow water equivalent are important for a variety of water resource management operations. In the western US, real-time SWE measurements are made using snow pillows that can experience errors from snow-bridging, poor installation configuration, and enhanced solar radiation absorption. Snow pillow installations that place the pillow abnormally above or below the surrounding terrain can affect snow catchment. Snow pillows made from dark materials can preferentially absorb solar radiation penetrating the snow causing accelerated melt. To reduce these problems, the NRCS and CRREL developed an electronic SWE sensor to replace the snow pillow. During the winter of 2005-2006 the NRCS/CRREL electronic sensor was deployed at Hogg Pass, Oregon, with a total SWE accumulation of about 1000 mm. The NRCS/CRREL sensor consists of a center panel surrounded by eight outer panels whose purpose is to buffer snow bridging loads. By separately monitoring load cell outputs from the sensor, snow-bridging events are directly measured. A snow-bridging event associated with a 180 mm SWE accumulation in a 24-hour period exhibited a SWE over-measurement of 60% at the sensor edge while the center panel showed less than a 10% effect. Individual load cell outputs were used to determine the most representative SWE value, which was within 5% of the adjacent snow pillow value. During the spring melt the NRCS/CRREL sensor melt recession lagged that of the snow pillow by about a week. Physical examination of the Hogg Pass site indicated that the CRREL sensor results were consistent with snow-on-the-ground observations. The snow pillow experienced accelerated melt because it was installed on a mound above the surrounding terrain and absorbed solar radiation through the snow. SWE pressure sensor accuracy is significantly improved by using an active center panel surrounded by buffer panels, monitoring several individual load cell to detect and correct snow-bridging errors, and

An update on the distribution and nomenclature of fleas (Order Siphonaptera) of bats (Order Chiroptera) and rodents (Order Rodentia) from La Rioja Province, Argentina

PubMed Central

Berrizbeitia, M. Fernanda López; Sánchez, R. Tatiana; Barquez, Ruben M.; Díaz, M. Monica

2017-01-01

Abstract The mammalian and flea fauna of La Rioja Province is one of the least known from northwestern Argentina. In this study, the distribution and nomenclature of 13 species of fleas of bats and rodents from La Rioja Province are updated. Four species of fleas are recorded for the first time in La Rioja Province including a new record for northwestern Argentina, and two new flea-host associations. An identification key and distribution map are included for all known species of Siphonaptera of bats and rodents from La Rioja Province, Argentina. PMID:28769701

High Prevalence of Rickettsia spp. in Dog Fleas (Siphonaptera: Pulicidae) in Rural Uganda.

PubMed

Palomar, Ana M; Cevidanes, Aitor; Portillo, Aránzazu; Kalema-Zikusoka, Gladis; Chirife, Andrea D; Romero, Lourdes; Muro, Jesús; Mugisha, Lawrence; Oteo, José A; Millán, Javier

2017-07-01

Fleas are known vectors of zoonotic agents. Thirty-five fleas, including 28 Ctenocephalides felis (Bouché), four Pulex irritans (L.), and three Echidnophaga gallinacea (Westwood) from 19 rural dogs from southwestern Uganda were analyzed for the presence of Rickettsia spp. (ompB, gltA, and 17 kDa fragment genes) and Bartonella spp. (rpoB and ITS genes) by PCR. Rickettsial DNA was detected in 27 out of 28 of Ct. felis and in two out of four P. irritans. None of the E. gallinacea specimens harbored Rickettsia DNA. Rickettsia felis was confirmed in 12 Ct. felis and in the two P. irritans specimens with positive PCR-results. In addition, the presence of Candidatus Rickettsia asemboensis was evidenced in 15 Ct. felis. Bartonella spp. was not amplified in any sample. Our survey indicates that R. felis, the agent of the flea-borne spotted fever, is present in the study area. Besides, this is the first description of Ca. R. asemboensis in Uganda. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Bartonella, Rodents, Fleas and Ticks: a Molecular Field Study on Host-Vector-Pathogen Associations in Saxony, Eastern Germany.

PubMed

Silaghi, Cornelia; Pfeffer, Martin; Kiefer, Daniel; Kiefer, Matthias; Obiegala, Anna

2016-11-01

Bartonellae cause zoonotic diseases and are transmitted by arthropods. Rodents are reservoirs for most Bartonella spp. As the knowledge about Bartonella in rodents and their parasitizing ectoparasites is scarce in Germany, this study's objectives were to investigate Bartonella spp. in small mammals and in their ectoparasites. A total of 79 small mammals (seven species) were captured and their ectoparasites collected at seven sites around Leipzig, Saxony, Germany, in 2010 and 2011. Altogether, 79 spleen samples, 135 fleas (five species) and 365 ticks (three species) were investigated for Bartonella spp. by PCR targeting the ITS 16S-23S rRNA region. In total, 52 (65.8 %) small mammals, 73 (54.1 %) fleas and 51 (16.3 %) ticks were positive for Bartonella spp. Most small mammals were positive for uncultured Bartonella sp. (n = 29) followed by Bartonella grahamii (n = 12), Bartonella taylorii (n = 8) and Bartonella sp. N40 (n = 3). Likewise, most fleas were positive for uncultured Bartonella sp. (n = 45) followed by B. grahamii (n = 14), B. taylorii (n = 8), B. sp. N40 (n = 5) and Bartonella elizabethae (n = 2). Most ticks were positive for B. sp. (n = 19) followed by B. grahamii (n = 10), Bartonella chomelii (n = 3), B. taylorii (n = 2) and B. sp. N40 (n = 1). This study's results suggest that rodents and fleas may be reservoirs and vectors, respectively. Zoonotic B. grahamii and B. elizabethae were found in rodents and their fleas. Therefore, humans may contract Bartonella infection by contact to wild rodents. Ticks seem of minor importance in transmitting Bartonella spp. found in fleas and rodents. However, ticks might be vectors of B. chomelii.

Evaluation of fluralaner and afoxolaner treatments to control flea populations, reduce pruritus and minimize dermatologic lesions in naturally infested dogs in private residences in west central Florida USA.

PubMed

Dryden, Michael W; Canfield, Michael S; Kalosy, Kimberly; Smith, Amber; Crevoiserat, Lisa; McGrady, Jennifer C; Foley, Kaitlin M; Green, Kathryn; Tebaldi, Chantelle; Smith, Vicki; Bennett, Tashina; Heaney, Kathleen; Math, Lisa; Royal, Christine; Sun, Fangshi

2016-06-28

A study was conducted to evaluate and compare the effectiveness of two different oral flea and tick products to control flea infestations, reduce pruritus and minimize dermatologic lesions over a 12 week period on naturally infested dogs in west central FL USA. Thirty-four dogs with natural flea infestations living in 17 homes were treated once with a fluralaner chew on study day 0. Another 27 dogs living in 17 different homes were treated orally with an afoxolaner chewable on day 0, once between days 28-30 and once again between days 54-60. All products were administered according to label directions by study investigators. Flea populations on pets were assessed using visual area counts and premise flea infestations were assessed using intermittent-light flea traps on days 0, 7, 14, 21, and once between days 28-30, 40-45, 54-60 and 82-86. Dermatologic assessments were conducted on day 0 and once monthly. Pruritus assessments were conducted by owners throughout the study. No concurrent treatments for existing skin disease (antibiotics, anti-inflammatories, anti-fungals) were allowed. Following the first administration of fluralaner or afoxolaner, flea populations on pets were reduced by 99.0 % and 99.3 %, respectively within 7 days. Flea populations on the fluralaner treated dogs were 0 (100 % efficacy) on days 54-60 and 82-86 after the administration of a single dose on day 0. Administration of 3 monthly doses of afoxolaner reduced flea populations by 100 % on days 82-86. Flea numbers in indoor-premises were markedly reduced in both treatment groups by days 82-86, with 100 % and 98.9 % reductions in flea trap counts in the fluralaner and afoxolaner treatment groups, respectively. Marked improvement was observed in FAD lesion scoring, Atopic Dermatitis lesions scoring (CADESI-4) and pruritus scores with both formulations. In a clinical field investigation conducted during the summer of 2015 in subtropical Florida, a single administration of an oral

Evaluation of indoxacarb and fipronil (s)-methoprene topical spot-on formulations to control flea populations in naturally infested dogs and cats in private residences in Tampa FL. USA

PubMed Central

2013-01-01

Background A study was conducted to evaluate and compare the effectiveness of two different spot-on topical flea products to control flea infestations on naturally infested dogs and cats in Tampa, FL USA. Methods Thirty-two dogs and 3 cats with natural flea infestations living in 18 homes were treated topically with a 19.53% w/w spot-on formulation of indoxacarb. Another thirty dogs and 2 cats living in 19 different homes were treated topically with either fipronil (9.8% w/w)/(s)-methoprene (8.89% w/w) or fipronil (9.8% w/w)/(s)-methoprene (11.8% w/w), respectively. All products were applied according to label directions by study investigators on day 0 and again between days 28 and 30. Flea populations on pets were assessed using visual area counts and premise flea infestations were assessed using intermittent-light flea traps on days 0, 7, 14, 21, 28–30, 40–45, and 54–60. Results A single application of the indoxacarb or fipronil (s)-methoprene formulations reduced flea populations on pets by 97.8% and 85.5%, respectively within 7 days. One month (28–30 days) after treatment the indoxacarb and fipronil (s)-methoprene formulations reduced on-animal flea burdens by 95.0% and 49.5%, respectively. Following two monthly applications of either the indoxacarb or fipronil (s)-methoprene formulations, pet flea burdens were reduced by 99.1% and 54.8%, respectively, by days 54 – 60. At the end of the two month study, 77.1% and 15.6% of the dogs and cats in the indoxacarb and fipronil (s)-methoprene treatment groups, respectively were flea free. Flea numbers in the indoor-premises were markedly reduced in both treatment groups by days 54–60, with 97.7% and 84.6% reductions in intermittent-light flea trap counts in the indoxacarb and fipronil (s)-methoprene treatment groups, respectively. Conclusions This in-home investigation conducted during the summer of 2013 in subtropical Tampa, FL, is the first published U.S field investigation of the indoxacarb topical

A field trial of a fixed combination of permethrin and fipronil (Effitix®) for the treatment and prevention of flea infestation in dogs living with sheep.

PubMed

Chatzis, Manolis K; Psemmas, Dimitris; Papadopoulos, Elias; Navarro, Christelle; Saridomichelakis, Manolis N

2017-04-28

A large number of fleas parasitize dogs living with sheep in Greece. The primary aim of this randomized, blinded, placebo-controlled trial was to examine the efficacy of a permethrin-fipronil combination (Effitix ® ) for the treatment and prevention of flea infestation in dogs living with sheep and the secondary aim was to examine the efficacy of this intervention on flea infestation, pruritus and skin lesions of the people in contact with these dogs. Thirty dogs living with sheep and infested by at least 10 fleas and all 80 sheep living on the same premises were randomly allocated into equal groups. Group A dogs were treated three times, every 4 weeks, with a spot-on containing 54.5% permethrin and 6.1% fipronil, group A sheep were treated, on the same days, with a pour-on containing 1% deltamethrin, whereas group B dogs were sham-treated and group B sheep were placebo-treated. Flea counting was performed at the beginning of the trial (day 0) and after 14, 28, 56 and 84 days and the first five fleas from each animal were used for species identification. At the same time points, flea infestation, pruritus and skin lesions of the people in contact with the dogs were assessed. The percentage of dogs with zero flea counts was significantly higher in group A than in group B on days 14, 28, 56 and 84 and flea counts were significantly lower in group A dogs than in group B dogs at the same time points. The percent efficacy of the permethrin-fipronil combination was higher than 78% (arithmetic means) or than 96% (geometric means) throughout the study. No adverse reactions were recorded. Between the two flea species found on dogs, Ctenocephalides canis was predominant over C. felis. Flea-infected sheep were not found at the beginning or during the study and no significant changes in flea infestation, pruritus and skin lesions of the people in contact with the dogs were witnessed throughout the study. A spot-on solution containing 54.5% permethrin and 6.1% fipronil is

Efficacy and safety of sarolaner (Simparica™) against fleas on dogs presented as veterinary patients in the United States.

PubMed

Cherni, Judith A; Mahabir, Sean P; Six, Robert H

2016-05-30

The efficacy and safety of a novel isoxazoline parasiticide, sarolaner (Simparica™), for the control of fleas on dogs was evaluated in a randomized, controlled clinical study conducted in 19 general veterinary practices throughout the United States. Four hundred and seventy nine (479) dogs from 293 households were enrolled. Each household was randomly assigned to treatment with either sarolaner oral tablets (Simparica™, Zoetis) at the proposed label dose or an approved comparator product at the label dose (spinosad, Comfortis(®), Elanco). Dogs were dosed by their owners at home on Day 0 and on approximately Days 30 and 60. Dogs were examined at the clinics for general health, flea and tick infestation, and clinical signs of flea allergy dermatitis (FAD) at the initial visit and Days 14, 30, 60 and 90. Blood was collected for clinical pathology at screening and Day 90. Sarolaner was well-accepted by dogs with the majority of flavored chewable tablets (91.5%) accepted free choice, by hand or in food. Geometric mean live flea counts were reduced by >99% at the first time measured (14 days) after initiation of treatment and continued to reduce through the study. Treatment success (proportion of dogs with ≥90% reduction in fleas) for the sarolaner-treated dogs was superior to that for spinosad-treated dogs at Days 14 and 30 and non-inferior on Days 60 and 90 (P≤0.025) The rapid reduction in flea infestations resulted in a similar rapid resolution of the clinical signs associated with FAD. Sarolaner chewable tablets were well tolerated with no treatment related adverse reactions. Most of the clinical signs reported were consistent with allergies and dermatitis or sporadic occurrences of conditions commonly observed in the general dog population. A wide variety of concomitant medications, including many commercially available heartworm preventatives and other anthelmintic drugs, were administered to study dogs and all were well tolerated. Sarolaner administered

Detection of Rickettsia in Rhipicephalus sanguineus Ticks and Ctenocephalides felis Fleas from Southeastern Tunisia by Reverse Line Blot Assay

PubMed Central

Khrouf, Fatma; M'Ghirbi, Youmna; Znazen, Abir; Ben Jemaa, Mounir; Hammami, Adnene

2014-01-01

Ticks (n = 663) and fleas (n = 470) collected from domestic animals from southeastern Tunisia were screened for Rickettsia infection using reverse line blot assay. Evidence of spotted fever group Rickettsia was obtained. We detected Rickettsia felis in fleas, Rickettsia massiliae Bar 29 and the Rickettsia conorii Israeli spotted fever strain in ticks, and Rickettsia conorii subsp. conorii and Rickettsia spp. in both arthropods. The sensitivity of the adopted technique allowed the identification of a new association between fleas and R. conorii subsp. conorii species. The presence of these vector-borne Rickettsia infections should be considered when diagnosing this disease in humans in Tunisia. PMID:24226919

Operation of Kelvin Effect in the Activities of an Antifreeze Protein: A Molecular Dynamics Simulation Study.

PubMed

Midya, Uday Sankar; Bandyopadhyay, Sanjoy

2018-03-29

Ice growth and melting inhibition activities of antifreeze proteins (AFPs) are better explained by the adsorption-inhibition mechanism. Inhibition occurs as a result of the Kelvin effect induced by adsorbed protein molecules onto the surface of seed ice crystal. However, the Kelvin effect has not been explored by the state-of-the-art experimental techniques. In this work, atomistic molecular dynamics simulations have been carried out with Tenebrio molitor antifreeze protein ( TmAFP) placed at ice-water interface to probe the Kelvin effect in the mechanism of AFPs. Simulations show that, below equilibrium melting temperature, ice growth is inhibited through the convex ice-water interface formation toward the water phase and, above equilibrium melting temperature, ice melting is inhibited through the concave ice-water interface formation inward to ice phase. Simulations further reveal that the radius of curvature of the interface formed to stop the ice growth increases with decrease in the degree of supercooling. Our results are in qualitative agreement with the theoretical prediction of the Kelvin effect and thus reveal its operation in the activities of AFPs.

Optimum Number of Anchored Clathrate Water and Its Instantaneous Fluctuations Dictate Ice Plane Recognition Specificities of Insect Antifreeze Protein.

PubMed

Chakraborty, Sandipan; Jana, Biman

2018-03-29

Ice recognition by antifreeze proteins (AFPs) is a subject of topical interest. Among several classes of AFPs, insect AFPs are hyperactive presumably due to their ability to adsorb on basal plane. However, the origin of the basal plane binding specificity is not clearly known. Present work aims to provide atomistic insight into the origin of basal plane recognition by an insect antifreeze protein. Free energy calculations reveal that the order of binding affinity of the AFP toward different ice planes is basal plane > prism plane > pyramidal plane. Critical insight reveals that the observed plane specificity is strongly correlated with the number and their instantaneous fluctuations of clathrate water forming hydrogen bonds with both ice binding surface (IBS) of AFP and ice surface, thus anchoring AFP to the ice surface. On basal plane, anchored clathrate water array is highly stable due to exact match in the periodicity of oxygen atom repeat distances of the ice surface and the threonine repeat distances at the IBS. The stability of anchored clathrate water array progressively decreases upon prism and pyramidal plane adsorption due to mismatch between the threonine ladder and oxygen atom repeat distance. Further analysis reveals that hydration around the methyl side-chains of threonine residues becomes highly significant at low temperature which stabilizes the anchored clathrate water array and dual hydrogen-bonding is a consequence of this stability. Structural insight gained from this study paves the way for rational designing of highly potent antifreeze-mimetic with potential industrial applications.

Supporting Snow Research: SnowEx Data and Services at the NASA National Snow and Ice Data Center DAAC

NASA Astrophysics Data System (ADS)

Leon, A.; Tanner, S.; Deems, J. S.

2017-12-01

The National Snow and Ice Data Center Distributed Active Archive Center (NSIDC DAAC), part of the Cooperative Institute for Research in Environmental Sciences (CIRES) at the University of Colorado Boulder, will archive and distribute all primary data sets collected during the NASA SnowEx campaigns. NSIDC DAAC's overarching goal for SnowEx data management is to steward the diverse SnowEx data sets to provide a reliable long-term archive, to enable effective data discovery, retrieval, and usage, and to support end user engagement. This goal will be achieved though coordination and collaboration with SnowEx project management and investigators. NSIDC DAAC's core functions for SnowEx data management include: Data Creation: Advise investigators on data formats and structure as well as metadata creation and content to enable preservation, usability, and discoverability. Data Documentation: Develop comprehensive data set documentation describing the instruments, data collection and derivation methods, and data file contents. Data Distribution: Provide discovery and access through NSIDC and NASA data portals to make SnowEx data available to a broad user community Data & User Support: Assist user communities with the selection and usage of SnowEx data products. In an effort to educate and broaden the SnowEx user community, we will present an overview of the SnowEx data products, tools, and services which will be available at the NSIDC DAAC. We hope to gain further insight into how the DAAC can enable the user community to seamlessly and effectively utilize SnowEx data in their research and applications.

A survey of cats and dogs for fleas: with particular reference to their role as intermediate hosts of Dipylidium caninum.

PubMed

Guzman, R F

1984-05-01

Three species of fleas, viz. Ctenocephalides felis, Ctenocephalides canis, and Pulex irritans were found in an examination of 81 cats and 48 dogs in Wellington. C. felis was the most prevalent flea in cats, and C. canis predominated in dogs. It is speculated that C. felis, and its primary host the cat, may assume greater medical and veterinary significance than C. canis. In an examination of 1578 fleas for cysticercoids of the dog tapeworm, Dipylidium caninum, all were found negative. These results do not necessarily reflect the availability of cysticercoids in the environment, and the reasons for this are discussed.

Hybridization assay of insect antifreezing protein gene by novel multilayered porous silicon nucleic acid biosensor.

PubMed

Lv, Xiaoyi; Chen, Liangliang; Zhang, Hongyan; Mo, Jiaqing; Zhong, Furu; Lv, Changwu; Ma, Ji; Jia, Zhenhong

2013-01-15

A fabrication of a novel simple porous silicon polybasic photonic crystal with symmetrical structure has been reported as a nucleic acid biosensor for detecting antifreeze protein gene in insects (Microdera puntipennis dzhungarica), which would be helpful in the development of some new transgenic plants with tolerance of freezing stress. Compared to various porous silicon-based photonic configurations, porous silicon polytype layered structure is quite easy to prepare and shows more stability; moreover, polybasic photonic crystals with symmetrical structure exhibit interesting optical properties with a sharp resonance in the reflectance spectrum, giving a higher Q factor which causes higher sensitivity for sensing performance. In this experiment, DNA oligonucleotides were immobilized into the porous silicon pores using a standard crosslink chemistry method. The porous silicon polybasic symmetrical structure sensor possesses high specificity in performing controlled experiments with non-complementary DNA. The detection limit was found to be 21.3nM for DNA oligonucleotides. The fabricated multilayered porous silicon-based DNA biosensor has potential commercial applications in clinical chemistry for determination of an antifreeze protein gene or other genes. Copyright © 2012 Elsevier B.V. All rights reserved.

Plague in a Colony of Gunnison's Prairie Dogs ( Cynomys gunnisoni) Despite Three Years of Infusions of Burrows with 0.05% Deltamethrin to Kill Fleas.

PubMed

Hoogland, John L; Biggins, Dean E; Blackford, Nathaniel; Eads, David A; Long, Dustin; Rodriguez, Mariana Rivera; Ross, Lauren M; Tobey, Sarah; White, Emma M

2018-04-01

At Valles Caldera National Preserve in New Mexico, US, infusing Gunnison's prairie dog ( Cynomys gunnisoni) burrows with an insecticide dust containing 0.05% deltamethrin killed fleas which transmit bubonic plague. The reduction in the number of fleas per prairie dog was significant and dramatic immediately after infusions, with a suggestion that the reduction persisted for as long as 12 mo. Despite the lower flea counts, however, a plague epizootic killed >95% of prairie dogs after 3 yr of infusions (once per year). More research is necessary for a better understanding of the efficacy of insecticide dusts at lowering flea counts and protecting prairie dogs from plague.

Role of the Yersinia pestis plasminogen activator in the incidence of distinct septicemic and bubonic forms of flea-borne plague

PubMed Central

Sebbane, Florent; Jarrett, Clayton O.; Gardner, Donald; Long, Daniel; Hinnebusch, B. Joseph

2006-01-01

Yersinia pestis is transmitted by fleas and causes bubonic plague, characterized by severe local lymphadenitis that progresses rapidly to systemic infection and life-threatening septicemia. Here, we show that although flea-borne transmission usually leads to bubonic plague in mice, it can also lead to primary septicemic plague. However, intradermal injection of Y. pestis, commonly used to mimic transmission by fleabite, leads only to bubonic plague. A Y. pestis strain lacking the plasmid-encoded cell-surface plasminogen activator, which is avirulent by intradermal or s.c. injection, was able to cause fatal primary septicemic plague at low incidence, but not bubonic plague, when transmitted by fleas. The results clarify a long-standing uncertainty about the etiology of primary septicemic plague and support an evolutionary scenario in which plague first emerged as a flea-borne septicemic disease of limited transmissibility. Subsequent acquisition of the plasminogen activator gene by horizontal transfer enabled the bubonic form of disease and increased the potential for epidemic spread. PMID:16567636

Role of the Yersinia pestis plasminogen activator in the incidence of distinct septicemic and bubonic forms of flea-borne plague.

PubMed

Sebbane, Florent; Jarrett, Clayton O; Gardner, Donald; Long, Daniel; Hinnebusch, B Joseph

2006-04-04

Yersinia pestis is transmitted by fleas and causes bubonic plague, characterized by severe local lymphadenitis that progresses rapidly to systemic infection and life-threatening septicemia. Here, we show that although flea-borne transmission usually leads to bubonic plague in mice, it can also lead to primary septicemic plague. However, intradermal injection of Y. pestis, commonly used to mimic transmission by fleabite, leads only to bubonic plague. A Y. pestis strain lacking the plasmid-encoded cell-surface plasminogen activator, which is avirulent by intradermal or s.c. injection, was able to cause fatal primary septicemic plague at low incidence, but not bubonic plague, when transmitted by fleas. The results clarify a long-standing uncertainty about the etiology of primary septicemic plague and support an evolutionary scenario in which plague first emerged as a flea-borne septicemic disease of limited transmissibility. Subsequent acquisition of the plasminogen activator gene by horizontal transfer enabled the bubonic form of disease and increased the potential for epidemic spread.

Grooming behaviors of black-tailed prairie dogs are influenced by flea parasitism, conspecifics, and proximity to refuge

USGS Publications Warehouse

Eads, David A.; Biggins, Dean E.; Eads, Samantha L.

2017-01-01

Grooming is a common animal behavior that aids in ectoparasite defense. Ectoparasites can stimulate grooming, and natural selection can also favor endogenous mechanisms that evoke periodic bouts of “programmed” grooming to dislodge or kill ectoparasites before they bite or feed. Moreover, grooming can function as a displacement or communication behavior. We compared the grooming behaviors of adult female black-tailed prairie dogs (Cynomys ludovicianus) on colonies with or without flea control via pulicide dust. Roughly 91% of the prairie dogs sampled on the non-dusted colony carried at least one flea, whereas we did not find fleas on two dusted colonies. During focal observations, prairie dogs on the non-dusted colony groomed at higher frequencies and for longer durations than prairie dogs on the dusted colonies, lending support to the hypothesis that fleas stimulated grooming. However, the reduced amount of time spent grooming on the dusted colonies suggested that approximately 25% of grooming might be attributed to factors other than direct stimulation from ectoparasites. Non-dusted colony prairie dogs rarely autogroomed when near each other. Dusted colony prairie dogs autogroomed for shorter durations when far from a burrow opening (refuge), suggesting a trade-off between self-grooming and antipredator defense. Allogrooming was detected only on the non-dusted colony and was limited to adult females grooming young pups. Grooming appears to serve an antiparasitic function in C. ludovicianus. Antiparasitic grooming might aid in defense against fleas that transmit the plague bacterium Yersinia pestis. Plague was introduced to North America ca. 1900 and now has a strong influence on most prairie dog populations, suggesting a magnified effect of grooming on prairie dog fitness.

Potential Roles of Pigs, Small Ruminants, Rodents, and Their Flea Vectors in Plague Epidemiology in Sinda District, Eastern Zambia.

PubMed

Nyirenda, Stanley S; Hang'ombe, Bernard M; Kilonzo, Bukheti S; Kangwa, Henry L; Mulenga, Evans; Moonga, Ladslav

2017-05-01

A cross-sectional study was conducted in the Eastern part of Zambia that previously reported a plague outbreak. The aim of the study was to evaluate the potential role of pigs, goats, and sheep as sero-surveillance hosts for monitoring plague, and to investigate the flea vectors and potential reservoir hosts to establish the current status of plague endemicity in the district. Serum samples were collected from 96 rodents, 10 shrews, 245 domestic pigs, 232 goats, and 31 sheep, whereas 106 organs were eviscerated from rodents and shrews. As for fleas, 1,064 Echidnophaga larina Jordan & Rothschild, 7 Xenopsylla cheopis (Rothschild), and 382 Echidnophaga gallinacea (Westwood) were collected from these animals in 34 villages. Enzyme-Linked Immunosorbent Assay (ELISA) and Polymerase Chain Reaction (PCR) tests were performed on serum, and organs and fleas to determine IgG antibodies against Fraction 1 antigen and pla gene of Yersinia pestis, respectively. ELISA results showed that 2.83% (95% CI = 0.59-8.05) rodents, 9.0% (95% CI = 5.71-13.28) domestic pigs, 4.7% (95% CI = 2.39-8.33) goats, and 3.2% (95% CI = 0.08-16.70) sheep were positive for IgG antibodies against Fra1 antigen of Y. pestis. On PCR, 8.4% (95% CI = 3.96-15.51) of the rodents were detected with Y. pestis pla gene, whereas all fleas were found negative. The common fleas identified were E. larina from pigs, whereas X. cheopis were the only fleas collected from rodents. The presence of sero-positive animals as well as the occurrence of X. cheopis on local rodents suggests that Y. pestis remains a risk in the district. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Target-site resistance to pyrethroid insecticides in German populations of the cabbage stem flea beetle, Psylliodes chrysocephala L. (Coleoptera: Chrysomelidae).

PubMed

Zimmer, Christoph T; Müller, Andreas; Heimbach, Udo; Nauen, Ralf

2014-01-01

Cabbage stem flea beetle, Psylliodes chrysocephala L. (Coleoptera: Chrysomelidae) is a major pest of winter oilseed rape in several European countries particularly attacking young emerging plants in autumn. Over the last several decades, pyrethroid insecticides have been foliarly applied to control flea beetle outbreaks. Recent control failures in northern Germany suggested pyrethroid resistance development in cabbage stem flea beetles, which were confirmed by resistance monitoring bioassays using lambda-cyhalothrin in an adult vial test. The purpose of this study was to investigate the presence of polymorphisms in the para-type voltage-gated sodium channel gene of P. chrysocephala known to be involved in knock-down resistance (kdr). By using a degenerate primer approach we PCR amplified part of the para-type sodium channel gene and identified in resistant flea beetles a single nucleotide polymorphism resulting in an L1014F (kdr) mutation within domain IIS6 of the channel protein, known as one of the chief pyrethroid target-site resistance mechanisms in several other pest insects. Twenty populations including four archived museum samples collected between 1945 and 1958 were analyzed using a newly developed pyrosequencing diagnostic assay. The assay revealed a kdr allele frequency of 90-100% in those flea beetle populations expressing high-level cross-resistance in discriminating dose bioassays against different pyrethroids such as lambda-cyhalothrin, tau-fluvalinate, etofenprox and bifenthrin. The presence of target-site resistance to pyrethroids in cabbage stem flea beetle is extremely worrying considering the lack of effective alternative modes of action to control this pest in Germany and other European countries, and is likely to result in major control problems once it expands to other geographies. The striking fact that cabbage stem flea beetle is next to pollen beetle, Meligethes aeneus the second coleopteran pest in European winter oilseed rape resisting

Identification, cloning, and characterization of a major cat flea salivary allergen (Cte f 1).

PubMed

McDermott, M J; Weber, E; Hunter, S; Stedman, K E; Best, E; Frank, G R; Wang, R; Escudero, J; Kuner, J; McCall, C

2000-05-01

An 18 kDa protein isolated from saliva of the cat flea, Ctenocephalides felis, elicits a positive intradermal skin test (IDST) in 100 and 80% of experimental and clinical flea allergic dogs, respectively. Using solid-phase enzyme-linked immuno assay (ELISA), this protein detected IgE in 100 and 80% of experimental and clinical flea allergic dogs, respectively. A cDNA (pFSI) encoding a full-length Cte f 1 protein was isolated from a C. felis salivary gland cDNA library, using a combination of PCR and hybridization screening. This cDNA is 658 bp in length, and contains an open reading frame of 528 bp. The open reading frame encodes a protein of 176 amino acids, consisting of an 18 amino acid signal sequence and a 158 amino acid mature protein. The calculated molecular weight and pI of the mature protein are 18106 Da and 9.3, respectively. The protein, named Cte f 1, is the first novel major allergen described for canine flea allergy. Recombinant Cte f 1 (rCte f 1) was expressed in Escherichia coli, Pichia pastoris and baculovirus infected Trichoplusia ni cells. Approximately, 90% of the rCte f 1 expressed in E. coli accumulated in insoluble inclusion bodies, which could be refolded to a soluble mixture of disulfide isomers with partial IgE binding activity. Small quantities of an apparently correctly refolded form of rCte f 1, which had IgE binding activity equal to the native antigen, was isolated from the soluble fraction of E. coli cells. However, P. pastoris and baculovirus infected insect cells expressed and secreted a fully processed, correctly refolded and fully active form of rCte f 1. Mass spectrometry analysis of the active forms of rCte f 1confirmed that eight intact disulfide bonds were present, matching the number observed in the native allergen. The relative ability of rCte f 1 to bind IgE in the serum of flea allergic animals, produced in these three expression systems, matched that of the native allergen. Competition ELISA demonstrated that

Fleas infesting pets in the era of emerging extra-intestinal nematodes

PubMed Central

2013-01-01

Modifications in climatic conditions, movements of hosts and goods, changes in animal phenology and human behaviour and increase of wildlife, are presently concurring in the geographic spread of vectors and cardio-respiratory nematodes, e.g. Dirofilaria immitis, Angiostrongylus vasorum, Aelurostrongylus abstrusus and Capillaria aerophila. All these factors may also influence dispersion and clinical significance of fleas, thus posing relevant challenges in those regions where other parasites are emerging at the same time. Ctenocephalides felis, Ctenocephalides canis and Pulex irritans cause discomfort, nuisance, allergic reactions, anaemia, and may transmit several pathogens, some of them are of importance for public health. The present article reviews the importance of fleas in small animal practice and their sanitary relevance for dogs, cats and humans, and discusses current control methods in the present era of emerging extra-intestinal nematodes, towards a possible changing perspective for controlling key parasites affecting companion animals. PMID:23497511

From the clouds to the ground - snow precipitation patterns vs. snow accumulation patterns

NASA Astrophysics Data System (ADS)

Gerber, Franziska; Besic, Nikola; Mott, Rebecca; Gabella, Marco; Germann, Urs; Bühler, Yves; Marty, Mauro; Berne, Alexis; Lehning, Michael

2017-04-01

Knowledge about snow distribution and snow accumulation patterns is important and valuable for different applications such as the prediction of seasonal water resources or avalanche forecasting. Furthermore, accumulated snow on the ground is an important ground truth for validating meteorological and climatological model predictions of precipitation in high mountains and polar regions. Snow accumulation patterns are determined by many different processes from ice crystal nucleation in clouds to snow redistribution by wind and avalanches. In between, snow precipitation undergoes different dynamical and microphysical processes, such as ice crystal growth, aggregation and riming, which determine the growth of individual particles and thereby influence the intensity and structure of the snowfall event. In alpine terrain the interaction of different processes and the topography (e.g. lifting condensation and low level cloud formation, which may result in a seeder-feeder effect) may lead to orographic enhancement of precipitation. Furthermore, the redistribution of snow particles in the air by wind results in preferential deposition of precipitation. Even though orographic enhancement is addressed in numerous studies, the relative importance of micro-physical and dynamically induced mechanisms on local snowfall amounts and especially snow accumulation patterns is hardly known. To better understand the relative importance of different processes on snow precipitation and accumulation we analyze snowfall and snow accumulation between January and March 2016 in Davos (Switzerland). We compare MeteoSwiss operational weather radar measurements on Weissfluhgipfel to a spatially continuous snow accumulation map derived from airborne digital sensing (ADS) snow height for the area of Dischma valley in the vicinity of the weather radar. Additionally, we include snow height measurements from automatic snow stations close to the weather radar. Large-scale radar snow accumulation

Simulating Snow in Canadian Boreal Environments with CLASS for ESM-SnowMIP

NASA Astrophysics Data System (ADS)

Wang, L.; Bartlett, P. A.; Derksen, C.; Ireson, A. M.; Essery, R.

2017-12-01

The ability of land surface schemes to provide realistic simulations of snow cover is necessary for accurate representation of energy and water balances in climate models. Historically, this has been particularly challenging in boreal forests, where poor treatment of both snow masking by forests and vegetation-snow interaction has resulted in biases in simulated albedo and snowpack properties, with subsequent effects on both regional temperatures and the snow albedo feedback in coupled simulations. The SnowMIP (Snow Model Intercomparison Project) series of experiments or `MIPs' was initiated in order to provide assessments of the performance of various snow- and land-surface-models at selected locations, in order to understand the primary factors affecting model performance. Here we present preliminary results of simulations conducted for the third such MIP, ESM-SnowMIP (Earth System Model - Snow Model Intercomparison Project), using the Canadian Land Surface Scheme (CLASS) at boreal forest sites in central Saskatchewan. We assess the ability of our latest model version (CLASS 3.6.2) to simulate observed snowpack properties (snow water equivalent, density and depth) and above-canopy albedo over 13 winters. We also examine the sensitivity of these simulations to climate forcing at local and regional scales.

Improvement of a snow albedo parameterization in the Snow-Atmosphere-Soil Transfer model: evaluation of impacts of aerosol on seasonal snow cover

NASA Astrophysics Data System (ADS)

Zhong, Efang; Li, Qian; Sun, Shufen; Chen, Wen; Chen, Shangfeng; Nath, Debashis

2017-11-01

The presence of light-absorbing aerosols (LAA) in snow profoundly influence the surface energy balance and water budget. However, most snow-process schemes in land-surface and climate models currently do not take this into consideration. To better represent the snow process and to evaluate the impacts of LAA on snow, this study presents an improved snow albedo parameterization in the Snow-Atmosphere-Soil Transfer (SAST) model, which includes the impacts of LAA on snow. Specifically, the Snow, Ice and Aerosol Radiation (SNICAR) model is incorporated into the SAST model with an LAA mass stratigraphy scheme. The new coupled model is validated against in-situ measurements at the Swamp Angel Study Plot (SASP), Colorado, USA. Results show that the snow albedo and snow depth are better reproduced than those in the original SAST, particularly during the period of snow ablation. Furthermore, the impacts of LAA on snow are estimated in the coupled model through case comparisons of the snowpack, with or without LAA. The LAA particles directly absorb extra solar radiation, which accelerates the growth rate of the snow grain size. Meanwhile, these larger snow particles favor more radiative absorption. The average total radiative forcing of the LAA at the SASP is 47.5 W m-2. This extra radiative absorption enhances the snowmelt rate. As a result, the peak runoff time and "snow all gone" day have shifted 18 and 19.5 days earlier, respectively, which could further impose substantial impacts on the hydrologic cycle and atmospheric processes.

Helical Antifreeze Proteins Have Independently Evolved in Fishes on Four Occasions

PubMed Central

Graham, Laurie A.; Hobbs, Rod S.; Fletcher, Garth L.; Davies, Peter L.

2013-01-01

Alanine-rich α-helical (type I) antifreeze proteins (AFPs) are produced by a variety of fish species from three different orders to protect against freezing in icy seawater. Interspersed amongst and within these orders are fishes making AFPs that are completely different in both sequence and structure. The origin of this variety of types I, II, III and antifreeze glycoproteins (AFGPs) has been attributed to adaptation following sea-level glaciations that occurred after the divergence of most of the extant families of fish. The presence of similar types of AFPs in distantly related fishes has been ascribed to lateral gene transfer in the case of the structurally complex globular type II lectin-like AFPs and to convergent evolution for the AFGPs, which consist of a well-conserved tripeptide repeat. In this paper, we examine the genesis of the type I AFPs, which are intermediate in complexity. These predominantly α-helical peptides share many features, such as putative capping structures, Ala-richness and amphipathic character. We have added to the type I repertoire by cloning additional sequences from sculpin and have found that the similarities between the type I AFPs of the four distinct groups of fishes are not borne out at the nucleotide level. Both the non-coding sequences and the codon usage patterns are strikingly different. We propose that these AFPs arose via convergence from different progenitor helices with a weak affinity for ice and that their similarity is dictated by the propensity of specific amino acids to form helices and to align water on one side of the helix into an ice-like pattern. PMID:24324684

Theoretical study of interaction of winter flounder antifreeze protein with ice

PubMed Central

Jorov, Alexander; Zhorov, Boris S.; Yang, Daniel S.C.

2004-01-01

Antifreeze proteins (AFPs) are synthesized by various organisms to enable their cells to survive subzero environment. These proteins bind to small ice crystals and inhibit their growth, which if left uncontrolled would be fatal to cells. The crystal structures of a number of AFPs have been determined; however, crystallographic analysis of AFP–ice complex is nearly impossible. Molecular modeling studies of AFPs’ interaction with ice surface is therefore invaluable. Early models of AFP–ice interaction suggested H-bond as the primary driving force behind such interaction. Recent experimental evidence, however, suggested that hydrophobic interactions could be the main contributor to AFP–ice association. All computational studies published to date were carried out to verify the H-bond model, and no works attempting to verify the hydrophobic interaction model have been published. In this work, we Monte Carlo–minimized complexes of several AFPs with ice taking into account nonbonded interactions, H-bonds, and the hydration potential for proteins. Parameters of the hydration potential for ice were developed with the assumption that the free energy of the water–ice association should be close to zero at equilibrium melting temperature. Our calculations demonstrate that desolvation of hydrophobic groups in the AFPs upon their binding to the grooves at the ice surface is indeed the major stabilizing contributor to the free energy of AFP–ice binding. This study is consistent with available structural and mutation data on AFPs. In particular, it explains the paradoxical finding that substitution of Thr residues with Val does not affect the potency of winter flounder AFP whereas substitution with Ser abolished its antifreeze activity. PMID:15152087

Disposition of 3H-selamectin and 3H-ivermectin in the brain of the cat flea Ctenocephalides felis felis using micro-image analysis.

PubMed

Phipps, A N; Martin-Short, M R; Littlewood, L; Blanchflower, S E; Gration, K A F

2005-07-15

In addition to intrinsic potency and metabolic stability, the disposition of an antiparasitic drug within the target parasite plays a major role in determining drug activity. A novel technique that allows the disposition of radiolabelled drugs to be visualised within the body of the cat flea (Ctenocephalides felis felis) is described. The concentrations of two macrocyclic lactones, (3)H-selamectin and (3)H-ivermectin, within the supra- and sub-oesophageal ganglia of the flea brain following in vitro feeding of fleas on different doses of drug solubilised in calf blood have been measured. Drug disposition was visualised in cryostat sections of fleas using a micro-image analysis (MIA). A relationship between the concentration of radioactivity in the ganglia and the dose of drug in the blood meal was obtained. The concentration of selamectin in the ganglia was significantly higher than ivermectin at all doses investigated. The enhanced concentration of selamectin, at a site rich in glutamate-gated chloride channels may, in part, explain the higher potency of selamectin against fleas compared to ivermectin.

Prevalence of Yersinia pestis in rodents and fleas associated with black-tailed prairie dogs (Cynomys ludovicianus) at Thunder Basin National Grassland, Wyoming

USGS Publications Warehouse

Thiagarajan, Bala; Bai, Ying; Gage, Kenneth L.; Cully, Jack F.

2008-01-01

Rodents (and their fleas) that are associated with prairie dogs are considered important for the maintenance and transmission of the bacterium (Yersinia pestis) that causes plague. Our goal was to identify rodent and flea species that were potentially involved in a plague epizootic in black-tailed prairie dogs at Thunder Basin National Grassland. We collected blood samples and ectoparasites from rodents trapped at off- and on-colony grids at Thunder Basin National Grassland between 2002 and 2004. Blood samples were tested for antibodies to Y. pestis F-1 antigen by a passive hemagglutination assay, and fleas were tested by a multiplex polymerase chain reaction, for the presence of the plague bacterium. Only one of 1,421 fleas, an Oropsylla hirsuta collected in 2002 from a deer mouse, Peromyscus maniculatus, tested positive for Y. pestis. Blood samples collected in summer 2004 from two northern grasshopper mice, Onychomys leucogaster, tested positive for Y. pestis antibodies. All three positive samples were collected from on-colony grids shortly after a plague epizootic occurred. This study confirms that plague is difficult to detect in rodents and fleas associated with prairie dog colonies, unless samples are collected immediately after a prairie dog die-off.

Prevalence of Yersinia pestis in rodents and fleas associated with black-tailed prairie dogs (Cynomys ludovicianus) at Thunder Basin National Grassland, Wyoming.

PubMed

Thiagarajan, Bala; Bai, Ying; Gage, Kenneth L; Cully, Jack F

2008-07-01

Rodents (and their fleas) that are associated with prairie dogs are considered important for the maintenance and transmission of the bacterium (Yersinia pestis) that causes plague. Our goal was to identify rodent and flea species that were potentially involved in a plague epizootic in black-tailed prairie dogs at Thunder Basin National Grassland. We collected blood samples and ectoparasites from rodents trapped at off- and on-colony grids at Thunder Basin National Grassland between 2002 and 2004. Blood samples were tested for antibodies to Y. pestis F-1 antigen by a passive hemagglutination assay, and fleas were tested by a multiplex polymerase chain reaction, for the presence of the plague bacterium. Only one of 1,421 fleas, an Oropsylla hirsuta collected in 2002 from a deer mouse, Peromyscus maniculatus, tested positive for Y. pestis. Blood samples collected in summer 2004 from two northern grasshopper mice, Onychomys leucogaster, tested positive for Y. pestis antibodies. All three positive samples were collected from on-colony grids shortly after a plague epizootic occurred. This study confirms that plague is difficult to detect in rodents and fleas associated with prairie dog colonies, unless samples are collected immediately after a prairie dog die-off.

Parasite spread at the domestic animal - wildlife interface: anthropogenic habitat use, phylogeny and body mass drive risk of cat and dog flea (Ctenocephalides spp.) infestation in wild mammals.

PubMed

Clark, Nicholas J; Seddon, Jennifer M; Šlapeta, Jan; Wells, Konstans

2018-01-08

Spillover of parasites at the domestic animal - wildlife interface is a pervasive threat to animal health. Cat and dog fleas (Ctenocephalides felis and C. canis) are among the world's most invasive and economically important ectoparasites. Although both species are presumed to infest a diversity of host species across the globe, knowledge on their distributions in wildlife is poor. We built a global dataset of wild mammal host associations for cat and dog fleas, and used Bayesian hierarchical models to identify traits that predict wildlife infestation probability. We complemented this by calculating functional-phylogenetic host specificity to assess whether fleas are restricted to hosts with similar evolutionary histories, diet or habitat niches. Over 130 wildlife species have been found to harbour cat fleas, representing nearly 20% of all mammal species sampled for fleas. Phylogenetic models indicate cat fleas are capable of infesting a broad diversity of wild mammal species through ecological fitting. Those that use anthropogenic habitats are at highest risk. Dog fleas, by contrast, have been recorded in 31 mammal species that are primarily restricted to certain phylogenetic clades, including canids, felids and murids. Both flea species are commonly reported infesting mammals that are feral (free-roaming cats and dogs) or introduced (red foxes, black rats and brown rats), suggesting the breakdown of barriers between wildlife and invasive reservoir species will increase spillover at the domestic animal - wildlife interface. Our empirical evidence shows that cat fleas are incredibly host-generalist, likely exhibiting a host range that is among the broadest of all ectoparasites. Reducing wild species' contact rates with domestic animals across natural and anthropogenic habitats, together with mitigating impacts of invasive reservoir hosts, will be crucial for reducing invasive flea infestations in wild mammals.

The effect of surface charge on the thermal stability and ice recrystallization inhibition activity of antifreeze protein III (AFP III).

PubMed

Deller, R C; Carter, B M; Zampetakis, I; Scarpa, F; Perriman, A W

2018-01-01

The aim of this study was to examine the effect of chemical cationization on the structure and function of antifreeze protein III (AFP III) over an extreme temperature range (-40°C to +90°C) using far-UV synchrotron radiation circular dichroism (SRCD) and ice recrystallization inhibition (IRI) assays. Chemical cationization was able to produce a modified AFP III with a net cationic charge at physiological pH that had enhanced resistance to denaturation at elevated temperatures, with no immediate negative impact on protein structure at subzero temperatures. Furthermore, cationized AFP III retained an IRI activity similar to that of native AFP III. Consequently, chemical cationization may provide a pathway to the development of more robust antifreeze proteins as supplementary cryoprotectants in the cryopreservation of clinically relevant cells. Copyright © 2017. Published by Elsevier Inc.

Integration of snow management practices into a detailed snow pack model

NASA Astrophysics Data System (ADS)

Spandre, Pierre; Morin, Samuel; Lafaysse, Matthieu; Lejeune, Yves; François, Hugues; George-Marcelpoil, Emmanuelle

2016-04-01

The management of snow on ski slopes is a key socio-economic and environmental issue in mountain regions. Indeed the winter sports industry has become a very competitive global market although this economy remains particularly sensitive to weather and snow conditions. The understanding and implementation of snow management in detailed snowpack models is a major step towards a more realistic assessment of the evolution of snow conditions in ski resorts concerning past, present and future climate conditions. Here we describe in a detailed manner the integration of snow management processes (grooming, snowmaking) into the snowpack model Crocus (Spandre et al., Cold Reg. Sci. Technol., in press). The effect of the tiller is explicitly taken into account and its effects on snow properties (density, snow microstructure) are simulated in addition to the compaction induced by the weight of the grooming machine. The production of snow in Crocus is carried out with respect to specific rules and current meteorological conditions. Model configurations and results are described in detail through sensitivity tests of the model of all parameters related to snow management processes. In-situ observations were carried out in four resorts in the French Alps during the 2014-2015 winter season considering for each resort natural, groomed only and groomed plus snowmaking conditions. The model provides realistic simulations of the snowpack properties with respect to these observations. The main uncertainty pertains to the efficiency of the snowmaking process. The observed ratio between the mass of machine-made snow on ski slopes and the water mass used for production was found to be lower than was expected from the literature, in every resort. The model now referred to as "Crocus-Resort" has been proven to provide realistic simulations of snow conditions on ski slopes and may be used for further investigations. Spandre, P., S. Morin, M. Lafaysse, Y. Lejeune, H. François and E. George

Development of a loop-mediated isothermal amplification (LAMP) assay for rapid screening of ticks and fleas for spotted fever group rickettsia.

PubMed

Noden, Bruce H; Martin, Jaclyn; Carrillo, Yisel; Talley, Justin L; Ochoa-Corona, Francisco M

2018-01-01

The importance of tick and flea-borne rickettsia infections is increasingly recognized worldwide. While increased focus has shifted in recent years to the development of point-of-care diagnostics for various vector-borne diseases in humans and animals, little research effort has been devoted to their integration into vector surveillance and control programs, particularly in resource-challenged countries. One technology which may be helpful for large scale vector surveillance initiatives is loop-mediated isothermal amplification (LAMP). The aim of this study was to develop a LAMP assay to detect spotted fever group (SFG) rickettsia DNA from field-collected ticks and fleas and compare with published end-point PCR results. A Spotted Fever Group rickettsia-specific loop-mediated isothermal amplification (SFGR-LAMP) assay was developed using primers based on a region of the R. rickettsii 17kDa protein gene. The sensitivity, specificity, and reproducibility of the assay were evaluated. The assay was then compared with the results of end-point PCR assays for pooled tick and flea samples obtained from field-based surveillance studies. The sensitivity of the SFGR-LAMP assay was 0.00001 ng/μl (25μl volume) which was 10 times more sensitive than the 17kDa protein gene end-point PCR used as the reference method. The assay only recognized gDNA from SFG and transitional group (TRG) rickettsia species tested but did not detect gDNA from typhus group (TG) rickettsia species or closely or distantly related bacterial species. The SFGR-LAMP assay detected the same positives from a set of pooled tick and flea samples detected by end-point PCR in addition to two pooled flea samples not detected by end-point PCR. To our knowledge, this is the first study to develop a functional LAMP assay to initially screen for SFG and TRG rickettsia pathogens in field-collected ticks and fleas. With a high sensitivity and specificity, the results indicate the potential use as a field

A snow cover climatology for the Pyrenees from MODIS snow products

NASA Astrophysics Data System (ADS)

Gascoin, S.; Hagolle, O.; Huc, M.; Jarlan, L.; Dejoux, J.-F.; Szczypta, C.; Marti, R.; Sánchez, R.

2014-11-01

The seasonal snow in the Pyrenees is critical for hydropower production, crop irrigation and tourism in France, Spain and Andorra. Complementary to in situ observations, satellite remote sensing is useful to monitor the effect of climate on the snow dynamics. The MODIS daily snow products (Terra/MOD10A1 and Aqua/MYD10A1) are widely used to generate snow cover climatologies, yet it is preferable to assess their accuracies prior to their use. Here, we use both in situ snow observations and remote sensing data to evaluate the MODIS snow products in the Pyrenees. First, we compare the MODIS products to in situ snow depth (SD) and snow water equivalent (SWE) measurements. We estimate the values of the SWE and SD best detection thresholds to 40 mm water equivalent (we) and 105 mm respectively, for both MOD10A1 and MYD10A1. Kappa coefficients are within 0.74 and 0.92 depending on the product and the variable. Then, a set of Landsat images is used to validate MOD10A1 and MYD10A1 for 157 dates between 2002 and 2010. The resulting accuracies are 97% (κ = 0.85) for MOD10A1 and 96% (κ = 0.81) for MYD10A1, which indicates a good agreement between both datasets. The effect of vegetation on the results is analyzed by filtering the forested areas using a land cover map. As expected, the accuracies decreases over the forests but the agreement remains acceptable (MOD10A1: 96%, κ = 0.77; MYD10A1: 95%, κ = 0.67). We conclude that MODIS snow products have a sufficient accuracy for hydroclimate studies at the scale of the Pyrenees range. Using a gapfilling algorithm we generate a consistent snow cover climatology, which allows us to compute the mean monthly snow cover duration per elevation band. We finally analyze the snow patterns for the atypical winter 2011-2012. Snow cover duration anomalies reveal a deficient snowpack on the Spanish side of the Pyrenees, which seems to have caused a drop in the national hydropower production.

NOAA's National Snow Analyses

NASA Astrophysics Data System (ADS)

Carroll, T. R.; Cline, D. W.; Olheiser, C. M.; Rost, A. A.; Nilsson, A. O.; Fall, G. M.; Li, L.; Bovitz, C. T.

2005-12-01

NOAA's National Operational Hydrologic Remote Sensing Center (NOHRSC) routinely ingests all of the electronically available, real-time, ground-based, snow data; airborne snow water equivalent data; satellite areal extent of snow cover information; and numerical weather prediction (NWP) model forcings for the coterminous U.S. The NWP model forcings are physically downscaled from their native 13 km2 spatial resolution to a 1 km2 resolution for the CONUS. The downscaled NWP forcings drive an energy-and-mass-balance snow accumulation and ablation model at a 1 km2 spatial resolution and at a 1 hour temporal resolution for the country. The ground-based, airborne, and satellite snow observations are assimilated into the snow model's simulated state variables using a Newtonian nudging technique. The principle advantages of the assimilation technique are: (1) approximate balance is maintained in the snow model, (2) physical processes are easily accommodated in the model, and (3) asynoptic data are incorporated at the appropriate times. The snow model is reinitialized with the assimilated snow observations to generate a variety of snow products that combine to form NOAA's NOHRSC National Snow Analyses (NSA). The NOHRSC NSA incorporate all of the available information necessary and available to produce a "best estimate" of real-time snow cover conditions at 1 km2 spatial resolution and 1 hour temporal resolution for the country. The NOHRSC NSA consist of a variety of daily, operational, products that characterize real-time snowpack conditions including: snow water equivalent, snow depth, surface and internal snowpack temperatures, surface and blowing snow sublimation, and snowmelt for the CONUS. The products are generated and distributed in a variety of formats including: interactive maps, time-series, alphanumeric products (e.g., mean areal snow water equivalent on a hydrologic basin-by-basin basis), text and map discussions, map animations, and quantitative gridded products

National Snow Analyses - NOHRSC - The ultimate source for snow information

Science.gov Websites

Equivalent Thumbnail image of Modeled Snow Water Equivalent Animate: Season --- Two weeks --- One Day Snow Depth Thumbnail image of Modeled Snow Depth Animate: Season --- Two weeks --- One Day Average Snowpack Temp Thumbnail image of Modeled Average Snowpack Temp Animate: Season --- Two weeks --- One Day SWE

The AMSR2 Satellite-based Microwave Snow Algorithm (SMSA) to estimate regional to global snow depth and snow water equivalent

NASA Astrophysics Data System (ADS)

Kelly, R. E. J.; Saberi, N.; Li, Q.

2017-12-01

With moderate to high spatial resolution (<1 km) regional to global snow water equivalent (SWE) observation approaches yet to be fully scoped and developed, the long-term satellite passive microwave record remains an important tool for cryosphere-climate diagnostics. A new satellite microwave remote sensing approach is described for estimating snow depth (SD) and snow water equivalent (SWE). The algorithm, called the Satellite-based Microwave Snow Algorithm (SMSA), uses Advanced Microwave Scanning Radiometer - 2 (AMSR2) observations aboard the Global Change Observation Mission - Water mission launched by the Japan Aerospace Exploration Agency in 2012. The approach is unique since it leverages observed brightness temperatures (Tb) with static ancillary data to parameterize a physically-based retrieval without requiring parameter constraints from in situ snow depth observations or historical snow depth climatology. After screening snow from non-snow surface targets (water bodies [including freeze/thaw state], rainfall, high altitude plateau regions [e.g. Tibetan plateau]), moderate and shallow snow depths are estimated by minimizing the difference between Dense Media Radiative Transfer model estimates (Tsang et al., 2000; Picard et al., 2011) and AMSR2 Tb observations to retrieve SWE and SD. Parameterization of the model combines a parsimonious snow grain size and density approach originally developed by Kelly et al. (2003). Evaluation of the SMSA performance is achieved using in situ snow depth data from a variety of standard and experiment data sources. Results presented from winter seasons 2012-13 to 2016-17 illustrate the improved performance of the new approach in comparison with the baseline AMSR2 algorithm estimates and approach the performance of the model assimilation-based approach of GlobSnow. Given the variation in estimation power of SWE by different land surface/climate models and selected satellite-derived passive microwave approaches, SMSA provides

The arthropod, but not the vertebrate host or its environment, dictates bacterial community composition of fleas and ticks

PubMed Central

Hawlena, Hadas; Rynkiewicz, Evelyn; Toh, Evelyn; Alfred, Andrew; Durden, Lance A; Hastriter, Michael W; Nelson, David E; Rong, Ruichen; Munro, Daniel; Dong, Qunfeng; Fuqua, Clay; Clay, Keith

2013-01-01

Bacterial community composition in blood-sucking arthropods can shift dramatically across time and space. We used 16S rRNA gene amplification and pyrosequencing to investigate the relative impact of vertebrate host-related, arthropod-related and environmental factors on bacterial community composition in fleas and ticks collected from rodents in southern Indiana (USA). Bacterial community composition was largely affected by arthropod identity, but not by the rodent host or environmental conditions. Specifically, the arthropod group (fleas vs ticks) determined the community composition of bacteria, where bacterial communities of ticks were less diverse and more dependent on arthropod traits—especially tick species and life stage—than bacterial communities of fleas. Our data suggest that both arthropod life histories and the presence of arthropod-specific endosymbionts may mask the effects of the vertebrate host and its environment. PMID:22739493

The importance of dissolved salts to the in vivo efficacy of antifreeze proteins.

PubMed

Evans, Robert P; Hobbs, Rod S; Goddard, Sally V; Fletcher, Garth L

2007-11-01

Antifreeze proteins (AFP) and antifreeze glycoproteins (AFGP) lower the freezing point of marine fish plasma non-colligatively by specifically adsorbing to certain surfaces of ice crystals, modifying their structure and inhibiting further growth. While the freezing point is lowered, the melting point is unaltered and the difference between the two is termed thermal hysteresis (TH). In pure water, the level of TH is directly related to the intrinsic activity of the specific AF(G)P in solution and to their concentration. Results of this study indicate that when AF(G)P are dissolved in salt solutions, such as NaCl, encompassing the range they could encounter in nature, there is a synergistic enhancement of basal TH that is positively related to the salt concentration. This enhancement is likely a result of the hydration shell surrounding the dissolved ions and, as a consequence, reducing freezable water. A secondary reason for the enhancement is that the salt could be influencing the hydration shell surrounding the AF(G)P, increasing their solubility and thus the protein surface area available to adsorb to the ice/water interface. The former hypothesis for the salt enhanced TH has implications for the in vivo function of AF(G)P, particularly at the seawater/external epithelia (gills, skin, stomach) interface. The latter hypothesis is likely only relevant to in vitro situations where freeze dried protein is dissolved in low salt solutions.

Rickettsial infections of fleas collected from small mammals on four islands in Indonesia.

PubMed

Barbara, Kathryn A; Farzeli, Arik; Ibrahim, Ima N; Antonjaya, Ungke; Yunianto, Andre; Winoto, Imelda; Ester; Perwitasari, Dian; Widjaya, Susana; Richards, Allen L; Williams, Maya; Blair, Patrick J

2010-11-01

Ectoparasites were sampled from small mammals collected in West Java, West Sumatra, North Sulawesi, and East Kalimantan, Indonesia, in 2007-2008 and were screened for evidence of infection from bacteria in the Rickettsaceae family. During eight trap nights at eight sites, 208 fleas were collected from 96 of 507 small mammals trapped from four orders (379 Rodentia; 123 Soricomorpha; two Carnivora; three Scandentia). Two species of fleas were collected: Xenopsylla cheopis (n = 204) and Nosopsyllus spp. (n = 4). Among the 208 fleas collected, 171 X. cheopis were removed from rats (Rattus spp.) and 33 X. cheopis from shrews (Suncus murinus). X. cheopis were pooled and tested for DNA from rickettsial agents Rickettsia typhi, Rickettsia felis, and spotted fever group rickettsiae. R. typhi, the agent of murine typhus, was detected in X. cheopis collected from small mammals in West Java and East Kalimantan. R. felis was detected in X. cheopis collected from small mammals in Manado, North Sulawesi. R. felis and spotted fever group rickettsiae were detected in a pool of X. cheopis collected from an animal in East Kalimantan. Sixteen percent of the X. cheopis pools were found positive for Rickettsia spp.; four (10.8%) R. typhi, one (2.7%) R. felis, and one (2.7%) codetection of R. felis and a spotted fever group rickettsia. These data suggest that rickettsial infections remain a threat to human health across Indonesia.

Development of a real-time quantitative PCR assay to enumerate Yersinia pestis in fleas.

PubMed

Gabitzsch, Elizabeth S; Vera-Tudela, Rommelle; Eisen, Rebecca J; Bearden, Scott W; Gage, Kenneth L; Zeidner, Nordin S

2008-07-01

A real-time quantitative polymerase chain reaction (qPCR) assay was developed for Yersina pestis. The qPCR assay was developed utilizing a conserved region of the Y. pestis ferric iron uptake regulator gene (fur) to design primers and a fluorescent (FAM-labeled) TaqMan probe. The assay was optimized using cultured Y. pestis (UG05-0454) and was confirmed to work with strains from 3 Y. pestis biovars. The optimized assay was capable of detecting a single organism of cultured Y. pestis and as little as 300 bacteria in infected flea triturates. This qPCR assay enables rapid enumeration of Y. pestis bacterium in laboratory-infected fleas when compared with conventional serial dilution plating.

Repellency Effect of Essential Oils of some Native Plants and Synthetic Repellents against Human Flea, Pulex irritans (Siphonaptera: Pulicidae)

PubMed Central

Ghavami, Mohammad Bagher; Poorrastgoo, Fahimeh; Taghiloo, Behrooz; Mohammadi, Jamshid

2017-01-01

Background: Fleas are important vectors of human and animal disease, and control measures for protection against their bites and flea-borne diseases are necessary. Methods: The essential oils (EOs) of four native medicinal plants, Ziziphora tenuiore, Myrtus communis, Achillea wilhelmsii and Mentha piperita were isolated by hydrodistillation technique and analyzed by GC-MC. The repellent activity of EOs and synthetic compounds, DEET and permethrin, were assayed on human subjects against field collected fleas. The effective doses of 50% and 90% of EOs and synthetic compounds were estimated by probit analysis of dose and response regression line. Results: Analysis of EOs revealed about 19 major components. All oils were found to be more repellent (ED50 range= 208–955μg cm−2) than DEET and permethrin (ED50 range= 27–182 × 103μg cm−2). Thyme and myrtle oils showed high repellent activities and among the total detected terpenes, thymol (36.26%) and α-pinene (32.5%) were the major components of those oils respectively. Conclusion: Low repellent potency of DEET and permethrin against fleas might be related to flea olfactory system and further molecular and electrophysiological studies are required to conceive new ideas for the discovery and development of the next generation of repellents. Based on high repellent activity of thyme and myrtle essential oils against Pulex irritans further studies should be staged to develop their appropriate effective formulations. Likewise, field trials should be carried out to evaluate the operational feasibility and dermal toxicity over a long period. PMID:29026857

Rainwater propagation through snow during artificial rain-on-snow events

NASA Astrophysics Data System (ADS)

Juras, Roman; Würzer, Sebastian; Pavlasek, Jiri; Jonas, Tobias

2016-04-01

The mechanism of rainwater propagation and runoff generation during rain-on-snow (ROS) is still insufficiently known. Understanding rainwater behaviour within the natural snowpack is crucial especially for forecasting of natural hazards like floods and wet snow avalanches. In this study, rainwater percolation through snow was investigated by sprinkling the naturally stable isotope deuterium on snow and conduct hydrograph separation on samples collected from the snowpack runoff. This allowed quantifying the contribution of rainwater and snowmelt in the water released from the snowpack. Four field experiments were carried out during the winter 2015 in the vicinity of Davos, Switzerland. A 1 by 1 m block of natural snow cover was isolated from the surrounding snowpack to enable a closed water balance. This experimental snow sample was exposed to artificial rainfall with 41 mm of deuterium enriched water. The sprinkling was run in four 30 minutes intervals separated by three 30 minutes non-sprinkling intervals. The runoff from the snow cube was monitored quantitatively by a snow lysimeter and output water was continuously sampled for the deuterium concentration. Further, snowpack properties were analysed before and after the sprinkling, including vertical profiles of snow density, liquid water content (LWC) and deuterium concentration. One experiment conducted on cold snowpack showed that rainwater propagated much faster as compared to three experiments conducted on ripe isothermal snowpack. Our data revealed that sprinkled rainwater initially pushed out pre-event LWC or mixed with meltwater created within the snowpack. Hydrographs from every single experiment showed four pronounced peaks, with the first peak always consisted of less rainwater than the following ones. The partial contribution of rainwater to the total runoff consistently increased over the course of the experiment, but never exceeded 63 %. Moreover, the development of preferential paths after the first

Changes in the relation between snow station observations and basin scale snow water resources

NASA Astrophysics Data System (ADS)

Sexstone, G. A.; Penn, C. A.; Clow, D. W.; Moeser, D.; Liston, G. E.

2017-12-01

Snow monitoring stations that measure snow water equivalent or snow depth provide fundamental observations used for predicting water availability and flood risk in mountainous regions. In the western United States, snow station observations provided by the Natural Resources Conservation Service Snow Telemetry (SNOTEL) network are relied upon for forecasting spring and summer streamflow volume. Streamflow forecast accuracy has declined for many regions over the last several decades. Changes in snow accumulation and melt related to climate, land use, and forest cover are not accounted for in current forecasts, and are likely sources of error. Therefore, understanding and updating relations between snow station observations and basin scale snow water resources is crucial to improve accuracy of streamflow prediction. In this study, we investigated the representativeness of snow station observations when compared to simulated basin-wide snow water resources within the Rio Grande headwaters of Colorado. We used the combination of a process-based snow model (SnowModel), field-based measurements, and remote sensing observations to compare the spatiotemporal variability of simulated basin-wide snow accumulation and melt with that of SNOTEL station observations. Results indicated that observations are comparable to simulated basin-average winter precipitation but overestimate both the simulated basin-average snow water equivalent and snowmelt rate. Changes in the representation of snow station observations over time in the Rio Grande headwaters were also investigated and compared to observed streamflow and streamflow forecasting errors. Results from this study provide important insight in the context of non-stationarity for future water availability assessments and streamflow predictions.

Janus effect of antifreeze proteins on ice nucleation.

PubMed

Liu, Kai; Wang, Chunlei; Ma, Ji; Shi, Guosheng; Yao, Xi; Fang, Haiping; Song, Yanlin; Wang, Jianjun

2016-12-20

The mechanism of ice nucleation at the molecular level remains largely unknown. Nature endows antifreeze proteins (AFPs) with the unique capability of controlling ice formation. However, the effect of AFPs on ice nucleation has been under debate. Here we report the observation of both depression and promotion effects of AFPs on ice nucleation via selectively binding the ice-binding face (IBF) and the non-ice-binding face (NIBF) of AFPs to solid substrates. Freezing temperature and delay time assays show that ice nucleation is depressed with the NIBF exposed to liquid water, whereas ice nucleation is facilitated with the IBF exposed to liquid water. The generality of this Janus effect is verified by investigating three representative AFPs. Molecular dynamics simulation analysis shows that the Janus effect can be established by the distinct structures of the hydration layer around IBF and NIBF. Our work greatly enhances the understanding of the mechanism of AFPs at the molecular level and brings insights to the fundamentals of heterogeneous ice nucleation.

A snow cover climatology for the Pyrenees from MODIS snow products

NASA Astrophysics Data System (ADS)

Gascoin, S.; Hagolle, O.; Huc, M.; Jarlan, L.; Dejoux, J.-F.; Szczypta, C.; Marti, R.; Sanchez, R.

2015-05-01

The seasonal snow in the Pyrenees is critical for hydropower production, crop irrigation and tourism in France, Spain and Andorra. Complementary to in situ observations, satellite remote sensing is useful to monitor the effect of climate on the snow dynamics. The MODIS daily snow products (Terra/MOD10A1 and Aqua/MYD10A1) are widely used to generate snow cover climatologies, yet it is preferable to assess their accuracies prior to their use. Here, we use both in situ snow observations and remote sensing data to evaluate the MODIS snow products in the Pyrenees. First, we compare the MODIS products to in situ snow depth (SD) and snow water equivalent (SWE) measurements. We estimate the values of the SWE and SD best detection thresholds to 40 mm water equivalent (w.e.) and 150 mm, respectively, for both MOD10A1 and MYD10A1. κ coefficients are within 0.74 and 0.92 depending on the product and the variable for these thresholds. However, we also find a seasonal trend in the optimal SWE and SD thresholds, reflecting the hysteresis in the relationship between the depth of the snowpack (or SWE) and its extent within a MODIS pixel. Then, a set of Landsat images is used to validate MOD10A1 and MYD10A1 for 157 dates between 2002 and 2010. The resulting accuracies are 97% (κ = 0.85) for MOD10A1 and 96% (κ = 0.81) for MYD10A1, which indicates a good agreement between both data sets. The effect of vegetation on the results is analyzed by filtering the forested areas using a land cover map. As expected, the accuracies decrease over the forests but the agreement remains acceptable (MOD10A1: 96%, κ = 0.77; MYD10A1: 95%, κ = 0.67). We conclude that MODIS snow products have a sufficient accuracy for hydroclimate studies at the scale of the Pyrenees range. Using a gap-filling algorithm we generate a consistent snow cover climatology, which allows us to compute the mean monthly snow cover duration per elevation band and aspect classes. There is snow on the ground at least 50% of the

Fleas (Siphonaptera) infesting giant kangaroo rats (Dipodomys ingens) on the Elkhorn and Carrizo Plains, San Luis Obispo County, California.

PubMed

Tabor, S P; Williams, D F; Germano, D J; Thomas, R E

1993-01-01

The giant kangaroo rat, Dipodomys ingens (Merriam), has a limited distribution in the San Joaquin Valley, CA. Because of reductions in its geographic range, largely resulting from humans, the species was listed as an endangered species in 1980 by the California Fish and Game Commission. As part of a study of the community ecology of southern California endangered species, including D. ingens, we were able to make flea collections from the rats when they were trapped and marked for population studies. All but one of the fleas collected from the D. ingens in this study were Hoplopsyllus anomalus, a flea normally associated with ground squirrels (Sciuridae). It has been suggested that giant kangaroo rats fill the ground squirrel niche within their range. Our data indicate that this role includes a normal association with Hoplopsyllus anomalus.

Preventive efficacy of Frontline® Combo and Certifect® against Dipylidium caninum infestation of cats and dogs using a natural flea (Ctenocephalides felis) infestation model.

PubMed

Beugnet, Frederic; Delport, Peet; Luus, Hermann; Crafford, Dione; Fourie, Josephus

2013-01-01

Two studies were performed to evaluate the effectiveness of two monthly topical anti-flea products for the prevention of Dipylidium caninum infestations in cats and dogs. A single treatment with Frontline(®) Combo spot-on for cats (fipronil-(S)-methoprene) and two successive monthly treatments of Certifect(®) for dogs (fipronil-amitraz-(S)-methoprene) were assessed for the prevention of D. caninum infestations following weekly challenges of treated cats or dogs with metacestode naturally-infected fleas. The rate of infestations using the model in cats versus dogs explains the choice of a 1-month trial in cats and a 2-month trial in dogs. The experimental flea-infection model resulted in a range of 22-53% of the fleas being infected by Dipylidium cysticercoids. The arithmetic mean flea counts recorded for the untreated cats ranged from 51.2 to 68. The geometric mean flea counts recorded for the Frontline Combo treated cats differed significantly (p < 0.05) from those of the untreated control cats on all assessment days. The arithmetic mean flea counts recorded for the untreated dogs ranged from 166.6 to 238.6. The geometric mean flea counts recorded for the Certifect treated dogs differed significantly (p < 0.001) from those of the untreated group on all assessment days. Frontline Combo treatment on cats provided ≥99.8% persistent anti-flea efficacy throughout the 30-day treatment period. In the dog study, the two Certifect treatments provided ≥97% persistent efficacy throughout the 60-day study. Based on the collection of expelled D. caninum proglottids by cats, 100% (6/6) of the control cats and 0% (0/6) of Frontline Combo treated cats were infested with D. caninum. Frontline Combo spot-on for cats was therefore 100% effective in preventing infection with D. caninum. In dogs, 7 out of the 8 control group dogs (87.5%) produced proglottids following infestation of infected fleas, whereas 0 out of 8 dogs (0%) in the treated group were infected. The infection

Preventive efficacy of Frontline® Combo and Certifect® against Dipylidium caninum infestation of cats and dogs using a natural flea (Ctenocephalides felis) infestation model

PubMed Central

Beugnet, Frederic; Delport, Peet; Luus, Hermann; Crafford, Dione; Fourie, Josephus

2013-01-01

Two studies were performed to evaluate the effectiveness of two monthly topical anti-flea products for the prevention of Dipylidium caninum infestations in cats and dogs. A single treatment with Frontline® Combo spot-on for cats (fipronil-(S)-methoprene) and two successive monthly treatments of Certifect® for dogs (fipronil-amitraz-(S)-methoprene) were assessed for the prevention of D. caninum infestations following weekly challenges of treated cats or dogs with metacestode naturally-infected fleas. The rate of infestations using the model in cats versus dogs explains the choice of a 1-month trial in cats and a 2-month trial in dogs. The experimental flea-infection model resulted in a range of 22–53% of the fleas being infected by Dipylidium cysticercoids. The arithmetic mean flea counts recorded for the untreated cats ranged from 51.2 to 68. The geometric mean flea counts recorded for the Frontline Combo treated cats differed significantly (p < 0.05) from those of the untreated control cats on all assessment days. The arithmetic mean flea counts recorded for the untreated dogs ranged from 166.6 to 238.6. The geometric mean flea counts recorded for the Certifect treated dogs differed significantly (p < 0.001) from those of the untreated group on all assessment days. Frontline Combo treatment on cats provided ≥99.8% persistent anti-flea efficacy throughout the 30-day treatment period. In the dog study, the two Certifect treatments provided ≥97% persistent efficacy throughout the 60-day study. Based on the collection of expelled D. caninum proglottids by cats, 100% (6/6) of the control cats and 0% (0/6) of Frontline Combo treated cats were infested with D. caninum. Frontline Combo spot-on for cats was therefore 100% effective in preventing infection with D. caninum. In dogs, 7 out of the 8 control group dogs (87.5%) produced proglottids following infestation of infected fleas, whereas 0 out of 8 dogs (0%) in the treated group were infected. The infection

MODIS Snow-Cover Products

NASA Technical Reports Server (NTRS)

Hall, Dorothy K.; Riggs, George A.; Salomonson, Vinvent V.; DiGirolamo, Nicolo; Bayr, Klaus J.; Houser, Paul (Technical Monitor)

2001-01-01

On December 18, 1999, the Terra satellite was launched with a complement of five instruments including the Moderate Resolution Imaging Spectroradiometer (MODIS). Many geophysical products are derived from MODIS data including global snow-cover products. These products have been available through the National Snow and Ice Data Center (NSIDC) Distributed Active Archive Center (DAAC) since September 13, 2000. MODIS snow-cover products represent potential improvement to the currently available operation products mainly because the MODIS products are global and 500-m resolution, and have the capability to separate most snow and clouds. Also the snow-mapping algorithms are automated which means that a consistent data set is generated for long-term climates studies that require snow-cover information. Extensive quality assurance (QA) information is stored with the product. The snow product suite starts with a 500-m resolution swath snow-cover map which is gridded to the Integerized Sinusoidal Grid to produce daily and eight-day composite tile products. The sequence then proceeds to a climate-modeling grid product at 5-km spatial resolution, with both daily and eight-day composite products. A case study from March 6, 2000, involving MODIS data and field and aircraft measurements, is presented. Near-term enhancements include daily snow albedo and fractional snow cover.

Assessment of the efficacy of a topical combination of fipronil-permethrin (Frontline Tri-Act®/Frontect®) against egg laying and adult emergence of the cat flea (Ctenocephalides felis) in dogs

PubMed Central

Beugnet, Frédéric; Halos, Lénaïg; Lebon, Wilfried; Liebenberg, Julian

2016-01-01

This study was conducted to assess the prevention of egg laying and the inhibition of the emergence of the cat flea (Ctenocephalides felis) resulting from the application of a combination of fipronil and permethrin (Frontline Tri-Act®/Frontect®, Merial) on dogs. Sixteen healthy dogs were included after pre-treatment live flea counts and randomly allocated to two groups. Eight dogs served as untreated controls and 8 dogs were treated on Day 0 and Day 30 with topical application of fipronil/permethrin at the minimum dose of 6.76 mg/kg fipronil and 50.48 mg/kg permethrin. On days −2, 7, 21, 28, 42 and 56, each dog was infested with 100 fleas. Flea eggs were collected from each dog in individual trays from 12 to 36 h after treatment or each flea re-infestation. All fleas were removed by combing and counted 36 h after treatment or infestations. The collected eggs were counted and incubated for 28 days for larval development and adult emergence assessment. The curative efficacy of Frontline Tri-Act®/Frontect® against adult fleas 36 h after treatment was 95.3% and the efficacy remained 100% after subsequent flea infestations for 8 weeks. Compared to the control group, the treatment reduced egg laying by 84.5% within 36 h after first treatment and was 99.9%, 100%, 100%, 100%, 100% on collection days 7, 21, 29, 43 and 57, respectively. Frontline Tri-Act®/Frontect® reduced by 28.7% the emergence of new adult fleas from eggs laid during the 48 h of pre-treatment infestation. The inhibition of adult emergence from incubated flea eggs could not be assessed after flea re-infestation in the treated group as no eggs were collected. PMID:27991415

BOREAS HYD-3 Snow Measurements

NASA Technical Reports Server (NTRS)

Hardy, Janet P.; Hall, Forrest G. (Editor); Knapp, David E. (Editor); Davis, Robert E.; Smith, David E. (Technical Monitor)

2000-01-01

The Boreal Ecosystem-Atmosphere Study (BOREAS) Hydrology (HYD)-3 team collected several data sets related to the hydrology of forested areas. This data set contains measurements of snow depth, snow density in three cm intervals, an integrated snow pack density and snow water equivalent (SWE), and snow pack physical properties from snow pit evaluation taken in 1994 and 1996. The data were collected from several sites in both the southern study area (SSA) and the northern study area (NSA). A variety of standard tools were used to measure the snow pack properties, including a meter stick (snow depth), a 100 cc snow density cutter, a dial stem thermometer, and the Canadian snow sampler as used by HYD-4 to obtain a snow pack-integrated measure of SWE. This study was undertaken to predict spatial distributions of snow properties important to the hydrology, remote sensing signatures, and the transmissivity of gases through the snow. The data are available in tabular ASCII files. The snow measurement data are available from the Earth Observing System Data and Information System (EOSDIS) Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC). The data files are available on a CD-ROM (see document number 20010000884).

Comparison of the Snow Simulations in Community Land Model Using Two Snow Cover Fraction Parameterizations

NASA Astrophysics Data System (ADS)

Xie, Zhipeng; Hu, Zeyong

2016-04-01

Snow cover is an important component of local- and regional-scale energy and water budgets, especially in mountainous areas. This paper evaluates the snow simulations by using two snow cover fraction schemes in CLM4.5 (NY07 is the original snow-covered area parameterization used in CLM4, and SL12 is the default scheme in CLM4.5). Off-line simulations are carried out forced by the China Meteorological forcing dataset from January 1, 2001 to December 31, 2010 over the Tibetan Plateau. Simulated snow cover fraction (SCF), snow depth, and snow water equivalent (SWE) were compared against a set of observations including the Interactive Multisensor Snow and Ice Mapping System (IMS) snow cover product, the daily snow depth dataset of China, and China Meteorological Administration (CMA) in-situ snow depth and SWE observations. The comparison results indicate significant differences existing between those two SCF parameterizations simulations. Overall, the SL12 formulation shows a certain improvement compared to the NY07 scheme used in CLM4, with the percentage of correctly modeled snow/no snow being 75.8% and 81.8% when compared with the IMS snow product, respectively. Yet, this improvement varies both temporally and spatially. Both these two snow cover schemes overestimated the snow depth, in comparison with the daily snow depth dataset of China, the average biases of simulated snow depth are 7.38cm (8.77cm), 6.97cm (8.2cm) and 5.49cm (5.76cm) NY07 (and SL12) in the snow accumulation period (September through next February), snowmelt period (March through May) and snow-free period (June through August), respectively. When compared with the CMA in-situ snow depth observations, averaged biases are 3.18cm (4.38cm), 2.85cm (4.34cm) and 0.34cm (0.34cm) for NY07 (SL12), respectively. Though SL12 does worse snow depth simulation than NY07, the simulated SWE by SL12 is better than that by NY07, with average biases being 2.64mm, 6.22mm, 1.33mm for NY07, and 1.47mm, 2.63mm, 0.31mm

MODIS Snow-Cover Products

NASA Technical Reports Server (NTRS)

Hall, Dorothy K.; Riggs, George A.; Salomonson, Vincent V.; DiGirolamo, Nicole E.; Bayr, Klaus J.; Houser, Paul R. (Technical Monitor)

2002-01-01

On December 18, 1999, the Terra satellite was launched with a complement of five instruments including the Moderate Resolution Imaging Spectroradiometer (MODIS). Many geophysical products are derived from MODIS data including global snow-cover products. MODIS snow and ice products have been available through the National Snow and Ice Data Center (NSIDC) Distributed Active Archive Center (DAAC) since September 13, 2000. MODIS snow-cover products represent potential improvement to or enhancement of the currently-available operational products mainly because the MODIS products are global and 500-m resolution, and have the capability to separate most snow and clouds. Also the snow-mapping algorithms are automated which means that a consistent data set may be generated for long-term climate studies that require snow-cover information. Extensive quality assurance (QA) information is stored with the products. The MODIS snow product suite begins with a 500-m resolution, 2330-km swath snow-cover map which is then gridded to an integerized sinusoidal grid to produce daily and 8-day composite tile products. The sequence proceeds to a climate-modeling grid (CMG) product at about 5.6-km spatial resolution, with both daily and 8-day composite products. Each pixel of the CMG contains fraction of snow cover from 40 - 100%. Measured errors of commission in the CMG are low, for example, on the continent of Australia in the spring, they vary from 0.02 - 0.10%. Near-term enhancements include daily snow albedo and fractional snow cover. A case study from March 6, 2000, involving MODIS data and field and aircraft measurements, is presented to show some early validation work.

Yeah!!! A Snow Day!

ERIC Educational Resources Information Center

Cone, Theresa Purcell; Cone, Stephen L.

2006-01-01

As children see the first snowflake fall from the sky, they are filled with anticipation of playing in the snow. The snowy environment presents a wonderful opportunity for presenting interdisciplinary activities that connect snow play, snow formation, and snow stories with manipulative activities, gymnastic balances, and dance sequences. In this…

A hyperactive, Ca2+-dependent antifreeze protein in an Antarctic bacterium.

PubMed

Gilbert, Jack A; Davies, Peter L; Laybourn-Parry, Johanna

2005-04-01

In cold climates, some plants and bacteria that cannot avoid freezing use antifreeze proteins (AFPs) to lessen the destructive effects of ice recrystallization. These AFPs have weak freezing point depression activity, perhaps to avoid sudden, uncontrolled growth of ice. Here, we report on an uncharacteristically powerful bacterial AFP found in an Antarctic strain of the bacterium, Marinomonas primoryensis. It is Ca(2+)-dependent, shows evidence of cooperativity, and can produce over 2 degrees C of freezing point depression. Unlike most AFPs, it does not produce obvious crystal faceting during thermal hysteresis. This AFP might be capable of imparting freezing avoidance to M. primoryensis in ice-covered Antarctic lakes. A hyperactive bacterial AFP has not previously been reported.

Knock-down and speed of kill of a combination of fipronil and permethrin for the prevention of Ctenocephalides felis flea infestation in dogs.

PubMed

Halos, Lénaïg; Fourie, Josephus J; Fankhauser, Becky; Beugnet, Frederic

2016-02-02

A topical combination of fipronil + permethrin (Frontline Tri-Act/Frontect, Merial) has recently been developed to control fleas, ticks, mosquitoes, sandflies and stable flies on dogs. Two studies were conducted to assess its speed of kill and knock-down effect on Ctenocephalides felis fleas. The combination was compared to either fipronil alone or to a combination of permethrin, dinotefuran, and pyriproxyfen, In each study, 18 dogs were randomly allocated to one of three groups: (Group 1: untreated dog; Group 2: treated once on D0 with the combination of fipronil and permethrin; Group 3: treated once on D0 either with fipronil alone (study 1) or with a combination of permethrin, dinetofuran and pyriproxyfen (study 2)). Each dog was infested with 100 unfed adult C. felis fleas on Days 2 (study 2), 7, 14, 21 and 28. Fleas were collected from dogs at 1 h and 12 h post- infestations (PI) (study 1) or at 2 h and 6 h PI (study 2) to assess efficacy and from collection pans underneath cages 1 h (study 1) or 5 min (study 2) PI to assess knock-down effect. All treated dogs had significantly (p ≤ 0.01) lower flea counts than untreated dogs at every time point in both studies. For a whole month, a significant knock-down effect against infesting fleas is obtained in five minutes PI with the combination of permethrin and fipronil. Complete efficacy (>95%) was achieved in 1 h (study 1) or 2 h (study 2) PI for 14 days and by 6 h PI for all challenges conducted throughout the month. Efficacy remains >85% at 2 h PI for the whole month. A significantly higher efficacy of the fipronil + permethrin combination compared to other treatments was demonstrated at the earliest time points for the month (1 h knock-down effect and insecticidal efficacy compared to fipronil alone; 5 min knock-down effect compared to the combination of permethrin + dinetofuran + pyriproxyfen). The rapid flea knock-down effect and speed of kill demonstrated by the spot on combination of

Improving snow density estimation for mapping SWE with Lidar snow depth: assessment of uncertainty in modeled density and field sampling strategies in NASA SnowEx

NASA Astrophysics Data System (ADS)

Raleigh, M. S.; Smyth, E.; Small, E. E.

2017-12-01

The spatial distribution of snow water equivalent (SWE) is not sufficiently monitored with either remotely sensed or ground-based observations for water resources management. Recent applications of airborne Lidar have yielded basin-wide mapping of SWE when combined with a snow density model. However, in the absence of snow density observations, the uncertainty in these SWE maps is dominated by uncertainty in modeled snow density rather than in Lidar measurement of snow depth. Available observations tend to have a bias in physiographic regime (e.g., flat open areas) and are often insufficient in number to support testing of models across a range of conditions. Thus, there is a need for targeted sampling strategies and controlled model experiments to understand where and why different snow density models diverge. This will enable identification of robust model structures that represent dominant processes controlling snow densification, in support of basin-scale estimation of SWE with remotely-sensed snow depth datasets. The NASA SnowEx mission is a unique opportunity to evaluate sampling strategies of snow density and to quantify and reduce uncertainty in modeled snow density. In this presentation, we present initial field data analyses and modeling results over the Colorado SnowEx domain in the 2016-2017 winter campaign. We detail a framework for spatially mapping the uncertainty in snowpack density, as represented across multiple models. Leveraging the modular SUMMA model, we construct a series of physically-based models to assess systematically the importance of specific process representations to snow density estimates. We will show how models and snow pit observations characterize snow density variations with forest cover in the SnowEx domains. Finally, we will use the spatial maps of density uncertainty to evaluate the selected locations of snow pits, thereby assessing the adequacy of the sampling strategy for targeting uncertainty in modeled snow density.

A passive microwave snow depth algorithm with a proxy for snow metamorphism

USGS Publications Warehouse

Josberger, E.G.; Mognard, N.M.

2002-01-01

Passive microwave brightness temperatures of snowpacks depend not only on the snow depth, but also on the internal snowpack properties, particularly the grain size, which changes through the winter. Algorithms that assume a constant grain size can yield erroneous estimates of snow depth or water equivalent. For snowpacks that are subject to temperatures well below freezing, the bulk temperature gradient through the snowpack controls the metamorphosis of the snow grains. This study used National Weather Service (NWS) station measurements of snow depth and air temperature from the Northern US Great Plains to determine temporal and spatial variability of the snow depth and bulk snowpack temperature gradient. This region is well suited for this study because it consists primarily of open farmland or prairie, has little relief, is subject to very cold temperatures, and has more than 280 reporting stations. A geostatistical technique called Kriging was used to grid the randomly spaced snow depth measurements. The resulting snow depth maps were then compared with the passive microwave observations from the Special Sensor Microwave Imager (SSM/I). Two snow seasons were examined: 1988-89, a typical snow year, and 1996-97, a record year for snow that was responsible for extensive flooding in the Red River Basin. Inspection of the time series of snow depth and microwave spectral gradient (the difference between the 19 and 37 GHz bands) showed that while the snowpack was constant, the spectral gradient continued to increase. However, there was a strong correlation (0.6 < R2 < 0.9) between the spectral gradient and the cumulative bulk temperature gradient through the snowpack (TGI). Hence, TGI is an index of grain size metamorphism that has occurred within the snowpack. TGI time series from 21 representative sites across the region and the corresponding SSM/I observations were used to develop an algorithm for snow depth that requires daily air temperatures. Copyright ?? 2002

Dipylidium caninum infection in dogs infested with fleas.

PubMed

Wani, Z A; Allaie, I M; Shah, B M; Raies, A; Athar, H; Junaid, S

2015-03-01

The present study pertains to the Dipylidium caninum infection in dogs infested with fleas. Twenty dogs were presented to the Divison of Surgery, SKUAST-K for different surgical procedures. Majority of the dogs had a history of pruritus, loss of weight as well as rubbing their perineal region against the wall. On external examination dogs were found infested with Ctenocephalides canis. When dogs were anesthetized, motile segments were seen coming out of their anus, which were then identified as mature segments of D. caninum.

Fleas, lice and mites on scrub hares (Lepus saxatilis) in northern and eastern Transvaal and in KwaZulu-Natal, South Africa.

PubMed

Louw, J P; Horak, I G; Horak, M L; Braack, L E

1995-06-01

Fleas, lice and mites were collected from 24 and 120 scrub hares at Pafuri and Skukuza, Northern and Eastern Transvaal, respectively, in the Kruger National Park, and from 34 scrub hares in the Hluhluwe region, north-eastern KwaZulu-Natal. Ctenocephalides felis damarensis, the only flea recovered, reached peak burdens on the hares at each locality during late winter or spring. Juvenile hares harboured significantly fewer fleas than did adult animals. The lice Haemodipsus lyriocephalus and Haemodipsus setoni were collected from hares at each locality, with H. setoni generally being the most abundant. Listrophorus leporicolus was found on hares at Skukuza and Hluhluwe, and mites of the genus Cheyletiella were collected from hares at Skukuza.

The significance of vertical moisture diffusion on drifting snow sublimation near snow surface

NASA Astrophysics Data System (ADS)

Huang, Ning; Shi, Guanglei

2017-12-01

Sublimation of blowing snow is an important parameter not only for the study of polar ice sheets and glaciers, but also for maintaining the ecology of arid and semi-arid lands. However, sublimation of near-surface blowing snow has often been ignored in previous studies. To study sublimation of near-surface blowing snow, we established a sublimation of blowing snow model containing both a vertical moisture diffusion equation and a heat balance equation. The results showed that although sublimation of near-surface blowing snow was strongly reduced by a negative feedback effect, due to vertical moisture diffusion, the relative humidity near the surface does not reach 100 %. Therefore, the sublimation of near-surface blowing snow does not stop. In addition, the sublimation rate near the surface is 3-4 orders of magnitude higher than that at 10 m above the surface and the mass of snow sublimation near the surface accounts for more than half of the total snow sublimation when the friction wind velocity is less than about 0.55 m s-1. Therefore, the sublimation of near-surface blowing snow should not be neglected.

Efficacy of fipronil, amitraz and (S)-methoprene combination spot-on for dogs against adult dog fleas (Ctenocephalides canis, Curtis, 1826).

PubMed

Bouhsira, Emilie; Yoon, Stephen S; Roques, Martine; Manavella, Coralie; Vermot, Solange; Cramer, Luiz G; Ollagnier, Catherine; Franc, Michel

2011-07-15

A novel spot-on formulation combining fipronil, amitraz and (S)-methoprene (CERTIFECT™, Merial Limited, GA, USA) was evaluated in adult Beagle dogs in a study to determine its adulticidal efficacy against the dog flea (Ctenocephalides canis, Curtis, 1826). Sixteen dogs were randomly allocated to treatment groups: 8 dogs served as untreated controls, and 8 dogs were treated once. Treatment consisted of applying a new combination formulation to deliver at least 6.7mg fipronil/kg body weight (bw), 8.0mg amitraz/kg bw, and 6.0mg (S)-methoprene/kg bw. The combination was designed to enhance the efficacy against ticks of the original fipronil/(S)-methoprene combination. Each dog was infested with 100 adult unfed dog fleas within 24h prior to treatment and then at weekly intervals for 8 weeks after treatment. At 24h after treatment or after each subsequent infestation, each dog was combed thoroughly to remove live fleas to be counted. A single treatment with CERTIFECT provided excellent knock-down of fleas within 24h after treatment and controlled re-infestations for up to 7 weeks (efficacy ≥96.5%, p<0.05). Copyright © 2011 Elsevier B.V. All rights reserved.

Numerical prediction of micro-channel LD heat sink operated with antifreeze based on CFD method

NASA Astrophysics Data System (ADS)

Liu, Gang; Liu, Yang; Wang, Chao; Wang, Wentao; Wang, Gang; Tang, Xiaojun

2014-12-01

To theoretically study the feasibility of antifreeze coolants applied as cooling fluids for high power LD heat sink, detailed Computational Fluid Dynamics (CFD) analysis of liquid cooled micro-channels heat sinks is presented. The performance operated with antifreeze coolant (ethylene glycol aqueous solution) compared with pure water are numerical calculated for the heat sinks with the same micro-channels structures. The maximum thermal resistance, total pressure loss (flow resistance), thermal resistance vs. flow-rate, and pressure loss vs. flow-rate etc. characteristics are numerical calculated. The results indicate that the type and temperature of coolants plays an important role on the performance of heat sinks. The whole thermal resistance and pressure loss of heat sinks increase significantly with antifreeze coolants compared with pure water mainly due to its relatively lower thermal conductivity and higher fluid viscosity. The thermal resistance and pressure loss are functions of the flow rate and operation temperature. Increasing of the coolant flow rate can reduce the thermal resistance of heat sinks; meanwhile increase the pressure loss significantly. The thermal resistance tends to a limit with increasing flow rate, while the pressure loss tends to increase exponentially with increasing flow rate. Low operation temperature chiefly increases the pressure loss rather than thermal resistance due to the remarkable increasing of fluid viscosity. The actual working point of the cooling circulation system can be determined on the basis of the pressure drop vs. flow rate curve for the micro-channel heat sink and that for the circulation system. In the same system, if the type or/and temperature of the coolant is changed, the working point is accordingly influenced, that is, working flow rate and pressure is changed simultaneously, due to which the heat sink performance is influenced. According to the numerical simulation results, if ethylene glycol aqueous

Spectral reflectance characteristics of different snow and snow-covered land surface objects and mixed spectrum fitting

USGS Publications Warehouse

Zhang, J.-H.; Zhou, Z.-M.; Wang, P.-J.; Yao, F.-M.; Yang, L.

2011-01-01

The field spectroradiometer was used to measure spectra of different snow and snow-covered land surface objects in Beijing area. The result showed that for a pure snow spectrum, the snow reflectance peaks appeared from visible to 800 nm band locations; there was an obvious absorption valley of snow spectrum near 1030 nm wavelength. Compared with fresh snow, the reflection peaks of the old snow and melting snow showed different degrees of decline in the ranges of 300~1300, 1700~1800 and 2200~2300 nm, the lowest was from the compacted snow and frozen ice. For the vegetation and snow mixed spectral characteristics, it was indicated that the spectral reflectance increased for the snow-covered land types(including pine leaf with snow and pine leaf on snow background), due to the influence of snow background in the range of 350~1300 nm. However, the spectrum reflectance of mixed pixel remained a vegetation spectral characteristic. In the end, based on the spectrum analysis of snow, vegetation, and mixed snow/vegetation pixels, the mixed spectral fitting equations were established, and the results showed that there was good correlation between spectral curves by simulation fitting and observed ones(correlation coefficient R2=0.9509).

Adsorption-induced conformational changes of antifreeze glycoproteins at the ice/water interface.

PubMed

Uda, Yukihiro; Zepeda, Salvador; Kaneko, Fumitoshi; Matsuura, Yoshiki; Furukawa, Yoshinori

2007-12-27

The conformation of antifreeze glycoprotein (AFGP) molecules adsorbed at the ice/water interface was studied by attenuated total reflection (ATR)-FTIR spectroscopy. Measurements were carried out for AFGP/D2O solution films formed on the surface of an ATR prism as a function of temperature. Using the FTIR spectrum from the O-D stretching band of D2O molecules, we monitored the supercooled and frozen states of the film and measured the thickness of the quasi-liquid layer (QLL) at the ice/prism interfaces. The AFGP structure was determined for the liquid, supercooled, and frozen states of the solution film using the amide I band spectra. No noticeable differences in conformation were observed in the solution conformation from room temperature down to the 15 K supercooling studied, whereas the alpha-helical content of AFGP suddenly increased when the supercooled solution film froze at -15 degrees C. This change in conformation can increase the overall interaction between the AFGP molecules and ice surface and allow a stronger adsorption. In contrast, the alpha-helical content of AFGP in the frozen film gradually decreased with increasing temperature and finally returned to its solution-state level at the melting point of D2O ice. This gradual decrease in the alpha-helix content directly correlates with the measured increase in QLL thickness. Finally, we conclude that the differences in the alpha-helix signals between the frozen and supercooled states indicate the conformational change of AFGP molecules upon adsorption at the ice/water interface, emphasizing the importance of the structure-function relationship, even for this highly flexible antifreeze.

Flea abundance, diversity, and plague in Gunnison's prairie dogs (Cynomys gunnisoni) and their burrows in montane grasslands in northern New Mexico

Treesearch

Megan M. Friggens; Robert R. Parmenter; Michael Boyden; Paulette L. Ford; Kenneth Gage; Paul Keim

2010-01-01

Plague, a flea-transmitted infectious disease caused by the bacterium Yersinia pestis, is a primary threat to the persistence of prairie dog populations (Cynomys spp.). We conducted a 3-yr survey (2004-2006) of fleas from Gunnison's prairie dogs (Cynomys gunnisoni) and their burrows in montane grasslands in Valles Caldera National Preserve in New Mexico. Our...

Development of a loop-mediated isothermal amplification (LAMP) assay for rapid screening of ticks and fleas for spotted fever group rickettsia

PubMed Central

Martin, Jaclyn; Carrillo, Yisel; Talley, Justin L.; Ochoa-Corona, Francisco M.

2018-01-01

Background The importance of tick and flea-borne rickettsia infections is increasingly recognized worldwide. While increased focus has shifted in recent years to the development of point-of-care diagnostics for various vector-borne diseases in humans and animals, little research effort has been devoted to their integration into vector surveillance and control programs, particularly in resource-challenged countries. One technology which may be helpful for large scale vector surveillance initiatives is loop-mediated isothermal amplification (LAMP). The aim of this study was to develop a LAMP assay to detect spotted fever group (SFG) rickettsia DNA from field-collected ticks and fleas and compare with published end-point PCR results. Methodology/Principal findings A Spotted Fever Group rickettsia-specific loop-mediated isothermal amplification (SFGR-LAMP) assay was developed using primers based on a region of the R. rickettsii 17kDa protein gene. The sensitivity, specificity, and reproducibility of the assay were evaluated. The assay was then compared with the results of end-point PCR assays for pooled tick and flea samples obtained from field-based surveillance studies. The sensitivity of the SFGR-LAMP assay was 0.00001 ng/μl (25μl volume) which was 10 times more sensitive than the 17kDa protein gene end-point PCR used as the reference method. The assay only recognized gDNA from SFG and transitional group (TRG) rickettsia species tested but did not detect gDNA from typhus group (TG) rickettsia species or closely or distantly related bacterial species. The SFGR-LAMP assay detected the same positives from a set of pooled tick and flea samples detected by end-point PCR in addition to two pooled flea samples not detected by end-point PCR. Conclusions/significance To our knowledge, this is the first study to develop a functional LAMP assay to initially screen for SFG and TRG rickettsia pathogens in field-collected ticks and fleas. With a high sensitivity and specificity

Recent research in snow hydrology

NASA Technical Reports Server (NTRS)

Dozier, Jeff

1987-01-01

Recent work on snow-pack energy exchange has involved detailed investigations on snow albedo and attempts to integrate energy-balance calculations over drainage basins. Along with a better understanding of the EM properties of snow, research in remote sensing has become more focused toward estimation of snow-pack properties. In snow metamorphism, analyses of the physical processes must now be coupled to better descriptions of the geometry of the snow microstructure. The dilution method now appears to be the best direct technique for measuring the liquid water content of snow; work on EM methods continues. Increasing attention to the chemistry of the snow pack has come with the general focus on acid precipitation in hydrology.

Energy expenditure and clearing snow: a comparison of shovel and snow pusher.

PubMed

Smolander, J; Louhevaara, V; Ahonen, E; Polari, J; Klen, T

1995-04-01

In order to assess the energy demands of manual clearing of snow, nine men did snow clearing work for 15 min with a shovel and a snow pusher. The depth of the snowcover was 400-600 mm representing a very heavy snowfall. Heart rate (HR), oxygen consumption (VO2), pulmonary ventilation (VE), respiratory exchange ratio (R), and rating of perceived exertion (RPE) were determined during the work tasks. HR, VE, R, and RPE were not significantly different between the shovel and snow pusher. HR averaged (+/- SD) 141 +/- 20 b min-1 with the shovel, and 142 +/- 19 beats.min-1 with the snow pusher. VO2 was 2.1 +/- 0.41.min-1 (63 +/- 12%VO2 max) in shovelling and 2.6 +/- 0.51.min-1 (75 +/- 14%VO2max) in snow pushing (p < 0.001). In conclusion manual clearing of snow in conditions representing heavy snowfalls was found to be strenuous physical work, not suitable for persons with cardiac risk factors, but which may serve as a mode of physical training in healthy adults.

A Comparison of Satellite-Derived Snow Maps with a Focus on Ephemeral Snow in North Carolina

NASA Technical Reports Server (NTRS)

Hall, Dorothy K.; Fuhrmann, Christopher M.; Perry, L. Baker; Riggs, George A.; Robinson, David A.; Foster, James L.

2010-01-01

In this paper, we focus on the attributes and limitations of four commonly-used daily snowcover products with respect to their ability to map ephemeral snow in central and eastern North Carolina. We show that the Moderate-Resolution Imaging Spectroradiometer (MODIS) fractional snow-cover maps can delineate the snow-covered area very well through the use of a fully-automated algorithm, but suffer from the limitation that cloud cover precludes mapping some ephemeral snow. The semi-automated Interactive Multi-sensor Snow and ice mapping system (IMS) and Rutgers Global Snow Lab (GSL) snow maps are often able to capture ephemeral snow cover because ground-station data are employed to develop the snow maps, The Rutgers GSL maps are based on the IMS maps. Finally, the Advanced Microwave Scanning Radiometer for EOS (AMSR-E) provides some good detail of snow-water equivalent especially in deeper snow, but may miss ephemeral snow cover because it is often very thin or wet; the AMSR-E maps also suffer from coarse spatial resolution. We conclude that the southeastern United States represents a good test region for validating the ability of satellite snow-cover maps to capture ephemeral snow cover,

Crystal Structure of an Insect Antifreeze Protein and Its Implications for Ice Binding*

PubMed Central

Hakim, Aaron; Nguyen, Jennifer B.; Basu, Koli; Zhu, Darren F.; Thakral, Durga; Davies, Peter L.; Isaacs, Farren J.; Modis, Yorgo; Meng, Wuyi

2013-01-01

Antifreeze proteins (AFPs) help some organisms resist freezing by binding to ice crystals and inhibiting their growth. The molecular basis for how these proteins recognize and bind ice is not well understood. The longhorn beetle Rhagium inquisitor can supercool to below −25 °C, in part by synthesizing the most potent antifreeze protein studied thus far (RiAFP). We report the crystal structure of the 13-kDa RiAFP, determined at 1.21 Å resolution using direct methods. The structure, which contains 1,914 nonhydrogen protein atoms in the asymmetric unit, is the largest determined ab initio without heavy atoms. It reveals a compressed β-solenoid fold in which the top and bottom sheets are held together by a silk-like interdigitation of short side chains. RiAFP is perhaps the most regular structure yet observed. It is a second independently evolved AFP type in beetles. The two beetle AFPs have in common an extremely flat ice-binding surface comprising regular outward-projecting parallel arrays of threonine residues. The more active, wider RiAFP has four (rather than two) of these arrays between which the crystal structure shows the presence of ice-like waters. Molecular dynamics simulations independently reproduce the locations of these ordered crystallographic waters and predict additional waters that together provide an extensive view of the AFP interaction with ice. By matching several planes of hexagonal ice, these waters may help freeze the AFP to the ice surface, thus providing the molecular basis of ice binding. PMID:23486477

Seasonal Snow Extent and Snow Volume in South America Using SSM/I Passive Microwave Data

NASA Technical Reports Server (NTRS)

Foster, James L.; Chang, A. T. C.; Hall, D. K.; Kelly, R.; Houser, Paul (Technical Monitor)

2001-01-01

Seasonal snow cover in South America was examined in this study using passive microwave satellite data from the Special Sensor Microwave Imagers (SSM/I) on board Defense Meteorological Satellite Program (DMSP) satellites. For the period from 1992-1998, both snow cover extent and snow depth (snow mass) were investigated during the winter months (May-August) in the Patagonia region of Argentina. Since above normal temperatures in this region are typically above freezing, the coldest winter month was found to be not only the month having the most extensive snow cover but also the month having the deepest snows. For the seven-year period of this study, the average snow cover extent (May-August) was about 0.46 million sq km and the average monthly snow mass was about 1.18 x 10(exp 13) kg. July 1992 was the month having the greatest snow extent (nearly 0.8 million sq km) and snow mass (approximately 2.6 x 10(exp 13) kg).

Analysis of ice-binding sites in fish type II antifreeze protein by quantum mechanics.

PubMed

Cheng, Yuhua; Yang, Zuoyin; Tan, Hongwei; Liu, Ruozhuang; Chen, Guangju; Jia, Zongchao

2002-10-01

Many organisms living in cold environments can survive subzero temperatures by producing antifreeze proteins (AFPs) or antifreeze glycoproteins. In this paper we investigate the ice-binding surface of type II AFP by quantum mechanical methods, which, to the best of our knowledge, represents the first time that molecular orbital computational approaches have been applied to AFPs. Molecular mechanical approaches, including molecular docking, energy minimization, and molecular dynamics simulation, were used to obtain optimal systems for subsequent quantum mechanical analysis. We selected 17 surface patches covering the entire surface of the type II AFP and evaluated the interaction energy between each of these patches and two different ice planes using semi-empirical quantum mechanical methods. We have demonstrated the weak orbital overlay phenomenon and the change of bond orders in ice. These results consistently indicate that a surface patch containing 19 residues (K37, L38, Y20, E22, Y21, I19, L57, T56, F53, M127, T128, F129, R17, C7, N6, P5, G10, Q1, and W11) is the most favorable ice-binding site for both a regular ice plane and an ice plane where water O atoms are randomly positioned. Furthermore, for the first time the computation results provide new insights into the weakening of the ice lattice upon AFP binding, which may well be a primary factor leading to AFP-induced ice growth inhibition.

Analysis of ice-binding sites in fish type II antifreeze protein by quantum mechanics.

PubMed Central

Cheng, Yuhua; Yang, Zuoyin; Tan, Hongwei; Liu, Ruozhuang; Chen, Guangju; Jia, Zongchao

2002-01-01

Many organisms living in cold environments can survive subzero temperatures by producing antifreeze proteins (AFPs) or antifreeze glycoproteins. In this paper we investigate the ice-binding surface of type II AFP by quantum mechanical methods, which, to the best of our knowledge, represents the first time that molecular orbital computational approaches have been applied to AFPs. Molecular mechanical approaches, including molecular docking, energy minimization, and molecular dynamics simulation, were used to obtain optimal systems for subsequent quantum mechanical analysis. We selected 17 surface patches covering the entire surface of the type II AFP and evaluated the interaction energy between each of these patches and two different ice planes using semi-empirical quantum mechanical methods. We have demonstrated the weak orbital overlay phenomenon and the change of bond orders in ice. These results consistently indicate that a surface patch containing 19 residues (K37, L38, Y20, E22, Y21, I19, L57, T56, F53, M127, T128, F129, R17, C7, N6, P5, G10, Q1, and W11) is the most favorable ice-binding site for both a regular ice plane and an ice plane where water O atoms are randomly positioned. Furthermore, for the first time the computation results provide new insights into the weakening of the ice lattice upon AFP binding, which may well be a primary factor leading to AFP-induced ice growth inhibition. PMID:12324437

Heterologous expression, refolding and functional characterization of two antifreeze proteins from Fragilariopsis cylindrus (Bacillariophyceae).

PubMed

Uhlig, Christiane; Kabisch, Johannes; Palm, Gottfried J; Valentin, Klaus; Schweder, Thomas; Krell, Andreas

2011-12-01

Antifreeze proteins (AFPs) provide protection for organisms subjected to the presence of ice crystals. The psychrophilic diatom Fragilariopsis cylindrus which is frequently found in polar sea ice carries a multitude of AFP isoforms. In this study we report the heterologous expression of two antifreeze protein isoforms from F. cylindrus in Escherichia coli. Refolding from inclusion bodies produced proteins functionally active with respect to crystal deformation, recrystallization inhibition and thermal hysteresis. We observed a reduction of activity in the presence of the pelB leader peptide in comparison with the GS-linked SUMO-tag. Activity was positively correlated to protein concentration and buffer salinity. Thermal hysteresis and crystal deformation habit suggest the affiliation of the proteins to the hyperactive group of AFPs. One isoform, carrying a signal peptide for secretion, produced a thermal hysteresis up to 1.53°C±0.53°C and ice crystals of hexagonal bipyramidal shape. The second isoform, which has a long preceding N-terminal sequence of unknown function, produced thermal hysteresis of up to 2.34°C±0.25°C. Ice crystals grew in form of a hexagonal column in presence of this protein. The different sequences preceding the ice binding domain point to distinct localizations of the proteins inside or outside the cell. We thus propose that AFPs have different functions in vivo, also reflected in their specific TH capability. Copyright © 2011 Elsevier Inc. All rights reserved.

[Effect of different snow depth and area on the snow cover retrieval using remote sensing data].

PubMed

Jiang, Hong-bo; Qin, Qi-ming; Zhang, Ning; Dong, Heng; Chen, Chao

2011-12-01

For the needs of snow cover monitoring using multi-source remote sensing data, in the present article, based on the spectrum analysis of different depth and area of snow, the effect of snow depth on the results of snow cover retrieval using normalized difference snow index (NDSI) is discussed. Meanwhile, taking the HJ-1B and MODIS remote sensing data as an example, the snow area effect on the snow cover monitoring is also studied. The results show that: the difference of snow depth does not contribute to the retrieval results, while the snow area affects the results of retrieval to some extents because of the constraints of spatial resolution.

An immunotherapeutic treatment against flea allergy dermatitis in cats by co-immunization of DNA and protein vaccines.

PubMed

Jin, Jin; Ding, Zheng; Meng, Fengxia; Liu, Qiyong; Ng, Terry; Hu, Yanxin; Zhao, Gan; Zhai, Bing; Chu, Hsien-Jue; Wang, Bin

2010-02-23

Flea allergy dermatitis (FAD) is considered a harmful and persistent allergic disease in cats, dogs and humans. Effective and safe antigen-specific treatments are lacking. Previously we reported that the simultaneous co-immunization with a DNA vaccine and its cognate coded protein antigen could induce antigen-specific iTreg cells (inducible Treg cells); demonstrating its potential to protect animals from FAD in a murine model. Its clinical efficacy however, remains to be demonstrated. In this report, we clinically tested this protocol to treat established FAD in cats following flea infestations. We present data showing a profound therapeutic improvement of dermatitis in these FAD cats following two co-immunizations, not only in relieving clinical symptoms, but also the amelioration of the allergic responses, including antigen-induced wheal formation, elevated T cell proliferation, infiltration of lymphocytes and migration of mast cells to the sites. This study demonstrates that a co-immunization approach as described can be used to treat flea-induced allergic disease in animals, thus implicating its potential for a practical clinical application. Copyright 2009 Elsevier Ltd. All rights reserved.

Evaluation of the Effect of Host Immune Status on Short-Term Yersinia pestis Infection in Fleas With Implications for the Enzootic Host Model for Maintenance of Y. pestis During Interepizootic Periods

PubMed Central

GRAHAM, CHRISTINE B.; WOODS, MICHAEL E.; VETTER, SARA M.; PETERSEN, JEANNINE M.; MONTENIERI, JOHN A.; HOLMES, JENNIFER L.; MAES, SARAH E.; BEARDEN, SCOTT W.; GAGE, KENNETH L.; EISEN, REBECCA J.

2015-01-01

Plague, a primarily flea-borne disease caused by Yersinia pestis, is characterized by rapidly spreading epizootics separated by periods of quiescence. Little is known about how and where Y. pestis persists between epizootics. It is commonly proposed, however, that Y. pestis is maintained during interepizootic periods in enzootic cycles involving flea vectors and relatively resistant host populations. According to this model, while susceptible individuals serve as infectious sources for feeding fleas and subsequently die of infection, resistant hosts survive infection, develop antibodies to the plague bacterium, and continue to provide bloodmeals to infected fleas. For Y. pestis to persist under this scenario, fleas must remain infected after feeding on hosts carrying antibodies to Y. pestis. Studies of other vector-borne pathogens suggest that host immunity may negatively impact pathogen survival in the vector. Here, we report infection rates and bacterial loads for fleas (both Xenopsylla cheopis (Rothschild) and Oropsylla montana (Baker)) that consumed an infectious bloodmeal and subsequently fed on an immunized or age-matched naive mouse. We demonstrate that neither the proportion of infected fleas nor the bacterial loads in infected fleas were significantly lower within 3 d of feeding on immunized versus naive mice. Our findings thus provide support for one assumption underlying the enzootic host model of interepizootic maintenance of Y. pestis. PMID:25276941

Snow mechanics and avalanche formation: field experiments on the dynamic response of the snow cover

NASA Astrophysics Data System (ADS)

Schweizer, Jürg; Schneebeli, Martin; Fierz, Charles; Föhn, Paul M. B.

1995-11-01

Knowledge about snow mechanics and snow avalanche formation forms the basis of any hazard mitigation measures. The crucial point is the snow stability. The most relevant mechanical properties - the compressive, tensile and shear strength of the individual snow layers within the snow cover - vary substantially in space and time. Among other things the strength of the snow layers depends strongly on the state of stress and the strain rate. The evaluation of the stability of the snow cover is hence a difficult task involving many extrapolations. To gain insight in the release mechanism of slab avalanches triggered by skiers, the skier's impact is measured with a load cell at different depths within the snow cover and for different snow conditions. The study focused on the effects of the dynamic loading and of the damping by snow compaction. In accordance with earlier finite-element (FE) calculations the results show the importance of the depth of the weak layer or interface and the snow conditions, especially the sublayering. In order to directly measure the impact force and to study the snow properties in more detail, a new instrument, called rammrutsch was developed. It combines the properties of the rutschblock with the defined impact properties of the rammsonde. The mechanical properties are determined using (i) the impact energy of the rammrutsch and (ii) the deformations of the snow cover measured with accelerometers and digital image processing of video sequences. The new method is well suited to detect and to measure the mechanical processes and properties of the fracturing layers. The duration of one test is around 10 minutes and the method seems appropriate for determining the spatial variability of the snow cover. A series of experiments in a forest opening showed a clear difference in the snow stability between sites below trees and ones in the free field of the opening.

Experimental and model based investigation of the links between snow bidirectional reflectance and snow microstructure

NASA Astrophysics Data System (ADS)

Dumont, M.; Flin, F.; Malinka, A.; Brissaud, O.; Hagenmuller, P.; Dufour, A.; Lapalus, P.; Lesaffre, B.; Calonne, N.; Rolland du Roscoat, S.; Ando, E.

2017-12-01

Snow optical properties are unique among Earth surface and crucial for a wide range of applications. The bi-directional reflectance, hereafter BRDF, of snow is sensible to snow microstructure. However the complex interplays between different parameters of snow microstructure namely size parameters and shape parameters on reflectance are challenging to disentangle both theoretically and experimentally. An accurate understanding and modelling of snow BRDF is required to correctly process satellite data. BRDF measurements might also provide means of characterizing snow morphology. This study presents one of the very few dataset that combined bi-directional reflectance measurements over 500-2500 nm and X-ray tomography of the snow microstructure for three different snow samples and two snow types. The dataset is used to evaluate the approach from Malinka, 2014 that relates snow optical properties to the chord length distribution in the snow microstructure. For low and medium absorption, the model accurately reproduces the measurements but tends to slightly overestimate the anisotropy of the reflectance. The model indicates that the deviation of the ice chord length distribution from an exponential distribution, that can be understood as a characterization of snow types, does not impact the reflectance for such absorptions. The simulations are also impacted by the uncertainties in the ice refractive index values. At high absorption and high viewing/incident zenith angle, the simulations and the measurements disagree indicating that some of the assumptions made in the model are not met anymore. The study also indicates that crystal habits might play a significant role for the reflectance under such geometries and wavelengths. However quantitative relationship between crystal habits and reflectance alongside with potential optical methodologies to classify snow morphology would require an extended dataset over more snow types. This extended dataset can likely be obtained

Snow [Chapter 10

Treesearch

R. A. Sommerfeld

1994-01-01

Generally, the annual snowpack at GLEES is established in November and lasts into July. Figure 10.1 is the 1987-91 recession curve of the snow-covered area fraction versus degree days. About 20% of the area consists of rocks, which are usually blown clear of snow, and trees. The trees may hide some of the snow in the aerial photographs that were used to develop the...

Synergy between dinotefuran and fipronil against the cat flea (Ctenocephalides felis): improved onset of action and residual speed of kill in adult cats.

PubMed

Delcombel, Romain; Karembe, Hamadi; Nare, Bakela; Burton, Audrey; Liebenberg, Julian; Fourie, Josephus; Varloud, Marie

2017-07-19

The cat flea, Ctenocephalides felis felis (C. felis), is a cosmopolitan hematophagous ectoparasite, and is considered to be the most prevalent flea species in both Europe and the USA. Clinical signs frequently associated with flea bites include pruritus, dermatitis and in severe cases even pyodermatitis and alopecia. Ctenocephalides felis is also a vector for several pathogens and is an intermediate host for the cestode Dipylidium caninum. Treatment of cats with a fast-acting pulicide, that is persistently effective in protecting the animal against re-infestation, is therefore imperative to their health. In addition, a rapid onset of activity ("speed of kill") may also reduce the risks of disease transmission and flea allergic dermatitis. The aim of this study was to evaluate the in vitro insecticidal activity and potential synergism between dinotefuran and fipronil against C. felis. A further aim was to evaluate the onset of activity and residual speed of kill of the combination in vivo on cats artificially infested with C. felis. In the first study, the insecticidal activity of dinotefuran and fipronil separately and dinotefuran/fipronil (DF) in combination, at a fixed ratio (2:1), was evaluated using an in vitro coated-vial bioassay. In the second study, the onset of activity against existing flea infestations and residual speed of kill of DF against artificial flea infestations on cats was assessed in vivo. Onset of activity against existing flea infestations was assessed in terms of knock-down effect within 2 h post-treatment and onset of speed of kill assessed at 3 h, 6 h and 12 h post-treatment. Residual speed of kill was evaluated 6 h and 48 h after infestation, over a period of six weeks post-treatment. In vitro results revealed that the DF combination was synergistic and more potent against fleas than either compound alone. The combination also proved effective when tested in vivo. Efficacy was > 97% [geometric mean (GM) and arithmetic mean (AM

Characterizing 2-D snow stratigraphy in forests based on high-resolution snow penetrometry

NASA Astrophysics Data System (ADS)

Teich, M.; Loewe, H.; Jenkins, M. J.; Schneebeli, M.

2016-12-01

Snow stratigraphy, the characteristic layering within a seasonal snowpack, has important implications for snow remote sensing, hydrology and avalanches. Forests modify snowpack properties through interception of falling snow by tree crowns, the reduction of near-surface wind speeds, and changes to the energy balance beneath and around trees leading to a highly variable stratigraphy in space and time. The lack of snowpack observations in forests limits our ability to understand the spatio-temporal evolution of snow stratigraphy as a function of forest structure and to observe snowpack response to changes in forest cover. We examined the snowpack in field campaigns using the SnowMicroPen (SMP) under tree canopies in an Engelmann spruce forest in the central Rocky Mountains in Utah, USA. Data were collected in plots beneath canopies of undisturbed, bark beetle-disturbed and salvage logged forest stands, and a non-forested meadow. In 2015 weekly-repeated SMP penetration measurements were taken along 10 m transects at 0.3 m intervals. In the winter of 2016 bi-weekly measurements were collected along 20 m transects every 0.5 m. Using a statistical model, we derived 2-D snow density profiles as a measure of stratigraphy. The small-scale patterns in snow density revealed a more heterogeneous stratigraphy in undisturbed dense stands and also beneath bark beetle-disturbed forest. In contrast, snow stratigraphy was more homogeneous in the harvested plot despite standing small diameter trees and woody debris with effective heights up to 95 cm. As expected, snow depth and layering in non-forested plots varied only slightly over the small spatial extent sampled. Observed patterns changed throughout the snow season dependent upon snow and meteorological conditions. The results contribute to the general understanding of forest-snowpack interactions at high spatial resolution, and can be used to validate snowpack and microwave models for avalanche formation processes and SWE

Oscillations and accelerations of ice crystal growth rates in microgravity in presence of antifreeze glycoprotein impurity in supercooled water.

PubMed

Furukawa, Yoshinori; Nagashima, Ken; Nakatsubo, Shun-Ichi; Yoshizaki, Izumi; Tamaru, Haruka; Shimaoka, Taro; Sone, Takehiko; Yokoyama, Etsuro; Zepeda, Salvador; Terasawa, Takanori; Asakawa, Harutoshi; Murata, Ken-Ichiro; Sazaki, Gen

2017-03-06

The free growth of ice crystals in supercooled bulk water containing an impurity of glycoprotein, a bio-macromolecule that functions as 'antifreeze' in living organisms in a subzero environment, was observed under microgravity conditions on the International Space Station. We observed the acceleration and oscillation of the normal growth rates as a result of the interfacial adsorption of these protein molecules, which is a newly discovered impurity effect for crystal growth. As the convection caused by gravity may mitigate or modify this effect, secure observations of this effect were first made possible by continuous measurements of normal growth rates under long-term microgravity condition realized only in the spacecraft. Our findings will lead to a better understanding of a novel kinetic process for growth oscillation in relation to growth promotion due to the adsorption of protein molecules and will shed light on the role that crystal growth kinetics has in the onset of the mysterious antifreeze effect in living organisms, namely, how this protein may prevent fish freezing.

SEASON OF DELTAMETHRIN APPLICATION AFFECTS FLEA AND PLAGUE CONTROL IN WHITE-TAILED PRAIRIE DOG (CYNOMYS LEUCURUS) COLONIES, COLORADO, USA.

PubMed

Tripp, Daniel W; Streich, Sean P; Sack, Danielle A; Martin, Daniel J; Griffin, Karen A; Miller, Michael W

2016-07-01

In 2008 and 2009, we evaluated the duration of prophylactic deltamethrin treatments in white-tailed prairie dog ( Cynomys leucurus ) colonies and compared effects of autumn or spring dust application in suppressing flea numbers and plague. Plague occurred before and during our experiment. Overall, flea abundance tended to increase from May or June to September, but it was affected by deltamethrin treatment and plague dynamics. Success in trapping prairie dogs (animals caught/trap days) declined between June and September at all study sites. However, by September trap success on dusted sites (19%; 95% confidence interval [CI] 16-22%) was about 15-fold greater than on undusted control sites (1%; CI 0.3-4%; P≤0.0001). Applying deltamethrin dust as early as 12 mo prior seemed to afford some protection to prairie dogs. Our data showed that dusting even a portion of a prairie dog colony can prolong its persistence despite epizootic plague. Autumn dusting may offer advantages over spring in suppressing overwinter or early-spring flea activity, but timing should be adjusted to precede the annual decline in aboveground activity for hibernating prairie dog species. Large colony complexes or collections of occupied but fragmented habitat may benefit from dusting some sites in spring and others in autumn to maximize flea suppression in a portion of the complex or habitat year-round.

River Flow Advisory Commission: Snow Survey

Science.gov Websites

Survey River Watch Home → Snow Survey RFAC Information About Us Reports Maine Cooperative Snow Survey About the Snow Survey Snow Survey Map Compare Snow Survey Data Snow Survey Graphs River Watch MEMA Home USGS (Maine) Home Maine Cooperative Snow Survey This information is provided by a partnership with

A root bond between ice and antifreeze protein.

PubMed

Hawes, Timothy C

2016-10-01

It has always been assumed that a three-dimensional protein structure is essential to antifreeze protein (AFP) ice interactions. Using a 9 kDa AFP isolated from the springtail, Gomphiocephalus hodgsoni, it was found that the bond between ice and protein is maintained independent of higher order protein structure. GomplyAFP9 remained bound to ice after denaturing by a range of agents (boiling, extreme pH, DTT, ethanol, urea). Thermal hysteresis was minimal (0.03-0.04 °C), but not lost. Crystal faceting and growth occurred normal to the c-axis, indicating the protein binds primarily to sites along the a-axis. These observations lend additional support to the hypothesis of irreversible binding. More significantly, they suggest that binding to ice and functional hysteresis may be achieved independently (i.e. are different operations). These results are consistent with the view that there is a root bond with ice and it is achieved via an amino acid derived interface that bonds to water molecules in aqueous solutions. Copyright © 2016 Elsevier Inc. All rights reserved.

Janus effect of antifreeze proteins on ice nucleation

PubMed Central

Liu, Kai; Wang, Chunlei; Ma, Ji; Shi, Guosheng; Yao, Xi; Fang, Haiping; Song, Yanlin; Wang, Jianjun

2016-01-01

The mechanism of ice nucleation at the molecular level remains largely unknown. Nature endows antifreeze proteins (AFPs) with the unique capability of controlling ice formation. However, the effect of AFPs on ice nucleation has been under debate. Here we report the observation of both depression and promotion effects of AFPs on ice nucleation via selectively binding the ice-binding face (IBF) and the non–ice-binding face (NIBF) of AFPs to solid substrates. Freezing temperature and delay time assays show that ice nucleation is depressed with the NIBF exposed to liquid water, whereas ice nucleation is facilitated with the IBF exposed to liquid water. The generality of this Janus effect is verified by investigating three representative AFPs. Molecular dynamics simulation analysis shows that the Janus effect can be established by the distinct structures of the hydration layer around IBF and NIBF. Our work greatly enhances the understanding of the mechanism of AFPs at the molecular level and brings insights to the fundamentals of heterogeneous ice nucleation. PMID:27930318

Snow snake performance monitoring.

DOT National Transportation Integrated Search

2008-12-01

A recent study, Three-Dimensional Roughness Elements for Snow Retention (FHWA-WY-06/04F) (Tabler 2006), demonstrated : positive evidence for the effectiveness of Snow Snakes, a new type of snow fence suitable for use within the highway right-of...

Structural Basis for Antifreeze Activity of Ice-binding Protein from Arctic Yeast*

PubMed Central

Lee, Jun Hyuck; Park, Ae Kyung; Do, Hackwon; Park, Kyoung Sun; Moh, Sang Hyun; Chi, Young Min; Kim, Hak Jun

2012-01-01

Arctic yeast Leucosporidium sp. produces a glycosylated ice-binding protein (LeIBP) with a molecular mass of ∼25 kDa, which can lower the freezing point below the melting point once it binds to ice. LeIBP is a member of a large class of ice-binding proteins, the structures of which are unknown. Here, we report the crystal structures of non-glycosylated LeIBP and glycosylated LeIBP at 1.57- and 2.43-Å resolution, respectively. Structural analysis of the LeIBPs revealed a dimeric right-handed β-helix fold, which is composed of three parts: a large coiled structural domain, a long helix region (residues 96–115 form a long α-helix that packs along one face of the β-helix), and a C-terminal hydrophobic loop region (243PFVPAPEVV251). Unexpectedly, the C-terminal hydrophobic loop region has an extended conformation pointing away from the body of the coiled structural domain and forms intertwined dimer interactions. In addition, structural analysis of glycosylated LeIBP with sugar moieties attached to Asn185 provides a basis for interpreting previous biochemical analyses as well as the increased stability and secretion of glycosylated LeIBP. We also determined that the aligned Thr/Ser/Ala residues are critical for ice binding within the B face of LeIBP using site-directed mutagenesis. Although LeIBP has a common β-helical fold similar to that of canonical hyperactive antifreeze proteins, the ice-binding site is more complex and does not have a simple ice-binding motif. In conclusion, we could identify the ice-binding site of LeIBP and discuss differences in the ice-binding modes compared with other known antifreeze proteins and ice-binding proteins. PMID:22303017

Structure-function relationship in the globular type III antifreeze protein: identification of a cluster of surface residues required for binding to ice.

PubMed Central

Chao, H.; Sönnichsen, F. D.; DeLuca, C. I.; Sykes, B. D.; Davies, P. L.

1994-01-01

Antifreeze proteins (AFPs) depress the freezing point of aqueous solutions by binding to and inhibiting the growth of ice. Whereas the ice-binding surface of some fish AFPs is suggested by their linear, repetitive, hydrogen bonding motifs, the 66-amino-acid-long Type III AFP has a compact, globular fold without any obvious periodicity. In the structure, 9 beta-strands are paired to form 2 triple-stranded antiparallel sheets and 1 double-stranded antiparallel sheet, with the 2 triple sheets arranged as an orthogonal beta-sandwich (Sönnichsen FD, Sykes BD, Chao H, Davies PL, 1993, Science 259:1154-1157). Based on its structure and an alignment of Type III AFP isoform sequences, a cluster of conserved, polar, surface-accessible amino acids (N14, T18, Q44, and N46) was noted on and around the triple-stranded sheet near the C-terminus. At 3 of these sites, mutations that switched amide and hydroxyl groups caused a large decrease in antifreeze activity, but amide to carboxylic acid changes produced AFPs that were fully active at pH 3 and pH 6. This is consistent with the observation that Type III AFP is optimally active from pH 2 to pH 11. At a concentration of 1 mg/mL, Q44T, N14S, and T18N had 50%, 25%, and 10% of the activity of wild-type antifreeze, respectively. The effects of the mutations were cumulative, such that the double mutant N14S/Q44T had 10% of the wild-type activity and the triple mutant N14S/T18N/Q44T had no activity. All mutants with reduced activity were shown to be correctly folded by NMR spectroscopy. Moreover, a complete characterization of the triple mutant by 2-dimensional NMR spectroscopy indicated that the individual and combined mutations did not significantly alter the structure of these proteins. These results suggest that the C-terminal beta-sheet of Type III AFP is primarily responsible for antifreeze activity, and they identify N14, T18, and Q44 as key residues for the AFP-ice interaction. PMID:7849594

Snow depth on Arctic and Antarctic sea ice derived from autonomous (Snow Buoy) measurements

NASA Astrophysics Data System (ADS)

Nicolaus, Marcel; Arndt, Stefanie; Hendricks, Stefan; Heygster, Georg; Huntemann, Marcus; Katlein, Christian; Langevin, Danielle; Rossmann, Leonard; Schwegmann, Sandra

2016-04-01

The snow cover on sea ice received more and more attention in recent sea ice studies and model simulations, because its physical properties dominate many sea ice and upper ocean processes. In particular; the temporal and spatial distribution of snow depth is of crucial importance for the energy and mass budgets of sea ice, as well as for the interaction with the atmosphere and the oceanic freshwater budget. Snow depth is also a crucial parameter for sea ice thickness retrieval algorithms from satellite altimetry data. Recent time series of Arctic sea ice volume only use monthly snow depth climatology, which cannot take into account annual changes of the snow depth and its properties. For Antarctic sea ice, no such climatology is available. With a few exceptions, snow depth on sea ice is determined from manual in-situ measurements with very limited coverage of space and time. Hence the need for more consistent observational data sets of snow depth on sea ice is frequently highlighted. Here, we present time series measurements of snow depths on Antarctic and Arctic sea ice, recorded by an innovative and affordable platform. This Snow Buoy is optimized to autonomously monitor the evolution of snow depth on sea ice and will allow new insights into its seasonality. In addition, the instruments report air temperature and atmospheric pressure directly into different international networks, e.g. the Global Telecommunication System (GTS) and the International Arctic Buoy Programme (IABP). We introduce the Snow Buoy concept together with technical specifications and results on data quality, reliability, and performance of the units. We highlight the findings from four buoys, which simultaneously drifted through the Weddell Sea for more than 1.5 years, revealing unique information on characteristic regional and seasonal differences. Finally, results from seven snow buoys co-deployed on Arctic sea ice throughout the winter season 2015/16 suggest the great importance of local

Effect of glycosylation on hydration behavior at the ice-binding surface of the Ocean Pout type III antifreeze protein: a molecular dynamics simulation.

PubMed

Halder, Swagata; Mukhopadhyay, Chaitali

2017-12-01

Antifreeze proteins (AFPs), found in certain vertebrates, plants, fungi and bacteria have the ability to permit their survival in subzero environments by thermal hysteresis mechanism. However, the exact mechanism of ice growth inhibition is still not clearly understood. Here, four long explicit molecular dynamics (MD) simulations have been carried out at two different temperatures (277 and 298 K) with and without glycan to study the conformational rigidity of the Ocean pout type III antifreeze protein in aqueous medium and the structural arrangements of water molecules hydrating its ice-binding surface. It is found that irrespective of the temperature the ice-binding surface (IBS) of the protein is relatively more rigid than its non ice-binding surface (NonIBS) in its native and glycosylated form. Hydrophilic residues N14, T18 and Q44 are essential to antifreeze activity. Radial distribution, density distribution function and nearest neighbor orientation plots with respect to individual two surfaces confirm that density of water molecule near these binding surface in native and glycosylated form are relatively more than the nonbinding surface. The glycosylated form shows a strong peak than the native one. From rotational auto correlation function of water molecules around ice-binding sites, it is prominent that with increase in temperature, strong interaction between the water oxygen and the hydrogen bond acceptor group on the protein-binding surface decreases. This provides a possible molecular reason behind the ice-binding activity of ocean pout at the prism plane of ice.

Silencing urease: a key evolutionary step that facilitated the adaptation of Yersinia pestis to the flea-borne transmission route.

PubMed

Chouikha, Iman; Hinnebusch, B Joseph

2014-12-30

The arthropod-borne transmission route of Yersinia pestis, the bacterial agent of plague, is a recent evolutionary adaptation. Yersinia pseudotuberculosis, the closely related food-and water-borne enteric species from which Y. pestis diverged less than 6,400 y ago, exhibits significant oral toxicity to the flea vectors of plague, whereas Y. pestis does not. In this study, we identify the Yersinia urease enzyme as the responsible oral toxin. All Y. pestis strains, including those phylogenetically closest to the Y. pseudotuberculosis progenitor, contain a mutated ureD allele that eliminated urease activity. Restoration of a functional ureD was sufficient to make Y. pestis orally toxic to fleas. Conversely, deletion of the urease operon in Y. pseudotuberculosis rendered it nontoxic. Enzymatic activity was required for toxicity. Because urease-related mortality eliminates 30-40% of infective flea vectors, ureD mutation early in the evolution of Y. pestis was likely subject to strong positive selection because it significantly increased transmission potential.

Silencing urease: A key evolutionary step that facilitated the adaptation of Yersinia pestis to the flea-borne transmission route

PubMed Central

Chouikha, Iman; Hinnebusch, B. Joseph

2014-01-01

The arthropod-borne transmission route of Yersinia pestis, the bacterial agent of plague, is a recent evolutionary adaptation. Yersinia pseudotuberculosis, the closely related food-and water-borne enteric species from which Y. pestis diverged less than 6,400 y ago, exhibits significant oral toxicity to the flea vectors of plague, whereas Y. pestis does not. In this study, we identify the Yersinia urease enzyme as the responsible oral toxin. All Y. pestis strains, including those phylogenetically closest to the Y. pseudotuberculosis progenitor, contain a mutated ureD allele that eliminated urease activity. Restoration of a functional ureD was sufficient to make Y. pestis orally toxic to fleas. Conversely, deletion of the urease operon in Y. pseudotuberculosis rendered it nontoxic. Enzymatic activity was required for toxicity. Because urease-related mortality eliminates 30–40% of infective flea vectors, ureD mutation early in the evolution of Y. pestis was likely subject to strong positive selection because it significantly increased transmission potential. PMID:25453069

Efficacy of Entomopathogenic Nematodes and Sprayable Polymer Gel Against Crucifer Flea Beetle (Coleoptera: Chrysomelidae) on Canola.

PubMed

Antwi, Frank B; Reddy, Gadi V P

2016-08-01

The crucifer flea beetle, Phyllotreta cruciferae (Goeze), is a key pest of canola (Brassica napus L.) in the northern Great Plains of North America. The efficacies of entomopathogenic nematodes (Steinernema spp. and Heterorhabditis spp.), a sprayable polymer gel, and a combination of both were assessed on canola for flea beetle management. Plots were treated soon after colonization by adult flea beetles, when canola was in the cotyledon to one-leaf stage. Ten plants along a 3.6-m section of row were selected and rated at pre-treatment and 7 and 14 d post treatment using the damage-rating scheme advanced by the European Plant Protection Organization, where 1 = 0%, 2 = 2%, 3 = 5%, 4 = 10%, and 5 = 25% leaf area injury. Under moderate flea beetle feeding pressure (1-3.3% leaf area damaged), seeds treated with Gaucho 600 (Bayer CropScience LP Raleigh, NC) (imidacloprid) produced the highest yield (843.2 kg/ha). Meanwhile, Barricade (Barricade International, Inc. Hobe Sound, FL) (polymer gel; 1%) + Scanmask (BioLogic Company Inc, Willow Hill, PA) (Steinernema feltiae) resulted in the highest yields: 1020.8 kg/ha under high (2.0-5.3% leaf area damaged), and 670.2 kg/ha at extremely high (4.3-8.6 % leaf area damaged) feeding pressure. Our results suggest that Barricade (1%) + Scanmask (S. feltiae) can serve as an alternative to the conventional chemical seed treatment. Moreover, Scanmask (S. feltiae) can be used to complement the effects of seed treatment after its protection has run out. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Evaluation and comparison of a flumethrin-imidacloprid collar and repeated monthly treatments of fipronil/(s)-methoprene to control flea, Ctenocephalides f. felis, infestations on cats for eight months.

PubMed

Dryden, Michael W; Smith, Vicki; Davis, Wendell L; Settje, Terry; Hostetler, Joe

2016-05-17

This controlled laboratory study was designed to evaluate the efficacy of the 10 % imidacloprid/4.5 % flumethrin collar (Seresto®, Bayer Animal Health) against fleas (Ctenocephalides f. felis) on cats, when compared to fipronil (9.8 %w/w)/(s)-methoprene (11.8 % w/w) topical spot-on formulation (Frontline® Plus for Cats and Kittens, Merial). Thirty cats were randomized into three groups of ten animals based on pre-treatment flea counts: Group 1: imidacloprid/flumethrin collar; Group 2: fipronil/(s)-methoprene topical spot-on and Group 3: non-treated controls. The imidacloprid/flumethrin collars were applied one time on Day 0, while the fipronil/(s)-methoprene spot-on was administered every 30 days from Day 0 through Day 210. Cats were infested with 100 fleas on study days 0, 7, 14, 29, 59, 89, 119, 149, 179, 209 and 239. All flea counts were conducted by combing to remove fleas on post-treatment days 2, 8, 15, 30, 60, 90, 120, 150, 180, 210 and 240. The efficacy of the imidacloprid/flumethrin collar ranged from 98.2 to 100 % for eight months. The efficacy of fipronil/(s)-methoprene spot-on ranged from 68.2 to 99.9 %. Efficacy was < 85 % for fipronil/(s)-methoprene on Days 90, 150 and 210. The flea counts in both treatment groups were significantly fewer than those in the non-treated control group at every post-treatment study day (P < 0.0001). In addition, there were significantly fewer fleas in the imidacloprid/flumethrin collar group when compared to the fipronil/(s)-methoprene group on Days 90, 150 and 210 (P < 0.0001). This study demonstrated that the imidacloprid/flumethrin collar (Seresto®, Bayer Animal Health) maintained excellent ( > 98.2 %) efficacy against fleas on cats for the entire 8 month study. Monthly applications of fipronil/(s)-methoprene (Frontline® Plus for Cats and Kittens, Merial) generally had high, but variable (68.2 to 99.9 %) efficacy over the course of the eight month study. Based on the very high residual

Potential for Monitoring Snow Cover in Boreal Forests by Combining MODIS Snow Cover and AMSR-E SWE Maps

NASA Technical Reports Server (NTRS)

Riggs, George A.; Hall, Dorothy K.; Foster, James L.

2009-01-01

Monitoring of snow cover extent and snow water equivalent (SWE) in boreal forests is important for determining the amount of potential runoff and beginning date of snowmelt. The great expanse of the boreal forest necessitates the use of satellite measurements to monitor snow cover. Snow cover in the boreal forest can be mapped with either the Moderate Resolution Imaging Spectroradiometer (MODIS) or the Advanced Microwave Scanning Radiometer for EOS (AMSR-E) microwave instrument. The extent of snow cover is estimated from the MODIS data and SWE is estimated from the AMSR-E. Environmental limitations affect both sensors in different ways to limit their ability to detect snow in some situations. Forest density, snow wetness, and snow depth are factors that limit the effectiveness of both sensors for snow detection. Cloud cover is a significant hindrance to monitoring snow cover extent Using MODIS but is not a hindrance to the use of the AMSR-E. These limitations could be mitigated by combining MODIS and AMSR-E data to allow for improved interpretation of snow cover extent and SWE on a daily basis and provide temporal continuity of snow mapping across the boreal forest regions in Canada. The purpose of this study is to investigate if temporal monitoring of snow cover using a combination of MODIS and AMSR-E data could yield a better interpretation of changing snow cover conditions. The MODIS snow mapping algorithm is based on snow detection using the Normalized Difference Snow Index (NDSI) and the Normalized Difference Vegetation Index (NDVI) to enhance snow detection in dense vegetation. (Other spectral threshold tests are also used to map snow using MODIS.) Snow cover under a forest canopy may have an effect on the NDVI thus we use the NDVI in snow detection. A MODIS snow fraction product is also generated but not used in this study. In this study the NDSI and NDVI components of the snow mapping algorithm were calculated and analyzed to determine how they changed

Monitoring global snow cover

NASA Technical Reports Server (NTRS)

Armstrong, Richard; Hardman, Molly

1991-01-01

A snow model that supports the daily, operational analysis of global snow depth and age has been developed. It provides improved spatial interpolation of surface reports by incorporating digital elevation data, and by the application of regionalized variables (kriging) through the use of a global snow depth climatology. Where surface observations are inadequate, the model applies satellite remote sensing. Techniques for extrapolation into data-void mountain areas and a procedure to compute snow melt are also contained in the model.

Estimation of Snow Particle Model Suitable for a Complex and Forested Terrain: Lessons from SnowEx

NASA Astrophysics Data System (ADS)

Gatebe, C. K.; Li, W.; Stamnes, K. H.; Poudyal, R.; Fan, Y.; Chen, N.

2017-12-01

SnowEx 2017 obtained consistent and coordinated ground and airborne remote sensing measurements over Grand Mesa in Colorado, which feature sufficient forested stands to have a range of density and height (and other forest conditions); a range of snow depth/snow water equivalent (SWE) conditions; sufficiently flat snow-covered terrain of a size comparable to airborne instrument swath widths. The Cloud Absorption Radiometer (CAR) data from SnowEx are unique and can be used to assess the accuracy of Bidirectional Reflectance-Distribution Functions (BRDFs) calculated by different snow models. These measurements provide multiple angle and multiple wavelength data needed for accurate surface BRDF characterization. Such data cannot easily be obtained by current satellite remote sensors. Compared to ground-based snow field measurements, CAR measurements minimize the effect of self-shading, and are adaptable to a wide variety of field conditions. We plan to use the CAR measurements as the validation data source for our snow modeling effort. By comparing calculated BRDF results from different snow models to CAR measurements, we can determine which model best explains the snow BRDFs, and is therefore most suitable for application to satellite remote sensing of snow parameters and surface energy budget calculations.

An electrostatic charge measurement of blowing snow particles focusing on collision frequency to the snow surface

NASA Astrophysics Data System (ADS)

Omiya, S.; Sato, A.

2010-12-01

Blowing snow particles are known to have an electrostatic charge. This charge may be a contributing factor in the formation of snow drifts and snow cornices and changing of the trajectory of blowing snow particles. These formations and phenomena can cause natural disaster such as an avalanche and a visibility deterioration, and obstruct transportation during winter season. Therefore, charging phenomenon of the blowing snow particles is an important issue in terms of not only precise understanding of the particle motion but disaster prevention. The primary factor of charge accumulation to the blowing snow particles is thought to be due to “saltation” of them. The “saltation” is one of movement forms of blowing snow: when the snow particles are transported by the wind, they repeat frictional collisions with the snow surface. In previous studies, charge-to-mass ratios measured in the field were approximately -50 to -10 μC/kg, and in the wind tunnel were approximately -0.8 to -0.1 μC/kg. While there were qualitatively consistent in sign, negative, there were huge gaps quantitatively between them. One reason of those gaps is speculated to be due to differences in fetch. In other words, the difference of the collision frequency of snow particles to the snow surface has caused the gaps. But it is merely a suggestion and that has not been confirmed. The purpose of this experiment is to measure the charge of blowing snow particles focusing on the collision frequency and clarify the relationship between them. Experiments were carried out in the cryogenic wind tunnel of Snow and Ice Research Center (NIED, JAPAN). A Faraday cage and an electrometer were used to measure the charge of snow particles. These experiments were conducted over the hard snow surface condition to prevent the erosion of the snow surface and the generation of new snow particles from the surface. The collision frequency of particle was controlled by changing the wind velocity (4.5 to 7 m/s) under

Effect of larval diet on cat flea (Siphonaptera: Pulicidae) developmental times and adult emergence.

PubMed

Moser, B A; Koehler, P G; Patterson, R S

1991-08-01

The natural diet of cat flea, Ctenocephalides felis (Bouche), larvae is primarily adult flea feces, but dried bovine blood may be substituted in the laboratory. Percentage adult emergence (79.4% on feces; 78.9% on blood) and developmental times (20.6 d on feces; 17.1 d on blood) did not significantly differ for the two diets. The drying temperature of blood determined its quality; blood dried at 120 degrees C was unsatisfactory for larval development. The dietary value of dried bovine blood was not enhanced when supplemented with brewer's yeast, rodent chow, or a combination of those constituents. Blood particle size ranging from less than 180 to greater than 500u did not affect the value of blood as a diet. Rodent chow, yeast, albumen, hemoglobin, and mixtures of these constituents were unsuitable as larval diets.

Efficacy of dinotefuran-pyriproxyfen, dinotefuran-pyriproxyfen-permethrin and fipronil-(S)-methoprene topical spot-on formulations to control flea populations in naturally infested pets and private residences in Tampa, FL.

PubMed

Dryden, Michael W; Payne, Patricia A; Vicki, Smith; Riggs, Breanne; Davenport, Jacob; Kobuszewski, Denise

2011-12-15

Thirteen cats and 7 dogs living in 14 homes were treated topically with either a dinotefuran (22%, w/w)/pyriproxyfen (3.00%, w/w) (DP) or dinotefuran (4.95%, w/w)/pyriproxyfen (0.44%, w/w)/permethrin (36.08%, w/w) (DPP) topical spot-on, respectively. Twenty cats and 7 dogs living in 16 homes were treated topically with either a fipronil (9.8%, w/w)/(S)-methoprene (11.8%, w/w) or fipronil (9.8%, w/w)/(S)-methoprene (8.8%, w/w) topical spot-on (FM), respectively. All products were applied according to label directions by study investigators on day 0 and again between days 28 and 30. Flea populations on pets were assessed using visual area counts and premise flea infestations were assessed using intermittent-light flea traps on days 0, 7, 14, 21, 28-30, 40-45, and 54-60. A single application of the DP-DPP and FM formations reduced flea populations by 87.35% and 88.44%, respectively within 7 days. Following two monthly applications of either the DP-DPP or FM formulations, pet flea burdens were reduced by 95.24% and 95.47%, respectively. Flea numbers in the indoor-premises were also markedly reduced by days 54-60, with 98.05% and 96.15% reductions in intermittent-light flea trap counts in the DP-DPP or FM treatment groups, respectively. Copyright © 2011 Elsevier B.V. All rights reserved.

Deriving Snow-Cover Depletion Curves for Different Spatial Scales from Remote Sensing and Snow Telemetry Data

NASA Technical Reports Server (NTRS)

Fassnacht, Steven R.; Sexstone, Graham A.; Kashipazha, Amir H.; Lopez-Moreno, Juan Ignacio; Jasinski, Michael F.; Kampf, Stephanie K.; Von Thaden, Benjamin C.

2015-01-01

During the melting of a snowpack, snow water equivalent (SWE) can be correlated to snow-covered area (SCA) once snow-free areas appear, which is when SCA begins to decrease below 100%. This amount of SWE is called the threshold SWE. Daily SWE data from snow telemetry stations were related to SCA derived from moderate-resolution imaging spectro radiometer images to produce snow-cover depletion curves. The snow depletion curves were created for an 80,000 sq km domain across southern Wyoming and northern Colorado encompassing 54 snow telemetry stations. Eight yearly snow depletion curves were compared, and it is shown that the slope of each is a function of the amount of snow received. Snow-cover depletion curves were also derived for all the individual stations, for which the threshold SWE could be estimated from peak SWE and the topography around each station. A stations peak SWE was much more important than the main topographic variables that included location, elevation, slope, and modelled clear sky solar radiation. The threshold SWE mostly illustrated inter-annual consistency.

Snow geese

USGS Publications Warehouse

Hupp, Jerry W.; Robertson, Donna G.; Brackney, Alan W.; Douglas, David C.; Reynolds, Patricia E.; Rhode, E.B.

2002-01-01

Part of the coastal plain of the Arctic National Wildlife Refuge, Alaska, is used as an autumn staging area by lesser snow geese (Chen caerulescens caerulescens) from the Western Canadian Arctic population (hereafter called the Western Arctic population). There were approximately 200,000 breeding adults in the Western Arctic population through the mid-1980s (Johnson and Herter 1989), but the population has recently increased to about 500,000 breeding adults (Kerbes et al. 1999).Early in their autumn migration, adult and juvenile snow geese from the Western Arctic population feed intensively while staging on the Beaufort Sea coastal plain in Canada and Alaska to build fat reserves needed for migration. Aerial censuses from 1973 to 1985 indicated that up to 600,000 adult and juvenile snow geese used the coastal plain for 2-4 weeks in late August until mid-September (Oates et al. 1987).We studied annual variation in numbers and spatial distribution of snow geese that staged on the coastal plain of the Arctic Refuge.

Flea (Ctenocephalides felis) control efficacy of topical indoxacarb on dogs subsequently bathed with a chlorhexidine–ketoconazole shampoo

PubMed Central

Liebenberg, JE; Heaney, K; Guerino, F

2015-01-01

Objective An evaluation of the effect of chlorhexidine/ketoconazole shampoo baths on the flea control efficacy of indoxacarb applied topically to dogs. Methods and Results We randomly allocated 18 healthy mixed‐breed dogs to 3 groups: shampoo only; indoxacarb treated and medicated shampoo; and indoxacarb treated but not shampooed. Indoxacarb was administered on day 0 and dogs were shampooed on days 9 and 23. Dogs were infested with 100 adult Ctenocephalides felis initially 2 days before treatment and then weekly from days 7 to 28. Fleas were removed and counted 48 h post‐infestation. Conclusion Medicated shampoo use did not significantly reduce indoxacarb efficacy against C. felis. PMID:26220323

Antarctic Sea Ice Thickness and Snow-to-Ice Conversion from Atmospheric Reanalysis and Passive Microwave Snow Depth

NASA Technical Reports Server (NTRS)

Markus, Thorsten; Maksym, Ted

2007-01-01

Passive microwave snow depth, ice concentration, and ice motion estimates are combined with snowfall from the European Centre for Medium Range Weather Forecasting (ECMWF) reanalysis (ERA-40) from 1979-200 1 to estimate the prevalence of snow-to-ice conversion (snow-ice formation) on level sea ice in the Antarctic for April-October. Snow ice is ubiquitous in all regions throughout the growth season. Calculated snow- ice thicknesses fall within the range of estimates from ice core analysis for most regions. However, uncertainties in both this analysis and in situ data limit the usefulness of snow depth and snow-ice production to evaluate the accuracy of ERA-40 snowfall. The East Antarctic is an exception, where calculated snow-ice production exceeds observed ice thickness over wide areas, suggesting that ERA-40 precipitation is too high there. Snow-ice thickness variability is strongly controlled not just by snow accumulation rates, but also by ice divergence. Surprisingly, snow-ice production is largely independent of snow depth, indicating that the latter may be a poor indicator of total snow accumulation. Using the presence of snow-ice formation as a proxy indicator for near-zero freeboard, we examine the possibility of estimating level ice thickness from satellite snow depths. A best estimate for the mean level ice thickness in September is 53 cm, comparing well with 51 cm from ship-based observations. The error is estimated to be 10-20 cm, which is similar to the observed interannual and regional variability. Nevertheless, this is comparable to expected errors for ice thickness determined by satellite altimeters. Improvement in satellite snow depth retrievals would benefit both of these methods.

Evaluation of forest snow processes models (SnowMKIP2)

Treesearch

Nick Rutter; Richard Essery; John Pomeroy; Nuria Altimir; Kostas Andreadis; Ian Baker; Alan Barr; Paul Bartlett; Aaron Boone; Huiping Deng; Herve Douville; Emanuel Dutra; Kelly Elder; others

2009-01-01

Thirty-three snowpack models of varying complexity and purpose were evaluated across a wide range of hydrometeorological and forest canopy conditions at five Northern Hemisphere locations, for up to two winter snow seasons. Modeled estimates of snow water equivalent (SWE) or depth were compared to observations at forest and open sites at each location. Precipitation...

Snow In the Sahara

NASA Image and Video Library

2017-12-08

In December 2016, snow fell in the Sahara for the first time since 1979. In 1984, the charitable supergroup Band Aid sang: “There won’t be snow in Africa this Christmas time.” In fact, it does snow in Africa at high elevations. Kilimanjaro has long had a cap of snow and ice, though it has been shrinking. Skiiers travel for natural and manufactured snow in the Atlas Mountains of Morocco and Algeria, as well as a few spots in South Africa and Lesotho. Nonetheless, snow on the edge of the Sahara Desert is rare. On December 19, 2016, snow fell on the Algerian town of Ain Sefra, which is sometimes referred to as the “gateway to the desert.” The town of roughly 35,000 people sits between the Atlas Mountains and the northern edge of the Sahara. The last recorded snowfall in Ain Sefra occurred in February 1979. The Enhanced Thematic Mapper Plus (ETM+) on the Landsat 7 satellite acquired this natural-color image of snow in North Africa on December 19, 2016. This scene shows an area near the border of Morocco and Algeria, south of the city of Bouarfa and southwest of Ain Sefra. Though the news has been dominated by snow in the Saharan city, a review of several years of satellite data suggests that snow is also pretty rare in this section of the Atlas range. Read more: go.nasa.gov/2hIH4Xe NASA Earth Observatory image by Joshua Stevens, using Landsat data from the U.S. Geological Survey. Caption by Mike Carlowicz. b>NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Efficacy of flea beetle control of leafy spurge in Montana and South Dakota

Treesearch

Jack L. Butler; Matthew S. Parker; John T. Murphy

2006-01-01

Black (Aphthona lacertosa and Aphthona czwalinae) and brown (Aphthona nigriscutis) flea beetles are among the more successful biological control agents used in the control and management of leafy spurge on a relatively large scale in the Northern Great Plains. The objectives of this study were to document leafy...

Assessing plague risk and presence through surveys of small mammal flea communities

Treesearch

M. M. Friggens; P. L. Ford; R. R. Parmenter; M. Boyden; K. Gage

2011-01-01

Plague, caused by the bacterium Yersinia pestis, remains a threat to human and wildlife populations in the Western United States (Gage and Kosoy 2005). Several rodent species have been implicated as important maintenance hosts in the U.S., including Peromyscus maniculatus and Dipodomys spp. Fleas are a critical component of plague foci (Gage and Kosoy 2005)....

Our sense of Snow: the myth of John Snow in medical geography.

PubMed

McLeod, K S

2000-04-01

In 1854, Dr. John Snow identified the Broad Street pump as the source of an intense cholera outbreak by plotting the location of cholera deaths on a dot-map. He had the pump handle removed and the outbreak ended...or so one version of the story goes. In medical geography, the story of Snow and the Broad Street cholera outbreak is a common example of the discipline in action. While authors in other health-related disciplines focus on Snow's "shoe-leather epidemiology", his development of a water-borne theory of cholera transmission, and/or his pioneering role in anaesthesia, it is the dot-map that makes him a hero in medical geography. The story forms part of our disciplinary identity. Geographers have helped to shape the Snow narrative: the map has become part of the myth. Many of the published accounts of Snow are accompanied by versions of the map, but which map did Snow use? What happens to the meaning of our story when the determinative use of the map is challenged? In his book On the Mode of Communication of Cholera (2nd ed., John Churchill, London, 1855), Snow did not write that he used a map to identify the source of the outbreak. The map that accompanies his text shows cholera deaths in Golden Square (the subdistrict of London's Soho district where the outbreak occurred) from August 19 to September 30, a period much longer than the intense outbreak. What happens to the meaning of the myth when the causal connection between the pump's disengagement and the end of the outbreak is examined? Snow's data and text do not support this link but show that the number of cholera deaths was abating before the handle was removed. With the drama of the pump handle being questioned and the map, our artifact, occupying a more illustrative than central role, what is our sense of Snow?

Seasonal changes in antifreeze protein gene transcription and water content of beetle Microdera punctipennis (Coleoptera, Tenebrionidae) from Gurbantonggut desert in Central Asia.

PubMed

Hou, F; Ma, J; Liu, X; Wang, Y; Liu, X N; Zhang, F C

2010-01-01

Desert beetle Microdera punctipennis (Coleoptera: Tenebriondae) is a special species in Gurbantonggut Desert in Central Asia. To investigate the possible strategy it employs for cold survival, seasonal changes in supercooling point (SCP), body water content, haemolymph osmolality and antifreeze protein gene (Mpafp) expression were measured over 13 months. Our results show SCPs in M. punctipennis adults changed from -8.0°C in summer to -18.7°C in winter. During winter, adults endured modest water loss; total water decreased from 65.4 percent in summer to 55.9% in winter. Mpafp mRNAs level increased by 13.1 fold from summer to early winter, and haemolymph osmolality increased accordingly from 550 mOsm to 1486 mOsm. Correlation coefficient of Mpafp mRNAs level and SCP indicates that Mpafp mRNA explained 65.3 percent of the variation in SCPs. The correlation between Mpafp mRNA level and total water reflected an indirect influence of antifreeze protein on water content via reducing SCP.

Estimating Snow Water Storage in North America Using CLM4, DART, and Snow Radiance Data Assimilation

NASA Technical Reports Server (NTRS)

Kwon, Yonghwan; Yang, Zong-Liang; Zhao, Long; Hoar, Timothy J.; Toure, Ally M.; Rodell, Matthew

2016-01-01

This paper addresses continental-scale snow estimates in North America using a recently developed snow radiance assimilation (RA) system. A series of RA experiments with the ensemble adjustment Kalman filter are conducted by assimilating the Advanced Microwave Scanning Radiometer for Earth Observing System (AMSR-E) brightness temperature T(sub B) at 18.7- and 36.5-GHz vertical polarization channels. The overall RA performance in estimating snow depth for North America is improved by simultaneously updating the Community Land Model, version 4 (CLM4), snow/soil states and radiative transfer model (RTM) parameters involved in predicting T(sub B) based on their correlations with the prior T(sub B) (i.e., rule-based RA), although degradations are also observed. The RA system exhibits a more mixed performance for snow cover fraction estimates. Compared to the open-loop run (0.171m RMSE), the overall snow depth estimates are improved by 1.6% (0.168m RMSE) in the rule-based RA whereas the default RA (without a rule) results in a degradation of 3.6% (0.177mRMSE). Significant improvement of the snow depth estimates in the rule-based RA as observed for tundra snow class (11.5%, p < 0.05) and bare soil land-cover type (13.5%, p < 0.05). However, the overall improvement is not significant (p = 0.135) because snow estimates are degraded or marginally improved for other snow classes and land covers, especially the taiga snow class and forest land cover (7.1% and 7.3% degradations, respectively). The current RA system needs to be further refined to enhance snow estimates for various snow types and forested regions.

Unexpected Patterns in Snow and Dirt

NASA Astrophysics Data System (ADS)

Ackerson, Bruce J.

2018-01-01

For more than 30 years, Albert A. Bartlett published "Thermal patterns in the snow" in this journal. These are patterns produced by heat sources underneath the snow. Bartlett's articles encouraged me to pay attention to patterns in snow and to understanding them. At winter's end the last snow becomes dirty and is heaped into piles. This snow comes from the final clearing of sidewalks and driveways. The patterns observed in these piles defied my intuition. This melting snow develops edges where dirt accumulates, in contrast to ice cubes, which lose sharp edges and become more spherical upon melting. Furthermore, dirt absorbs more radiation than snow and yet doesn't melt and round the sharp edges of snow, where dirt accumulates.

Impact of the snow cover scheme on snow distribution and energy budget modeling over the Tibetan Plateau

NASA Astrophysics Data System (ADS)

Xie, Zhipeng; Hu, Zeyong; Xie, Zhenghui; Jia, Binghao; Sun, Genhou; Du, Yizhen; Song, Haiqing

2018-02-01

This paper presents the impact of two snow cover schemes (NY07 and SL12) in the Community Land Model version 4.5 (CLM4.5) on the snow distribution and surface energy budget over the Tibetan Plateau. The simulated snow cover fraction (SCF), snow depth, and snow cover days were evaluated against in situ snow depth observations and a satellite-based snow cover product and snow depth dataset. The results show that the SL12 scheme, which considers snow accumulation and snowmelt processes separately, has a higher overall accuracy (81.8%) than the NY07 (75.8%). The newer scheme performs better in the prediction of overall accuracy compared with the NY07; however, SL12 yields a 15.1% underestimation rate while NY07 overestimated the SCF with a 15.2% overestimation rate. Both two schemes capture the distribution of the maximum snow depth well but show large positive biases in the average value through all periods (3.37, 3.15, and 1.48 cm for NY07; 3.91, 3.52, and 1.17 cm for SL12) and overestimate snow cover days compared with the satellite-based product and in situ observations. Higher altitudes show larger root-mean-square errors (RMSEs) in the simulations of snow depth and snow cover days during the snow-free period. Moreover, the surface energy flux estimations from the SL12 scheme are generally superior to the simulation from NY07 when evaluated against ground-based observations, in particular for net radiation and sensible heat flux. This study has great implications for further improvement of the subgrid-scale snow variations over the Tibetan Plateau.

Modeling the influence of snow cover temperature and water content on wet-snow avalanche runout

NASA Astrophysics Data System (ADS)

Valero, Cesar Vera; Wever, Nander; Christen, Marc; Bartelt, Perry

2018-03-01

Snow avalanche motion is strongly dependent on the temperature and water content of the snow cover. In this paper we use a snow cover model, driven by measured meteorological data, to set the initial and boundary conditions for wet-snow avalanche calculations. The snow cover model provides estimates of snow height, density, temperature and liquid water content. This information is used to prescribe fracture heights and erosion heights for an avalanche dynamics model. We compare simulated runout distances with observed avalanche deposition fields using a contingency table analysis. Our analysis of the simulations reveals a large variability in predicted runout for tracks with flat terraces and gradual slope transitions to the runout zone. Reliable estimates of avalanche mass (height and density) in the release and erosion zones are identified to be more important than an exact specification of temperature and water content. For wet-snow avalanches, this implies that the layers where meltwater accumulates in the release zone must be identified accurately as this defines the height of the fracture slab and therefore the release mass. Advanced thermomechanical models appear to be better suited to simulate wet-snow avalanche inundation areas than existing guideline procedures if and only if accurate snow cover information is available.

Black carbon aerosol size in snow.

PubMed

Schwarz, J P; Gao, R S; Perring, A E; Spackman, J R; Fahey, D W

2013-01-01

The effect of anthropogenic black carbon (BC) aerosol on snow is of enduring interest due to its consequences for climate forcing. Until now, too little attention has been focused on BC's size in snow, an important parameter affecting BC light absorption in snow. Here we present first observations of this parameter, revealing that BC can be shifted to larger sizes in snow than are typically seen in the atmosphere, in part due to the processes associated with BC removal from the atmosphere. Mie theory analysis indicates a corresponding reduction in BC absorption in snow of 40%, making BC size in snow the dominant source of uncertainty in BC's absorption properties for calculations of BC's snow albedo climate forcing. The shift reduces estimated BC global mean snow forcing by 30%, and has scientific implications for our understanding of snow albedo and the processing of atmospheric BC aerosol in snowfall.

Polar View Snow Service- Operational Snow Cover Mapping for Downstream Runoff Modeling and Hydropower Predictions

NASA Astrophysics Data System (ADS)

Bach, Heike; Appel, Florian; Rust, Felix; Mauser, Wolfram

2010-12-01

Information on snow cover and snow properties are important for hydrology and runoff modelling. Frequent updates of snow cover observation, especially for areas characterized by short-term snow dynamics, can help to improve water balance and discharge calculations. Within the GMES service element Polar View, VISTA offers a snow mapping service for Central Europe since several years [1, 2]. We outline the use of this near-real- time product for hydrological applications in Alpine environment. In particular we discuss the integration of the Polar View product into a physically based hydrological model (PROMET). This allows not only the provision of snow equivalent values, but also enhances river runoff modelling and its use in hydropower energy yield prediction. The GMES snow products of Polar View are thus used in a downstream service for water resources management, providing information services for renewable energy suppliers and energy traders.

The Goddard Snow Radiance Assimilation Project: An Integrated Snow Radiance and Snow Physics Modeling Framework for Snow/cold Land Surface Modeling

NASA Technical Reports Server (NTRS)

Kim, E.; Tedesco, M.; Reichle, R.; Choudhury, B.; Peters-Lidard C.; Foster, J.; Hall, D.; Riggs, G.

2006-01-01

Microwave-based retrievals of snow parameters from satellite observations have a long heritage and have so far been generated primarily by regression-based empirical "inversion" methods based on snapshots in time. Direct assimilation of microwave radiance into physical land surface models can be used to avoid errors associated with such retrieval/inversion methods, instead utilizing more straightforward forward models and temporal information. This approach has been used for years for atmospheric parameters by the operational weather forecasting community with great success. Recent developments in forward radiative transfer modeling, physical land surface modeling, and land data assimilation are converging to allow the assembly of an integrated framework for snow/cold lands modeling and radiance assimilation. The objective of the Goddard snow radiance assimilation project is to develop such a framework and explore its capabilities. The key elements of this framework include: a forward radiative transfer model (FRTM) for snow, a snowpack physical model, a land surface water/energy cycle model, and a data assimilation scheme. In fact, multiple models are available for each element enabling optimization to match the needs of a particular study. Together these form a modular and flexible framework for self-consistent, physically-based remote sensing and water/energy cycle studies. In this paper we will describe the elements and the integration plan. All modules will operate within the framework of the Land Information System (LIS), a land surface modeling framework with data assimilation capabilities running on a parallel-node computing cluster. Capabilities for assimilation of snow retrieval products are already under development for LIS. We will describe plans to add radiance-based assimilation capabilities. Plans for validation activities using field measurements will also be discussed.

Evaluation of the effectiveness of a novel oral formulation of sarolaner (Simparica™) for the treatment and control of fleas on dogs.

PubMed

Six, Robert H; Geurden, Thomas; Packianathan, Raj; Colgan, Sally; Everett, William R; Grace, Sarah; Hodge, Andrew; Mahabir, Sean P; Myers, Melanie R; Slootmans, Nathalie; Davis, Kylie

2016-05-30

The efficacy of a single oral dose of a novel isoxazoline, sarolaner (Simparica™, Zoetis), for the treatment and control of flea infestations on dogs was confirmed in five laboratory studies. The studies were conducted using adult purpose-bred Beagles and/or mixed breed dogs. All animals were individually identified and housed, and were allocated randomly to treatment with either placebo or sarolaner (eight to 10 per group) based on pretreatment parasite counts. Three studies used cat flea (Ctenocephalides felis felis) strains recently isolated from the field from the US, EU, or Australia; in the fourth study a laboratory strain (KS1) with documented tolerance to a number of insecticides such as fipronil, imidacloprid, and permethrin was used. In the fifth study, dogs were infested with dog fleas, Ctenocephalides canis. Dogs were treated orally on Day 0 with a placebo or a sarolaner tablet providing a minimum dose of 2mg/kg. Dogs were infested with approximately 100 unfed, adult fleas prior to treatment and at weekly intervals post-treatment. Comb counts were conducted to determine the numbers of viable fleas at 24h after treatment and after each subsequent infestation. Efficacy against C. felis and C. canis was 99.8-100% from treatment through Day 35. In all five studies, elimination of existing infestations was achieved within 24h after dosing, with only a single live C. felis found on one dog on Day 1. Similarly, control of flea challenges was achieved within 24h after infestation throughout the 35day study periods, with only single live C. felis found on two dogs on Day 28 in one study, and on a single dog on Day 35 in another study. There were no adverse reactions to treatment with sarolaner. These studies confirmed that a single oral dose of sarolaner at 2mg/kg provided highly effective treatment of existing C. felis infestations and persistent control of C. felis on dogs for 35days after treatment. Efficacy equivalent to that seen with C. felis was

Evaluation of snow cover and snow depth on the Qinghai-Tibetan Plateau derived from passive microwave remote sensing

NASA Astrophysics Data System (ADS)

Dai, Liyun; Che, Tao; Ding, Yongjian; Hao, Xiaohua

2017-08-01

Snow cover on the Qinghai-Tibetan Plateau (QTP) plays a significant role in the global climate system and is an important water resource for rivers in the high-elevation region of Asia. At present, passive microwave (PMW) remote sensing data are the only efficient way to monitor temporal and spatial variations in snow depth at large scale. However, existing snow depth products show the largest uncertainties across the QTP. In this study, MODIS fractional snow cover product, point, line and intense sampling data are synthesized to evaluate the accuracy of snow cover and snow depth derived from PMW remote sensing data and to analyze the possible causes of uncertainties. The results show that the accuracy of snow cover extents varies spatially and depends on the fraction of snow cover. Based on the assumption that grids with MODIS snow cover fraction > 10 % are regarded as snow cover, the overall accuracy in snow cover is 66.7 %, overestimation error is 56.1 %, underestimation error is 21.1 %, commission error is 27.6 % and omission error is 47.4 %. The commission and overestimation errors of snow cover primarily occur in the northwest and southeast areas with low ground temperature. Omission error primarily occurs in cold desert areas with shallow snow, and underestimation error mainly occurs in glacier and lake areas. With the increase of snow cover fraction, the overestimation error decreases and the omission error increases. A comparison between snow depths measured in field experiments, measured at meteorological stations and estimated across the QTP shows that agreement between observation and retrieval improves with an increasing number of observation points in a PMW grid. The misclassification and errors between observed and retrieved snow depth are associated with the relatively coarse resolution of PMW remote sensing, ground temperature, snow characteristics and topography. To accurately understand the variation in snow depth across the QTP, new algorithms

The value of snow cover

NASA Astrophysics Data System (ADS)

Sokratov, S. A.

2009-04-01

Snow is the natural resource, like soil and water. It has specific properties which allow its use not just for skiing but also for houses cooling in summer (Swedish experience), for air fields construction (Arctic and Antarctic), for dams (north of Russia), for buildings (not only snow-houses of some Polar peoples but artistic hotel attracting tourists in Sweden), and as art material (Sapporo snow festival, Finnish events), etc. "Adjustment" of snow distribution and amount is not only rather common practice (avalanche-protection constructions keeping snow on slopes) but also the practice with long history. So-called "snow irrigation" was used in Russia since XIX century to protect winter crop. What is now named "artificial snow production", is part of much larger pattern. What makes it special—it is unavoidable in present climate and economy situation. 5% of national income in Austria is winter tourism. 50% of the economy in Savoy relay on winter tourism. In terms of money this can be less, but in terms of jobs and income involved this would be even more considerable in Switzerland. As an example—the population of Davos is 14000 in Summer and 50000 in Winter. Skiing is growing business. In present time you can find ski slopes in Turkey and Lebanon. To keep a cite suitable for attracting tourists you need certain amount of sunny days and certain amount of snow. The snow cannons are often the only way to keep a place running. On the other hand, more artificial snow does not necessary attract more tourists, while heavy natural snowfall does attract them. Artificial snow making is costly and requires infrastructure (ponds and electric lines) with very narrow range of weather conditions. Related companies are searching for alternatives and one of them can be "weather regulation" by distribution of some chemical components in clouds. It did not happen yet, but can happen soon. The consequences of such interference in Nature is hardly known. The ski tourism is not the

Snow-Cover Variability in North America in the 2000-2001 Winter as Determined from MODIS Snow Products

NASA Technical Reports Server (NTRS)

Hall, Dorothy K.; Salomonson, Vincent V.; Riggs, George A.; Chien, Janet Y. L.; Houser, Paul R. (Technical Monitor)

2001-01-01

Moderate Resolution Imaging Spectroradiometer (MODIS) snow-cover maps have been available since September 13, 2000. These products, at 500 m spatial resolution, are available through the National Snow and Ice Data Center Distributed Active Archive Center in Boulder, Colorado. By the 2001-02 winter, 5 km climate-modeling grid (CMG) products will be available for presentation of global views of snow cover and for use in climate models. All MODIS snow-cover products are produced from automated algorithms that map snow in an objective manner. In this paper, we describe the MODIS snow products, and show snow maps from the fall of 2000 in North America.

Snow-Cover Variability in North America in the 2000-2001 Winter as Determined from MODIS Snow Products

NASA Technical Reports Server (NTRS)

Hall, Dorothy K.; Salomonson, Vincent V.; Riggs, George A.; Chien, Y. L.; Houser, Paul R. (Technical Monitor)

2001-01-01

Moderate Resolution Imaging Spectroradiometer (MODIS) snow-cover maps have been available since September 13, 2000. These products, at 500-m spatial resolution, are available through the National Snow and Ice Data Center Distributed Active Archive Center in Boulder, Colorado. By the 2001-02 winter, 5-km climate-modeling grid (CMG) products will be available for presentation of global views of snow cover and for use in climate models. All MODIS snow-cover products are produced from automated algorithms that map snow in an objective manner. In this paper, we describe the MODIS snow products, and show snow maps from the fall of 2000 in North America.

The prevalence of Bartonella, hemoplasma, and Rickettsia felis infections in domestic cats and in cat fleas in Ontario.

PubMed

Kamrani, Ali; Parreira, Valeria R; Greenwood, Janice; Prescott, John F

2008-10-01

The prevalence of persistent bacteremic Bartonella spp. and hemoplasma infections was determined in healthy pet cats in Ontario. Blood samples from healthy cats sent to a diagnostic laboratory for routine health assessment over the course of 1 y were tested for Bartonella spp. using both polymerase chain reaction (PCR) and blood culture, and for the presence of hemoplasma by PCR. The overall prevalence of Bartonella spp. by PCR and by culture combined was 4.3% (28/646) [3.7% (24/646) Bartonella henselae, 0.6% (4/646) Bartonella clarridgeiae]. The novel B. henselae PCR developed for this study demonstrated nearly twice the sensitivity of bacterial isolation. The overall prevalence of hemoplasma was 4% (30/742) [3.3% (25/742) Candidatus Mycoplasma haemominutum, 0.7% (5/742) Mycoplasma haemofelis]. There was no significant difference between the prevalence of infection by season or by age (< or = 2 y, > 2 y). Candidatus Mycoplasma turicensis was identified, for the first time in Canada, in 1 cat. The prevalence of Bartonella (58%) and hemoplasma (47% M. haemofelis, 13% M. haemominutum) in blood from a small sampling (n = 45) of stray cats was considerably higher than that found in healthy pet cats. The prevalence of Rickettsia felis in cat fleas was also assessed. A pool of fleas from each of 50 flea-infested cats was analyzed for the presence of R. felis by PCR. Rickettsia felis was confirmed, for the first time in Canada, in 9 of the 50 samples. Therefore, the prevalence of Bartonella and hemoplasma infection in healthy pet cats is relatively low. Further, the control of cat fleas is important because of the public health significance of Bartonella and R. felis infection.

Snow depth and snow cover retrieval from FengYun3B microwave radiation imagery based on a snow passive microwave unmixing method in Northeast China

NASA Astrophysics Data System (ADS)

Gu, Lingjia; Ren, Ruizhi; Zhao, Kai; Li, Xiaofeng

2014-01-01

The precision of snow parameter retrieval is unsatisfactory for current practical demands. The primary reason is because of the problem of mixed pixels that are caused by low spatial resolution of satellite passive microwave data. A snow passive microwave unmixing method is proposed in this paper, based on land cover type data and the antenna gain function of passive microwaves. The land cover type of Northeast China is partitioned into grass, farmland, bare soil, forest, and water body types. The component brightness temperatures (CBT), namely unmixed data, with 1 km data resolution are obtained using the proposed unmixing method. The snow depth determined by the CBT and three snow depth retrieval algorithms are validated through field measurements taken in forest and farmland areas of Northeast China in January 2012 and 2013. The results show that the overall of the retrieval precision of the snow depth is improved by 17% in farmland areas and 10% in forest areas when using the CBT in comparison with the mixed pixels. The snow cover results based on the CBT are compared with existing MODIS snow cover products. The results demonstrate that more snow cover information can be obtained with up to 86% accuracy.

The ASMEx snow slab experiment: snow microwave radiative transfer (SMRT) model evaluation

NASA Astrophysics Data System (ADS)

Sandells, Melody; Löwe, Henning; Picard, Ghislain; Dumont, Marie; Essery, Richard; Floury, Nicolas; Kontu, Anna; Lemmetyinen, Juha; Maslanka, William; Mätzler, Christian; Morin, Samuel; Wiesmann, Andreas

2017-04-01

A major uncertainty in snow microwave modelling to date has been the treatment of the snow microstructure. Although observations of microstructural parameters such as the optical grain diameter, specific surface area and correlation length have improved drastically over the last few years, scale factors have been used to derive the parameters needed in microwave emission models from these observations. Previous work has shown that a major difference between electromagnetic models of scattering coefficients is due to the specific snow microstructure models used. The snow microwave radiative transfer model (SMRT) is a new model developed to advance understanding of the role of microstructure and isolate different assumptions in existing microwave models that collectively hinder interpretation of model intercomparison studies. SMRT is implemented in Python and is modular, thus allows switching between different representations in its various components. Here, the role of microstructure is examined with the Improved Born Approximation electromagnetic model. The model is evaluated against scattering and absorption coefficients derived from radiometer measurements of snow slabs taken as part of the Arctic Snow Microstructure Experiment (ASMEx), which took place in Sodankylä, Finland over two seasons. Microtomography observations of slab samples were used to determine parameters for five microstructure models: spherical, exponential, sticky hard sphere, Teubner-Strey and Gaussian random field. SMRT brightness temperature simulations are also compared with radiometric observations of the snow slabs over a reflector plate and an absorber substrate. Agreement between simulations and observations is generally good except for slabs that are highly anisotropic.

Snow Depth Depicted on Mt. Lyell by NASA Airborne Snow Observatory

NASA Image and Video Library

2013-05-02

A natural color image of Mt. Lyell, the highest point in the Tuolumne River Basin top image is compared with a three-dimensional color composite image of Mt. Lyell from NASA Airborne Snow Observatory depicting snow depth bottom image.

Snow and Glacier Hydrology

NASA Astrophysics Data System (ADS)

Brubaker, Kaye

The study of snow and ice is rich in both fundamental science and practical applications. Snow and Glacier Hydrology offers something for everyone, from resource practitioners in regions where water supply depends on seasonal snow pack or glaciers, to research scientists seeking to understand the role of the solid phase in the water cycle and climate. The book is aimed at the advanced undergraduate or graduate-level student. A perusal of online documentation for snow hydrology classes suggests that there is currently no single text or reference book on this topic in general use. Instructors rely on chapters from general hydrology texts or operational manuals, collections of journal papers, or their own notes. This variety reflects the fact that snow and ice regions differ in climate, topography, language, water law, hazards, and resource use (hydropower, irrigation, recreation). Given this diversity, producing a universally applicable book is a challenge.

Comparing different snow products to assess spatio-temporal snow cover patterns in the Central Taurus Mountains, Turkey

NASA Astrophysics Data System (ADS)

Sturm, K.; Helmschrot, J.

2013-12-01

Snow and its spatial and temporal patterns are important for catchment hydrology in the semi-arid eastern Mediterranean. Since most of the annual rainfall is stored as snow during winter and released during drier conditions in spring and summer, downstream regions of the Taurus Mountains relying on snow water temporarily stored in reservoirs for agricultural use are heavily dependent on the timing of snowmelt discharge. Runoff is controlled by the amount of accumulated snow, its distribution, and the climatic conditions controlling spring snowmelt. Thus, knowledge about spatial and temporal snow cover dynamics is essential for sustainable water resources management. The lack of observations in high-altitude regions reinforces the application of different snow products for a better assessment of spatio-temporal snow cover patterns. To better assess the quality of such products, simulated daily snow cover and EO-based snow cover products were compared for the Egribuk subcatchment, in the Central Taurus Mountains, Turkey. Daily information on snow cover, depths, and snow water equivalent was derived from distributed hydrological modeling using the J2000 model. Furthermore, 8-day MODIS snow cover data from Terra (MOD10A2) and Aqua (MYD10A2) satellites at a spatial resolution of 500 m were synchronized to receive cloud-free images. From this effort, 253 images covering the period between 07/04/2002 and 12/27/2007 were used for further analyses. The products were analyzed individually to determine the number of snow-covered days in relation to freezing days, spring snowmelt onsets, and temporal patterns, reflecting the effect of altitude on the percentage snow-covered area (SCA) along a topographic gradient at various time-steps. Monthly and 8-day spatial patterns of a single snow season were also examined. When SCA peaks at all altitudes, in February and March, the results of both products show a good agreement regarding SCA extent. In contrast, the extent of SCA

MODIS Snow and Sea Ice Products

NASA Technical Reports Server (NTRS)

Hall, Dorothy K.; Riggs, George A.; Salomonson, Vincent V.

2004-01-01

In this chapter, we describe the suite of Earth Observing System (EOS) Moderate-Resolution Imaging Spectroradiometer (MODIS) Terra and Aqua snow and sea ice products. Global, daily products, developed at Goddard Space Flight Center, are archived and distributed through the National Snow and Ice Data Center at various resolutions and on different grids useful for different communities Snow products include binary snow cover, snow albedo, and in the near future, fraction of snow in a 5OO-m pixel. Sea ice products include ice extent determined with two different algorithms, and sea ice surface temperature. The algorithms used to develop these products are described. Both the snow and sea ice products, available since February 24,2000, are useful for modelers. Validation of the products is also discussed.

Mobility of lightweight robots over snow

NASA Astrophysics Data System (ADS)

Lever, James H.; Shoop, Sally A.

2006-05-01

Snowfields are challenging terrain for lightweight (<50 kg) unmanned ground vehicles. Deep sinkage, high snowcompaction resistance, traction loss while turning and ingestion of snow into the drive train can cause immobility within a few meters of travel. However, for suitably designed vehicles, deep snow offers a smooth, uniform surface that can obliterate obstacles. Key requirements for good over-snow mobility are low ground pressure, large clearance relative to vehicle size and a drive system that tolerates cohesive snow. A small robot will invariably encounter deep snow relative to its ground clearance. Because a single snowstorm can easily deposit 30 cm of fresh snow, robots with ground clearance less than about 10 cm must travel over the snow rather than gain support from the underlying ground. This can be accomplished using low-pressure tracks (< 1.5 kPa). Even still, snow-compaction resistance can exceed 20% of vehicle weight. Also, despite relatively high traction coefficients for low track pressures, differential or skid steering is difficult because the outboard track can easily break traction as the vehicle attempts to turn against the snow. Short track lengths (relative to track separation) or coupled articulated robots offer steering solutions for deep snow. This paper presents preliminary guidance to design lightweight robots for good mobility over snow based on mobility theory and tests of PackBot, Talon and SnoBot, a custom-designed research robot. Because many other considerations constrain robot designs, this guidance can help with development of winterization kits to improve the over-snow performance of existing robots.

Georectification and snow classification of webcam images: potential for complementing satellite-derrived snow maps over Switzerland

NASA Astrophysics Data System (ADS)

Dizerens, Céline; Hüsler, Fabia; Wunderle, Stefan

2016-04-01

The spatial and temporal variability of snow cover has a significant impact on climate and environment and is of great socio-economic importance for the European Alps. Satellite remote sensing data is widely used to study snow cover variability and can provide spatially comprehensive information on snow cover extent. However, cloud cover strongly impedes the surface view and hence limits the number of useful snow observations. Outdoor webcam images not only offer unique potential for complementing satellite-derived snow retrieval under cloudy conditions but could also serve as a reference for improved validation of satellite-based approaches. Thousands of webcams are currently connected to the Internet and deliver freely available images with high temporal and spatial resolutions. To exploit the untapped potential of these webcams, a semi-automatic procedure was developed to generate snow cover maps based on webcam images. We used daily webcam images of the Swiss alpine region to apply, improve, and extend existing approaches dealing with the positioning of photographs within a terrain model, appropriate georectification, and the automatic snow classification of such photographs. In this presentation, we provide an overview of the implemented procedure and demonstrate how our registration approach automatically resolves the orientation of a webcam by using a high-resolution digital elevation model and the webcam's position. This allows snow-classified pixels of webcam images to be related to their real-world coordinates. We present several examples of resulting snow cover maps, which have the same resolution as the digital elevation model and indicate whether each grid cell is snow-covered, snow-free, or not visible from webcams' positions. The procedure is expected to work under almost any weather condition and demonstrates the feasibility of using webcams for the retrieval of high-resolution snow cover information.

Snow Water Equivalent Retrieval By Markov Chain Monte Carlo Based on Memls and Hut Snow Emission Model

NASA Astrophysics Data System (ADS)

Pan, J.; Durand, M. T.; Vanderjagt, B. J.

2014-12-01

The Markov chain Monte Carlo (MCMC) method had been proved to be successful in snow water equivalent retrieval based on synthetic point-scale passive microwave brightness temperature (TB) observations. This method needs only general prior information about distribution of snow parameters, and could estimate layered snow properties, including the thickness, temperature, density and snow grain size (or exponential correlation length) of each layer. In this study, the multi-layer HUT (Helsinki University of Technology) model and the MEMLS (Microwave Emission Model of Layered Snowpacks) will be used as observation models to assimilate the observed TB into snow parameter prediction. Previous studies had shown that the multi-layer HUT model tends to underestimate TB at 37 GHz for deep snow, while the MEMLS does not show sensitivity of model bias to snow depth. Therefore, results using HUT model and MEMLS will be compared to see how the observation model will influence the retrieval of snow parameters. The radiometric measurements at 10.65, 18.7, 36.5 and 90 GHz at Sodankyla, Finland will be used as MCMC input, and the statistics of all snow property measurement will be used to calculate the prior information. 43 dry snowpits with complete measurements of all snow parameters will be used for validation. The entire dataset are from NorSREx (Nordic Snow Radar Experiment) experiments carried out by Juha Lemmetyinen, Anna Kontu and Jouni Pulliainen in FMI in 2009-2011 winters, and continued two more winters from 2011 to Spring of 2013. Besides the snow thickness and snow density that are directly related to snow water equivalent, other parameters will be compared with observations, too. For thin snow, the previous studies showed that influence of underlying soil is considerable, especially when the soil is half frozen with part of unfrozen liquid water and part of ice. Therefore, this study will also try to employ a simple frozen soil permittivity model to improve the

Heterologous expression of type I antifreeze peptide GS-5 in baker's yeast increases freeze tolerance and provides enhanced gas production in frozen dough.

PubMed

Panadero, Joaquin; Randez-Gil, Francisca; Prieto, Jose Antonio

2005-12-28

The demand for frozen-dough products has increased notably in the baking industry. Nowadays, no appropriate industrial baker's yeast with optimal gassing capacity in frozen dough is, however, available, and it is unlikely that classical breeding programs could provide significant improvements of this trait. Antifreeze proteins, found in diverse organisms, display the ability to inhibit the growth of ice, allowing them to survive at temperatures below 0 degrees C. In this study a recombinant antifreeze peptide GS-5 was expressed from the polar fish grubby sculpin (Myoxocephalus aenaeus) in laboratory and industrial baker's yeast strains of Saccharomyces cerevisiae. Production of the recombinant protein increased freezing tolerance in both strains tested. Furthermore, expression of the GS-5 encoding gene enhanced notably the gassing rate and total gas production in frozen and frozen sweet doughs. These effects are unlikely to be due to reduced osmotic damage during freezing/thawing, because recombinant cells showed growth behavior similar to that of the parent under hypermosmotic stress conditions.

Use of proline mutants to help solve the NMR solution structure of type III antifreeze protein.

PubMed Central

Chao, H.; Davies, P. L.; Sykes, B. D.; Sönnichsen, F. D.

1993-01-01

To help understand the structure/function relationships in antifreeze proteins (AFP), and to define the motifs required for ice binding, a Type III AFP suitable for two-dimensional (2D) NMR studies was produced in Escherichia coli. A synthetic gene for one of the Type III AFP isoforms was assembled in a T7 polymerase-directed expression vector. The 67-amino acid-long gene product differed from the natural AFP by inclusion of an N-terminal methionine but was indistinguishable in activity. The NMR spectra of this AFP were complicated by cis-trans proline isomerization from the C-terminal sequence YPPA. Substitution of this sequence by YAA eliminated isomer signals without altering the activity or structure of the mutant AFP. This variant (rQAE m1.1) was selected for sequential assignment and the secondary structure determination using 2D 1H NMR spectroscopy. Nine beta-strands are paired to form two triple-stranded antiparallel sheets and one double-stranded antiparallel sheet. Two further proline replacements, P29A and P33A, were made to delineate the role of conserved prolines in Type III AFP. These mutants were valuable in clarifying ambiguous NMR spectral assignments amongst the remaining six prolines of rQAE m1.1. In contrast to the replacement of the C-terminal prolyl residues, the exchange of P29 and P33 caused some structural changes and significantly decreased protein solubility and antifreeze activity. PMID:8401227

Snow Micro-Structure Model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Micah Johnson, Andrew Slaughter

PIKA is a MOOSE-based application for modeling micro-structure evolution of seasonal snow. The model will be useful for environmental, atmospheric, and climate scientists. Possible applications include application to energy balance models, ice sheet modeling, and avalanche forecasting. The model implements physics from published, peer-reviewed articles. The main purpose is to foster university and laboratory collaboration to build a larger multi-scale snow model using MOOSE. The main feature of the code is that it is implemented using the MOOSE framework, thus making features such as multiphysics coupling, adaptive mesh refinement, and parallel scalability native to the application. PIKA implements three equations:more » the phase-field equation for tracking the evolution of the ice-air interface within seasonal snow at the grain-scale; the heat equation for computing the temperature of both the ice and air within the snow; and the mass transport equation for monitoring the diffusion of water vapor in the pore space of the snow.« less

Snow water equivalent mapping in Norway

NASA Astrophysics Data System (ADS)

Tveito, O. E.; Udnæs, H.-C.; Engeset, R.; Førland, E. J.; Isaksen, K.; Mengistu, Z.

2003-04-01

In high latitude area snow covers the ground large parts of the year. Information about the water volume as snow is of major importance in many respects. Flood forecasters at NVE need it in order to assess possible flood risks. Hydropower producers need it to plan the most efficient production of the water in their reservoirs, traders to estimate the potential energy available for the market. Meteorologists on their side use the information as boundary conditions in weather forecasting models. The Norwegian meteorological institute has provided snow accumulation maps for Norway for more than 50 years. These maps are now produced twice a month in the winter season. They show the accumulated precipitation in the winter season from the day the permanent snow cover is established. They do however not take melting into account, and do therefore not give a good description of the actual snow amounts during and after periods with snowmelt. Due to an increased need for a direct measure of water volumes as snow cover, met.no and NVE initialized a joint project in order to establish maps of the actual snow cover expressed in water equivalents. The project utilizes recent developments in the use of GIS in spatial modeling. Daily precipitation and temperature are distributed in space by using objective spatial interpolation methods. The interpolation considers topographical and other geographical parameters as well as weather type information. A degree-day model is used at each modeling point to calculate snow-accumulation and snowmelt. The maps represent a spatial scale of 1x1 km2. The modeled snow reservoir is validated by snow pillow values as well traditional snow depth observations. Preliminary results show that the new snow modeling approach reproduces the snow water equivalent well. The spatial approach also opens for a wide use in the terms of areal analysis.

Polyproline as a Minimal Antifreeze Protein Mimic That Enhances the Cryopreservation of Cell Monolayers

PubMed Central

Graham, Ben; Bailey, Trisha L.; Healey, Joseph R. J.; Marcellini, Moreno; Deville, Sylvain

2017-01-01

Abstract Tissue engineering, gene therapy, drug screening, and emerging regenerative medicine therapies are fundamentally reliant on high‐quality adherent cell culture, but current methods to cryopreserve cells in this format can give low cell yields and require large volumes of solvent “antifreezes”. Herein, we report polyproline as a minimum (bio)synthetic mimic of antifreeze proteins that is accessible by solution, solid‐phase, and recombinant methods. We demonstrate that polyproline has ice recrystallisation inhibition activity linked to its amphipathic helix and that it enhances the DMSO cryopreservation of adherent cell lines. Polyproline may be a versatile additive in the emerging field of macromolecular cryoprotectants. PMID:29044869

Structural analysis of Ca²⁺ dependent and Ca²⁺ independent type II antifreeze proteins: a comparative molecular dynamics simulation study.

PubMed

Kundu, Sangeeta; Roy, Debjani

2012-09-01

Comparative molecular dynamics simulations of Ca²⁺ dependent psychrophilic type II antifreeze protein (AFP) from herring (Clupea harengus) (hAFP) and Ca²⁺ dependent type II antifreeze protein from long snout poacher (Brachyopsis rostratus) (lpAFP) have been performed for 10 ns each at five different temperatures. We have tried to investigate whether the Ca²⁺ dependent protein obtains any advantage in nature over the independent one. To this end the dynamic properties of these two proteins have been compared in terms of secondary structure content, molecular flexibility, solvent accessibility, intra molecular hydrogen bonds and protein-solvent interactions. At 298 and 373 K the flexibility of the Ca²⁺ independent molecule is higher which indicates that Ca²⁺ could contribute to stabilize the structure. The thermal unfolding pathways of the two proteins have also been monitored. The rate of unfolding is similar up to 373 K, beyond that hAFP shows faster unfolding than lpAFP. The essential subspaces explored by the simulations of hAFP and lpAFP at different temperatures are significantly different as revealed from principal component analysis. Our results may help in understanding the role of Ca²⁺ for hAFP to express antifreeze activity. Furthermore our study may also help in elucidating the molecular basis of thermostability of two structurally similar proteins, which perform the same function in different manner, one in presence of Ca²⁺, and the other in absence of the same. Copyright © 2012 Elsevier Inc. All rights reserved.

Myxomatosis: passive immunity in the offspring of immune rabbits (Oryctolagus cuniculus) infested with fleas (Spilopsyllus cuniculi Dale) and exposed to myxoma virus.

PubMed

Sobey, W R; Conolly, D

1975-02-01

Kittens with maternal antibodies to myxoma virus, the offspring of rabbits which had recovered from myxomatosis, were exposed to fleas contaminated with myxoma virus and/or contact with infected rabbits from birth. All kittens died or became infected before 8 weeks of age. When compared with adult animals similarly infected the kittens showed no advantage in terms of survival time or recovery rate attributable to maternal antibodies. Flea transmission of virus was found more effective than contact transmissions.

Combining snow depth and innovative skier flow measurements in order to improve snow grooming techniques

NASA Astrophysics Data System (ADS)

Carmagnola, Carlo Maria; Albrecht, Stéphane; Hargoaa, Olivier

2017-04-01

In the last decades, ski resort managers have massively improved their snow management practices, in order to adapt their strategies to the inter-annual variability in snow conditions and to the effects of climate change. New real-time informations, such as snow depth measurements carried out on the ski slopes by grooming machines during their daily operations, have become available, allowing high saving, efficiency and optimization gains (reducing for instance the groomer fuel consumption and operation time and the need for machine-made snow production). In order to take a step forward in improving the grooming techniques, it would be necessary to keep into account also the snow erosion by skiers, which depends mostly on the snow surface properties and on the skier attendance. Today, however, most ski resort managers have only a vague idea of the evolution of the skier flows on each slope during the winter season. In this context, we have developed a new sensor (named Skiflux) able to measure the skier attendance using an infrared beam crossing the slopes. Ten Skiflux sensors have been deployed during the 2016/17 winter season at Val Thorens ski area (French Alps), covering a whole sector of the resort. A dedicated software showing the number of skier passages in real time as been developed as well. Combining this new Skiflux dataset with the snow depth measurements from grooming machines (Snowsat System) and the snow and meteorological conditions measured in-situ (Liberty System from Technoalpin), we were able to create a "real-time skiability index" accounting for the quality of the surface snow and its evolution during the day. Moreover, this new framework allowed us to improve the preparation of ski slopes, suggesting new strategies for adapting the grooming working schedule to the snow quality and the skier attendance. In the near future, this work will benefit from the advances made within the H2020 PROSNOW project ("Provision of a prediction system allowing

Resolving Size Distribution of Black Carbon Internally Mixed With Snow: Impact on Snow Optical Properties and Albedo

NASA Astrophysics Data System (ADS)

He, Cenlin; Liou, Kuo-Nan; Takano, Yoshi

2018-03-01

We develop a stochastic aerosol-snow albedo model that explicitly resolves size distribution of aerosols internally mixed with various snow grains. We use the model to quantify black carbon (BC) size effects on snow albedo and optical properties for BC-snow internal mixing. Results show that BC-induced snow single-scattering coalbedo enhancement and albedo reduction decrease by a factor of 2-3 with increasing BC effective radii from 0.05 to 0.25 μm, while polydisperse BC results in up to 40% smaller visible single-scattering coalbedo enhancement and albedo reduction compared to monodisperse BC with equivalent effective radii. We further develop parameterizations for BC size effects for application to climate models. Compared with a realistic polydisperse assumption and observed shifts to larger BC sizes in snow, respectively, assuming monodisperse BC and typical atmospheric BC effective radii could lead to overestimates of 24% and 40% in BC-snow albedo forcing averaged over different BC and snow conditions.

Spatial properties of snow cover in the Upper Merced River Basin: implications for a distributed snow measurement network

NASA Astrophysics Data System (ADS)

Bouffon, T.; Rice, R.; Bales, R.

2006-12-01

The spatial distributions of snow water equivalent (SWE) and snow depth within a 1, 4, and 16 km2 grid element around two automated snow pillows in a forested and open- forested region of the Upper Merced River Basin (2,800 km2) of Yosemite National Park were characterized using field observations and analyzed using binary regression trees. Snow surveys occurred at the forested site during the accumulation and ablation seasons, while at the open-forest site a survey was performed only during the accumulation season. An average of 130 snow depth and 7 snow density measurements were made on each survey, within the 4 km2 grid. Snow depth was distributed using binary regression trees and geostatistical methods using the physiographic parameters (e.g. elevation, slope, vegetation, aspect). Results in the forest region indicate that the snow pillow overestimated average SWE within the 1, 4, and 16 km2 areas by 34 percent during ablation, but during accumulation the snow pillow provides a good estimate of the modeled mean SWE grid value, however it is suspected that the snow pillow was underestimating SWE. However, at the open forest site, during accumulation, the snow pillow was 28 percent greater than the mean modeled grid element. In addition, the binary regression trees indicate that the independent variables of vegetation, slope, and aspect are the most influential parameters of snow depth distribution. The binary regression tree and multivariate linear regression models explain about 60 percent of the initial variance for snow depth and 80 percent for density, respectively. This short-term study provides motivation and direction for the installation of a distributed snow measurement network to fill the information gap in basin-wide SWE and snow depth measurements. Guided by these results, a distributed snow measurement network was installed in the Fall 2006 at Gin Flat in the Upper Merced River Basin with the specific objective of measuring accumulation and ablation

Flea (Ctenocephalides felis) control efficacy of topical indoxacarb on dogs subsequently bathed with a chlorhexidine-ketoconazole shampoo.

PubMed

Armstrong, R D; Liebenberg, J E; Heaney, K; Guerino, F

2015-08-01

An evaluation of the effect of chlorhexidine/ketoconazole shampoo baths on the flea control efficacy of indoxacarb applied topically to dogs. We randomly allocated 18 healthy mixed-breed dogs to 3 groups: shampoo only; indoxacarb treated and medicated shampoo; and indoxacarb treated but not shampooed. Indoxacarb was administered on day 0 and dogs were shampooed on days 9 and 23. Dogs were infested with 100 adult Ctenocephalides felis initially 2 days before treatment and then weekly from days 7 to 28. Fleas were removed and counted 48 h post-infestation. Medicated shampoo use did not significantly reduce indoxacarb efficacy against C. felis. © 2015 MSD Animal Health. Australian Veterinary Journal published by Wiley Publishing Asia Pty Ltd on behalf of Australian Veterinary Association.

Solution structure of an antifreeze protein CfAFP-501 from Choristoneura fumiferana.

PubMed

Li, Congmin; Guo, Xianrong; Jia, Zongchao; Xia, Bin; Jin, Changwen

2005-07-01

Antifreeze proteins (AFPs) are widely employed by various organisms as part of their overwintering survival strategy. AFPs have the unique ability to suppress the freezing point of aqueous solution and inhibit ice recrystallization through binding to the ice seed crystals and restricting their growth. The solution structure of CfAFP-501 from spruce budworm has been determined by NMR spectroscopy. Our result demonstrates that CfAFP-501 retains its rigid and highly regular structure in solution. Overall, the solution structure is similar to the crystal structure except the N- and C-terminal regions. NMR spin-relaxation experiments further indicate the overall rigidity of the protein and identify a collection of residues with greater flexibilities. Furthermore, Pro91 shows a cis conformation in solution instead of the trans conformation determined in the crystal structure.

The Yersinia pestis caf1M1A1 fimbrial capsule operon promotes transmission by flea bite in a mouse model of bubonic plague.

PubMed

Sebbane, Florent; Jarrett, Clayton; Gardner, Donald; Long, Daniel; Hinnebusch, B Joseph

2009-03-01

Plague is a zoonosis transmitted by fleas and caused by the gram-negative bacterium Yersinia pestis. During infection, the plasmidic caf1M1A1 operon that encodes the Y. pestis F1 protein capsule is highly expressed, and anti-F1 antibodies are protective. Surprisingly, the capsule is not required for virulence after injection of cultured bacteria, even though it is an antiphagocytic factor and capsule-deficient Y. pestis strains are rarely isolated. We found that a caf-negative Y. pestis mutant was not impaired in either flea colonization or virulence in mice after intradermal inoculation of cultured bacteria. In contrast, absence of the caf operon decreased bubonic plague incidence after a flea bite. Successful development of plague in mice infected by flea bite with the caf-negative mutant required a higher number of infective bites per challenge. In addition, the mutant displayed a highly autoaggregative phenotype in infected liver and spleen. The results suggest that acquisition of the caf locus via horizontal transfer by an ancestral Y. pestis strain increased transmissibility and the potential for epidemic spread. In addition, our data support a model in which atypical caf-negative strains could emerge during climatic conditions that favor a high flea burden. Human infection with such strains would not be diagnosed by the standard clinical tests that detect F1 antibody or antigen, suggesting that more comprehensive surveillance for atypical Y. pestis strains in plague foci may be necessary. The results also highlight the importance of studying Y. pestis pathogenesis in the natural context of arthropod-borne transmission.

The Impact of Detailed Snow Physics on the Simulation of Snow Cover and Subsurface Thermodynamics at Continental Scales

NASA Technical Reports Server (NTRS)

Stieglitz, Marc; Ducharne, Agnes; Koster, Randy; Suarez, Max; Busalacchi, Antonio J. (Technical Monitor)

2000-01-01

The three-layer snow model is coupled to the global catchment-based Land Surface Model (LSM) of the NASA Seasonal to Interannual Prediction Project (NSIPP) project, and the combined models are used to simulate the growth and ablation of snow cover over the North American continent for the period 1987-1988. The various snow processes included in the three-layer model, such as snow melting and re-freezing, dynamic changes in snow density, and snow insulating properties, are shown (through a comparison with the corresponding simulation using a much simpler snow model) to lead to an improved simulation of ground thermodynamics on the continental scale.

Combining low-cost GPS receivers with upGPR to derive continuously liquid water content, snow height and snow water equivalent in Alpine snow covers

NASA Astrophysics Data System (ADS)

Koch, Franziska; Schmid, Lino; Prasch, Monika; Heilig, Achim; Eisen, Olaf; Schweizer, Jürg; Mauser, Wolfram

2015-04-01

The temporal evolution of Alpine snowpacks is important for assessing water supply, hydropower generation, flood predictions and avalanche forecasts. Especially in high mountain regions with an extremely varying topography, it is until now often difficult to derive continuous and non-destructive information on snow parameters. Since autumn 2012, we are running a new low-cost GPS (Global Positioning System) snow measurement experiment at the high alpine study site Weissfluhjoch (2450 m a.s.l.) in Switzerland. The globally and freely broadcasted GPS L1-band (1.57542 GHz) was continuously recorded with GPS antennas, which are installed at the ground surface underneath the snowpack. GPS raw data, containing carrier-to-noise power density ratio (C/N0) as well as elevation and azimuth angle information for each time step of 1 s, was stored and analyzed for all 32 GPS satellites. Since the dielectric permittivity of an overlying wet snowpack influences microwave radiation, the bulk volumetric liquid water content as well as daily melt-freeze cycles can be derived non-destructively from GPS signal strength losses and external snow height information. This liquid water content information is qualitatively in good accordance with meteorological and snow-hydrological data and quantitatively highly agrees with continuous data derived from an upward-looking ground-penetrating radar (upGPR) working in a similar frequency range. As a promising novelty, we combined the GPS signal strength data with upGPR travel-time information of active impulse radar rays to the snow surface and back from underneath the snow cover. This combination allows determining liquid water content, snow height and snow water equivalent from beneath the snow cover without using any other external information. The snow parameters derived by combining upGPR and GPS data are in good agreement with conventional sensors as e.g. laser distance gauges or snow pillows. As the GPS sensors are cheap, they can easily

Everywhere and nowhere: snow and its linkages

NASA Astrophysics Data System (ADS)

Hiemstra, C. A.

2017-12-01

Interest has grown in quantifying higher latitude precipitation change and snow-related ecosystem and economic impacts. There is a high demand for creating and using snow-related datasets, yet available datasets contain limitations, aren't scale appropriate, or lack thorough validation. Much of the uncertainty in snow estimates relates to ongoing snow measurement problems that are chronic and pervasive in windy, Arctic environments. This, coupled with diminishing support for long-term snow field observations, creates formidable hydrologic gaps in snow dominated landscapes. Snow touches most aspects of high latitude landscapes and spans albedo, ecosystems, soils, permafrost, and sea ice. In turn, snow can be impacted by disturbances, landscape change, ecosystem, structure, and later arrival of sea or lake ice. Snow, and its changes touch infrastructure, housing, and transportation. Advances in snow measurements, modeling, and data assimilation are under way, but more attention and a concerted effort is needed in a time of dwindling resources to make required advances during a time of rapid change.

The prevalence of Bartonella, hemoplasma, and Rickettsia felis infections in domestic cats and in cat fleas in Ontario

PubMed Central

Kamrani, Ali; Parreira, Valeria R.; Greenwood, Janice; Prescott, John F.

2008-01-01

The prevalence of persistent bacteremic Bartonella spp. and hemoplasma infections was determined in healthy pet cats in Ontario. Blood samples from healthy cats sent to a diagnostic laboratory for routine health assessment over the course of 1 y were tested for Bartonella spp. using both polymerase chain reaction (PCR) and blood culture, and for the presence of hemoplasma by PCR. The overall prevalence of Bartonella spp. by PCR and by culture combined was 4.3% (28/646) [3.7% (24/646) Bartonella henselae, 0.6% (4/646) Bartonella clarridgeiae]. The novel B. henselae PCR developed for this study demonstrated nearly twice the sensitivity of bacterial isolation. The overall prevalence of hemoplasma was 4% (30/742) [3.3% (25/742) Candidatus Mycoplasma haemominutum, 0.7% (5/742) Mycoplasma haemofelis]. There was no significant difference between the prevalence of infection by season or by age (≤ 2 y, > 2 y). Candidatus Mycoplasma turicensis was identified, for the first time in Canada, in 1 cat. The prevalence of Bartonella (58%) and hemoplasma (47% M. haemofelis, 13% M. haemominutum) in blood from a small sampling (n = 45) of stray cats was considerably higher than that found in healthy pet cats. The prevalence of Rickettsia felis in cat fleas was also assessed. A pool of fleas from each of 50 flea-infested cats was analyzed for the presence of R. felis by PCR. Rickettsia felis was confirmed, for the first time in Canada, in 9 of the 50 samples. Therefore, the prevalence of Bartonella and hemoplasma infection in healthy pet cats is relatively low. Further, the control of cat fleas is important because of the public health significance of Bartonella and R. felis infection. PMID:19086373

[Characteristics of mercury exchange flux between soil and atmosphere under the snow retention and snow melting control].

PubMed

Zhang, Gang; Wang, Ning; Ai, Jian-Chao; Zhang, Lei; Yang, Jing; Liu, Zi-Qi

2013-02-01

Jiapigou gold mine, located in the upper Songhua River, was once the largest mine in China due to gold output, where gold extraction with algamation was widely applied to extract gold resulting in severe mercury pollution to ambient environmental medium. In order to study the characteristics of mercury exchange flux between soil (snow) and atmosphere under the snow retention and snow melting control, sampling sites were selected in equal distances along the slope which is situated in the typical hill-valley terrain unit. Mercury exchange flux between soil (snow) and atmosphere was determined with the method of dynamic flux chamber and in all sampling sites the atmosphere concentration from 0 to 150 cm near to the earth in the vertical direction was measured. Furthermore, the impact factors including synchronous meteorology, the surface characteristics under the snow retention and snow melting control and the mercury concentration in vertical direction were also investigated. The results are as follows: During the period of snow retention and melting the air mercury tends to gather towards valley bottom along the slope and an obvious deposit tendency process was found from air to the earth's surface under the control of thermal inversion due to the underlying surface of cold source (snow surface). However, during the period of snow melting, mercury exchange flux between the soil and atmosphere on the surface of the earth with the snow being melted demonstrates alternative deposit and release processes. As for the earth with snow covered, the deposit level of mercury exchange flux between soil and atmosphere is lower than that during the period of snow retention. The relationship between mercury exchange flux and impact factors shows that in snow retention there is a remarkable negative linear correlation between mercury exchange flux and air mercury concentration as well as between the former and the air temperature. In addition, in snow melting mercury exchange

Snow specific surface area simulation using the one-layer snow model in the Canadian LAnd Surface Scheme (CLASS)

NASA Astrophysics Data System (ADS)

Roy, A.; Royer, A.; Montpetit, B.; Bartlett, P. A.; Langlois, A.

2012-12-01

Snow grain size is a key parameter for modeling microwave snow emission properties and the surface energy balance because of its influence on the snow albedo, thermal conductivity and diffusivity. A model of the specific surface area (SSA) of snow was implemented in the one-layer snow model in the Canadian LAnd Surface Scheme (CLASS) version 3.4. This offline multilayer model (CLASS-SSA) simulates the decrease of SSA based on snow age, snow temperature and the temperature gradient under dry snow conditions, whereas it considers the liquid water content for wet snow metamorphism. We compare the model with ground-based measurements from several sites (alpine, Arctic and sub-Arctic) with different types of snow. The model provides simulated SSA in good agreement with measurements with an overall point-to-point comparison RMSE of 8.1 m2 kg-1, and a RMSE of 4.9 m2 kg-1 for the snowpack average SSA. The model, however, is limited under wet conditions due to the single-layer nature of the CLASS model, leading to a single liquid water content value for the whole snowpack. The SSA simulations are of great interest for satellite passive microwave brightness temperature assimilations, snow mass balance retrievals and surface energy balance calculations with associated climate feedbacks.

Satellite Snow-Cover Mapping: A Brief Review

NASA Technical Reports Server (NTRS)

Hall, Dorothy K.

1995-01-01

Satellite snow mapping has been accomplished since 1966, initially using data from the reflective part of the electromagnetic spectrum, and now also employing data from the microwave part of the spectrum. Visible and near-infrared sensors can provide excellent spatial resolution from space enabling detailed snow mapping. When digital elevation models are also used, snow mapping can provide realistic measurements of snow extent even in mountainous areas. Passive-microwave satellite data permit global snow cover to be mapped on a near-daily basis and estimates of snow depth to be made, but with relatively poor spatial resolution (approximately 25 km). Dense forest cover limits both techniques and optical remote sensing is limited further by cloudcover conditions. Satellite remote sensing of snow cover with imaging radars is still in the early stages of research, but shows promise at least for mapping wet or melting snow using C-band (5.3 GHz) synthetic aperture radar (SAR) data. Observing System (EOS) Moderate Resolution Imaging Spectroradiometer (MODIS) data beginning with the launch of the first EOS platform in 1998. Digital maps will be produced that will provide daily, and maximum weekly global snow, sea ice and lake ice cover at 1-km spatial resolution. Statistics will be generated on the extent and persistence of snow or ice cover in each pixel for each weekly map, cloudcover permitting. It will also be possible to generate snow- and ice-cover maps using MODIS data at 250- and 500-m resolution, and to study and map snow and ice characteristics such as albedo. been under development. Passive-microwave data offer the potential for determining not only snow cover, but snow water equivalent, depth and wetness under all sky conditions. A number of algorithms have been developed to utilize passive-microwave brightness temperatures to provide information on snow cover and water equivalent. The variability of vegetative Algorithms are being developed to map global snow

Measured Black Carbon Deposition on the Sierra Nevada Snow Pack and Implication for Snow Pack Retreat

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hadley, O.L.; Corrigan, C.E.; Kirchstetter, T.W.

2010-01-12

Modeling studies show that the darkening of snow and ice by black carbon deposition is a major factor for the rapid disappearance of arctic sea ice, mountain glaciers and snow packs. This study provides one of the first direct measurements for the efficient removal of black carbon from the atmosphere by snow and its subsequent deposition to the snow packs of California. The early melting of the snow packs in the Sierras is one of the contributing factors to the severe water problems in California. BC concentrations in falling snow were measured at two mountain locations and in rain atmore » a coastal site. All three stations reveal large BC concentrations in precipitation, ranging from 1.7 ng/g to 12.9 ng/g. The BC concentrations in the air after the snow fall were negligible suggesting an extremely efficient removal of BC by snow. The data suggest that below cloud scavenging, rather than ice nuclei, was the dominant source of BC in the snow. A five-year comparison of BC, dust, and total fine aerosol mass concentrations at multiple sites reveals that the measurements made at the sampling sites were representative of large scale deposition in the Sierra Nevada. The relative concentration of iron and calcium in the mountain aerosol indicates that one-quarter to one-third of the BC may have been transported from Asia.« less

Camping in the Snow.

ERIC Educational Resources Information Center

Brown, Constance

1979-01-01

Describes the experience of winter snow camping. Provides suggestions for shelter, snow kitchens, fires and stoves, cooking, latrines, sleeping warm, dehydration prevention, and clothing. Illustrated with full color photographs. (MA)

Evaluation of SNODAS snow depth and snow water equivalent estimates for the Colorado Rocky Mountains, USA

USGS Publications Warehouse

Clow, David W.; Nanus, Leora; Verdin, Kristine L.; Schmidt, Jeffrey

2012-01-01

The National Weather Service's Snow Data Assimilation (SNODAS) program provides daily, gridded estimates of snow depth, snow water equivalent (SWE), and related snow parameters at a 1-km2 resolution for the conterminous USA. In this study, SNODAS snow depth and SWE estimates were compared with independent, ground-based snow survey data in the Colorado Rocky Mountains to assess SNODAS accuracy at the 1-km2 scale. Accuracy also was evaluated at the basin scale by comparing SNODAS model output to snowmelt runoff in 31 headwater basins with US Geological Survey stream gauges. Results from the snow surveys indicated that SNODAS performed well in forested areas, explaining 72% of the variance in snow depths and 77% of the variance in SWE. However, SNODAS showed poor agreement with measurements in alpine areas, explaining 16% of the variance in snow depth and 30% of the variance in SWE. At the basin scale, snowmelt runoff was moderately correlated (R2 = 0.52) with SNODAS model estimates. A simple method for adjusting SNODAS SWE estimates in alpine areas was developed that uses relations between prevailing wind direction, terrain, and vegetation to account for wind redistribution of snow in alpine terrain. The adjustments substantially improved agreement between measurements and SNODAS estimates, with the R2 of measured SWE values against SNODAS SWE estimates increasing from 0.42 to 0.63 and the root mean square error decreasing from 12 to 6 cm. Results from this study indicate that SNODAS can provide reliable data for input to moderate-scale to large-scale hydrologic models, which are essential for creating accurate runoff forecasts. Refinement of SNODAS SWE estimates for alpine areas to account for wind redistribution of snow could further improve model performance. Published 2011. This article is a US Government work and is in the public domain in the USA.

Astronomy (communication arising): black holes, fleas and microlithography.

PubMed

Skinner, Gerry; Gorenstein, Paul

2003-11-20

Fresnel lenses allow almost perfect imaging in widely different circumstances, but their focus is perfect only for a single wavelength. Wang et al. have shown how the effective bandpass may be widened for X-ray microscopy by using a compound diffractive/refractive lens near to an absorption edge. A compound lens has also been proposed for high-energy astronomy, working well above all absorption edges. Although the scale is very different, we point out here that the principle is the same. Ever since Galileo constructed an astronomical telescope that he was able to reconfigure to study fleas and gnats, astronomy and microscopy have relied on optics that are closely related, but different in detail.

Spatiotemporal variability of snow cover and snow water equivalent in the last three decades over Eurasia

NASA Astrophysics Data System (ADS)

Zhang, Yinsheng; Ma, Ning

2018-04-01

Changes in the extent and amount of snow cover in Eurasia are of great interest because of their vital impacts on the global climate system and regional water resource management. This study investigated the spatial and temporal variability of the snow cover extent (SCE) and snow water equivalent (SWE) of the continental Eurasia using the Northern Hemisphere Equal-Area Scalable Earth Grid (EASE-Grid) Weekly SCE data for 1972-2006 and the Global Monthly EASE-Grid SWE data for 1979-2004. The results indicated that, in general, the spatial extent of snow cover significantly decreased during spring and summer, but varied little during autumn and winter over Eurasia in the study period. The date at which snow cover began to disappear in spring has significantly advanced, whereas the timing of snow cover onset in autumn did not vary significantly during 1972-2006. The snow cover persistence period declined significantly in the western Tibetan Plateau as well as partial area of Central Asia and northwestern Russia, but varied little in other parts of Eurasia. "Snow-free breaks" (SFBs) with intermittent snow cover in the cold season were principally observed in the Tibetan Plateau and Central Asia, causing a low sensitivity of snow cover persistence period to the timings of snow cover onset and disappearance over the areas with shallow snow. The averaged SFBs were 1-14 weeks during the study period and the maximum intermittence could even reach 25 weeks in certain years. At a seasonal scale, SWE usually peaked in February or March, but fell gradually since April across Eurasia. Both annual mean and annual maximum SWE decreased significantly during 1979-2004 in most parts of Eurasia except for eastern Siberia as well as northwestern and northeastern China. The possible cross-platform inconsistencies between two passive microwave radiometers may cause uncertainties in the detected trends of SWE here, suggesting an urgent need of producing a long-term, more homogeneous SWE

Snow observations in Mount Lebanon (2011-2016)

NASA Astrophysics Data System (ADS)

Fayad, Abbas; Gascoin, Simon; Faour, Ghaleb; Fanise, Pascal; Drapeau, Laurent; Somma, Janine; Fadel, Ali; Bitar, Ahmad Al; Escadafal, Richard

2017-08-01

We present a unique meteorological and snow observational dataset in Mount Lebanon, a mountainous region with a Mediterranean climate, where snowmelt is an essential water resource. The study region covers the recharge area of three karstic river basins (total area of 1092 km2 and an elevation up to 3088 m). The dataset consists of (1) continuous meteorological and snow height observations, (2) snowpack field measurements, and (3) medium-resolution satellite snow cover data. The continuous meteorological measurements at three automatic weather stations (MZA, 2296 m; LAQ, 1840 m; and CED, 2834 m a.s.l.) include surface air temperature and humidity, precipitation, wind speed and direction, incoming and reflected shortwave irradiance, and snow height, at 30 min intervals for the snow seasons (November-June) between 2011 and 2016 for MZA and between 2014 and 2016 for CED and LAQ. Precipitation data were filtered and corrected for Geonor undercatch. Observations of snow height (HS), snow water equivalent, and snow density were collected at 30 snow courses located at elevations between 1300 and 2900 m a.s.l. during the two snow seasons of 2014-2016 with an average revisit time of 11 days. Daily gap-free snow cover extent (SCA) and snow cover duration (SCD) maps derived from MODIS snow products are provided for the same period (2011-2016). We used the dataset to characterize mean snow height, snow water equivalent (SWE), and density for the first time in Mount Lebanon. Snow seasonal variability was characterized with high HS and SWE variance and a relatively high snow density mean equal to 467 kg m-3. We find that the relationship between snow depth and snow density is specific to the Mediterranean climate. The current model explained 34 % of the variability in the entire dataset (all regions between 1300 and 2900 m a.s.l.) and 62 % for high mountain regions (elevation 2200-2900 m a.s.l.). The dataset is suitable for the investigation of snow dynamics and for the forcing

Basic Snow Pressure Calculation

NASA Astrophysics Data System (ADS)

Hao, Shouzhi; Su, Jian

2018-03-01

As extreme weather rising in recent years, the damage of large steel structures caused by weather is frequent in China. How to consider the effect of wind and snow loads on the structure in structural design has become the focus of attention in engineering field. In this paper, based on the serious snow disasters in recent years and comparative analysis of some scholars, influence factors and the value of the snow load, the probability model are described.

Snow Bank Detectives

ERIC Educational Resources Information Center

Olson, Eric A.; Rule, Audrey C.; Dehm, Janet

2005-01-01

In the city where the authors live, located on the shore of Lake Ontario, children have ample opportunity to interact with snow. Water vapor rising from the relatively warm lake surface produces tremendous "lake effect" snowfalls when frigid winter winds blow. Snow piles along roadways after each passing storm, creating impressive snow…

How Much Water is in That Snowpack? Improving Basin-wide Snow Water Equivalent Estimates from the Airborne Snow Observatory

NASA Astrophysics Data System (ADS)

Bormann, K.; Painter, T. H.; Marks, D. G.; Kirchner, P. B.; Winstral, A. H.; Ramirez, P.; Goodale, C. E.; Richardson, M.; Berisford, D. F.

2014-12-01

In the western US, snowmelt from the mountains contribute the vast majority of fresh water supply, in an otherwise dry region. With much of California currently experiencing extreme drought, it is critical for water managers to have accurate basin-wide estimations of snow water content during the spring melt season. At the forefront of basin-scale snow monitoring is the Jet Propulsion Laboratory's Airborne Snow Observatory (ASO). With combined LiDAR /spectrometer instruments and weekly flights over key basins throughout California, the ASO suite is capable of retrieving high-resolution basin-wide snow depth and albedo observations. To make best use of these high-resolution snow depths, spatially distributed snow density data are required to leverage snow water equivalent (SWE) from the measured depths. Snow density is a spatially and temporally variable property and is difficult to estimate at basin scales. Currently, ASO uses a physically based snow model (iSnobal) to resolve distributed snow density dynamics across the basin. However, there are issues with the density algorithms in iSnobal, particularly with snow depths below 0.50 m. This shortcoming limited the use of snow density fields from iSnobal during the poor snowfall year of 2014 in the Sierra Nevada, where snow depths were generally low. A deeper understanding of iSnobal model performance and uncertainty for snow density estimation is required. In this study, the model is compared to an existing climate-based statistical method for basin-wide snow density estimation in the Tuolumne basin in the Sierra Nevada and sparse field density measurements. The objective of this study is to improve the water resource information provided to water managers during ASO operation in the future by reducing the uncertainty introduced during the snow depth to SWE conversion.

Crystal growth of artificial snow

NASA Technical Reports Server (NTRS)

Kimura, S.; Oka, A.; Taki, M.; Kuwano, R.; Ono, H.; Nagura, R.; Narimatsu, Y.; Tanii, J.; Kamimiytat, Y.

1984-01-01

Snow crystals were grown onboard the space shuttle during STS-7 and STS-8 to facilitate the investigation of crystal growth under conditions of weightlessness. The experimental design and hardware are described. Space-grown snow crystals were polyhedrons looking like spheres, which were unlike snow crystals produced in experiments on Earth.

Unexpected Patterns in Snow and Dirt

ERIC Educational Resources Information Center

Ackerson, Bruce J.

2018-01-01

For more than 30 years, Albert A. Bartlett published "Thermal patterns in the snow" in this journal. These are patterns produced by heat sources underneath the snow. Bartlett's articles encouraged me to pay attention to patterns in snow and to understanding them. At winter's end the last snow becomes dirty and is heaped into piles. This…

Growth inhibition at the ice prismatic plane induced by a spruce budworm antifreeze protein: a molecular dynamics simulation study.

PubMed

Nada, H; Furukawa, Y

2011-11-28

A molecular dynamics simulation was conducted to investigate the growth kinetics at the ice prismatic interface to which a spruce budworm antifreeze protein was bound. Two initial binding conformations of the protein at the interface--one energetically stable and the other energetically unstable--were examined. For both binding conformations, the growth of ice was observed around the protein. A sharp decrease in the rate of ice growth was observed around the protein that initially had the energetically stable binding conformation. Simulation results suggest that the observed decrease in the ice growth rate was attributable to melting point depression caused by the Gibbs-Thomson effect. The protein that initially had the energetically unstable binding conformation markedly relaxed so as to stably bind to the prismatic plane interface of the grown ice; thereafter, a decrease in the ice growth rate was observed as well. However, the binding conformation that the protein approached during the relaxation was different from that of the protein that initially had the energetically stable binding conformation. Thus, the simulation indicates the existence of two binding conformations for inducing a decrease in the ice growth rate. The results are possibly related to the hyperactivity of a spruce budworm antifreeze protein in real systems.

Testing a blowing snow model against distributed snow measurements at Upper Sheep Creek, Idaho, United States of America

Treesearch

Rajiv Prasad; David G. Tarboton; Glen E. Liston; Charles H. Luce; Mark S. Seyfried

2001-01-01

In this paper a physically based snow transport model (SnowTran-3D) was used to simulate snow drifting over a 30 m grid and was compared to detailed snow water equivalence (SWE) surveys on three dates within a small 0.25 km2 subwatershed, Upper Sheep Creek. Two precipitation scenarios and two vegetation scenarios were used to carry out four snow transport model runs in...

Volatiles emissions from the flea beetle Altica litigata (Coleoptera: Chrysomelidae) associated with invasive Ludwigia hexapetala

USDA-ARS?s Scientific Manuscript database

The water primrose flea beetle Altica litigata (family Chrysomelidae) is a known insect pest to several nursery plants due to its aggressive feeding behavior – typically carried out in significant numbers. This aggregate feeding usually results in severe defoliation of their host plant. However, bec...

Myxomatosis: passive immunity in the offspring of immune rabbits (Oryctolagus cuniculus) infested with fleas (Spilopsyllus cuniculi Dale) and exposed to myxoma virus.

PubMed Central

Sobey, W. R.; Conolly, D.

1975-01-01

Kittens with maternal antibodies to myxoma virus, the offspring of rabbits which had recovered from myxomatosis, were exposed to fleas contaminated with myxoma virus and/or contact with infected rabbits from birth. All kittens died or became infected before 8 weeks of age. When compared with adult animals similarly infected the kittens showed no advantage in terms of survival time or recovery rate attributable to maternal antibodies. Flea transmission of virus was found more effective than contact transmissions. PMID:1054058

[The systemic effects of imidacloprid and fipronil on Xenopsylla cheopis fleas (Siphonaptera) and blood-sucking Ornithonyssus bacoti gamasid mites (Gamasina: Macronyssidae)].

PubMed

Lopatina, Iu V; Eremina, O Iu

2013-01-01

The systemic effects of imidacloprid and fipronil on Xenopsylla cheopis fleas and blood-sucking Ornithonyssus bacoti gamasid mites were studied under laboratory conditions. Albino rats were forcibly administered insectoacaricides per os in doses of 1, 10, 30 mg/kg or fed with dietary bait (the doses of fipronil and imidacloprid were 10-33 and 18-70 mg/kg/day, respectively) for 3 or more days. Fipronil had a pronounced systemic effect on both X. cheopis and O. baconi. Imidacloprid was markedly active against the fleas and, on the contrary, inactive against the mites.

Utilizing Multiple Datasets for Snow Cover Mapping

NASA Technical Reports Server (NTRS)

Tait, Andrew B.; Hall, Dorothy K.; Foster, James L.; Armstrong, Richard L.

1999-01-01

Snow-cover maps generated from surface data are based on direct measurements, however they are prone to interpolation errors where climate stations are sparsely distributed. Snow cover is clearly discernable using satellite-attained optical data because of the high albedo of snow, yet the surface is often obscured by cloud cover. Passive microwave (PM) data is unaffected by clouds, however, the snow-cover signature is significantly affected by melting snow and the microwaves may be transparent to thin snow (less than 3cm). Both optical and microwave sensors have problems discerning snow beneath forest canopies. This paper describes a method that combines ground and satellite data to produce a Multiple-Dataset Snow-Cover Product (MDSCP). Comparisons with current snow-cover products show that the MDSCP draws together the advantages of each of its component products while minimizing their potential errors. Improved estimates of the snow-covered area are derived through the addition of two snow-cover classes ("thin or patchy" and "high elevation" snow cover) and from the analysis of the climate station data within each class. The compatibility of this method for use with Moderate Resolution Imaging Spectroradiometer (MODIS) data, which will be available in 2000, is also discussed. With the assimilation of these data, the resolution of the MDSCP would be improved both spatially and temporally and the analysis would become completely automated.

Sentinels for snow science

NASA Astrophysics Data System (ADS)

Gascoin, S.; Grizonnet, M.; Baba, W. M.; Hagolle, O.; Fayad, A.; Mermoz, S.; Kinnard, C.; Fatima, K.; Jarlan, L.; Hanich, L.

2017-12-01

Current spaceborne sensors do not allow retrieving the snow water equivalent in mountain regions, "the most important unsolved problem in snow hydrology" (Dozier, 2016). While the NASA is operating an airborne mission to survey the SWE in the western USA, elsewhere, however, snow scientists and water managers do not have access to routine SWE measurements at the scale of a mountain range. In this presentation we suggest that the advent of the Copernicus Earth Observation programme opens new perspectives to address this issue in mountain regions worldwide. The Sentinel-2 mission will provide global-scale multispectral observations at 20 m resolution every 5-days (cloud permitting). The Sentinel-1 mission is already imaging the global land surface with a C-band radar at 10 m resolution every 6 days. These observations are unprecedented in terms of spatial and temporal resolution. However, the nature of the observation (radiometry, wavelength) is in the continuity of previous and ongoing missions. As a result, it is relatively straightforward to re-use algorithms that were developed by the remote sensing community over the last decades. For instance, Sentinel-2 data can be used to derive maps of the snow cover extent from the normalized difference snow index, which was initially proposed for Landsat. In addition, the 5-days repeat cycle allows the application of gap-filling algorithms, which were developed for MODIS based on the temporal dimension. The Sentinel-1 data can be used to detect the wet snow cover and track melting areas as proposed for ERS in the early 1990's. Eventually, we show an example where Sentinel-2-like data improved the simulation of the SWE in the data-scarce region of the High Atlas in Morocco through assimilation in a distributed snowpack model. We encourage snow scientists to embrace Sentinel-1 and Sentinel-2 data to enhance our knowledge on the snow cover dynamics in mountain regions.

Improving snow water equivalent simulations in an alpine basin using blended gage precipitation and snow pillow measurements

NASA Astrophysics Data System (ADS)

Sohrabi, M.; Safeeq, M.; Conklin, M. H.

2017-12-01

Snowpack is a critical freshwater reservoir that sustains ecosystem, natural habitat, hydropower, agriculture, and urban water supply in many areas around the world. Accurate estimation of basin scale snow water equivalent (SWE), through both measurement and modeling, has been significantly recognized to improve regional water resource management. Recent advances in remote data acquisition techniques have improved snow measurements but our ability to model snowpack evolution is largely hampered by poor knowledge of inherently variable high-elevation precipitation patterns. For a variety of reasons, majority of the precipitation gages are located in low and mid-elevation range and function as drivers for basin scale hydrologic modeling. Here, we blend observed gage precipitation from low and mid-elevation with point observations of SWE from high-elevation snow pillow into a physically based snow evolution model (SnowModel) to better represent the basin-scale precipitation field and improve snow simulations. To do this, we constructed two scenarios that differed in only precipitation. In WTH scenario, we forced the SnowModel using spatially distributed gage precipitation data. In WTH+SP scenario, the model was forced with spatially distributed precipitation data derived from gage precipitation along with observed precipitation from snow pillows. Since snow pillows do not directly measure precipitation, we uses positive change in SWE as a proxy for precipitation. The SnowModel was implemented at daily time step and 100 m resolution for the Kings River Basin, USA over 2000-2014. Our results show an improvement in snow simulation under WTH+SP as compared to WTH scenario, which can be attributed to better representation in high-elevation precipitation patterns under WTH+SP. The average Nash Sutcliffe efficiency over all snow pillow and course sites was substantially higher for WTH+SP (0.77) than for WTH scenario (0.47). The maximum difference in observed and simulated

Seasonal Snow Extent and Snow Mass in South America Using SMMR and SSM/I Passive Microwave Data (1979-2003)

NASA Technical Reports Server (NTRS)

Foster, J. L.; Hall, D. K.; Chiu, L.; Kelly, R. E.; Powell, H.; Chiu, L.

2007-01-01

Seasonal snow cover in South America was examined in this study using passive microwave satellite data from the Scanning Multichannel Microwave Radiometer (SMMR) on board the Nimbus-satellite and the Special Sensor Microwave Imagers (SSM/I) on board Defense Meteorological Satellite Program (DMSP) satellites. For the period from 1979-2003, both snow cover extent and snow depth (snow mass) were investigated during coldest months (May-September), primarily in the Patagonia area of Argentina and in Chile. Most of the seasonal snow in South America is in the Patagonia region of Argentina. Since winter temperatures in this region are often above freezing, the coldest winter month was found to be the month having the most extensive snow cover and also usually the month having the deepest snow cover as well. Sharp year-to-year differences were recorded using the passive microwave observations. The average snow cover extent for July, the month with the greatest average snow extent during the 25-year period of record, is 320,700 km(exp 2). In July of 1984, the average monthly snow cover was 701,250 km(exp 2) - the most extensive coverage observed between 1979 and 2003. However, in July of 1989, snow cover extent was only 120 km(exp 2). The 25-year period of record shows a sinusoidal like pattern, though there appears to be no obvious trend in either increasing or decreasing snow extent or snow mass between 1979 and 2003.

Low temperature stress modulated secretome analysis and purification of antifreeze protein from Hippophae rhamnoides, a Himalayan wonder plant.

PubMed

Gupta, Ravi; Deswal, Renu

2012-05-04

Plants' distribution and productivity are adversely affected by low temperature (LT) stress. LT induced proteins were analyzed by 2-DE-nano-LC-MS/MS in shoot secretome of Hippophae rhamnoides (seabuckthorn), a Himalayan wonder shrub. Seedlings were subjected to direct freezing stress (-5 °C), cold acclimation (CA), and subzero acclimation (SZA), and extracellular proteins (ECPs) were isolated using vacuum infiltration. Approximately 245 spots were reproducibly detected in 2-DE gels of LT treated secretome, out of which 61 were LT responsive. Functional categorization of 34 upregulated proteins showed 47% signaling, redox regulated, and defense associated proteins. LT induced secretome contained thaumatin like protein and Chitinase as putative antifreeze proteins (AFPs). Phase contrast microscopy with a nanoliter osmometer showed hexagonal ice crystals with 0.13 °C thermal hysteresis (TH), and splat assay showed 1.5-fold ice recrystallization inhibition (IRI), confirming antifreeze activity in LT induced secretome. A 41 kDa polygalacturonase inhibitor protein (PGIP), purified by ice adsorption chromatography (IAC), showed hexagonal ice crystals, a TH of 0.19 °C, and 9-fold IRI activity. Deglycosylated PGIP retained its AFP activity, suggesting that glycosylation is not required for AFP activity. This is the first report of LT modulated secretome analysis and purification of AFPs from seabuckthorn. Overall, these findings provide an insight in probable LT induced signaling in the secretome.

Snow in Italy

NASA Image and Video Library

2012-02-24

NASA image acquired February 24, 2012 By late February, 2012, the great European cold wave had begun to loosen its frigid grip, but significant snow still remained in the region. The Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the Aqua satellite captured this true-color image of snow in Italy on February 24 at 12:35 UTC (1:30 p.m. local time). In the north of the image, bright white clouds blanket the region in a broad arc. Snow, which tends to be generally less bright that clouds, covers the Alps in the north of Italy. The Apennine Mountains, which form the backbone of the Italian peninsula, also carry a blanket of snow. Although clouds and snow can, at times, be distinguished visually in a true-color image, sometimes they can appear very similar. When it is important to clearly define snow from cloud, false color images are often helpful. Rome, which can be seen as a gray smudge on the southwestern coast of the peninsula, recorded highs of a spring-like 50°F the day this image was captured, but earlier in the month the temperatures dove as low as 26°F on February 5. During that cold snap a rare intense snowfall blanketed Rome, causing the closure of the Colosseum, the Roman Forum and the Palatine Hill due to concerns of the risk of icy footing for tourists, and roads became impassible. Further north, temperatures plummeted to −21 °C (−6 °F) on 7 February. On February 11, news media reported over 2 meters (6.5 feet) of snow had fallen in Urbino, a walled town situated on a high sloping hillside on the eastern side of the Apennine Mountains. That same snowfall cut access to many remote towns in the Apennines, blocking roads and trapping some people in the homes. Credit: NASA/GSFC/Jeff Schmaltz/MODIS Land Rapid Response Team NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA�

Tenebrio molitor antifreeze protein gene identification and regulation.

PubMed

Qin, Wensheng; Walker, Virginia K

2006-02-15

The yellow mealworm, Tenebrio molitor, is a freeze susceptible, stored product pest. Its winter survival is facilitated by the accumulation of antifreeze proteins (AFPs), encoded by a small gene family. We have now isolated 11 different AFP genomic clones from 3 genomic libraries. All the clones had a single coding sequence, with no evidence of intervening sequences. Three genomic clones were further characterized. All have putative TATA box sequences upstream of the coding regions and multiple potential poly(A) signal sequences downstream of the coding regions. A TmAFP regulatory region, B1037, conferred transcriptional activity when ligated to a luciferase reporter sequence and after transfection into an insect cell line. A 143 bp core promoter including a TATA box sequence was identified. Its promoter activity was increased 4.4 times by inserting an exotic 245 bp intron into the construct, similar to the enhancement of transgenic expression seen in several other systems. The addition of a duplication of the first 120 bp sequence from the 143 bp core promoter decreased promoter activity by half. Although putative hormonal response sequences were identified, none of the five hormones tested enhanced reporter activity. These studies on the mechanisms of AFP transcriptional control are important for the consideration of any transfer of freeze-resistance phenotypes to beneficial hosts.

Long-term analyses of snow dynamics within the french Alps on the 1900-2100 period. Analyses of historical snow water equivalent observations, modelisations and projections of a hundred of snow courses.

NASA Astrophysics Data System (ADS)

Mathevet, T.; Joel, G.; Gottardi, F.; Nemoz, B.

2017-12-01

The aim of this communication is to present analyses of climate variability and change on snow water equivalent (SWE) observations, reconstructions (1900-2016) and scenarii (2020-2100) of a hundred of snow courses dissiminated within the french Alps. This issue became particularly important since a decade, in regions where snow variability had a large impact on water resources availability, poor snow conditions in ski resorts and artificial snow production. As a water resources manager in french mountainuous regions, EDF (french hydropower company) has developed and managed a hydrometeorological network since 1950. A recent data rescue research allowed to digitize long term SWE manual measurments of a hundred of snow courses within the french Alps. EDF have been operating an automatic SWE sensors network, complementary to the snow course network. Based on numerous SWE observations time-series and snow accumulation and melt model (Garavaglia et al., 2017), continuous daily historical SWE time-series have been reconstructed within the 1950-2016 period. These reconstructions have been extented to 1900 using 20 CR reanalyses (ANATEM method, Kuentz et al., 2015) and up to 2100 using GIEC Climate Change scenarii. Considering various mountainous areas within the french Alps, this communication focuses on : (1) long term (1900-2016) analyses of variability and trend of total precipitation, air temperature, snow water equivalent, snow line altitude, snow season length , (2) long term variability of hydrological regime of snow dominated watersheds and (3) future trends (2020 -2100) using GIEC Climate Change scenarii. Comparing historical period (1950-1984) to recent period (1984-2016), quantitative results within a region in the north Alps (Maurienne) shows an increase of air temperature by 1.2 °C, an increase of snow line height by 200m, a reduction of SWE by 200 mm/year and a reduction of snow season length by 15 days. These analyses will be extended from north to south

Sublimation From Snow in Northern Environments

NASA Astrophysics Data System (ADS)

Pomeroy, J. W.

2002-12-01

Sublimation from snow is an often neglected component of water and energy balances. Research under the Mackenzie GEWEX Study has attempted to understand the snow and atmospheric processes controlling sublimation and to estimate the magnitude of sublimation in high latitude catchments. Eddy correlation units were used to measure vertical water vapour fluxes from a high latitude boreal forest, snow-covered tundra and shrub-covered tundra in Wolf Creek Research Basin, near Whitehorse Yukon, Territory Canada. Over Jan-Apr. water vapour fluxes from the forest canopy amounted to 18.3 mm, a significant loss from winter snowfall of 54 mm. Most of this loss occurred when the canopy was snow-covered. The weight of snow measured on a suspended, weighed tree indicates that this flux is dominated by sublimation of intercepted snow. In the melt period (April), water vapour fluxes were uniformly small ranging from 0.21 mm/day on the tundra slope, 0.23 mm/day for the forest and 0.27 mm/day for the shrub-tundra. During the melt period the forest and shrub canopies was snow-free and roots were frozen, so the primary source of water vapour from all sites was the surface snow.

[Snow cover pollution monitoring in Ufa].

PubMed

Daukaev, R A; Suleĭmanov, R A

2008-01-01

The paper presents the results of examining the snow cover polluted with heavy metals in the large industrial town of Ufa. The level of man-caused burden on the snow cover of the conventional parts of the town was estimated and compared upon exposure to a wide range of snow cover pollutants. The priority snow cover pollutants were identified among the test heavy metals.

Effects of multilayer snow scheme on the simulation of snow: Offline Noah and coupled with NCEP CFSv2

NASA Astrophysics Data System (ADS)

Saha, Subodh Kumar; Sujith, K.; Pokhrel, Samir; Chaudhari, Hemantkumar S.; Hazra, Anupam

2017-03-01

The Noah version 2.7.1 is a moderately complex land surface model (LSM), with a single layer snowpack, combined with vegetation and underlying soil layer. Many previous studies have pointed out biases in the simulation of snow, which may hinder the skill of a forecasting system coupled with the Noah. In order to improve the simulation of snow by the Noah, a multilayer snow scheme (up to a maximum of six layers) is introduced. As Noah is the land surface component of the Climate Forecast System version 2 (CFSv2) of the National Centers for Environmental Prediction (NCEP), the modified Noah is also coupled with the CFSv2. The offline LSM shows large improvements in the simulation of snow depth, snow water equivalent (SWE), and snow cover area during snow season (October to June). CFSv2 with the modified Noah reveals a dramatic improvements in the simulation of snow depth and 2 m air temperature and moderate improvements in SWE. As suggested in the previous diagnostic and sensitivity study, improvements in the simulation of snow by CFSv2 have lead to the reduction in dry bias over the Indian subcontinent (by a maximum of 2 mm d-1). The multilayer snow scheme shows promising results in the simulation of snow as well as Indian summer monsoon rainfall and hence this development may be the part of the future version of the CFS.

On charging of snow particles in blizzard

NASA Technical Reports Server (NTRS)

Shio, Hisashi

1991-01-01

The causes of the charge polarity on the blizzard, which consisted of fractured snow crystals and ice particles, were investigated. As a result, the charging phenomena showed that the characteristics of the blizzard are as follows: (1) In the case of the blizzard with snowfall, the fractured snow particles drifting near the surface of snow field (lower area: height 0.3 m) had positive charge, while those drifting at higher area (height 2 m) from the surface of snow field had negative charge. However, during the series of blizzards two kinds of particles positively and negatively charged were collected in equal amounts in a Faraday Cage. It may be considered that snow crystals with electrically neutral properties were separated into two kinds of snow flakes (charged positively and negatively) by destruction of the snow crystals. (2) In the case of the blizzard which consisted of irregularly formed ice drops (generated by peeling off the hardened snow field), the charge polarity of these ice drops salting over the snow field was particularly controlled by the crystallographic characteristics of the surface of the snow field hardened by the powerful wind pressure.

Effects of antifreeze proteins on the vitrification of mouse oocytes: comparison of three different antifreeze proteins.

PubMed

Lee, Hyang Heun; Lee, Hee Jun; Kim, Hak Jun; Lee, Jun Hyuck; Ko, Yong; Kim, Sun Mie; Lee, Jung Ryeol; Suh, Chang Suk; Kim, Seok Hyun

2015-09-01

Can antifreeze proteins (AFPs) from three different sources improve the efficacy of mouse oocyte vitrification? Treatment with AFPs can improve both murine oocyte quality and embryo development, and reduce reactive oxygen species (ROS) production in vitrified-warmed oocytes. A previous study discovered that vitrification of immature oocytes and 2-cell stage embryos of mice augmented with antifreeze glycoproteins at 40 mg/ml dramatically improved the morphological integrity of the samples, suggesting that AFPs have the ability to inhibit ice formation and stabilize the plasma membrane. Metaphase II oocytes were obtained from 4-week-old BD-F1 mice. AFPs from bacteria (Flavobacterium frigoris ice-binding protein (FfIBP)), yeast (Glaciozyma sp. ice-binding protein (LeIBP)) and fish (Type III AFP) were added to the vitrification and warming solutions individually. Survival and development, meiotic spindle organization, intracellular ROS, mitochondrial activity, DNA double-strand breaks (DSBs) and repair of damaged DNA were analyzed. Vitrification of oocytes was performed with the CryoTop (equilibration solution: 7.5% ethylene glycol (EG) and 7.5% 1,2-propandiol (PROH) for 5 min; vitrification solution: 15% EG, 15% PROH and 0.5 M sucrose for 1 min). Warming was performed in three steps with decreasing concentrations of sucrose (1.0, 0.5 and 0.25 M sucrose). AFP treatment can improve murine oocyte quality and embryo development. Survival rates, cleavage rates and blastocyst rates (blastocyst per cleaved and per survived oocytes) of oocytes in AFP-treated groups were significantly higher than those in the control group [75.0, 89.0, 90.0 and 85.0% for survival rate (P = 0.012); 58.7, 89.0, 87.8 and 81.2% for cleavage rate (P = 0.003); 52.3, 87.7, 78.5 and 76.8% for blastocyst per cleaved oocytes (P < 0.01); 30.7, 78.0, 68.9 and 62.4% for blastocyst per survived oocytes (P < 0.01) in control, FfIBP, LeIBP and Type III AFP-treated groups, respectively]. The mean (±SD) number

Impact of Snow Grain Shape and Internal Mixing with Black Carbon Aerosol on Snow Optical Properties for use in Climate Models

NASA Astrophysics Data System (ADS)

He, C.; Liou, K. N.; Takano, Y.; Yang, P.; Li, Q.; Chen, F.

2017-12-01

A set of parameterizations is developed for spectral single-scattering properties of clean and black carbon (BC)-contaminated snow based on geometric-optic surface-wave (GOS) computations, which explicitly resolves BC-snow internal mixing and various snow grain shapes. GOS calculations show that, compared with nonspherical grains, volume-equivalent snow spheres show up to 20% larger asymmetry factors and hence stronger forward scattering, particularly at wavelengths <1 mm. In contrast, snow grain sizes have a rather small impact on the asymmetry factor at wavelengths <1 mm, whereas size effects are important at longer wavelengths. The snow asymmetry factor is parameterized as a function of effective size, aspect ratio, and shape factor, and shows excellent agreement with GOS calculations. According to GOS calculations, the single-scattering coalbedo of pure snow is predominantly affected by grain sizes, rather than grain shapes, with higher values for larger grains. The snow single-scattering coalbedo is parameterized in terms of the effective size that combines shape and size effects, with an accuracy of >99%. Based on GOS calculations, BC-snow internal mixing enhances the snow single-scattering coalbedo at wavelengths <1 mm, but it does not alter the snow asymmetry factor. The BC-induced enhancement ratio of snow single-scattering coalbedo, independent of snow grain size and shape, is parameterized as a function of BC concentration with an accuracy of >99%. Overall, in addition to snow grain size, both BC-snow internal mixing and snow grain shape play critical roles in quantifying BC effects on snow optical properties. The present parameterizations can be conveniently applied to snow, land surface, and climate models including snowpack radiative transfer processes.

Snow hydrology in a general circulation model

NASA Technical Reports Server (NTRS)

Marshall, Susan; Roads, John O.; Glatzmaier, Gary

1994-01-01

A snow hydrology has been implemented in an atmospheric general circulation model (GCM). The snow hydrology consists of parameterizations of snowfall and snow cover fraction, a prognostic calculation of snow temperature, and a model of the snow mass and hydrologic budgets. Previously, only snow albedo had been included by a specified snow line. A 3-year GCM simulation with this now more complete surface hydrology is compared to a previous GCM control run with the specified snow line, as well as with observations. In particular, the authors discuss comparisons of the atmospheric and surface hydrologic budgets and the surface energy budget for U.S. and Canadian areas. The new snow hydrology changes the annual cycle of the surface moisture and energy budgets in the model. There is a noticeable shift in the runoff maximum from winter in the control run to spring in the snow hydrology run. A substantial amount of GCM winter precipitation is now stored in the seasonal snowpack. Snow cover also acts as an important insulating layer between the atmosphere and the ground. Wintertime soil temperatures are much higher in the snow hydrology experiment than in the control experiment. Seasonal snow cover is important for dampening large fluctuations in GCM continental skin temperature during the Northern Hemisphere winter. Snow depths and snow extent show good agreement with observations over North America. The geographic distribution of maximum depths is not as well simulated by the model due, in part, to the coarse resolution of the model. The patterns of runoff are qualitatively and quantitatively similar to observed patterns of streamflow averaged over the continental United States. The seasonal cycles of precipitation and evaporation are also reasonably well simulated by the model, although their magnitudes are larger than is observed. This is due, in part, to a cold bias in this model, which results in a dry model atmosphere and enhances the hydrologic cycle everywhere.

Snow micro-structure at Kongsvegen glacier, Svalbard

NASA Astrophysics Data System (ADS)

Bilgeri, F.; Karner, F.; Steinkogler, W.; Fromm, R.; Obleitner, F.; Kohler, J.

2012-04-01

Measurements of physical snow properties have been performed at several sites at Kongsvegen glacier, which is a key Arctic glacier in western Spitzbergen (79N, 13E). The data were collected at six locations along the flow line of the glacier at different elevations (161 to 741m asl.) and describe snow that was deposited during winter 2010/11. We basically consider the vertical profiles of snow temperature, density, hardness, grain size and crystal shapes derived from standard stratigraphic methods (snow pits)and measurements using advanced instruments like Snow Micropen® and NIR imagery. Some parameters were measured repeatedly and with different instruments which proves a high quality as well as long-term and spatial representativeness of the data. The general snow conditions at the end of winter are characterized by a linear increase of snow depth and water equivalent with elevation. Snow hardness also increases with elevation while density remains remarkably constant. At most sites the snow temperature, density, hardness and grain size increase from the surface towards the snow-ice interface. The surface and the bottom layers stand out by specific changes in snow signature (crystal types) and delineate the bulk of the snow pack which itself features a rather complex layering. Comparison of the high-resolution profiles measured at different elevations at the glacier suggests some principal correlations of the signatures of hardness, grain size and crystal type. Thus, some major features (e.g. particularly hard layers) can be traced along the glacier, but the high-resolution layering can not straightforwardly be related from one site to the other. This basically reflects a locally different history of the snow pack in terms of precipitation events and post-depositional snow metamorphism. The issue is investigated more quantitatively by enhanced statistical processing of the observed signatures and simulation of the history of individual layers. These studies are

Snow measurement system for airborne snow surveys (GPR system from helicopter) in high mountian areas.

NASA Astrophysics Data System (ADS)

Sorteberg, Hilleborg K.

2010-05-01

In the hydropower industry, it is important to have precise information about snow deposits at all times, to allow for effective planning and optimal use of the water. In Norway, it is common to measure snow density using a manual method, i.e. the depth and weight of the snow is measured. In recent years, radar measurements have been taken from snowmobiles; however, few energy supply companies use this method operatively - it has mostly been used in connection with research projects. Agder Energi is the first Norwegian power producer in using radar tecnology from helicopter in monitoring mountain snow levels. Measurement accuracy is crucial when obtaining input data for snow reservoir estimates. Radar screening by helicopter makes remote areas more easily accessible and provides larger quantities of data than traditional ground level measurement methods. In order to draw up a snow survey system, it is assumed as a basis that the snow distribution is influenced by vegetation, climate and topography. In order to take these factors into consideration, a snow survey system for fields in high mountain areas has been designed in which the data collection is carried out by following the lines of a grid system. The lines of this grid system is placed in order to effectively capture the distribution of elevation, x-coordinates, y-coordinates, aspect, slope and curvature in the field. Variation in climatic conditions are also captured better when using a grid, and dominant weather patterns will largely be captured in this measurement system.

Comparison of Snow Mass Estimates from a Prototype Passive Microwave Snow Algorithm, a Revised Algorithm and a Snow Depth Climatology

NASA Technical Reports Server (NTRS)

Foster, J. L.; Chang, A. T. C.; Hall, D. K.

1997-01-01

While it is recognized that no single snow algorithm is capable of producing accurate global estimates of snow depth, for research purposes it is useful to test an algorithm's performance in different climatic areas in order to see how it responds to a variety of snow conditions. This study is one of the first to develop separate passive microwave snow algorithms for North America and Eurasia by including parameters that consider the effects of variations in forest cover and crystal size on microwave brightness temperature. A new algorithm (GSFC 1996) is compared to a prototype algorithm (Chang et al., 1987) and to a snow depth climatology (SDC), which for this study is considered to be a standard reference or baseline. It is shown that the GSFC 1996 algorithm compares much more favorably to the SDC than does the Chang et al. (1987) algorithm. For example, in North America in February there is a 15% difference between the GSFC 198-96 Algorithm and the SDC, but with the Chang et al. (1987) algorithm the difference is greater than 50%. In Eurasia, also in February, there is only a 1.3% difference between the GSFC 1996 algorithm and the SDC, whereas with the Chang et al. (1987) algorithm the difference is about 20%. As expected, differences tend to be less when the snow cover extent is greater, particularly for Eurasia. The GSFC 1996 algorithm performs better in North America in each month than dose the Chang et al. (1987) algorithm. This is also the case in Eurasia, except in April and May when the Chang et al.(1987) algorithms is in closer accord to the SDC than is GSFC 1996 algorithm.

The biological function of an insect antifreeze protein simulated by molecular dynamics

PubMed Central

Kuiper, Michael J; Morton, Craig J; Abraham, Sneha E; Gray-Weale, Angus

2015-01-01

Antifreeze proteins (AFPs) protect certain cold-adapted organisms from freezing to death by selectively adsorbing to internal ice crystals and inhibiting ice propagation. The molecular details of AFP adsorption-inhibition is uncertain but is proposed to involve the Gibbs–Thomson effect. Here we show by using unbiased molecular dynamics simulations a protein structure-function mechanism for the spruce budworm Choristoneura fumiferana AFP, including stereo-specific binding and consequential melting and freezing inhibition. The protein binds indirectly to the prism ice face through a linear array of ordered water molecules that are structurally distinct from the ice. Mutation of the ice binding surface disrupts water-ordering and abolishes activity. The adsorption is virtually irreversible, and we confirm the ice growth inhibition is consistent with the Gibbs–Thomson law. DOI: http://dx.doi.org/10.7554/eLife.05142.001 PMID:25951514

Seasonal Snow Extent and Snow Mass in South America using SMMR and SSM/I Passive Microwave Data (1979-2006)

NASA Technical Reports Server (NTRS)

Foster, J. L.; Hall, D. K.; Kelly, R. E. J.; Chiu, L.

2008-01-01

Seasonal snow cover in South America was examined in this study using passive microwave satellite data from the Scanning Multichannel Microwave Radiometer (SMMR) on board the Nimbus-7 satellite and the Special Sensor Microwave Imagers (SSM/I) onboard Defense Meteorological Satellite Program (DMSP) satellites. For the period from 1979-2006, both snow cover extent and snow water equivalent (snow mass) were investigated during the coldest months (May-September), primarily in the Patagonia area of Argentina and in the Andes of Chile, Argentina and Bolivia, where most of the seasonal snow is found. Since winter temperatures in this region are often above freezing, the coldest winter month was found to be the month having the most extensive snow cover and usually the month having the deepest snow cover as well. Sharp year-to-year differences were recorded using the passive microwave observations. The average snow cover extent for July, the month with the greatest average extent during the 28-year period of record, is 321,674 km(exp 2). In July of 1984, the average monthly snow cover extent was 701,250 km(exp 2) the most extensive coverage observed between 1979 and 2006. However, in July of 1989, snow cover extent was only 120,000 km(exp 2). The 28-year period of record shows a sinusoidal like pattern for both snow cover and snow mass, though neither trend is significant at the 95% level.

The Snow Must Go On: Ground Ice Encasement, Snow Compaction and Absence of Snow Differently Cause Soil Hypoxia, CO2 Accumulation and Tree Seedling Damage in Boreal Forest

PubMed Central

Vuosku, Jaana; Ovaskainen, Anu; Stark, Sari; Rautio, Pasi

2016-01-01

At high latitudes, the climate has warmed at twice the rate of the global average with most changes observed in autumn, winter and spring. Increasing winter temperatures and wide temperature fluctuations are leading to more frequent rain-on-snow events and freeze-thaw cycles causing snow compaction and formation of ice layers in the snowpack, thus creating ice encasement (IE). By decreasing the snowpack insulation capacity and restricting soil-atmosphere gas exchange, modification of the snow properties may lead to colder soil but also to hypoxia and accumulation of trace gases in the subnivean environment. To test the effects of these overwintering conditions changes on plant winter survival and growth, we established a snow manipulation experiment in a coniferous forest in Northern Finland with Norway spruce and Scots pine seedlings. In addition to ambient conditions and prevention of IE, we applied three snow manipulation levels: IE created by artificial rain-on-snow events, snow compaction and complete snow removal. Snow removal led to deeper soil frost during winter, but no clear effect of IE or snow compaction done in early winter was observed on soil temperature. Hypoxia and accumulation of CO2 were highest in the IE plots but, more importantly, the duration of CO2 concentration above 5% was 17 days in IE plots compared to 0 days in ambient plots. IE was the most damaging winter condition for both species, decreasing the proportion of healthy seedlings by 47% for spruce and 76% for pine compared to ambient conditions. Seedlings in all three treatments tended to grow less than seedlings in ambient conditions but only IE had a significant effect on spruce growth. Our results demonstrate a negative impact of winter climate change on boreal forest regeneration and productivity. Changing snow conditions may thus partially mitigate the positive effect of increasing growing season temperatures on boreal forest productivity. PMID:27254100

The Snow Must Go On: Ground Ice Encasement, Snow Compaction and Absence of Snow Differently Cause Soil Hypoxia, CO2 Accumulation and Tree Seedling Damage in Boreal Forest.

PubMed

Martz, Françoise; Vuosku, Jaana; Ovaskainen, Anu; Stark, Sari; Rautio, Pasi

2016-01-01

At high latitudes, the climate has warmed at twice the rate of the global average with most changes observed in autumn, winter and spring. Increasing winter temperatures and wide temperature fluctuations are leading to more frequent rain-on-snow events and freeze-thaw cycles causing snow compaction and formation of ice layers in the snowpack, thus creating ice encasement (IE). By decreasing the snowpack insulation capacity and restricting soil-atmosphere gas exchange, modification of the snow properties may lead to colder soil but also to hypoxia and accumulation of trace gases in the subnivean environment. To test the effects of these overwintering conditions changes on plant winter survival and growth, we established a snow manipulation experiment in a coniferous forest in Northern Finland with Norway spruce and Scots pine seedlings. In addition to ambient conditions and prevention of IE, we applied three snow manipulation levels: IE created by artificial rain-on-snow events, snow compaction and complete snow removal. Snow removal led to deeper soil frost during winter, but no clear effect of IE or snow compaction done in early winter was observed on soil temperature. Hypoxia and accumulation of CO2 were highest in the IE plots but, more importantly, the duration of CO2 concentration above 5% was 17 days in IE plots compared to 0 days in ambient plots. IE was the most damaging winter condition for both species, decreasing the proportion of healthy seedlings by 47% for spruce and 76% for pine compared to ambient conditions. Seedlings in all three treatments tended to grow less than seedlings in ambient conditions but only IE had a significant effect on spruce growth. Our results demonstrate a negative impact of winter climate change on boreal forest regeneration and productivity. Changing snow conditions may thus partially mitigate the positive effect of increasing growing season temperatures on boreal forest productivity.

New nitrogen uptake strategy: specialized snow roots.

PubMed

Onipchenko, Vladimir G; Makarov, Mikhail I; van Logtestijn, Richard S P; Ivanov, Viktor B; Akhmetzhanova, Assem A; Tekeev, Dzhamal K; Ermak, Anton A; Salpagarova, Fatima S; Kozhevnikova, Anna D; Cornelissen, Johannes H C

2009-08-01

The evolution of plants has yielded a wealth of adaptations for the acquisition of key mineral nutrients. These include the structure, physiology and positioning of root systems. We report the discovery of specialized snow roots as a plant strategy to cope with the very short season for nutrient uptake and growth in alpine snow-beds, i.e. patches in the landscape that remain snow-covered well into the summer. We provide anatomical, chemical and experimental (15)N isotope tracking evidence that the Caucasian snow-bed plant Corydalis conorhiza forms extensive networks of specialized above-ground roots, which grow against gravity to acquire nitrogen directly from within snow packs. Snow roots capture nitrogen that would otherwise partly run off down-slope over a frozen surface, thereby helping to nourish these alpine ecosystems. Climate warming is changing and will change mountain snow regimes, while large-scale anthropogenic N deposition has increased snow N contents. These global changes are likely to impact on the distribution, abundance and functional significance of snow roots.

Hyperactive antifreeze proteins from longhorn beetles: some structural insights.

PubMed

Kristiansen, Erlend; Wilkens, Casper; Vincents, Bjarne; Friis, Dennis; Lorentzen, Anders Blomkild; Jenssen, Håvard; Løbner-Olesen, Anders; Ramløv, Hans

2012-11-01

This study reports on structural characteristics of hyperactive antifreeze proteins (AFPs) from two species of longhorn beetles. In Rhagium mordax, eight unique mRNAs coding for five different mature AFPs were identified from cold-hardy individuals. These AFPs are apparently homologues to a previously characterized AFP from the closely related species Rhagium inquisitor, and consist of six identifiable repeats of a putative ice binding motif TxTxTxT spaced irregularly apart by segments varying in length from 13 to 20 residues. Circular dichroism spectra show that the AFPs from both species have a high content of β-sheet and low levels of α-helix and random coil. Theoretical predictions of residue-specific secondary structure locate these β-sheets within the putative ice-binding motifs and the central parts of the segments separating them, consistent with an overall β-helical structure with the ice-binding motifs stacked in a β-sheet on one side of the coil. Molecular dynamics models based on these findings show that these AFPs would be energetically stable in a β-helical conformation. Copyright © 2012 Elsevier Ltd. All rights reserved.

High fidelity remote sensing of snow properties from MODIS and the Airborne Snow Observatory: Snowflakes to Terabytes

NASA Astrophysics Data System (ADS)

Painter, T.; Mattmann, C. A.; Brodzik, M.; Bryant, A. C.; Goodale, C. E.; Hart, A. F.; Ramirez, P.; Rittger, K. E.; Seidel, F. C.; Zimdars, P. A.

2012-12-01

The response of the cryosphere to climate forcings largely determines Earth's climate sensitivity. However, our understanding of the strength of the simulated snow albedo feedback varies by a factor of three in the GCMs used in the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, mainly caused by uncertainties in snow extent and the albedo of snow-covered areas from imprecise remote sensing retrievals. Additionally, the Western US and other regions of the globe depend predominantly on snowmelt for their water supply to agriculture, industry and cities, hydroelectric power, and recreation, against rising demand from increasing population. In the mountains of the Upper Colorado River Basin, dust radiative forcing in snow shortens snow cover duration by 3-7 weeks. Extended to the entire upper basin, the 5-fold increase in dust load since the late-1800s results in a 3-week earlier peak runoff and a 5% annual loss of total runoff. The remotely sensed dynamics of snow cover duration and melt however have not been factored into hydrological modeling, operational forecasting, and policymaking. To address these deficiencies in our understanding of snow properties, we have developed and validated a suite of MODIS snow products that provide accurate fractional snow covered area and radiative forcing of dust and carbonaceous aerosols in snow. The MODIS Snow Covered Area and Grain size (MODSCAG) and MODIS Dust Radiative Forcing in Snow (MODDRFS) algorithms, developed and transferred from imaging spectroscopy techniques, leverage the complete MODIS surface reflectance spectrum. The two most critical properties for understanding snowmelt runoff and timing are the spatial and temporal distributions of snow water equivalent (SWE) and snow albedo. We have created the Airborne Snow Observatory (ASO), an imaging spectrometer and scanning LiDAR system, to quantify SWE and snow albedo, generate unprecedented knowledge of snow properties, and provide complete

Morphological evidence of mechanoreceptive gravity perception in a water flea - Daphnia magna

NASA Technical Reports Server (NTRS)

Meyers, D. G.

1985-01-01

Hair-like structures or setae located in the basal membrane of the swimming antennae of the water flea, D. magna, were observed by scanning electron microscopy and compared to mechanoreceptors in the Higher Order Crustacea. Similarities in anatomy, size, attachment, number, length, and orientation support the hypothesis that the setae are rheoceptive mechanoreceptors which mediate gravity perception through deflection by water currents during the sink phase of hop-and-sink swimming behavior.

Intercomparison of Satellite-Derived Snow-Cover Maps

NASA Technical Reports Server (NTRS)

Hall, Dorothy K.; Tait, Andrew B.; Foster, James L.; Chang, Alfred T. C.; Allen, Milan

1999-01-01

In anticipation of the launch of the Earth Observing System (EOS) Terra, and the PM-1 spacecraft in 1999 and 2000, respectively, efforts are ongoing to determine errors of satellite-derived snow-cover maps. EOS Moderate Resolution Imaging Spectroradiometer (MODIS) and Advanced Microwave Scanning Radiometer-E (AMSR-E) snow-cover products will be produced. For this study we compare snow maps covering the same study area acquired from different sensors using different snow- mapping algorithms. Four locations are studied: 1) southern Saskatchewan; 2) a part of New England (New Hampshire, Vermont and Massachusetts) and eastern New York; 3) central Idaho and western Montana; and 4) parts of North and South Dakota. Snow maps were produced using a prototype MODIS snow-mapping algorithm used on Landsat Thematic Mapper (TM) scenes of each study area at 30-m and when the TM data were degraded to 1 -km resolution. National Operational Hydrologic Remote Sensing Center (NOHRSC) 1 -km resolution snow maps were also used, as were snow maps derived from 1/2 deg. x 1/2 deg. resolution Special Sensor Microwave Imager (SSM/1) data. A land-cover map derived from the International Geosphere-Biosphere Program (IGBP) land-cover map of North America was also registered to the scenes. The TM, NOHRSC and SSM/I snow maps, and land-cover maps were compared digitally. In most cases, TM-derived maps show less snow cover than the NOHRSC and SSM/I maps because areas of incomplete snow cover in forests (e.g., tree canopies, branches and trunks) are seen in the TM data, but not in the coarser-resolution maps. The snow maps generally agree with respect to the spatial variability of the snow cover. The 30-m resolution TM data provide the most accurate snow maps, and are thus used as the baseline for comparison with the other maps. Comparisons show that the percent change in amount of snow cover relative to the 3 0-m resolution TM maps is lowest using the TM I -km resolution maps, ranging from 0 to 40

Catchment-scale snow depth monitoring with balloon photogrammetry

NASA Astrophysics Data System (ADS)

Durand, M. T.; Li, D.; Wigmore, O.; Vanderjagt, B. J.; Molotch, N. P.; Bales, R. C.

2016-12-01

Field campaigns and permanent in-situ facilities provide extensive measurements of snowpack properties at catchment (or smaller) scales, and have consistently improved our understanding of snow processes and the estimation of snow water resources. However, snow depth, one of the most important snow states, has been measured almost entirely with discrete point-scale samplings in field measurements; spatiotemporally continuous snow depth measurements are nearly nonexistent, mainly due to the high cost of airborne flights and the ban of Unmanned Aerial Systems in many areas (e.g. in all the national parks). In this study, we estimate spatially continuous snow depth from photogrammetric reconstruction of aerial photos taken from a weather balloon. The study was conducted in a 0.2 km2 watershed in Wolverton, Sequoia National Park, California. We tied a point-and-shoot camera on a helium-inflated weather balloon to take aerial images; the camera was scripted to automatically capture images every 3 seconds and to record the camera position and orientation at the imaging times using a built-in GPS. With the 2D images of the snow-covered ground and the camera position and orientation data, the 3D coordinates of the snow surface were reconstructed at 10 cm resolution using photogrammetry software PhotoScan. Similar measurements were taken for the snow-free ground after snowmelt, and the snow depth was estimated from the difference between the snow-on and snow-off measurements. Comparing the photogrammetric-estimated snow depths with the 32 manually measured depths, taken at the same time as the snow-on balloon flight, we find the RMSE of the photogrammetric snow depth is 7 cm, which is 2% of the long-term peak snow depth in the study area. This study suggests that the balloon photogrammetry is a repeatable, economical, simple, and environmental-friendly method to continuously monitor snow at small-scales. Spatiotemporally continuous snow depth could be regularly measured in