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1

First Report of Cucurbit yellow stunting disorder virus in California and Arizona, in association with Cucurbit leaf crumple virus and Squash leaf curl virus.  

Technology Transfer Automated Retrieval System (TEKTRAN)

In August and September of 2006, melon plants (Cucumis melo L.) near Niland in California’s Imperial Valley and near Yuma, Arizona began exhibiting interveinal chlorosis and leaf mottling and spotting symptoms resembling those resulting from infection by viruses of the genus Crinivirus, family Clost...

2

Molecular Characterization of Tomato leaf curl Palampur virus and Pepper leaf curl betasatellite Naturally Infecting Pumpkin (Cucurbita moschata) in India.  

PubMed

Pumpkin cultivation in India is affected by severe incidence of a yellow vein mosaic disease. Tomato leaf curl New Delhi virus and Squash leaf curl China virus are known to be associated with this disease in India. We were able to identify a third begomovirus-Tomato leaf curl Palampur virus (ToLCPMV), from pumpkin showing typical symptoms of the disease at Varanasi based on the sequence of complete DNA-A genome of the virus. The complete DNA-A sequence of the virus shared more than 99% sequence identity with other ToLCPMV isolates available in the GenBank and clustered with them in the phylogenetic analysis. This betasatellite amplified from the same infected sample has been identified as Pepper leaf curl betasatellite (PepLCB) which also infects chilli in India. There was 92% sequence identity between the two isolates. This is the first report of natural infection of ToLCPMV on pumpkin and association of PepLCB with yellow vein mosaic disease of pumpkin in India. PMID:23637491

Namrata, Jaiswal; Saritha, R K; Datta, D; Singh, M; Dubey, R S; Rai, A B; Rai, M

2011-03-16

3

Leaf Curl Disease of Chilli Peppers in Maharashtra, India  

Microsoft Academic Search

Chilli leaf curl, an important disease of chilli peppers in India is caused by thrips, Scirtothrips dorsalis Hood and mites, Polyphagotarsonemus latus (Banks). Feeding activities resulted in curling and other malformations. The incidence of leaf curl was proportional to thrips and mite infestation. Diseased plants recovered when thrips and mites were removed.

P. W. Amin

1979-01-01

4

A worldwide survey of tomato yellow leaf curl viruses  

Microsoft Academic Search

Summary.  ?The name tomato yellow leaf curl virus (TYLCV) has been given to several whitefly-transmitted geminiviruses affecting tomato\\u000a cultures in many tropical and subtropical regions. Hybridization tests with two DNA probes derived from a cloned isolate of\\u000a TYLCV from Israel (TYLCV-ISR) were used to assess the affinities of viruses in naturally infected tomato plants with yellow\\u000a leaf curl or leaf curl

H. Czosnek; H. Laterrot

1997-01-01

5

Natural recombination between Tomato yellow leaf curl virus-Is and Tomato leaf curl virus  

Microsoft Academic Search

The complete genome sequences (2791 and 2793 nt) of isolates of Tomato yellow leaf curl virus- Is (TYLCV-Is) from Spain (SP72\\/97) and Portugal (Port2\\/95) were determined. These isolates are closely related to TYLCV-Is isolates reported in Japan (Japan-A and Japan-S) and Israel (Israel\\/ Mild). Comparison of all sequenced isolates of TYLCV-Is showed that part of the genome com- prising the

J. Navas-Castillo; S. Sa; E. Noris; D. Louro; G. P. Accotto; E. Moriones

2000-01-01

6

Pepper leaf curl Lahore virus requires the DNA B component of Tomato leaf curl New Delhi virus to cause leaf curl symptoms  

PubMed Central

Background Begomoviruses are whitefly-transmitted geminiviruses with genomes that consist of either two components (known as DNA A and DNA B) or a single component (homologous to the DNA A component of bipartite begomoviruses). Monopartite begomoviruses are often associated with a symptom-modulating DNA satellite (collectively known as betasatellites). Both bipartite and monopartite begomoviruses with associated satellites have previously been identified in chillies showing leaf curl symptoms in Pakistan. Results A chilli plant (Capsicum annum) with chilli leaf curl disease symptoms was found to contain a begomovirus, a betasatellite and the DNA B component of Tomato leaf curl New Delhi virus (ToLCNDV). The begomovirus consisted of 2747 nucleotides and had the highest sequence identity (99%) with Pepper leaf curl Lahore virus (PepLCLV-[PK: Lah:04], acc. no. AM404179). Agrobacterium-mediated inoculation of the clone to Nicotiana benthamiana, induced very mild symptoms and low levels of viral DNA, detected in systemically infected leaves by PCR. No symptoms were induced in Nicotiana tabacum or chillies either in the presence or absence of a betasatellite. However, inoculation of PepLCLV with the DNA B component of ToLCNDV induced leaf curl symptoms in N. benthamiana, N. tabacum and chillies and viral DNA accumulated to higher levels in comparison to plants infected with just PepLCLV. Conclusions Based on our previous efforts aimed at understanding of diversity of begomoviruses associated with chillies, we propose that PepLCLV was recently mobilized into chillies upon its interaction with DNA B of ToLCNDV. Interestingly, the putative rep-binding iterons found on PepLCLV (GGGGAC) differ at two base positions from those of ToLCNDV (GGTGTC). This is the first experimental demonstration of the infectivity for a bipartite begomovirus causing chilli leaf curl disease in chillies from Pakistan and suggests that component capture is contributing to the emerging complexity of begomovirus diseases in the region.

2010-01-01

7

Small RNA mediated silencing to target Tomato leaf curl virus  

Microsoft Academic Search

Plant RNA silencing systems are organized into different networks with overlapping functions. Primarily, micro RNAs (miRNAs) help in regulating development and small interfering RNAs (siRNAs) regulate transgene induced or virus induced silencing functions at the post transcriptional level. Small RNA silencing, using potent RNAi silencing target sequences from viral genome of leaf curl virus, was designed via artificial micro RNAs

Shelly Praveen; S. V. Ramesh; Vikas Koundal; Anil K. Mishra; R. K. Jain

2007-01-01

8

Tomato leaf curl Bangalore virus (ToLCBV): infectivity and enhanced pathogenicity with diverse betasatellites.  

PubMed

Genomic components of a begomovirus isolated from tomato plants showing leaf curl and stunting symptoms in farmer's fields at Hessarghatta village near Bangalore, India, were cloned by rolling-circle amplification. The virus was identified as a variant of strain C of the species Tomato leaf curl Bangalore virus and designated as Tomato leaf curl Bangalore virus-C[India:Hessarghatta:2008], ToLCBV-C[IN:Hess:08]. The betasatellite isolated from these samples belongs to the betasatellite species Tomato leaf curl Bangalore betasatellite. ToLCBV-C[IN:Hess:08] induced severe symptoms in Nicotiana benthamiana and Solanum lycopersicum plants when co-inoculated with the cognate betasatellite, Tomato leaf curl Bangalore betasatellite-[India:Hessarghatta:2008], ToLCBB-[IN:Hess:08] and with two other non-cognate betasatellites, Cotton leaf curl Multan betasatellite-[India:SriGanganagar:2002] and Luffa leaf distortion betasatellite-[India:Luffa:2004]. PMID:20526636

Tiwari, Neha; Padmalatha, K V; Singh, V B; Haq, Q M I; Malathi, V G

2010-06-05

9

Suppressor of RNA silencing encoded by the monopartite tomato leaf curl Java begomovirus  

Microsoft Academic Search

Summary  We previously isolated the monopartite begomovirus tomato leaf curl Java virus (ToLCJAV) and satellite DNA?02 from the same\\u000a naturally infected tomato source in Indonesia. ToLCJAV induced mild leaf curl symptoms in Nicotiana benthamiana plants; DNA?02 encoded the ?C1 gene and produced severe leaf curl symptoms when co-inoculated with ToLCJAV in N. benthamiana. However, DNA?02m?C1, which contains a frame shift mutation,

T. Kon; P. Sharma; M. Ikegami

2007-01-01

10

Suppressors of RNA silencing encoded by tomato leaf curl betasatellites.  

PubMed

Virus encoded RNA-silencing suppressors (RSSs) are the key components evolved by the viruses to counter RNA-silencing defense of plants. Whitefly-transmitted begomoviruses infecting tomato crop code for five different proteins, ORF AC4, ORF AC2 and ORF AV2 in DNA-A component, ORF BV1 in DNA-B and ORF beta C1 in satellite DNA beta which are predicted to function as silencing suppressors. In the present study suppressor function of ORF beta C1 of three betasatellites Tomato leaf curl Bangalore betasatellite ToLCBB-[IN:Hess:08], Cotton leaf curl Multan betasatellite CLCuMB-[IN:Sri:02] and Luffa leaf distortion betasatellite LuLDB-[IN:Lu:04] were examined. Agroinfiltration of GFP-silenced Nicotiana tabaccum cv. Xanthi with the cells expressing betaC1 protein resulted in reversal of silenced GFP expression. GFP-siRNA level was more than 50-fold lower compared to silenced plants in plants infiltrated with betaC1 gene from ToLCBB. However, in the case of 35S-beta C1 CLCuMB and 35S- beta C1 LuLDB construct, although GFP was expressed, siRNA level was not reduced, indicating that the step at which beta C1 interfere in RNA-silencing pathway is different. PMID:23385812

Shukla, Richa; Dalal, Sunita; Malathi, V G

2013-03-01

11

Genetic variability of begomoviruses associated with cotton leaf curl disease originating from India.  

PubMed

Cotton leaf curl disease (CLCuD) causing viruses belong to the Begomovirus genus of the family Geminiviridae. Most begomoviruses are bipartite with two molecules of circular single stranded DNA (A and B) encapsidated in icosahedral geminate particles. However, the begomoviruses associated with CLCuD have DNA-beta instead of DNA-B. In this communication we report the complete genomic sequence of DNA-A component of two CLCuD-causing begomoviruses, cotton leaf curl Kokhran virus-Dabawali (CLCuKV-Dab), tomato leaf curl Bangalore virus-Cotton [Fatehabad] (ToLCBV-Cotton [Fat]) and partial sequences of two other isolates cotton leaf curl Rajasthan virus-Bangalore (CLCuRV-Ban) and cotton leaf curl Kokhran virus-Ganganagar (CLCuKV-Gang). A phylogenetic analysis of these isolates along with other related begomoviruses showed that ToLCBV-Cotton [Fat] isolate was closest to the tomato leaf curl Bangalore virus-5 (ToLCBV-Ban5) where as CLCuKV-Dab isolate was close to the cotton leaf curl Kokhran virus-Faisalabad1 (CLCuKV-Fai1), cotton leaf curl Kokhran virus-72b (CLCuKV-72b) and cotton leaf curl Kokhran virus-806b (CLCuKV-806b) isolates from Pakistan. The phylogenetic analysis further showed that the ToLCBV-Cotton [Fat] and CLCuKV-Dab isolates along with CLCuKV-Fai1, CLCuKV-72b and CLCuKV-806b are closer to the ToLCBV, tomato leaf curl Gujarat virus (ToLCGV), tomato leaf curl Gujarat virus-Varanasi (ToLCGV-Var) and tomato leaf curl Sri Lanka virus (ToLCSLV) isolates, where as cotton leaf curl Alabad virus-804a (CLCuAV-804a), cotton leaf curl Multhan virus (CLCuMV) cluster with the isolates from cotton leaf curl Rajasthan virus (CLCuRV) and okra yellow vein mosaic virus (OYVMV). These results demonstrate the extensive variability observed in this group of viruses. The AC4 ORF is the least conserved among these viruses. In order to further asses the variability in the CLCuD-causing begomoviruses, the region showing minimum similarity in the DNA-A sequence was first determined by a comparison of segments of different lengths of the aligned sequences. The results indicated that region 2411-424 (771 nt) was the least conserved. A phylogenetic tree constructed using the sequences of all the CLCuD causing begomoviruses, corresponding to the least conserved region showed that they form two distinct clusters. PMID:15669112

Kirthi, N; Priyadarshini, C G P; Sharma, P; Maiya, S P; Hemalatha, V; Sivaraman, P; Dhawan, P; Rishi, N; Savithri, H S

2004-10-01

12

Molecular diversity of Cotton leaf curl Gezira virus isolates and their satellite DNAs associated with okra leaf curl disease in Burkina Faso  

PubMed Central

Okra leaf curl disease (OLCD) is a major constraint on okra (Abelmoschus esculentus) production and is widespread in Africa. Using a large number of samples representative of the major growing regions in Burkina Faso (BF), we show that the disease is associated with a monopartite begomovirus and satellite DNA complexes. Twenty-three complete genomic sequences of Cotton leaf curl Gezira virus (CLCuGV) isolates associated with OLCD, sharing 95 to 99% nucleotide identity, were cloned and sequenced. Six betasatellite and four alphasatellite (DNA-1) molecules were also characterized. The six isolates of betasatellite associated with CLCuGV isolates correspond to Cotton leaf curl Gezira betasatellite (CLCuGB) (88 to 98% nucleotide identity). One isolate of alphasatellite is a variant of Cotton leaf curl Gezira alphasatellite (CLCuGA) (89% nucleotide identity), whereas the three others isolates appear to correspond to a new species of alphasatellite (CLCuGA most similar sequence present 52 to 60% nucleotide identity), provisionally named Okra leaf curl Burkina Faso alphasatellite (OLCBFA). Recombination analysis of the viruses demonstrated the interspecies recombinant origin of all CLCuGV isolates, with parents being close to Hollyhock leaf crumple virus (AY036009) and Tomato leaf curl Diana virus (AM701765). Combined with the presence of satellites DNA, these results highlight the complexity of begomoviruses associated with OLCD.

2010-01-01

13

?C1 of chili leaf curl betasatellite is a pathogenicity determinant  

PubMed Central

Background Cotton leaf curl disease in the Indian subcontinent is associated with several distinct begomoviruses that interact with a disease-specific DNA satellite named Cotton leaf curl Multan betasatellite (CLCuMB). However, we have recently reported that Chili leaf curl betasatellite (ChLCB) is also occasionally found associated with the disease in Pakistan. The question as to whether ChLCB contributes to the development of disease symptoms such as leaf curling and enations remain to be answered. We have previously shown that the expression of ?C1 of CLCuMB develops all symptoms of cotton leaf curl disease in Nicotiana benthamiana when expressed from PVX vector. Findings The role of ChLCB in the induction of typical disease symptoms was studied by its expression from PVX vector in N. benthamiana. The expression of ?C1 from PVX vector developed severe leaf curl symptoms and leaf-like enations that resemble the phenotype induced by ?C1 of CLCuMB. Conclusions The results presented here show that the expression of ?C1 of ChLCB from PVX vector exhibit phenotype typical of cotton leaf curl and therefore ChLCB may contribute to the disease symptoms.

2011-01-01

14

RESISTANCE TO CUCURBIT LEAF CRUMPLE VIRUS IN MELON  

Technology Transfer Automated Retrieval System (TEKTRAN)

Cucurbit leaf crumple geminivirus (CuLCrV) is transmitted by sweetpotato whitefly (Bemisia tabaci) biotype B (SPWF-B) and occurs on cucurbits in Arizona, California, Texas, and Mexico. This virus is identical to Cucurbit leaf curl virus, and their symptoms are similar to Squash leaf curl virus on sq...

15

Materials and Methods for Producing Tomato Yellow Leaf Curl Virus Resistance in Plants.  

National Technical Information Service (NTIS)

The subject invention concerns materials and methods for providing genetically-engineered resistance in plants to tomato yellow leaf curl geminivirus using a truncated version of the replication associated protein (Rep) gene of TYLCV. Virus-resistant plan...

E. Hiebert J. E. Polston

2002-01-01

16

Identification of DNA Components Required for Induction of Cotton Leaf Curl Disease  

Microsoft Academic Search

Cotton leaf curl disease (CLCuD) is a major constraint to cotton production in Pakistan. Infectious clones of the monopartite begomovirus cotton leaf curl virus (CLCuV), associated with diseased cotton, are unable to induce typical symptoms in host plants. We have identified and isolated a single-stranded DNA molecule approximately 1350 nucleotides in length which, when coinoculated with the begomovirus to cotton,

R. W. Briddon; S. Mansoor; I. D. Bedford; M. S. Pinner; K. Saunders; Y. Zafar; K. A. Malik; P. G. Markham

2001-01-01

17

Capsicum Species: Symptomless Hosts and Reservoirs of Tomato yellow leaf curl virus  

Microsoft Academic Search

Polston, J. E., Cohen, L., Sherwood, T. A., Ben-Joseph, R., and Lapidot, M. 2006. Capsicum species: Symptomless hosts and reservoirs of Tomato yellow leaf curl virus. Phytopathology 96:447-452. Five Capsicum species were tested for susceptibility to Tomato yellow leaf curl virus (TYLCV) and the mild strain of TYLCV (TYLCV-Mld). TYLCV was able to infect 30 of 55 genotypes of C.

J. E. Polston; L. Cohen; T. A. Sherwood; R. Ben-Joseph; M. Lapidot

2006-01-01

18

Engineering tomato for resistance to tomato leaf curl disease using viral rep gene sequences  

Microsoft Academic Search

Transgenic tomato resistant to tomato leaf curl disease (ToLCD) using replicase (rep) gene sequences of Tomato leaf curl virus in antisense orientation were developed via Agrobacterium-mediated transformation. A binary vector carrying the antisense rep gene (untranslatable full length sequence, 1086 bp) along with the npt II gene was used for transformation. High level of resistance and inheritability of the transgene was

Shelly Praveen; C. M. Kushwaha; Anil K. Mishra; V. Singh; R. K. Jain; Anupam Varma

2005-01-01

19

Correlation Between Whitefly (Homoptera: Aleyrodidae) Feeding Behavior and Transmission of Tomato Yellow Leaf Curl Virus  

Microsoft Academic Search

The feeding behavior of the whitefly Bemisia tabaci (Gennadius) was monitored using the electrical penetration graph (EPG) technique during the transmission process of tomato yellow leaf curl geminivirus (TYLCV). The behavior of individual viruliferous whiteflies was recorded on two-leaf stage tomato test plants (Lycopersicon esculentum Mill 'Riofuego'). A total of 213 whitefly individuals was recorded on single test plants during

Y. X. Jiang; Carmen de Blas; L. Barrios; A. Fereres

2000-01-01

20

Infectious clones of Tomato leaf curl Palampur virus with a defective DNA B and their pseudo-recombination with Tomato leaf curl New Delhi virus  

PubMed Central

Background Tomato leaf curl Palampur virus (ToLCPMV) is a bipartite begomovirus which has been reported from India and Iran but infectious clones have not been obtained. We have previously shown the association of Zucchini yellow mosaic virus (ZYMV), a potyvirus, with severe leaf curl disease of muskmelon in Pakistan. However, the severity of symptoms in the field and yield losses led us to believe that some other agent, such as a begomovirus, could be associated with the disease. Results A bipartite begomovirus associated with a severe yellow leaf curl disease on muskmelon in Pakistan has been characterized. Analysis of the complete nucleotide sequence of the DNA A and DNA B components of the begomovirus showed that it has the highest DNA sequence identity with ToLCPMV. However, the gene encoding the nuclear shuttle protein (NSP) was truncated in comparison to previously characterised isolates. Agrobacterium-mediated inoculation of Nicotiana benthamiana with the ToLCPMV clones obtained here did not result in symptoms. However, inoculation of plants with the DNA A component of ToLCPMV and the DNA B component of Tomato leaf curl New Delhi virus (ToLCNDV) lead to systemic infection with leaf curl symptoms. This suggested that the lack of infectivity of the ToLCPMV clones was due to the defect in DNA B. The DNA B of ToLCPMV was able to move systemically when inoculated with DNA A of the either virus. Agro-infiltration of muskmelon with the DNA A and DNA B components of ToLCPMV did not lead to symptomatic infection whereas inoculation with the DNA A with the DNA B of ToLCNDV resulted in a hypersensitive response (HR) along the veins. Additionally, agro-infiltration of muskmelon with a construct for the expression of the NSP gene of ToLCNDV under the control of the cauliflower mosaic virus 35S promoter induced a HR, suggesting that this is the gene causing the HR. Conclusions Both ToLCPMV and ZYMV are associated with muskmelon leaf curl disease in Pakistan. However, the ToLCPMV variant identified in association with ZYMV has a defective NSP. The results suggest that a variant with a defective NSP may have been selected for in muskmelon, as this protein is an avirulence determinant in this species, and possibly that infection requires the synergistic interaction with ZYMV.

2011-01-01

21

Molecular characterization of begomoviruses and DNA satellites associated with okra leaf curl disease in Cameroon.  

PubMed

Okra leaf curl disease (OLCD) is the most important viral disease of okra in West Africa. In this study, a complex of begomoviruses and associated DNA satellites were identified in symptomatic okra plants from southwestern Cameroon. Sequence analyses showed that two of the plants (Lik1 and Njo5) were infected with a begomovirus being a recombinant of cotton leaf curl Gezira virus (CLCuGeV) and okra yellow crinkle virus (OYCrV). The recombinant genome shared highest nucleotide identity with isolates of CLCuGeV at 87.8% and is therefore considered to be member of a new begomovirus species, Okra leaf curl Cameroon virus (OLCuCMV). One plant (Mue5) was infected by a begomovirus with 95.8% nucleotide identy to CLCuGeV, while in the plants Lik1, Mue1 and Njo5, a begomovirus was identified showing highest nucleotide identity at 93.7% with OYCrV. The nucleotide comparisons and phylogenetic analyses suggest that these isolates represent new Cameroonian strains of CLCuGeV and OYCrV (CLCuGeV-CM and OYCrV-CM). Mixed infection of OLCuCMV and OYCrV-CM was found in two of the plants. A betasatellite and two divergent alphasatellites were also associated with the begomoviruses. The betasatellite was identified as cotton leaf curl Gezira betasatellite (CLCuGeB) with the highest nucleotide identity at 93.3% to other African isolates of CLCuGeB. The alphasatellites, herein named Alpha-1 and Alpha-2, shared 97.3% and 95.2% identity, respectively, with cotton leaf curl Gezira alphasatellite (CLCuGeA) and okra leaf curl Burkina Faso alphasatellite (OLCuBFA). These collective results emphasize the extent of diversity among okra-infecting begomovirus-satellite complexes in western Africa. PMID:23535770

Leke, Walter N; Sattar, Muhammad N; Ngane, Emilia B; Ngeve, Jacob M; Kvarnheden, Anders; Brown, Judith K

2013-03-25

22

First report of an alphasatellite associated with Okra enation leaf curl virus.  

PubMed

An alphasatellite DNA associated with Okra enation leaf curl virus (OELCuV) which causes enation and leaf curling in okra (Abelmoschus esculentus) plants was characterized. The full-length DNA comprises 1,350 nucleotides and shows typical genome organization of an alphasatellite. It shows the highest nucleotide sequence identity (79.7 %) to Hollyhock yellow vein virus-associated symptomless alphasatellite (HoYVSLA). This is the first report of the association of an alphasatellite with OELCuV from India. PMID:23475199

Chandran, S A; Packialakshmi, R M; Subhalakshmi, K; Prakash, C; Poovannan, K; Nixon Prabu, A; Gopal, P; Usha, R

2013-03-10

23

Spatial and temporal diversity of begomoviral complexes in papayas with leaf curl disease.  

PubMed

Old World, monopartite begomoviruses associated with satellite DNA ? were observed in papaya showing symptoms of leaf curl disease sampled randomly over five years from within a radius of 250 km in north-central India. Three groups of DNA A sequences were evident. One group resembled chili leaf curl virus infecting tomatoes (ChiLCuV). Another group resembled tomato leaf curl New Delhi virus (ToLCuNDV). The third group was novel (tentatively named papaya leaf crumple virus, PaLCrV), with less than 89% identity to known begomovirus sequences in the GenBank database. At least seven DNA A sequences were putative recombinants. The AC4-encoding regions exhibited highest numbers of non-synonymous substitutions. Most DNA ? sequences resembled tomato leaf curl virus-associated DNA ?s. A few DNA ? sequences were similar to that of croton yellow vein mosaic virus-associated DNA ? (CroYVMV?). One DNA ? sequence was novel and showed <65% similarity to its counterparts. Mixed infections and sequence diversity among 25 cloned av1 genes indicated that papayas grown in plantations, kitchen gardens and feral patches in the region are vulnerable to disease outbreak. No geographic or temporal patterns were discernable in the distribution of these viruses. PMID:22437254

Singh-Pant, P; Pant, P; Mukherjee, S K; Mazumdar-Leighton, S

2012-03-22

24

Antisense suppression of replicase gene expression recovers tomato plants from leaf curl virus infection  

Microsoft Academic Search

Many examples of extreme virus resistance and gene silencing of endogenous genes have been described in transgenic plants containing antisense transgenes. We show that transforming Tomato leaf curl virus-infected plants with the homologous replicase gene constructs that produce RNAs capable of duplex formation confers gene silencing and results in recovery of infected plants. We propose that the antisense suppression in

Shelly Praveen; Anil K. Mishra; Arupratan Dasgupta

2005-01-01

25

Acquisition of tomato yellow leaf curl virus by the whitefly Bemisia tabaci  

Microsoft Academic Search

Tomato yellow leaf curl virus (TYLCV) genomic DNA can be detected by Southern blot analysis in nucleic acid extracted from a single whitefly. Acquisition of TYLCV by individual whiteflies in relation to the length of the access period, the virus concentration in, and the developmental stage of plant tissues was studied. The frequency of TYLCV detection increased with the length

Muhammad Zeidan; Henryk Czosnek

1991-01-01

26

Evolutionary and Molecular Aspects of Indian Tomato Leaf Curl Virus Coat Protein  

PubMed Central

Tomato leaf curl disease (ToLCD) is manifested by yellowing of leaf lamina with upward leaf curl, leaf distortion, shrinking of the leaf surface, and stunted plant growth caused by tomato leaf curl virus (ToLCV). In the present study, using computational methods we explored the evolutionary and molecular prospects of viral coat protein derived from an isolate of Vadodara district, Gujarat (ToLCGV-[Vad]), India. We found that the amino acids in coat protein required for systemic infection, viral particle formation, and insect transmission to host cells were conserved amongst Indian strains. Phylogenetic studies on Indian ToLCV coat proteins showed evolutionary compatibility with other viral taxa. Modeling of coat protein revealed a topology similar to characteristic Geminate viral particle consisting of antiparallel ?-barrel motif with N-terminus ?-helix. The molecular interaction of coat protein with the viral DNA required for encapsidation and nuclear shuttling was investigated through sequence- and structure-based approaches. We further emphasized the role of loops in coat protein structure as molecular recognition interface.

Kumar, Sivakumar Prasanth; Patel, Saumya K.; Kapopara, Ravi G.; Jasrai, Yogesh T.; Pandya, Himanshu A.

2012-01-01

27

A DNA? Associated with Tomato Yellow Leaf Curl China Virus Is Required for Symptom Induction  

PubMed Central

We report here that all 25 isolates of Tomato yellow leaf curl China virus (TYLCCNV) collected from tobacco, tomato, or Siegesbeckia orientalis plants in different regions of Yunnan Province, China, were associated with DNA? molecules. To investigate the biological role of DNA?, full-length infectious clones of viral DNA and DNA? of TYLCCNV isolate Y10 (TYLCCNV-Y10) were agroinoculated into Nicotiana benthamiana, Nicotiana glutinosa, Nicotiana. tabacum Samsun (NN or nn), tomato, and petunia plants. We found that TYLCCNV-Y10 alone could systemically infect these plants, but no symptoms were induced. TYLCCNV-Y10 DNA? was required, in addition to TYLCCNV-Y10, for induction of leaf curl disease in these hosts. Similar to TYLCCNV-Y10, DNA? of TYLCCNV isolate Y64 was also found to be required for induction of typical leaf curl diseases in the hosts tested. When the ?C1 gene of TYLCCNV-Y10 DNA? was mutated, the mutants failed to induce leaf curl symptoms in N. benthamiana when coinoculated with TYLCCNV-Y10. However, Southern blot hybridization analyses showed that the mutated DNA? molecules were replicated. When N. benthamiana and N. tabacum plants were transformed with a construct containing the ?C1 gene under the control of the Cauliflower mosaic virus 35S promoter, many transgenic plants developed leaf curl symptoms similar to those caused by a virus, the severity of which paralleled the level of ?C1 transcripts, while transgenic plants transformed with the ?C1 gene containing a stop codon after the start codon remained symptomless. Thus, expression of a ?C1 gene is adequate for induction of symptoms of viral infection in the absence of virus.

Cui, Xiaofeng; Tao, Xiaorong; Xie, Yan; Fauquet, Claude M.; Zhou, Xueping

2004-01-01

28

Biology and interactions of two distinct monopartite begomoviruses and betasatellites associated with radish leaf curl disease in India  

PubMed Central

Background Emerging whitefly transmitted begomoviruses are major pathogens of vegetable and fibre crops throughout the world, particularly in tropical and sub-tropical regions. Mutation, pseudorecombination and recombination are driving forces for the emergence and evolution of new crop-infecting begomoviruses. Leaf curl disease of field grown radish plants was noticed in Varanasi and Pataudi region of northern India. We have identified and characterized two distinct monopartite begomoviruses and associated beta satellite DNA causing leaf curl disease of radish (Raphanus sativus) in India. Results We demonstrate that RaLCD is caused by a complex of two Old World begomoviruses and their associated betasatellites. Radish leaf curl virus-Varanasi is identified as a new recombinant species, Radish leaf curl virus (RaLCV) sharing maximum nucleotide identity of 87.7% with Tomato leaf curl Bangladesh virus-[Bangladesh:2] (Accession number AF188481) while the virus causing radish leaf curl disease-Pataudi is an isolate of Croton yellow vein mosaic virus-[India] (CYVMV-IN) (Accession number AJ507777) sharing 95.8% nucleotide identity. Further, RDP analysis revealed that the RaLCV has a hybrid genome, a putative recombinant between Euphorbia leaf curl virus and Papaya leaf curl virus. Cloned DNA of either RaLCV or CYVMV induced mild leaf curl symptoms in radish plants. However, when these clones (RaLCV or CYVMV) were individually co-inoculated with their associated cloned DNA betasatellite, symptom severity and viral DNA levels were increased in radish plants and induced typical RaLCD symptoms. To further extend these studies, we carried out an investigation of the interaction of these radish-infecting begomoviruses and their associated satellite, with two tomato infecting begomoviruses (Tomato leaf curl Gujarat virus and Tomato leaf curl New Delhi virus). Both of the tomato-infecting begomoviruses showed a contrasting and differential interaction with DNA satellites, not only in the capacity to interact with these molecules but also in the modulation of symptom phenotypes by the satellites. Conclusion This is the first report and experimental demonstration of Koch's postulate for begomoviruses associated with radish leaf curl disease. Further observations also provide direct evidence of lateral movement of weed infecting begomovirus in the cultivated crops and the present study also suggests that the exchange of betasatellites with other begomoviruses would create a new disease complex posing a serious threat to crop production.

2012-01-01

29

Phylogenetic lineage of Tobacco leaf curl virus in Korea and estimation of recombination events implicated in their sequence variation.  

PubMed

New strains of Tobacco leaf curl virus (TbLCV) were isolated from tomato plants in four different local communities of Korea, and hence were designated TbLCV-Kr. Phylogenetic analysis of the sequences of the whole genome and of individual ORFs of these viruses indicated that they are closely related to the Tobacco leaf curl Japan virus (TbLCJV) cluster, which includes Honeysuckle yellow vein virus (HYVV), Honeysuckle yellow vein mosaic virus (HYVMV), and TbLCJV isolates. Four putative recombination events were recognized within these virus sequences, suggesting that the sequence variations observed in these viruses may be attributable to intraspecific and interspecific recombination events involving some TbLCV-Kr isolates, Papaya leaf curl virus (PaLCV), and a local isolate of Tomato yellow leaf curl virus (TYLCV). PMID:21549772

Park, Jungan; Lee, Hyejung; Kim, Mi-Kyung; Kwak, Hae-Ryun; Auh, Chung-Kyoon; Lee, Kyeong-Yeoll; Kim, Sunghan; Choi, Hong-Soo; Lee, Sukchan

2011-04-28

30

Leaf curl disease of tomato in Haldwani (Uttarakhand), India region is caused by a begomovirus with satellite molecule DNA ?  

Microsoft Academic Search

The leaf curl disease of tomato was observed in the Haldwani region of Uttarakhand, India during 2004–2007 with an average disease incidence of 49.8 and 73.7% during the month of October and February, respectively. The virus isolate from the infected tomato plants was transmissible to healthy tomato plants by whiteflies (Bemisia tabaci), and the inoculated plants showed typical leaf curl

S. Anandhan; P. N. Sivalingam; V. Satheesh; R. K. Saritha; B. Parameshwari

2011-01-01

31

Insight from ?C1 protein model for implication in cotton leaf curl disease  

PubMed Central

DNA ? is approximately half of the size of Begomovirus DNA. It encodes a ?C1 gene that is conserved in position and size. This gene has the capacity to encode a 13 to 14 kDa protein comprising 118 amino acid residues. It has been shown earlier that ?C1 protein is necessary for inducing symptoms of cotton leaf curl disease. The structure for ?C1 (CLCuD?01-Pakistan) is still unknown. Therefore, a model of ?C1 (CLCuD?01-Pakistan) was developed using DoBo and I-TASSER servers followed by validation by PROCHECK and VERIFY 3D servers. The developed model provides an insight in a role for this multifunctional protein in causing Cotton Leaf Curl Disease (CLCuD). A possible function of this protein might be the suppression of RNAsilencing in cotton plants.

Shahzad, Khuram; Hai, Abdul; Kizilbash, Nadeem; Ambreen, Jawaria; Alruwaili, Jamal

2013-01-01

32

V2 protein encoded by Tomato yellow leaf curl China virus is an RNA silencing suppressor  

Microsoft Academic Search

The V2 protein of Tomato yellow leaf curl China virus (TYLCCNV) was identified as an RNA silencing suppressor by Agrobacterium-mediated co-infiltration. The V2 protein could inhibit local RNA silencing, systemic RNA silencing of the green fluorescent protein (GFP) gene and the spread of a systemic GFP RNA silencing signal. However, the V2 could not interfere with the cell-to-cell spread of

Jie Zhang; Jingyun Dong; Yi Xu; Jianxiang Wu

33

Suppressor of RNA silencing encoded by Tomato yellow leaf curl virus-Israel  

Microsoft Academic Search

The Israeli isolate of Tomato yellow leaf curl geminivirus (TYLCV-Is) is a major tomato pathogen, causing extensive crop losses both in the New and Old World. Surprisingly, however, little is known about the molecular mechanisms of TYLCV-Is interactions with tomato cells. Here, we have identified a TYLCV-Is protein, V2, which acts as a suppressor of RNA silencing and which is

Avi Zrachya; Efrat Glick; Yael Levy; Tzahi Arazi; Vitaly Citovsky; Yedidya Gafni

2007-01-01

34

Detection of tomato yellow leaf curl thailand virus by PCR without DNA extraction  

Microsoft Academic Search

We report the simple and rapid method for detection of tomato yellow leaf curl Thailand virus (TYLCTHV) based on the direct\\u000a capture of virus particles to the surface of a polymerase chain reaction (PCR) tube. This method allowed PCR without the time-consuming\\u000a procedures of DNA extraction from infected plant tissue. A small amount of tomato tissue (?10 mg) was ground

Supaporn Ieamkhang; Lumpueng Riangwong; Orawan Chatchawankanphanich

2005-01-01

35

Short Communication Characterization of Cestrum yellow leaf curling virus: a new member of the family Caulimoviridae  

Microsoft Academic Search

Cestrum yellow leaf curling virus (CmYLCV) has been characterized as the aetiological agent of the Cestrum parqui mosaic disease. The virus genome was cloned and the clone was proven to be infectious to C. parqui. The presence of typical viroplasms in virus-infected plant tissue and the information obtained from the complete genomic sequence confirmed CmYLCV as a member oftheCaulimoviridaefamily.All characteristic

Livia Stavolone; Antonio Ragozzino; Thomas Hohn

36

Detection of tomato yellow leaf curl virus by loop-mediated isothermal amplification reaction  

Microsoft Academic Search

The genomic DNA molecule of tomato yellow leaf curl virus (TYLCV), a whitefly-transmitted geminivirus, was amplified from total DNA extracts of TYLCV-infected tomato (Lycopersicon esculentum) by the use of loop-mediated isothermal amplification (LAMP). The procedure was also used to amplify TYLCV DNA from total DNA extracts of individual whiteflies (Bemisia tabaci) that had fed on TYLCV-infected plants. One of the

Shiro Fukuta; Shinro Kato; Keiko Yoshida; Yuko Mizukami; Akira Ishida; Junnichi Ueda; Michio Kanbe; Yoshiyuki Ishimoto

2003-01-01

37

Genetic diversity of tomato-infecting Tomato yellow leaf curl virus (TYLCV) isolates in Korea  

Microsoft Academic Search

Epidemic outbreaks of Tomato yellow leaf curl virus (TYLCV) diseases occurred in greenhouse grown tomato (Solanum lycopersicum) plants of Busan (TYLCV-Bus), Boseong (TYLCV-Bos), Hwaseong (TYLCV-Hwas), Jeju Island (TYLCV-Jeju), and Nonsan (TYLCV-Nons)\\u000a in Korea during 2008–2009. Tomato disease by TYLCV has never occurred in Korea before. We synthesized the full-length genomes\\u000a of each TYLCV isolate from the tomato plants collected at

Sue Hoon Kim; Sung Oh; Tae-Kyun Oh; Jae Sung Park; Sei Chang Kim; Seong Hwan Kim; Young Shik Kim; Jeum Kyu Hong; Sang-Yun Sim; Kwon Seo Park; Hwan Gu Lee; Kyung Jae Kim; Chang Won Choi

2011-01-01

38

Bemisia tabaci – Tomato Yellow Leaf Curl Virus Interaction Causing Worldwide Epidemics  

Microsoft Academic Search

\\u000a \\u000a Tomato yellow leaf curl virus (TYLCV) is a begomovirus that threatens tomato production worldwide. TYLCV is transmitted in a circulative manner by the\\u000a whitefly Bemisia tabaci. Once ingested, TYLCV was detected in the insect midgut after 1 h, in the haemolymph after 1.5 h, and in the salivary glands\\u000a after 7 h. Whiteflies were able to infect tomato plants after

Henryk Czosnek; Murad Ghanim

39

International Networks to deal with Tomato Yellow Leaf Curl Disease: the Middle East Regional Cooperation Program  

Microsoft Academic Search

Management of this disease has mainly involved methods for reducing the vector population; and in many cases, this was primarily\\u000a by the application of insecticides. Tomatoes with resistance to Tomato yellow leaf curl virus (TYLCV) would effectively reduce losses and reduce the quantity of insecticides needed to obtain satisfactory yields. Several\\u000a breeding programs were initiated in the 1970s (see Part

DOUGLAS P. MAXWELL; Henryk Czosnek

40

Agroinoculation Shows Tobacco leaf curl Yunnan virus is a Monopartite Begomovirus  

Microsoft Academic Search

We demonstrated that only 2 out of 15 isolates of Tobacco leaf curl Yunnan virus (TbLCYNV) were associated with the satellite DNA? molecules. To investigate the infectivity of this virus, an infectious clone of TbLCYNV isolate Y143 (TbLCYNV-Y143) was agroinoculated or whitefly transmitted into Nicotiana benthamiana, N. glutinasa, Petunia hybrida and N. tabacum. TbLCYNV-Y143 alone was able to induce severe

Yan Xie; Tong Jiang; Xueping Zhou

2006-01-01

41

Isolation and identification of a super strong plant promoter from cotton leaf curl Multan virus  

Microsoft Academic Search

The activity of the C1 and the V1 gene promoter of cotton leaf curl Multan virus (CLCuMV) was investigated in transgenic plants with the gus gene as a reporter gene. Quantitative GUS activity analysis of the transgenic plant leaves showed the average activity of the CLCuMV C1 gene promoter was 3- to 5-fold higher than that of the CaMV 35S

Yingqiu Xie; Yule Liu; Meng Meng; Lei Chen; Zhen Zhu

2003-01-01

42

Molecular characterization and infectivity of Papaya leaf curl China virus infecting tomato in China*  

PubMed Central

Papaya leaf curl China virus (PaLCuCNV) was previously reported as a distinct begomovirus infecting papaya in southern China. Based on molecular diagnostic survey, 13 PaLCuCNV isolates were obtained from tomato plants showing leaf curl symptoms in Henan and Guangxi Provinces of China. Complete nucleotide sequences of 5 representative isolates (AJ558116, AJ558117, AJ704604, FN256260, and FN297834) were determined to be 2738–2751 nucleotides, which share 91.7%–97.9% sequence identities with PaLCuCNV isolate G2 (AJ558123). DNA-? was not found to be associated with PaLCuCNV isolates. To investigate the infectivity of PaLCuCNV, an infectious clone of PaLCuCNV-[CN:HeNZM1] was constructed and agro-inoculated into Nicotiana benthamiana, N. tabacum Samsun, N. glutinosa, Solanum lycopersicum and Petunia hybrida plants, which induced severe leaf curling and crinkling symptoms in these plants. Southern blot analysis and polymerase chain reaction (PCR) indicated a systemic infection of test plants by the agro-infectious clone.

Zhang, Hui; Ma, Xin-ying; Qian, Ya-juan; Zhou, Xue-ping

2010-01-01

43

Evidence for Cytokinin Involvement in Rhizobium (IC3342)-Induced Leaf Curl Syndrome of Pigeonpea (Cajanus cajan Millsp.).  

PubMed

A uniquely abnormal shoot development (shoot tip-bending, leaf curling, release from apical dominance, and stunted growth) in pigeonpea (Cajanus cajan Millsp) induced by a nodulating Rhizobium strain, IC3342, is thought to be due to a hormonal imbalance. Amaranthus betacyanin bioassay indicated that xylem exudate and leaf extracts from pigeonpea plants with Rhizobium-induced leaf curl symptoms contained high concentrations of cytokinin relative to those in normal plants. Radioimmunoassay (RIA) of samples purified with high performance liquid chromatography revealed that zeatin riboside (ZR) and dihydrozeatin riboside (DZR) concentrations in xylem sap from plants with leaf curl symptoms were 7 to 9 times higher than those in the sap from symptomless, nodulated plants. The sap from symptomless plants nodulated by a Curl(-) mutant had ZR and DZR concentrations comparable to those in the normal plant sap. RIA indicated that the respective concentrations of zeatin and N(6)-isopenteny-ladenine in culture filtrates of the curl-inducing strain IC3342 were 26 and 8 times higher than those in filtrates of a related normal nodulating strain (ANU240). Gas chromatographic-mass spectrometric analyses revealed similar differences. Gene-specific hybridization and sequence comparisons failed to detect any homology of IC3342 DNA to Agrobacterium tumefaciens or Pseudomonas savastanoi genetic loci encoding enzymes involved in cytokinin biosynthesis. PMID:16668086

Upadhyaya, N M; Parker, C W; Letham, D S; Scott, K F; Dart, P J

1991-04-01

44

Evidence for Cytokinin Involvement in Rhizobium (IC3342)-Induced Leaf Curl Syndrome of Pigeonpea (Cajanus cajan Millsp.)  

PubMed Central

A uniquely abnormal shoot development (shoot tip-bending, leaf curling, release from apical dominance, and stunted growth) in pigeonpea (Cajanus cajan Millsp) induced by a nodulating Rhizobium strain, IC3342, is thought to be due to a hormonal imbalance. Amaranthus betacyanin bioassay indicated that xylem exudate and leaf extracts from pigeonpea plants with Rhizobium-induced leaf curl symptoms contained high concentrations of cytokinin relative to those in normal plants. Radioimmunoassay (RIA) of samples purified with high performance liquid chromatography revealed that zeatin riboside (ZR) and dihydrozeatin riboside (DZR) concentrations in xylem sap from plants with leaf curl symptoms were 7 to 9 times higher than those in the sap from symptomless, nodulated plants. The sap from symptomless plants nodulated by a Curl? mutant had ZR and DZR concentrations comparable to those in the normal plant sap. RIA indicated that the respective concentrations of zeatin and N6-isopenteny-ladenine in culture filtrates of the curl-inducing strain IC3342 were 26 and 8 times higher than those in filtrates of a related normal nodulating strain (ANU240). Gas chromatographic-mass spectrometric analyses revealed similar differences. Gene-specific hybridization and sequence comparisons failed to detect any homology of IC3342 DNA to Agrobacterium tumefaciens or Pseudomonas savastanoi genetic loci encoding enzymes involved in cytokinin biosynthesis.

Upadhyaya, Narayana M.; Parker, C. William; Letham, David S.; Scott, Kieran F.; Dart, Peter J.

1991-01-01

45

Tomato yellow leaf curl virus from Sardinia is a whitefly-transmitted monopartite geminivirus.  

PubMed Central

The genome of an isolate of tomato yellow leaf curl virus from Sardinia, Italy (TYLCV-S), a geminivirus transmitted by the whitefly Bemisia tabaci, has been cloned and sequenced. The single circular DNA molecule comprises 2770 nucleotides. Genome organisation closely resembles that of the DNA A component of the whitefly-transmitted geminiviruses with a bipartite genome. A 1.8 mer of the TYLCV-S genome in a binary vector of Agrobacterium tumefaciens is infectious upon agroinoculation of tomato plants. Typical tomato yellow leaf curl disease symptoms developed about three weeks after inoculation. The disease was transmitted by the natural vector B.tabaci from agroinfected plants to test plants, reproducing in this way the full biological cycle and proving that the genome of TYLCV-S consists of only one circular single-stranded DNA molecule. Contrary to the other whitefly-transmitted geminiviruses described so far, there is no evidence for the existence nor the necessity of a second component (B DNA) in the TYLCV-S genome. Images

Kheyr-Pour, A; Bendahmane, M; Matzeit, V; Accotto, G P; Crespi, S; Gronenborn, B

1991-01-01

46

Is expression of aquaporins (plasma membrane intrinsic protein 2s, PIP2s) associated with thermonasty (leaf-curling) in Rhododendron?  

PubMed

It is postulated that leaf thermonasty (leaf curling) in rhododendrons under sub-freezing temperatures is caused by water redistribution due to extracellular freezing. We hypothesize that aquaporins (AQPs), the transmembrane water-channels, may be involved in regulating water redistribution and thus leaf curling. Our experimental system includes two Rhododendron species with contrasting leaf curling behavior whereby it was observed in R. catawbiense but not in R. ponticum. We compared leaf movements and the expression of two AQPs, i.e. R. catawbiense/ponticum plasma-membrane intrinsic protein 2 (Rc/RpPIP2;1 and Rc/RpPIP2;2), in the two species under freezing-rewarming and dehydration-rehydration cycles. To determine the relationship between extracellular freezing and leaf-curling, we monitored leaf-curling in R. catawbiense with or without controlled ice-nucleation. Our data indicate that extracellular freezing may be required for leaf curling. Moreover, in both species, PIP2s were up-regulated at temperatures that fell in ice-nucleation temperature range. Such up-regulation could be associated with the bulk-water efflux caused by extracellular freezing. When leaves were frozen beyond the ice-nucleation temperature range, PIP2s were continuously down-regulated in R. catawbiense along with the progressive leaf curling, as also observed for RcPIP2;2 in dehydrated leaves; as leaves uncurled during re-warming/rehydration, RcPIP2 expression was restored. On the other hand, R. ponticum, a non-curling species, exhibited substantial up-regulation of RpPIP2s during freezing/dehydration. Taken together, our data suggest that RcPIP2 down-regulation was associated with leaf curling. Moreover, the contrasting PIP2 expression patterns combined with leaf behavior of R. catawbiense and R. ponticum under these two cycles may reflect different strategies employed by these two species to tolerate/resist cellular dehydration. PMID:23850223

Chen, Keting; Wang, Xiang; Fessehaie, Anania; Yin, Yanhai; Wang, Xiaolei; Arora, Rajeev

2013-07-11

47

Molecular Characterization of Tomato Leaf Curl China Virus, Infecting Tomato Plants in China, and Functional Analyses of Its Associated Betasatellite?†  

PubMed Central

A novel tomato-infecting begomovirus from Guangxi province, China, was identified and characterized, for which the name Tomato leaf curl China virus (ToLCCNV) was proposed. Phylogenetic and recombination analyses of the virus genomic sequences suggested that ToLCCNV may have arisen by recombination among Tomato leaf curl Vietnam virus (ToLCVV), Tomato leaf curl Gujarat virus (ToLCGV), and an unknown virus. A betasatellite molecule was found to be associated with ToLCCNV (ToLCCNB), and its complete nucleotide sequences were determined. Infectious clones of ToLCCNV and ToLCCNB were constructed and then used for agro-inoculation of plants; ToLCCNV alone infected Nicotiana benthamiana, Nicotiana glutinosa, Petunia hybrida, and Solanum lycopersicum plants, but no symptoms were induced. ToLCCNB was required for induction of leaf curl disease in these hosts. The ?C1 protein of ToLCCNB was identified as a suppressor of RNA silencing and accumulated primarily in the nucleus. Deletion mutagenesis of ?C1 showed that the central part of ?C1 (amino acids 44 to 74) was responsible for both the suppressor activity and nuclear localization.

Yang, Xiuling; Guo, Wei; Ma, Xinying; An, Qianli; Zhou, Xueping

2011-01-01

48

Rapid Spread of Tomato Yellow Leaf Curl Virus in China Is Aided Differentially by Two Invasive Whiteflies  

Microsoft Academic Search

BackgroundTomato yellow leaf curl virus (TYLCV) was introduced into China in 2006, approximately 10 years after the introduction of an invasive whitefly, Bemisia tabaci (Genn.) B biotype. Even so the distribution and prevalence of TYLCV remained limited, and the economic damage was minimal. Following the introduction of Q biotype into China in 2003, the prevalence and spread of TYLCV started

Huipeng Pan; Dong Chu; Wenqian Yan; Qi Su; Baiming Liu; Shaoli Wang; Qingjun Wu; Wen Xie; Xiaoguo Jiao; Rumei Li; Nina Yang; Xin Yang; Baoyun Xu; Judith K. Brown; Xuguo Zhou; Youjun Zhang

2012-01-01

49

Evidence for Transovarial Transmission of Tomato Yellow Leaf Curl Virus by Its Vector, the Whitefly Bemisia tabaci  

Microsoft Academic Search

The whiteflyBemisia tabaciis the only vector of the tomato yellow leaf curl geminivirus (TYLCV). The insect transmits the virus in a persistent-circulative manner. TYLCV DNA was detected by polymerase chain reaction and by Southern blot hybridization in progeny (eggs, first and second instars, adults) of single viruliferous whiteflies that developed on eggplant or on cotton (two TYLCV nonhost plants). Furthermore,

Murad Ghanim; Shai Morin; Muhammad Zeidan; Henryk Czosnek

1998-01-01

50

Inhibition of Tomato Yellow Leaf Curl Virus (TYLCV) using whey proteins  

PubMed Central

The antiviral activity of native and esterified whey proteins fractions (?-lactalbumin, ?-lactoglobulin, and lactoferrin) was studied to inhibit tomato yellow leaf curl virus (TYLCV) on infected tomato plants. Whey proteins fractions and their esterified derivatives were sprayed into TYLCV-infected plants. Samples were collected from infected leaves before treatment, 7 and 15 days after treatment for DNA and molecular hybridization analysis. The most evident inhibition of virus replication was observed after 7 and 15 days using ?-lactoferrin and ?-lactalbumin, respectively. Native and esterified lactoferrin showed complete inhibition after 7 days. On the other hand, native ?-lactoglobulin showed inhibition after 7 and 15 days whereas esterified ?-lactoglobulin was comparatively more effective after 7 days. The relative amount of viral DNA was less affected by the esterified ?-lactalbumin whereas native ?-lactalbumin inhibited virus replication completely after 15 days. These results indicate that native or modified whey proteins fractions can be used for controlling the TYLCV-infected plants.

2010-01-01

51

Within-host dynamics of the emergence of Tomato yellow leaf curl virus recombinants.  

PubMed

Tomato yellow leaf curl virus (TYLCV) is a highly damaging begomovirus native to the Middle East. TYLCV has recently spread worldwide, recombining with other begomoviruses. Recent analysis of mixed infections between TYLCV and Tomato leaf curl Comoros begomovirus (ToLCKMV) has shown that, although natural selection preserves certain co-evolved intra-genomic interactions, numerous and diverse recombinants are produced at 120 days post-inoculation (dpi), and recombinant populations from different tomato plants are very divergent. Here, we investigate the population dynamics that lead to such patterns in tomato plants co-infected with TYLCV and ToLCKMV either by agro-inoculation or using the natural whitefly vector Bemisia tabaci. We monitored the frequency of parental and recombinant genotypes independently in 35 plants between 18 and 330 dpi and identified 177 recombinants isolated at different times. Recombinants were detected from 18 dpi and their frequency increased over time to reach about 50% at 150 dpi regardless of the inoculation method. The distribution of breakpoints detected on 96 fully sequenced recombinants was consistent with a continuous generation of new recombinants as well as random and deterministic effects in their maintenance. A severe population bottleneck of around 10 genomes was estimated during early systemic infection-a phenomenon that could account partially for the heterogeneity in recombinant patterns observed among plants. The detection of the same recombinant genome in six of the thirteen plants analysed beyond 30 dpi supported the influence of selection on observed recombination patterns. Moreover, a highly virulent recombinant genotype dominating virus populations within one plant has, apparently, the potential to be maintained in the natural population according to its infectivity, within-host accumulation, and transmission efficiency - all of which were similar or intermediate to those of the parent genotypes. Our results anticipate the outcomes of natural encounters between TYLCV and ToLCKMV. PMID:23472190

Urbino, Cica; Gutiérrez, Serafin; Antolik, Anna; Bouazza, Nabila; Doumayrou, Juliette; Granier, Martine; Martin, Darren P; Peterschmitt, Michel

2013-03-05

52

Within-Host Dynamics of the Emergence of Tomato Yellow Leaf Curl Virus Recombinants  

PubMed Central

Tomato yellow leaf curl virus (TYLCV) is a highly damaging begomovirus native to the Middle East. TYLCV has recently spread worldwide, recombining with other begomoviruses. Recent analysis of mixed infections between TYLCV and Tomato leaf curl Comoros begomovirus (ToLCKMV) has shown that, although natural selection preserves certain co-evolved intra-genomic interactions, numerous and diverse recombinants are produced at 120 days post-inoculation (dpi), and recombinant populations from different tomato plants are very divergent. Here, we investigate the population dynamics that lead to such patterns in tomato plants co-infected with TYLCV and ToLCKMV either by agro-inoculation or using the natural whitefly vector Bemisia tabaci. We monitored the frequency of parental and recombinant genotypes independently in 35 plants between 18 and 330 dpi and identified 177 recombinants isolated at different times. Recombinants were detected from 18 dpi and their frequency increased over time to reach about 50% at 150 dpi regardless of the inoculation method. The distribution of breakpoints detected on 96 fully sequenced recombinants was consistent with a continuous generation of new recombinants as well as random and deterministic effects in their maintenance. A severe population bottleneck of around 10 genomes was estimated during early systemic infection–a phenomenon that could account partially for the heterogeneity in recombinant patterns observed among plants. The detection of the same recombinant genome in six of the thirteen plants analysed beyond 30 dpi supported the influence of selection on observed recombination patterns. Moreover, a highly virulent recombinant genotype dominating virus populations within one plant has, apparently, the potential to be maintained in the natural population according to its infectivity, within-host accumulation, and transmission efficiency - all of which were similar or intermediate to those of the parent genotypes. Our results anticipate the outcomes of natural encounters between TYLCV and ToLCKMV.

Urbino, Cica; Gutierrez, Serafin; Antolik, Anna; Bouazza, Nabila; Doumayrou, Juliette; Granier, Martine; Martin, Darren P.; Peterschmitt, Michel

2013-01-01

53

Yield and fibre quality associated with cotton leaf curl disease of Bt-cotton in Punjab.  

PubMed

Cotton leaf curl disease (CLCuD), caused by Gemini virus and transmitted through whitefly (Bemisia tabaci) is a serious problem in Northern India, affecting the productivity to a great extent. Depending upon the severity of infection in susceptible varieties, the disease can cause upto 90.0 % yield losses besides this, it also causes deterioration in fibre quality. The objective of the present study was to determine the effect of cotton leaf curl disease on seed cotton yield and fibre characters of two popular Bt-cotton hybrids in Punjab. The disease caused 52.7% reduction in number of bolls and 54.2 % in boll weight in Bt cotton hybrid RCH 134. Similarly, it reduced the fibre length from 29.1 to 26.2 mm (9.9%); fibre uniformity from 68.9 to 68.1% (1.1%); fibre strength from 29.1 to 26.9 g per texture (7.5%) and miconaire value from 5.2 to 5.0 g inch(-1) (3.8%). Similar results were reported in Bt cotton hybrid MRC 6304, where the disease reduced the boll number and boll weight by 46.1 and 43.4%, respectively. However, to the fibre quality was not much affected by varying level of disease severity. The studies clearly reflect the adverse impact of CLCuD on yield and fibre quality especially 2.5% span length. Thus suggesting the management of disease using integrated disease management strategies to avoid quantitative and qualitative losses. PMID:24006816

Singh, Daljeet; Gill, J S; Gumber, R K; Singh, Ramandeep; Singh, Satnam

2013-01-01

54

AC2 and AC4 proteins of Tomato yellow leaf curl China virus and Tobacco curly shoot virus mediate suppression of RNA silencing  

Microsoft Academic Search

Tomato yellow leaf curl China virus Y10 isolate (TYLCCNV-Y10) alone could systemically infect host plants such as Nicotiana benthamiana without symptoms. In contrast, Tobacco curly shoot virus Y35 isolate (TbCSV-Y35) alone induces leaf curl symptoms in N. benthamiana. When inoculated into transgenic N. benthamiana plants expressing GFP gene (line 16c), TYLCCNV-Y10 neither reverses the established GFP silencing nor blocks the

Xiaofeng Cui; Xueping Zhou

2004-01-01

55

Nucleotide sequences from tomato leaf curl viruses from different countries: evidence for three geographically separate branches in evolution of the coat protein of whitefly-transmitted geminiviruses  

Microsoft Academic Search

The coat protein (CP) gene-containing circular DNA molecule of an isolate of tomato leaf curl geminivirns (ITmLCV; 2749 nt) obtained from southern India, and the CP genes of tomato yellow leaf curl geminivirus isolates from Nigeria and two regions of Saudi Arabia were sequenced. ITmLCV DNA had the same ar- rangement of ORFs, and the same pattern of repeats in

Y. G. Hongl; B. D. Harrison

1995-01-01

56

Artificial microRNA-mediated resistance against the monopartite begomovirus Cotton leaf curl Burewala virus  

PubMed Central

Background Cotton leaf curl disease, caused by single-stranded DNA viruses of the genus Begomovirus (family Geminiviridae), is a major constraint to cotton cultivation across Pakistan and north-western India. At this time only cotton varieties with moderate tolerance are available to counter the disease. microRNAs (miRNAs) are a class of endogenous small RNA molecules that play an important role in plant development, signal transduction, and response to biotic and a biotic stress. Studies have shown that miRNAs can be engineered to alter their target specificity. Such artificial miRNAs (amiRNAs) have been shown to provide resistance against plant-infecting viruses. Results Two amiRNA constructs, based on the sequence of cotton miRNA169a, were produced containing 21 nt of the V2 gene sequence of Cotton leaf curl Burewala virus (CLCuBuV) and transformed into Nicotiana benthamiana. The first amiRNA construct (P1C) maintained the miR169a sequence with the exception of the replaced 21 nt whereas in the second (P1D) the sequence of the miRNA169a backbone was altered to restore some of the hydrogen bonding of the mature miRNA duplex. P1C transgenic plants showed good resistance when challenge with CLCuBV; plants being asymptomatic with low viral DNA levels. The resistance to heterologous viruses was lower and correlated with the numbers of sequence mismatches between the amiRNA and the V2 gene sequence. P1D plants showed overall poorer resistance to challenge with all viruses tested. Conclusions The results show that the amiRNA approach can deliver efficient resistance in plants against a monopartite begomoviruses and that this has the potential to be broad-spectrum, providing protection from a number of viruses. Additionally the findings indicate that the levels of resistance depend upon the levels of complementarity between the amiRNA and the target sequence and the sequence of the miRNA backbone, consistent with earlier studies.

2013-01-01

57

Tomato yellow leaf curl virus in Australia: distribution, detection and discovery of naturally occurring defective DNA molecules  

Microsoft Academic Search

Tomato yellow leaf curl virus (TYLCV) was detected for the first time in Australia in March 2006 in field-grown tomatoes in Brisbane, Queensland. Surveys\\u000a showed that the virus was confined to south-east Queensland. Virus transmission studies carried out using Bemisia tabaci (B biotype) verified that resistant tomato lines containing the Ty-1 or Ty-5 genes displayed tolerance to infection by TYLCV

S. L. Van Brunschot; D. M. Persley; A. D. W. Geering; P. R. Campbell; J. E. Thomas

2010-01-01

58

A NAC Domain Protein Interacts with Tomato leaf curl virus Replication Accessory Protein and Enhances Viral Replication  

Microsoft Academic Search

Geminivirus replication enhancer (REn) proteins dramatically increase the accumulation of viral DNA species by an unknown mechanism. In this study, we present evidence implicating SlNAC1, a new member of the NAC domain protein family from tomato (Solanum lycopersicum), in Tomato leaf curl virus (TLCV) REn function. We isolated SlNAC1 using yeast (Saccharomyces cerevisiae) two-hybrid technology and TLCV REn as bait,

Luke A. Selth; Satish C. Dogra; M. Saif Rasheed; Helen Healy; John W. Randles; M. Ali Rezaiana

2005-01-01

59

Identification and Characterization of a Host Reversibly Glycosylated Peptide that Interacts with the Tomato leaf curl virus V1 Protein  

Microsoft Academic Search

Monopartite geminiviruses of the genus Begomovirus have two virion-sense genes, V1 and V2. V2 encodes the viral coat protein, but the function of V1 is largely unknown, although some studies suggest that it may play a role in cell-to-cell movement. Yeast two-hybrid technology\\u000a was used to identify possible host binding partners of V1 from Tomato leaf curl virus (TLCV) to

Luke A. Selth; Satish C. Dogra; M. Saif Rasheed; John. W. Randles; M. Ali Rezaian

2006-01-01

60

Viral Suppression in Transgenic Plants Expressing Chimeric Transgene from Tomato Leaf Curl Virus and Cucumber Mosaic Virus  

Microsoft Academic Search

The genes CMV-cp and ToLCV-cons-rep from the isolates of cucumber mosaic virus (CMV) and tomato leaf curl virus (ToLCV) were transcriptionally fused under the control of CaMV 35 S promotor. This construct was used to transform tobacco and tomato using Agrobacterium. We show transforming ToLCV and CMV infected plants with the homologous chimeric gene construct, that produces RNAs, capable of

Shelly Praveen; Anil K. Mishra; Ginny Antony

2006-01-01

61

A severe symptom phenotype in tomato in Mali is caused by a reassortant between a novel recombinant begomovirus (Tomato yellow leaf curl Mali virus) and a betasatellite.  

PubMed

Tomato production in West Africa has been severely affected by begomovirus diseases, including yellow leaf curl and a severe symptom phenotype, characterized by extremely stunted and distorted growth and small deformed leaves. Here, a novel recombinant begomovirus from Mali, Tomato yellow leaf curl Mali virus (TYLCMLV), is described that, alone, causes tomato yellow leaf curl disease or, in combination with a betasatellite, causes the severe symptom phenotype. TYLCMLV is an Old World monopartite begomovirus with a hybrid genome composed of sequences from Tomato yellow leaf curl virus-Mild (TYLCV-Mld) and Hollyhock leaf crumple virus (HoLCrV). A TYLCMLV infectious clone induced leaf curl and yellowing in tomato, leaf curl, crumpling and yellowing in Nicotiana benthamiana and common bean, mild symptoms in N. glutinosa, and a symptomless infection in Datura stramonium. In a field-collected sample from a tomato plant showing the severe symptom phenotype in Mali, TYLCMLV was detected together with a betasatellite, identified as Cotton leaf curl Gezira betasatellite (CLCuGB). Tomato plants co-agroinoculated with TYLCMLV and CLCuGB developed severely stunted and distorted growth and small crumpled leaves. These symptoms were more severe than those induced by TYLCMLV alone, and were similar to the severe symptom phenotype observed in the field in Mali and in other West African countries. TYLCMLV and CLCuGB also induced more severe symptoms than TYLCMLV in the other solanaceous hosts, but not in common bean. The increased symptom severity was associated with hyperplasia of phloem-associated cells, but relatively little increase in TYLCMLV DNA levels. In surveys of tomato virus diseases in West Africa, TYLCMLV was commonly detected in plants with leaf curl and yellow leaf curl symptoms, whereas CLCuGB was infrequently detected and always in association with the severe symptom phenotype. Together, these results indicate that TYLCMLV causes tomato yellow leaf curl disease throughout West Africa, whereas TYLCMLV and CLCuGB represent a reassortant that causes the severe symptom phenotype in tomato. PMID:19400843

Chen, Li-Fang; Rojas, Maria; Kon, Tatsuya; Gamby, Kadiatou; Xoconostle-Cazares, Beatriz; Gilbertson, Robert L

2009-05-01

62

Detection of tomato yellow leaf curl Thailand virus by PCR without DNA extraction.  

PubMed

We report the simple and rapid method for detection of tomato yellow leaf curl Thailand virus (TYLCTHV) based on the direct capture of virus particles to the surface of a polymerase chain reaction (PCR) tube. This method allowed PCR without the time-consuming procedures of DNA extraction from infected plant tissue. A small amount of tomato tissue (approximately 10 mg) was ground in extraction buffer to release viruses from plant tissues. The constituents of the plant extract that might inhibit PCR activity were discarded by washing the tube with PBST buffer before adding the PCR mixture to the tube. This method was used for detection of TYLCTHV with plant sap solution diluted up to 1:20,000 and was more sensitive than an enzyme-linked immunosorbent assay (ELISA) method. In addition, this method can be used for detection of TYLCTHV in viruliferous whiteflies. The PCR tubes with captured TYLCTHV could be used for PCR, after storage at 4 degrees C for 4 wk. The method presented here was used for detection of begomoviruses in cucurbit and pepper. In addition, this method was effectively used to detect papaya ringspot virus in papaya and zucchini yellow mosaic virus in cucumber by reverse transcriptase (RT)-PCR. PMID:16230773

Ieamkhang, Supaporn; Riangwong, Lumpueng; Chatchawankanphanich, Orawan

2005-11-01

63

Characterization of Cestrum yellow leaf curling virus: a new member of the family Caulimoviridae.  

PubMed

Cestrum yellow leaf curling virus (CmYLCV) has been characterized as the aetiological agent of the Cestrum parqui mosaic disease. The virus genome was cloned and the clone was proven to be infectious to C. parqui. The presence of typical viroplasms in virus-infected plant tissue and the information obtained from the complete genomic sequence confirmed CmYLCV as a member of the Caulimoviridae family. All characteristic domains conserved in plant pararetroviruses were found in CmYLCV. Its genome is 8253 bp long and contains seven open reading frames (ORFs). Phylogenetic analysis of the relationships with other members of the Caulimoviridae revealed that CmYLCV is closely related to the Soybean chlorotic mottle virus (SbCMV)-like genus and particularly to SbCMV. However, in contrast to the other members of this genus, the primer-binding site is located in the intercistronic region following ORF Ib rather than within this ORF, and an ORF corresponding to ORF VII is missing. PMID:14645927

Stavolone, Livia; Ragozzino, Antonio; Hohn, Thomas

2003-12-01

64

Tomato yellow leaf curl virus alters the host preferences of its vector Bemisia tabaci.  

PubMed

Bemisia tabaci, the whitefly vector of Tomato yellow leaf curl virus (TYLCV), seriously reduces tomato production and quality. Here, we report the first evidence that infection by TYLCV alters the host preferences of invasive B. tabaci B (Middle East-Minor Asia 1) and Q (Mediterranean genetic group), in which TYLCV-free B. tabaci Q preferred to settle on TYLCV-infected tomato plants over healthy ones. TYLCV-free B. tabaci B, however, preferred healthy tomato plants to TYLCV-infected plants. In contrast, TYLCV-infected B. tabaci, either B or Q, did not exhibit a preference between TYLCV-infected and TYLCV-free tomato plants. Based on gas chromatography-mass spectrometry (GCMS)analysis of plant terpene volatiles, significantly more ?-myrcene, thymene, ?-phellandrene, caryophyllene, (+)-4-carene, and ?-humulene were released from the TYLCV-free tomato plants than from the TYLCV-infected ones. The results indicate TYLCV can alter the host preferences of its vector Bemisia tabaci B and Q. PMID:24096821

Fang, Yong; Jiao, Xiaoguo; Xie, Wen; Wang, Shaoli; Wu, Qingjun; Shi, Xiaobin; Chen, Gong; Su, Qi; Yang, Xin; Pan, Huipeng; Zhang, Youjun

2013-10-07

65

Tomato yellow leaf curl virus alters the host preferences of its vector Bemisia tabaci  

PubMed Central

Bemisia tabaci, the whitefly vector of Tomato yellow leaf curl virus (TYLCV), seriously reduces tomato production and quality. Here, we report the first evidence that infection by TYLCV alters the host preferences of invasive B. tabaci B (Middle East-Minor Asia 1) and Q (Mediterranean genetic group), in which TYLCV-free B. tabaci Q preferred to settle on TYLCV-infected tomato plants over healthy ones. TYLCV-free B. tabaci B, however, preferred healthy tomato plants to TYLCV-infected plants. In contrast, TYLCV-infected B. tabaci, either B or Q, did not exhibit a preference between TYLCV-infected and TYLCV-free tomato plants. Based on gas chromatography-mass spectrometry (GCMS)analysis of plant terpene volatiles, significantly more ?-myrcene, thymene, ?-phellandrene, caryophyllene, (+)-4-carene, and ?-humulene were released from the TYLCV-free tomato plants than from the TYLCV-infected ones. The results indicate TYLCV can alter the host preferences of its vector Bemisia tabaci B and Q.

Fang, Yong; Jiao, Xiaoguo; Xie, Wen; Wang, Shaoli; Wu, Qingjun; Shi, Xiaobin; Chen, Gong; Su, Qi; Yang, Xin; Pan, Huipeng; Zhang, Youjun

2013-01-01

66

Cotton leaf curl disease - an emerging threat to cotton production worldwide.  

PubMed

Cotton leaf curl disease (CLCuD) is a serious disease of cotton which has characteristic symptoms, the most unusual of which is the formation of leaf-like enations on the undersides of leaves. The disease is caused by whitefly-transmitted geminiviruses (family Geminiviridae, genus Begomovirus) in association with specific, symptom-modulating satellites (betasatellites) and an evolutionarily distinct group of satellite-like molecules known as alphasatellites. CLCuD occurs across Africa as well as in Pakistan and north-western India. Over the past 25 years, Pakistan and India have experienced two epidemics of the disease, the most recent of which involved a virus and satellite that are resistance breaking. Loss of this conventional host-plant resistance, which saved the cotton growers from ruin in the late 1990s, leaves farmers with only relatively poor host plant tolerance to counter the extensive losses the disease causes. There has always been the fear that CLCuD could spread from the relatively limited geographical range it encompasses at present to other cotton-growing areas of the world where, although the disease is not present, the environmental conditions are suitable for its establishment and the whitefly vector occurs. Unfortunately recent events have shown this fear to be well founded, with CLCuD making its first appearance in China. Here, we outline recent advances made in understanding the molecular biology of the components of the disease complex, their interactions with host plants, as well as efforts being made to control CLCuD. PMID:23324471

Sattar, M Naeem; Kvarnheden, Anders; Saeed, Muhammad; Briddon, Rob W

2013-01-16

67

Genetic diversity of tomato-infecting Tomato yellow leaf curl virus (TYLCV) isolates in Korea.  

PubMed

Epidemic outbreaks of Tomato yellow leaf curl virus (TYLCV) diseases occurred in greenhouse grown tomato (Solanum lycopersicum) plants of Busan (TYLCV-Bus), Boseong (TYLCV-Bos), Hwaseong (TYLCV-Hwas), Jeju Island (TYLCV-Jeju), and Nonsan (TYLCV-Nons) in Korea during 2008-2009. Tomato disease by TYLCV has never occurred in Korea before. We synthesized the full-length genomes of each TYLCV isolate from the tomato plants collected at each area and determined their nucleotides (nt) sequences and deduced the amino acids of six open reading frames in the genomes. TYLCV-Bus and -Bos genomes shared higher nt identities with four Japanese isolates -Ng, -Omu, -Mis, and -Miy. On the other hand, TYLCV-Hwas, -Jeju, and -Nons genomes shared higher nt identities with five Chinese isolates TYLCV-AH1, -ZJ3, -ZJHZ12, -SH2, -Sh10, and two Japanese isolates -Han and -Tosa. On the basis of a neighbor-joining tree, five Korean TYLCV isolates were separated into three clades. TYLCV-Bus and -Bos formed the first clade, clustering with four Japanese isolates TYLCV-Mis, -Omu, -Ng, and -Miy. TYLCV-Jeju and -Nons formed the second clade, clustering with two Chinese isolates -ZJHZ212 and -Sh10. TYLCV-Hwas was clustered with two Japanese isolates -Han and -Tosa and three Chinese isolates -AH1, -ZJ3, and -SH2. Two fragments that had a potentially recombinant origin were identified using the RDP, GENECONV, BootScan, MaxChi, Chimaera, SiScan, and 3Seq methods implemented in RDP3.41. On the basis of RDP analysis, all TYLCV isolates could originated from the interspecies recombination between TYLCV-Mld[PT] isolated from Portugal as a major parent and TYLCTHV-MM isolated from Myanmar as a minor parent. PMID:20963475

Kim, Sue Hoon; Oh, Sung; Oh, Tae-Kyun; Park, Jae Sung; Kim, Sei Chang; Kim, Seong Hwan; Kim, Young Shik; Hong, Jeum Kyu; Sim, Sang-Yun; Park, Kwon Seo; Lee, Hwan Gu; Kim, Kyung Jae; Choi, Chang Won

2010-10-21

68

Properties of a virus causing mosaic and leaf curl disease of Celosia argentea L. in Nigeria.  

PubMed

A sap transmissible virus, causing mosaic and leaf curl disease of Celosia argentea, was isolated at vegetable farms in Amuwo Odofin, Tejuoso, and Abule Ado, Lagos, Nigeria. The virus had a restricted host range confined to a few species of the Amaranthaceae, Chenopodiaceae and Solanaceae families. It failed to infect several other species of the Aizoaceae, Brassicaceae, Cucurbitaceae, Fabaceae, Lamiaceae, Malvaceae, Poaceae and Tiliaceae families. The virus was transmitted in a non-persistent manner by Aphis spiraecola and Toxoptera citricidus but not by eight other aphid species tested. There was no evidence of transmission by seeds of C. argentae varieties. The viral coat protein had a relative molecular mass (M(r)) of about 30.2 K. Electron microscopy of purified virus preparations revealed flexuous rod shaped particles of about 750 nm in length. Serological studies were performed using the enzyme-linked immunosorbent assay (ELISA), immunosorbent electron microscopy (ISEM) and Western blot analysis. The virus reacted positively with an universal potyvirus group monoclonal antibody (MoAb) and MoAb P-3-3H8 raised against peanut stripe potyvirus. It also reacted with polyclonal antibodies raised against several potyviruses including asparagus virus-1 (AV-1), turnip mosaic virus (TuMV), maize dwarf mosaic virus (MDMV), watermelon mosaic virus (WMV-2), plum pox virus (PPV), soybean mosaic virus (SoyMV), lettuce mosaic virus (LMV), bean common mosaic virus (BCMV) and beet mosaic virus (BMV) in at least one of the serological assays used. On the basis of host range, mode of transmission, and available literature data, the celosia virus seems to be different from potyviruses previously reported to infect vegetables in Nigeria. The name celosia mosaic virus (CIMV) has been proposed for this virus. PMID:9842442

Owolabi, T A; Taiwo, M A; Thottappilly, G A; Shoyinka, S A; Proll, E; Rabenstein, F

1998-06-01

69

The Merging of Two Dynasties--Identification of an African Cotton Leaf Curl Disease-Associated Begomovirus with Cotton in Pakistan  

PubMed Central

Cotton leaf curl disease (CLCuD) is a severe disease of cotton that occurs in Africa and Pakistan/northwestern India. The disease is caused by begomoviruses in association with specific betasatellites that differ between Africa and Asia. During survey of symptomatic cotton in Sindh (southern Pakistan) Cotton leaf curl Gezira virus (CLCuGV), the begomovirus associated with CLCuD in Africa, was identified. However, the cognate African betasatellite (Cotton leaf curl Gezira betasatellite) was not found. Instead, two Asian betasatellites, the CLCuD-associated Cotton leaf curl Multan betasatellite (CLCuMB) and Chilli leaf curl betasatellite (ChLCB) were identified. Inoculation of the experimental plant species Nicotiana benthamiana showed that CLCuGV was competent to maintain both CLCuMB and ChLCB. Interestingly, the enations typical of CLCuD were only induced by CLCuGV in the presence of CLCuMB. Also in infections involving both CLCuMB and ChLCB the enations typical of CLCuMB were less evident. This is the first time an African begomovirus has been identified on the Indian sub-continent, highlight the growing threat of begomoviruses and particularly the threat of CLCuD causing viruses to cotton cultivation in the rest of the world.

Tahir, Muhammad Nouman; Amin, Imran; Briddon, Rob W.; Mansoor, Shahid

2011-01-01

70

Severe outbreak of tomato yellow leaf curl Sardinia virus on pepper in southern Italy.  

PubMed

During summer and autumn 2008 a severe outbreak of pepper leaf curl disease (PLCD) was observed in pepper crops under plastic tunnels in the ionic coast of Basilicata region. Its incidence reached, in some cases, values close to 50%. The beginning of infections was recorded along the perimeter of the tunnels, where it reached a percentage of almost 100%. The infection then progressively spread towards the central areas of the greenhouses. Large populations of whiteflies, identificated as Bemisia tabaci, were observed on the infected crops. Detection assays for TYLCSV and TYLCV were performed in order to ascertain the etiologic agent: 190 symptomatic samples were collected from different fields and assayed in DAS-ELISA using a broad-spectrum reagent combination (distributed by Bioreba AG) detecting TYLCV, TYLCSV and other Begamoviruses: of these, 176 samples resulted positive. In order to discriminate between TYLCSV, TYLCV or any other Begamovirus, 15 positive samples were analyzed by PCR using a couple of synthetic oligonucleotides allowing the amplification of the whole coat protein (CP) gene. RFLP analysis performed on the PCR product, 1008 bp long, showed the presence of only TYLCSV in all assayed samples. The molecular characterization performed by phylogenetic analysis of the sequenced coat protein gene revealed that the isolate shares a similarity of about 97% with the corresponding sequence of a tomato TYLCSV isolate from Sicily (Z28390) and is almost identical with the pepper isolate CAB-It recovered in the same area in 2007 (TYLCSV was first recorded on pepper in Italy in 2007 in Policoro-MT, Fanigliulo et al., 2008. Comm. Appl. Biol. Sci, Ghent University, 73/2, 2008), indicating that there is a very low variability in TYLCSV population in the surveyed area. The further diffusion of PLCD and its hazard has to be connected with the presence of wide tomato cultivations, of weed hosts alternative to pepper (Solanum nigrum, Datura stramonium, Sonchus asper, Cardaria draba and Abutilon theophrasti) and with the strong presence of the vector B. tabaci of the B biotype, more efficient than Q biotype in the virus transmission, and able to feed and reproduce on peppers as well as on tomatoes. PMID:20222578

Comes, Soccorsa; Fanigliulo, Angela; Pacella, Rosa; Crescenzi, Aniello

2009-01-01

71

Efficient Regeneration and Selection of Virus-free Sweetpotato Plants from Sweet Potato Leaf Curl Virus Infected Materials and Their Effects on Yields in Field Trials  

Technology Transfer Automated Retrieval System (TEKTRAN)

Sweet potato leaf curl virus (SPLCV) is an emerging virus disease in sweetpotato (Ipomoea batata) in the U.S. The incidence of SPLCV infection on sweetpotato increased dramatically in recent years due to the explosion of whitefly, Bemisia tabaci (Gennadius) populations. Among several sweetpotato v...

72

Molecular cloning of Indian tomato leaf curl vims genome following a simple method of concentrating the supercoiled replicative form of viral DNA  

Microsoft Academic Search

DNA-A and DNA-B components of the genome of a whitefly transmitted virus causing yellowing and leaf curl in tomato (ITLCV) were cloned following a simple procedure for isolation of the double stranded replicative form of viral DNA from infected tomato plants. The method is based on extraction of total DNA from infected plants followed by concentration of the double stranded

K. M. Srivastava; Vipin Hallan; R. K. Raizada; Govind Chandra; B. P. Singh; P. V. Sane

1995-01-01

73

Long-term association of tomato yellow leaf curl virus with its whitefly vector Bemisia tabaci: effect on the insect transmission capacity, longevity and fecundity  

Microsoft Academic Search

The association between tomato yellow leaf curl geminivirus (TYLCV, Israeli isolate) and its insect vector, the whitefly Bemisia tabaci, was investigated. Insects that emerged during a 24 h period were caged with TYLCV-infected plants for a 48 h ac- quisition access period, then with egg-plants - a TYLCV non-host - for the rest of their lives. While TYLCV DNA was

Galina Rubinstein; Henryk Czosnek

1997-01-01

74

Host range and genetic diversity of croton yellow vein mosaic virus, a weed-infecting monopartite begomovirus causing leaf curl disease in tomato.  

PubMed

Croton yellow vein mosaic virus (CYVMV) is a widely occurring begomovirus in Croton bonplandianum, a common weed in the Indian subcontinent. In this study, CYVMV (genus Begomovirus, family Geminiviridae) was transmitted by whiteflies (Bemisia tabaci) to as many as 35 plant species belonging to 11 families, including many vegetables, tobacco varieties, ornamentals and weeds. CYVMV produced bright yellow vein symptoms in croton, whereas in all the other host species, the virus produced leaf curl symptoms. CYVMV produced leaf curl in 13 tobacco species and 22 cultivars of Nicotiana tabacum and resembled tobacco leaf curl virus (TobLCV) in host reactions. However, CYVMV was distinguished from TobLCV in four differential hosts, Ageratum conyzoides, C. bonplandianum, Euphorbia geniculata and Sonchus bracyotis. The complete genome sequences of four isolates originating from northern, eastern and southern India revealed that a single species of DNA-A and a betasatellite, croton yellow vein mosaic betasatellite (CroYVMB) were associated with the yellow vein mosaic disease of croton. The sequence identity among the isolates of CYVMV DNA-A and CroYVMB occurring in diverse plant species was 91.8-97.9 % and 83.3-100 %, respectively. The CYVMV DNA-A and CroYVMB generated through rolling-circle amplification of the cloned DNAs produced typical symptoms of yellow vein mosaic and leaf curling in croton and tomato, respectively. The progeny virus from both the croton and tomato plants was transmitted successfully by B. tabaci. The present study establishes the etiology of yellow vein mosaic disease of C. bonplandianum and provides molecular evidence that a weed-infecting monopartite begomovirus causes leaf curl in tomato. PMID:23096697

Pramesh, D; Mandal, Bikash; Phaneendra, Chigurupati; Muniyappa, V

2012-10-25

75

Rep protein of tomato yellow leaf curl geminivirus has an ATPase activity required for viral DNA replication.  

PubMed Central

The Rep protein of geminiviruses is the sole viral protein required for their DNA replication. The amino acid sequence of Rep protein contains an NTP binding consensus motif (P-loop). Here we show that purified Rep protein of tomato yellow leaf curl virus expressed in Escherichia coli exhibits an ATPase activity in vitro. Amino acid exchanges in the P-loop sequence of Rep causes a substantial decrease or loss of the ATPase activity. In vivo, mutant viruses carrying these Rep mutations do not replicate in plant cells. These results show that ATP binding by the Rep protein of geminiviruses is required for its function in viral DNA replication. Images Fig. 2 Fig. 4 Fig. 6

Desbiez, C; David, C; Mettouchi, A; Laufs, J; Gronenborn, B

1995-01-01

76

Silencing of ORFs C2 and C4 of Tomato Yellow Leaf Curl Virus Engenders Resistant or Tolerant Plants  

PubMed Central

The IL-60 system is a transient universal vector system for expression and silencing in plants [1]. This vector has been derived from Tomato yellow leaf curl virus (TYLCV). The viral intergenic region (IR) is a non-coding short (314 b) sequence separating the viral sense-oriented genes from the complementary-oriented genes. IR carries the viral origin of replication as well as a promoter at each end. Placing a gene segment between two IRs at opposite orientations followed by trans-activation of the construct by the plasmid IL-60-BS, caused silencing of the pertinent gene as indicated by the silencing of the endogenous gene PDS.. The viral genes C2 and C4 are implicated as having a role in viral-directed silencing suppression. The silencing of C2 and C4 intervened with the virus ability to counter-react to viral silencing by the host plant, thus engendering resistance or tolerance.

Peretz, Yuval; Eybishtz, Assaf; Sela, Ilan

2011-01-01

77

[Molecular characterization of cotton leaf Curl Multan virus and its satellite DNA that infects Hibiscus rosa-sinensis].  

PubMed

Virus isolate G6 was obtained from Hibiscus rosa-sinensis showing yellow and leaf curl symptoms in Guangzhou, Guangdong Province. The complete nucleotide sequence of DNA-A was determined to be 2 737 nucleotides encoding six potential ORFs. Comparison showed that G6 DNA-A had more than 89% sequence identify with all isolates of Cotton leaf curl Multan virus (CLCuMV) and shared the highest sequence identify (96.1%) with CLCuMV isolate 62. G6 DNA-A had 87.1%-89.8% sequence identity with those of CLCuRV isolates, while less than 87% identities with other begomoviruses. Phylogenetic analysis of G6 DNA-A and selected begomoviruses showed that G6 was most closely related to CLCuMV isolates, and they clustered together as a separate branch. Satellite DNA molecule (G6 DNAbeta) was found to be associated with G6 using the primers beta01 and beta02. G6 DNAbeta contains 1346 nucleotides, with a potential functional ORF (C1) in complementary sense DNA. Pairwise comparison indicated that G6 DNAbeta had the highest sequence identities with CLCuMV DNAbeta (92.1%) and CLCuRV DNAbeta (88.7%), but less than 80% sequence identities with other reported satellite DNA molecules. Phylogenetic analysis indicated that G6 DNAbeta was most closely related to CLCuMV DNAbeta and the two DNAbetas clustered together as a separate branch, and formed the main branch with DNAbeta of CLCuRV and MYVV-Y47. It is concluded that G6 infecting Hibiscus rosa-sinensis is an isolate of CLCuMV. PMID:18320825

Mao, Ming-Jie; He, Zi-Fu; Yu, Hao; Li, Hua-Ping

2008-01-01

78

Intron–hairpin RNA Derived from Replication Associated Protein C1 Gene Confers Immunity to Tomato Yellow Leaf Curl Virus Infection in Transgenic Tomato Plants  

Microsoft Academic Search

The whitefly-transmitted Tomato Yellow Leaf Curl Virus (TYLCV) is the major pathogen of tomato crop in Cuba and one of the\\u000a most outstanding viral diseases of plants worldwide. In this work, we have developed transgenic tomato plants, transformed\\u000a with an intron–hairpin genetic construction to induce post- transcriptional gene silencing against the early TYLCV replication\\u000a associated protein gene (C1). The intron–hairpin

Alejandro Fuentes; Pedro L. Ramos; Elvira Fiallo; Danay Callard; Yadira Sánchez; Rudy Peral; Raidel Rodríguez; Merardo Pujol

2006-01-01

79

Tomato leaf curl virus from Bangalore (ToLCV-Ban4): sequence comparison with Indian ToLCV isolates, detection in plants and insects, and vector relationships}  

Microsoft Academic Search

Summary.  ?Tomato leaf curl virus (ToLCV) is a whitefly (Bemisia tabaci) transmitted geminivirus (family Geminiviridae, genus Begomovirus) causing a destructive disease of tomato in many regions of India, East Asia and Australia. While ToLCV isolates from Australia\\u000a and Taiwan have a single genomic component (designated DNA-A), those from Northern India have two components (DNA-A and DNA-B).\\u000a The ToLCV isolates from Southern

V. Muniyappa; H. M. Venkatesh; H. K. Ramappa; R. S. Kulkarni; M. Zeidan; C.-Y. Tarba; M. Ghanim; H. Czosnek

2000-01-01

80

In vitro Cleavage and Joining at the Viral Origin of Replication by the Replication Initiator Protein of Tomato Yellow Leaf Curl Virus  

Microsoft Academic Search

Replication of the single-stranded DNA genome of geminiviruses occurs via a double-stranded intermediate that is subsequently used as a template for rolling-circle replication of the viral strand. Only one of the proteins encoded by the virus, here referred to as replication initiator protein (Rep protein), is indispensable for replication. We show that the Rep protein of tomato yellow leaf curl

Jurgen Laufs; Wolfgang Traut; Francoise Heyraud; Volker Matzeit; Stephen G. Rogers; Jeff Schell; Bruno Gronenborn

1995-01-01

81

Evaluation of whitefly-mediated inoculation techniques to screen Lycopersicon esculentum and wild relatives for resistance to Tomato yellow leaf curl virus  

Microsoft Academic Search

For two consecutive years nine hybrids and three varieties of tomato, four Lycopersicon peruvianum and four Lycopersicon chilense\\u000a accessions were screened for Tomato yellow leaf curl virus (TYLCV) resistance. Three inoculation techniques using Bemisia\\u000a tabaci, the vector of TYLCV, were compared: (1) artificial mass inoculation-simultaneous infection of cultivated and wild\\u000a material in greenhouses; (2) artificial cage inoculation-individual infection in insect-proof

Belén Picó; Ma. José Díez; Fernando Nuez

1998-01-01

82

Evidence for recombination among isolates of Tobacco leaf curl Japan virus and Honeysuckle yellow vein mosaic virus.  

PubMed

Complete nucleotide sequences of Tobacco leaf curl Japan virus (TbLCJV) isolates from infected tomato ( Lycopersicon esculentum) plants in Nara (-[Jp2], 2764 nt; -[Jp3], 2761 nt), Kochi (-[Koc], 2760 nt) and Yamaguchi (-[Yam], 2758 nt) Prefectures, of Japan were determined. These sequences were compared with each other and the sequences of further begomoviruses from Japan. TbLCJV, TbLCJV-[Jp2], TbLCJV-[Jp3], TbLCJV-[Koc], TbLCJV-[Yam], Honeysuckle yellow vein mosaic virus (HYVMV), Eupatorium yellow vein virus (EpYVV), EpYVV-[MNS2], EpYVV-[SOJ3], EpYVV-[Yam] and EpYVV-[Tob] are monophyletic. The intergenic region (IR) of TbLCJV has highest nucleotide sequence identity with that of HYVMV (93%) whereas the rest of the genomic DNA had higher identity with that of TbLCJV-[Jp2] or -[Jp3] (91 approximately 100%) than with that of HYVMV. In conclusion, TbLCJV has a chimeric genome which may have arisen by recombination between TbLCV-[Jp2] or -[Jp3]-like and HYVMV-like ancestors. Similarly, TbLCJV-[Yam] DNA has a hybrid genome, with a major parent HYVMV and minor parent TbLCJV-[Koc]. PMID:15168208

Kitamura, K; Murayama, A; Ikegami, M

2004-02-16

83

Correlation of meteorological parameters and remotely sensed normalized difference vegetation index (NDVI) with cotton leaf curl virus (CLCV) in Multan  

NASA Astrophysics Data System (ADS)

Climate change and weather has a profound effect on the spread of Cotton Leaf Curl Virus (CLCV) which is transmitted by whitefly. Climate change is altering temperature and precipitation patterns, resulting in the shift of some insect/pest from small population to large population thus effecting crops yield. To find out the relationship between the weather conditions, outburst of CLCV and changes in Normalized Difference Vegetation Index (NDVI) values due to the outburst of CLCV, a study was carried out for tehsil Multan. Data was acquired for the months of June, July, August and September for the year 2010. Regression analysis between CLCV and meteorological conditions as well as between CLCV and NDVI was performed. Meteorological parameters included temperature, humidity, precipitation, cloud cover, wind direction, pan evaporation and sunshine hours. NDVI values were calculated from SPOT satellite imagery (1km) using ArcMap10 and WinDisp v5.1. Correlation coefficients obtained in most of the cases were acceptable however the significance F and P-value were higher than their critical value at 95% level of significance. Therefore significant correlation was found only between CLCV and temperature and between CLCV and PAN evaporation during the month of July.

Ahmed, A.; Akhtar, A.; Khalid, B.; Shamim, A.

2013-06-01

84

Identification of the replication-associated protein binding domain within the intergenic region of tomato leaf curl geminivirus.  

PubMed Central

The geminiviral replication-associated protein (Rep) is the only viral protein required for viral DNA replication. Tomato leaf curl virus (TLCV) Rep was expressed in Escherichia coli as a histidine-tagged fusion protein and purified to homogeneity in non-denaturing form. The fusion protein was used in in vitro binding experiments to identify the Rep-binding elements within the origin of replication of TLCV. Electrophoretic mobility shift assays demonstrated that the Rep binds specifically to a 120 bp fragment within the TLCV intergenic region. Fine resolution of the binding regions within the 120 bp fragment, using DNase I footprinting, demonstrated two footprints covering the sequences GCAATTGGTGTCTCTCAA and TGAATCGGTGTCTGGGG containing a direct repeat of the motif GGTGTCT (underlined). Our results suggest that the repeated motif is involved in virus-specific Rep-binding, but may not constitute the entire binding element. This is the first demonstration of geminivirus sequence elements involved in Rep-binding by direct protein-DNA interaction assays.

Akbar Behjatnia, S A; Dry, I B; Ali Rezaian, M

1998-01-01

85

Molecular characterization and infectivity of a Tomato leaf curl New Delhi virus variant associated with newly emerging yellow mosaic disease of eggplant in India  

PubMed Central

Background Begomoviruses have emerged as serious problem for vegetable and fiber crops in the recent past, frequently in tropical and subtropical region of the world. The association of begomovirus with eggplant yellow mosaic disease is hitherto unknown apart from one report from Thailand. A survey in Nagpur, Central India, in 2009-2010 showed severe incidence of eggplant yellow mosaic disease. Here, we have identified and characterized a begomovirus responsible for the newly emerging yellow mosaic disease of eggplant in India. Results The complete DNA-A and DNA-B genomic components of the causative virus were cloned and sequenced. Nucleotide sequence analysis of DNA-A showed that it shared highest 97.6% identity with Tomato leaf curl New Delhi virus-India[India:Udaipur:Okra:2007] and lowest 87.9% identity with Tomato leaf curl New Delhi virus-India[India:NewDelhi:Papaya:2005], while DNA-B showed highest 94.1% identity with ToLCNDV-IN[IN:UD:Ok:07] and lowest 76.2% identity with ToLCNDV-India[India:Lucknow]. Thus, it appears that this begomovirus is a variant of ubiquitous ToLCNDV and hence, we suggest the name ToLCNDV-India[India:Nagpur:Eggplant:2009] for this variant. The pathogenicity of ToLCNDV-IN[IN:Nag:Egg:09] isolate was confirmed by agroinfiltraion and dimeric clones of DNA-A and DNA-B induced characteristic yellow mosaic symptoms in eggplants and leaf curling in tomato plants. Conclusion This is the first report of a ToLCNDV variant moving to a new agriculturally important host, eggplant and causing yellow mosaic disease. This is also a first experimental demonstration of Koch's postulate for a begomovirus associated with eggplant yellow mosaic disease.

2011-01-01

86

A GroEL Homologue from Endosymbiotic Bacteria of the Whitefly Bemisia tabaciIs Implicated in the Circulative Transmission of Tomato Yellow Leaf Curl Virus  

Microsoft Academic Search

Evidence for the involvement of aBemisia tabaciGroEL homologue in the transmission of tomato yellow leaf curl geminivirus (TYLCV) is presented. A ?63-kDa protein was identified inB. tabaciwhole-body extracts using an antiserum raised against aphidBuchneraGroEL. The GroEL homologue was immunolocalized to a coccoid-shaped whitefly endosymbiont. The 30 N-terminal amino acids of the whitefly GroEL homologue showed 80% homology with that from

Shai Morin; Murad Ghanim; Muhammad Zeidan; Henryk Czosnek; Martin Verbeek; Johannes F. J. M. van den Heuvel

1999-01-01

87

Interaction with host SGS3 is required for suppression of RNA silencing by tomato yellow leaf curl virus V2 protein.  

PubMed

The V2 protein of tomato yellow leaf curl geminivirus (TYLCV) functions as an RNA-silencing suppressor that counteracts the innate immune response of the host plant. The host-cell target of V2, however, remains unknown. Here we show that V2 interacts directly with SlSGS3, the tomato homolog of the Arabidopsis SGS3 protein (AtSGS3), which is known to be involved in the RNA-silencing pathway. SlSGS3 genetically complemented an AtSGS3 mutation and restored RNA silencing, indicating that SlSGS3 is indeed a functional homolog of AtSGS3. A point mutant of V2 that is unable to bind SlSGS3 also lost its ability to suppress RNA silencing, suggesting a correlation between the V2-SlSGS3 interaction in planta and the suppressor activity of V2. PMID:18165314

Glick, Efrat; Zrachya, Avi; Levy, Yael; Mett, Anahit; Gidoni, David; Belausov, Eduard; Citovsky, Vitaly; Gafni, Yedidya

2007-12-28

88

Interaction with host SGS3 is required for suppression of RNA silencing by tomato yellow leaf curl virus V2 protein  

PubMed Central

The V2 protein of tomato yellow leaf curl geminivirus (TYLCV) functions as an RNA-silencing suppressor that counteracts the innate immune response of the host plant. The host-cell target of V2, however, remains unknown. Here we show that V2 interacts directly with SlSGS3, the tomato homolog of the Arabidopsis SGS3 protein (AtSGS3), which is known to be involved in the RNA-silencing pathway. SlSGS3 genetically complemented an AtSGS3 mutation and restored RNA silencing, indicating that SlSGS3 is indeed a functional homolog of AtSGS3. A point mutant of V2 that is unable to bind SlSGS3 also lost its ability to suppress RNA silencing, suggesting a correlation between the V2–SlSGS3 interaction in planta and the suppressor activity of V2.

Glick, Efrat; Zrachya, Avi; Levy, Yael; Mett, Anahit; Gidoni, David; Belausov, Eduard; Citovsky, Vitaly; Gafni, Yedidya

2008-01-01

89

In vitro cleavage and joining at the viral origin of replication by the replication initiator protein of tomato yellow leaf curl virus.  

PubMed Central

Replication of the single-stranded DNA genome of geminiviruses occurs via a double-stranded intermediate that is subsequently used as a template for rolling-circle replication of the viral strand. Only one of the proteins encoded by the virus, here referred to as replication initiator protein (Rep protein), is indispensable for replication. We show that the Rep protein of tomato yellow leaf curl virus initiates viral-strand DNA synthesis by introducing a nick in the plus strand within the nonanucleotide 1TAATATT decreases 8AC, identical among all geminiviruses. After cleavage, the Rep protein remains bound to the 5' end of the cleaved strand. In addition, we show that the Rep protein has a joining activity, suggesting that it acts as a terminase, thus resolving the nascent viral single strand into genome-sized units. Images Fig. 1 Fig. 3 Fig. 4 Fig. 5

Laufs, J; Traut, W; Heyraud, F; Matzeit, V; Rogers, S G; Schell, J; Gronenborn, B

1995-01-01

90

Tomato yellow leaf curl virus in the Dominican Republic: Characterization of an Infectious Clone, Virus Monitoring in Whiteflies, and Identification of Reservoir Hosts.  

PubMed

ABSTRACT Epidemics of tomato yellow leaf curl disease (TYLCD) in the Dominican Republic in the early to mid-1990s resulted in catastrophic losses to processing tomato production. As part of an integrated management approach to TYLCD, the complete nucleotide sequence of a full-length infectious clone of an isolate of Tomato yellow leaf curl virus (TYLCV) from the Dominican Republic (TYLCV-[DO]) was determined. The TYLCV-[DO] genome was nearly identical in sequence (>97%) and genome organization to TYLCV isolates from Israel and Cuba. This established that TYLCV-[DO] is a bonafide TYLCV isolate (rather than a recombinant virus, such as isolates from Israel [Mild], Portugal, Japan, and Iran), and provided further evidence for the introduction of the virus from the eastern Mediterranean. A reduction in the incidence of TYLCV in the northern and southern processing tomato production areas of the Dominican Republic has been associated with the implementation of a mandatory 3-month whitefly host-free period (including tomato, common bean, cucurbits, eggplant, and pepper). Monitoring TYLCV levels in whiteflies, by polymerase chain reaction with TYLCV-specific primers, established that the incidence of TYLCV decreased markedly during the host-free period, and then gradually increased during the tomato-growing season. In contrast, TYLCV persisted in whiteflies and tomato plants in an area in which the host-free period was not implemented. Surveys for TYLCV reservoir hosts, conducted to identify where TYLCV persists during the host-free period, revealed symptomless infections in a number of weed species. The implications of these findings for TYLCV management in the Dominican Republic are discussed. PMID:18943022

Salati, Raquel; Nahkla, Medhat K; Rojas, Maria R; Guzman, Pablo; Jaquez, Jose; Maxwell, Douglas P; Gilbertson, Robert L

2002-05-01

91

Curling paper  

NASA Astrophysics Data System (ADS)

As many soft materials, paper is mechanically sensitive to humidity. Owing to its hygroscopic cellulose-based structure, it is known to wrinkle when subject to humidity fluctuations. Here, we present experimental results on the more extreme deformations observed when a sheet of tracing paper is put on a bath of water. After contact with the liquid surface, water diffuses into the hygroscopic material from below and induces differential swelling, resulting in the curling of the paper. Within seconds, a spectacular roll-up motion follows. We explain the observed shapes and curling dynamics.

Reyssat, Etienne; Mahadevan, L.

2012-02-01

92

Recruitment of the Host Plant Heat Shock Protein 70 by Tomato Yellow Leaf Curl Virus Coat Protein Is Required for Virus Infection  

PubMed Central

A functional capsid protein (CP) is essential for host plant infection and insect transmission of Tomato yellow leaf curl virus (TYLCV) and other monopartite begomoviruses. We have previously shown that TYLCV CP specifically interacts with the heat shock protein 70 (HSP70) of the virus insect vector, Bemisia tabaci. Here we demonstrate that during the development of tomato plant infection with TYLCV, a significant amount of HSP70 shifts from a soluble form into insoluble aggregates. CP and HSP70 co-localize in these aggregates, first in the cytoplasm, then in the nucleus of cells associated with the vascular system. CP-HSP70 interaction was demonstrated by co-immunopreciptation in cytoplasmic - but not in nuclear extracts from leaf and stem. Inhibition of HSP70 expression by quercetin caused a decrease in the amount of nuclear CP aggregates and a re-localization of a GFP-CP fusion protein from the nucleus to the cytoplasm. HSP70 inactivation resulted in a decrease of TYLCV DNA levels, demonstrating the role of HSP70 in TYLCV multiplication in planta. The current study reveals for the first time the involvement of plant HSP70 in TYLCV CP intracellular movement. As described earlier, nuclear aggregates contained TYLCV DNA-CP complexes and infectious virions. Showing that HSP70 localizes in these large nuclear aggregates infers that these structures operate as nuclear virus factories.

Gorovits, Rena; Moshe, Adi; Ghanim, Murad; Czosnek, Henryk

2013-01-01

93

Curling's paradox  

Microsoft Academic Search

There is an age old debate in curling about whether it is better to be down one point with last shot, or ahead by one point without. The objective of this paper is to apply sensitivity analysis as a methodology to differentiate what appears to be two seemingly equal scenarios. A probability tree is developed for each scenario and a

Kent J. Kostuk; Keith A. Willoughby

2006-01-01

94

Progressive aggregation of Tomato yellow leaf curl virus coat protein in systemically infected tomato plants, susceptible and resistant to the virus.  

PubMed

Tomato yellow leaf curl virus (TYLCV) coat protein (CP) accumulated in tomato leaves during infection. The CP was immuno-detected in the phloem associated cells. At the early stages of infection, punctate signals were detected in the cytoplasm, while in the later stages aggregates of increasing size were localized in cytoplasm and nuclei. Sedimentation of protein extracts through sucrose gradients confirmed that progress of infection was accompanied by the formation of CP aggregates of increasing size. Genomic ssDNA was found in the cytoplasm and in the nucleus, while the dsDNA replicative form was exclusively associated with the nucleus. CP-DNA complexes were detected by immuno-capture PCR in nuclear and cytoplasmic large aggregates. Nuclear aggregates contained infectious particles transmissible to test plants by whiteflies. In contrast to susceptible tomatoes, the formation of large CP aggregates in resistant plants was delayed. By experimentally changing the level of resistance/susceptibility of plants, we showed that maintenance of midsized CP aggregates was associated with resistance, while large aggregates where characteristic of susceptibility. We propose that sequestering of virus CP into midsized aggregates and retarding the formation of large insoluble aggregates containing infectious particles is part of the response of resistant plants to TYLCV. PMID:23099086

Gorovits, Rena; Moshe, Adi; Kolot, Mikhail; Sobol, Iris; Czosnek, Henryk

2012-10-22

95

Functional Characterization of Coat Protein and V2 Involved in Cell to Cell Movement of Cotton Leaf Curl Kokhran Virus-Dabawali  

PubMed Central

The functional attributes of coat protein (CP) and V2 of the monopartite begomovirus, Cotton leaf curl Kokhran virus- Dabawali were analyzed in vitro and in vivo by their overexpression in E coli, insect cells and transient expression in the plant system. Purified recombinant V2 and CP proteins were shown to interact with each other using ELISA and surface plasmon resonance. Confocal microscopy of Sf21 cells expressing V2 and CP proteins revealed that V2 localized to the cell periphery and CP to the nucleus. Deletion of the N terminal nuclear localization signal of CP restricted its distribution to the cytoplasm. GFP-V2 and YFP-CP transiently expressed in N.benthamiana plants by agroinfiltration substantiated the localization of V2 to the cell periphery and CP predominantly to the nucleus. Interestingly, upon coinfiltration, CP was found both in the nucleus and in the cytoplasm along with V2. These results suggest that the interaction of V2 and CP may have important implications in the cell to cell movement.

Poornima Priyadarshini, C. G.; Ambika, M. V.; Tippeswamy, R.; Savithri, H. S.

2011-01-01

96

Kinetics of interaction of Cotton Leaf Curl Kokhran Virus-Dabawali (CLCuKV-Dab) coat protein and its mutants with ssDNA  

SciTech Connect

Gemini viral assembly and transport of viral DNA into nucleus for replication, essentially involve DNA-coat protein interactions. The kinetics of interaction of Cotton Leaf Curl Kokhran Virus-Dabawali recombinant coat protein (rCP) with DNA was studied by electrophoretic mobility shift assay (EMSA) and surface plasmon resonance (SPR). The rCP interacted with ssDNA with a K{sub A}, of 2.6 +- 0.29 x 10{sup 8} M{sup -1} in a sequence non-specific manner. The CP has a conserved C2H2 type zinc finger motif composed of residues C68, C72, H81 and H85. Mutation of these residues to alanine resulted in reduced binding to DNA probes. The H85A mutant rCP showed the least binding with approximately 756 fold loss in the association rate and a three order magnitude decrease in the binding affinity as compared to rCP. The CP-DNA interactions via the zinc finger motif could play a crucial role in virus assembly and in nuclear transport.

Priyadarshini, C.G. Poornima [Department of Biochemistry, Indian Institute of Science, Bangalore 560012 (India); Savithri, H.S., E-mail: bchss@biochem.iisc.ernet.i [Department of Biochemistry, Indian Institute of Science, Bangalore 560012 (India)

2009-04-10

97

The begomoviruses Honeysuckle yellow vein mosaic virus and Tobacco leaf curl Japan virus with DNAbeta satellites cause yellow dwarf disease of tomato.  

PubMed

The complete nucleotide sequences of two begomoviruses (Nara virus-1 and Nara virus-2), a satellite DNA (DNAbeta-Nara) and defective DNAs were obtained from honeysuckle (Lonicera japonica) showing characteristic yellow vein mosaic symptoms in Nara Prefecture, Japan. One begomovirus (Ibaraki virus) and a satellite DNA (DNAbeta-Ibaraki) was isolated and cloned from honeysuckle plants exhibited typical yellowing of veins and small elliptical shaped enations along veins on the under side of the leaves in Ibaraki Prefecture, Japan. The genome organization of the three viruses is the same as those of other Old World monopartite begomoviruses. Nara virus-1 had overall nucleotide sequence identity with Nara virus-2 of 94% and Ibaraki virus of 90%. DNAbeta-Nara had overall nucleotide sequence identity with DNAbeta-Ibaraki of 83%. Comparison of the nucleotide sequences with other begomoviruses revealed that Nara virus-1 and Nara virus-2 are strains of Honeysuckle yellow vein mosaic virus (HYVMV), hence named as HYVMV-Nara1 and HYVMV-Nara2, whereas Ibaraki virus was a strain of Tobacco leaf curl Japan virus (TbLCJV), designated as TbLCJV-Hs[Iba]. HYVMV-Nara1 and HYVMV-Nara2 have hybrid genomes, which are likely to have formed recombination between HYVMV and TbLCJV. TbLCJV-Hs[Iba] or HYVMV-Nara2 could infect and cause yellowing, leaf crinkling and stunting symptoms when partial tandem dimeric constructs were agroinoculated on tomato plants. However, in the presence of DNAbeta, both TbLCJV-Hs[Iba] or HYVMV-Nara2 produced more severe stunting symptoms in tomato plants. Therefore, these viruses along with their satellites are causal agents of tomato yellow dwarf disease in Japan, and honeysuckle acts as a potential reservoir host. Previously available evidence indicated that DNAbeta elements do not contain iteron sequences of their helper viruses; hence this is the first evidence that DNAbeta satellites have the iteron of their helper virus. PMID:18722488

Ogawa, T; Sharma, P; Ikegami, M

2008-09-13

98

The transmission efficiency of tomato yellow leaf curl virus by the whitefly Bemisia tabaci is correlated with the presence of a specific symbiotic bacterium species.  

PubMed

Tomato yellow leaf curl virus (TYLCV) (Geminiviridae: Begomovirus) is exclusively vectored by the whitefly Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae). TYLCV transmission depends upon a 63-kDa GroEL protein produced by the vector's endosymbiotic bacteria. B. tabaci is a species complex comprising several genetically distinct biotypes that show different secondary-symbiont fauna. In Israel, the B biotype harbors Hamiltonella, and the Q biotype harbors Wolbachia and Arsenophonus. Both biotypes harbor Rickettsia and Portiera (the obligatory primary symbionts). The aim of this study was to determine which B. tabaci symbionts are involved in TYLCV transmission using B. tabaci populations collected in Israel. Virus transmission assays by B. tabaci showed that the B biotype efficiently transmits the virus, while the Q biotype scarcely transmits it. Yeast two-hybrid and protein pulldown assays showed that while the GroEL protein produced by Hamiltonella interacts with TYLCV coat protein, GroEL produced by Rickettsia and Portiera does not. To assess the role of Wolbachia and Arsenophonus GroEL proteins (GroELs), we used an immune capture PCR (IC-PCR) assay, employing in vivo- and in vitro-synthesized GroEL proteins from all symbionts and whitefly artificial feeding through membranes. Interaction between GroEL and TYLCV was found to occur in the B biotype, but not in the Q biotype. This assay further showed that release of virions protected by GroEL occurs adjacent to the primary salivary glands. Taken together, the GroEL protein produced by Hamiltonella (present in the B biotype, but absent in the Q biotype) facilitates TYLCV transmission. The other symbionts from both biotypes do not seem to be involved in transmission of this virus. PMID:20631135

Gottlieb, Yuval; Zchori-Fein, Einat; Mozes-Daube, Netta; Kontsedalov, Svetlana; Skaljac, Marisa; Brumin, Marina; Sobol, Iris; Czosnek, Henryk; Vavre, Fabrice; Fleury, Frédéric; Ghanim, Murad

2010-07-14

99

Silencing of a single gene in tomato plants resistant to Tomato yellow leaf curl virus renders them susceptible to the virus.  

PubMed

A reverse-genetics approach was applied to identify genes involved in Tomato yellow leaf curl virus (TYLCV) resistance, taking advantage of two tomato inbred lines from the same breeding program-one susceptible (S), one resistant (R-that used Solanum habrochaites as the source of resistance. cDNA libraries from inoculated and non-inoculated R and S plants were compared, postulating that genes preferentially expressed in the R line may be part of the network sustaining resistance to TYLCV. Further, we assumed that silencing genes located at important nodes of the network would lead to collapse of resistance. Approximately 70 different cDNAs representing genes preferentially expressed in R plants were isolated and their genes identified by comparison with public databases. A Permease I-like protein gene encoding a transmembranal transporter was further studied: it was preferentially expressed in R plants and its expression was enhanced several-fold following TYLCV inoculation. Silencing of the Permease gene of R plants using Tobacco rattle virus-induced gene silencing led to loss of resistance, expressed as development of disease symptoms typical of infected susceptible plants and accumulation of large amounts of virus. Silencing of another membrane protein gene preferentially expressed in R plants, Pectin methylesterase, previously shown to be involved in Tobacco mosaic virus translocation, did not lead to collapse of resistance of R plants. Thus, silencing of a single gene can lead to collapse of resistance, but not every gene preferentially expressed in the R line has the same effect, upon silencing, on resistance. PMID:19533378

Eybishtz, Assaf; Peretz, Yuval; Sade, Dagan; Akad, Fouad; Czosnek, Henryk

2009-06-17

100

The Transmission Efficiency of Tomato Yellow Leaf Curl Virus by the Whitefly Bemisia tabaci Is Correlated with the Presence of a Specific Symbiotic Bacterium Species?  

PubMed Central

Tomato yellow leaf curl virus (TYLCV) (Geminiviridae: Begomovirus) is exclusively vectored by the whitefly Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae). TYLCV transmission depends upon a 63-kDa GroEL protein produced by the vector's endosymbiotic bacteria. B. tabaci is a species complex comprising several genetically distinct biotypes that show different secondary-symbiont fauna. In Israel, the B biotype harbors Hamiltonella, and the Q biotype harbors Wolbachia and Arsenophonus. Both biotypes harbor Rickettsia and Portiera (the obligatory primary symbionts). The aim of this study was to determine which B. tabaci symbionts are involved in TYLCV transmission using B. tabaci populations collected in Israel. Virus transmission assays by B. tabaci showed that the B biotype efficiently transmits the virus, while the Q biotype scarcely transmits it. Yeast two-hybrid and protein pulldown assays showed that while the GroEL protein produced by Hamiltonella interacts with TYLCV coat protein, GroEL produced by Rickettsia and Portiera does not. To assess the role of Wolbachia and Arsenophonus GroEL proteins (GroELs), we used an immune capture PCR (IC-PCR) assay, employing in vivo- and in vitro-synthesized GroEL proteins from all symbionts and whitefly artificial feeding through membranes. Interaction between GroEL and TYLCV was found to occur in the B biotype, but not in the Q biotype. This assay further showed that release of virions protected by GroEL occurs adjacent to the primary salivary glands. Taken together, the GroEL protein produced by Hamiltonella (present in the B biotype, but absent in the Q biotype) facilitates TYLCV transmission. The other symbionts from both biotypes do not seem to be involved in transmission of this virus.

Gottlieb, Yuval; Zchori-Fein, Einat; Mozes-Daube, Netta; Kontsedalov, Svetlana; Skaljac, Marisa; Brumin, Marina; Sobol, Iris; Czosnek, Henryk; Vavre, Fabrice; Fleury, Frederic; Ghanim, Murad

2010-01-01

101

Transgenically Expressed T-Rep of Tomato Yellow Leaf Curl Sardinia Virus Acts as a trans-Dominant-Negative Mutant, Inhibiting Viral Transcription and Replication  

PubMed Central

We have previously shown that transgenic expression of a truncated C1 gene of Tomato yellow leaf curl Sardinia virus (TYLCSV), expressing the first 210 amino acids of the replication-associated protein (T-Rep) and potentially coexpressing the C4 protein, confers resistance to the homologous virus in Nicotiana benthamiana plants. In the present study we have investigated the role of T-Rep and C4 proteins in the resistance mechanism, analyzing changes in virus transcription and replication. Transgenic plants and protoplasts were challenged with TYLCSV and the related TYLCSV Murcia strain (TYLCSV-ES[1]). TYLCSV-resistant plants were susceptible to TYLCSV-ES[1]; moreover, TYLCSV but not TYLCSV-ES[1] replication was strongly inhibited in transgenic protoplasts as well as in wild-type (wt) protoplasts transiently expressing T-Rep but not the C4 protein. Viral circular single-stranded DNA (cssDNA) was usually undetectable in transgenically and transiently T-Rep-expressing protoplasts, while viral DNAs migrating more slowly than the cssDNA were observed. Biochemical studies showed that these DNAs were partial duplexes with the minus strand incomplete. Interestingly, similar viral DNA forms were also found at early stages of TYLCSV replication in wt N. benthamiana protoplasts. Transgenically expressed T-Rep repressed the transcription of the GUS reporter gene up to 300-fold when fused to the homologous (TYLCSV) but not to the heterologous (TYLCSV-ES[1]) C1 promoter. Similarly, transiently expressed T-Rep but not C4 protein strongly repressed GUS transcription when fused to the C1 promoter of TYLCSV. A model of T-Rep interference with TYLCSV transcription-replication is proposed.

Brunetti, Angela; Tavazza, Raffaela; Noris, Emanuela; Lucioli, Alessandra; Accotto, Gian Paolo; Tavazza, Mario

2001-01-01

102

Mutation of three cysteine residues in Tomato yellow leaf curl virus-China C2 protein causes dysfunction in pathogenesis and posttranscriptional gene-silencing suppression.  

PubMed

The nuclear localized C2 protein of the monopartite begomovirus Tomato yellow leaf curl virus-China (TYLCV-C) contributes to viral pathogenicity. Here, we have investigated TYLCV-C C2 protein domains that play a role in the phenotype. Alignment of the C2 protein with 67 homologues from monopartite and bipartite begomoviruses revealed that a putative zinc-finger motif C36-X1-C38-X7-C46-X6-H53-X4-H58C59 and four potential phosphorylation sites (T52, S61, Y68, and S74) are highly conserved. When expressed from a Potato virus X (PVX) vector, TYLCV-C C2 protein mutants C2-T52M, C2-H58S, C2-C59S, C2-S61R, and C2-S74D, like the wild-type C2 protein, induced local necrotic ringspots and systemic necrosis in Nicotiana benthamiana plants. Mutants C2-H53P and C2-Y68D produced irregular necrotic lesions on inoculated leaves that were distinct from the wild-type phenotype. In contrast, mutants C2-C36R, C2-C38N, and C2-C46I induced chlorosis and mosaic symptoms rather than necrosis. We demonstrate that TYLCV-C C2, like its counterpart in the bipartite begomovirus African cassava mosaic virus, mediates suppression of posttranscriptional gene silencing (PTGS). Moreover, the individual mutations C36R, C38N, and C46I abolished the ability of C2 protein to suppress PTGS. These results suggest that the three cysteine residues within the putative zinc-finger motif are essential for C2 protein to induce necrosis and to act as a suppressor of PTGS. PMID:11952122

van, Wezel Rene; Dong, Xiangli; Liu, Huanting; Tien, Po; Stanley, John; Hong, Yiguo

2002-03-01

103

Virion Stability Is Important for the Circulative Transmission of Tomato Yellow Leaf Curl Sardinia Virus by Bemisia tabaci, but Virion Access to Salivary Glands Does Not Guarantee Transmissibility? †  

PubMed Central

The capsid protein (CP) of the monopartite begomovirus Tomato yellow leaf curl Sardinia virus (TYLCSV), family Geminiviridae, is indispensable for plant infection and vector transmission. A region between amino acids 129 and 152 is critical for virion assembly and insect transmissibility. Two previously described mutants, one with a double Q129P Q134H mutation (PNHD) and another with a further D152E change (PNHE), were found nontransmissible (NT). Another NT mutant with a single N130D change (QDQD) was retrieved from a new mutational analysis. In this study, these three NT mutants and the wild-type (wt) virus were compared in their relationships with the whitefly vector Bemisia tabaci and the nonvector Trialeurodes vaporariorum. Retention kinetics of NT mutants were analyzed by quantitative dot blot hybridization in whiteflies fed on infected plants. The QDQD mutant, whose virions appeared nongeminate following purification, was hardly detectable in either whitefly species at any sampling time. The PNHD mutant was acquired and circulated in both whitefly species for up to 10 days, like the wt virus, while PNHE circulated in B. tabaci only. Using immunogold labeling, both PNHD and PNHE CPs were detected in B. tabaci salivary glands (SGs) like the wt virus, while no labeling was found in any whitefly tissue with the QDQD mutant. Significant inhibition of transmission of the wt virus was observed after prior feeding of the insects on plants infected with the PNHE mutant, but not on plants infected with the other mutants. Virion stability and ability to cross the SG barrier are necessary for TYLCSV transmission, but interactions with molecular components inside the SGs are also critical for transmissibility.

Caciagli, Piero; Medina Piles, Vicente; Marian, Daniele; Vecchiati, Manuela; Masenga, Vera; Mason, Giovanna; Falcioni, Tania; Noris, Emanuela

2009-01-01

104

Virion stability is important for the circulative transmission of tomato yellow leaf curl sardinia virus by Bemisia tabaci, but virion access to salivary glands does not guarantee transmissibility.  

PubMed

The capsid protein (CP) of the monopartite begomovirus Tomato yellow leaf curl Sardinia virus (TYLCSV), family Geminiviridae, is indispensable for plant infection and vector transmission. A region between amino acids 129 and 152 is critical for virion assembly and insect transmissibility. Two previously described mutants, one with a double Q129P Q134H mutation (PNHD) and another with a further D152E change (PNHE), were found nontransmissible (NT). Another NT mutant with a single N130D change (QDQD) was retrieved from a new mutational analysis. In this study, these three NT mutants and the wild-type (wt) virus were compared in their relationships with the whitefly vector Bemisia tabaci and the nonvector Trialeurodes vaporariorum. Retention kinetics of NT mutants were analyzed by quantitative dot blot hybridization in whiteflies fed on infected plants. The QDQD mutant, whose virions appeared nongeminate following purification, was hardly detectable in either whitefly species at any sampling time. The PNHD mutant was acquired and circulated in both whitefly species for up to 10 days, like the wt virus, while PNHE circulated in B. tabaci only. Using immunogold labeling, both PNHD and PNHE CPs were detected in B. tabaci salivary glands (SGs) like the wt virus, while no labeling was found in any whitefly tissue with the QDQD mutant. Significant inhibition of transmission of the wt virus was observed after prior feeding of the insects on plants infected with the PNHE mutant, but not on plants infected with the other mutants. Virion stability and ability to cross the SG barrier are necessary for TYLCSV transmission, but interactions with molecular components inside the SGs are also critical for transmissibility. PMID:19321611

Caciagli, Piero; Medina Piles, Vicente; Marian, Daniele; Vecchiati, Manuela; Masenga, Vera; Mason, Giovanna; Falcioni, Tania; Noris, Emanuela

2009-03-25

105

Whitefly resistance traits derived from the wild tomato Solanum pimpinellifolium affect the preference and feeding behavior of Bemisia tabaci and reduce the spread of Tomato yellow leaf curl virus.  

PubMed

Breeding of tomato genotypes that limit whitefly (Bemisia tabaci) access and feeding might reduce the spread of Tomato yellow leaf curl virus (TYLCV), a begomovirus (genus Begomovirus, family Geminiviridae) that is the causal agent of tomato yellow leaf curl disease. TYLCV is restricted to the phloem and is transmitted in a persistent manner by B. tabaci. The tomato breeding line ABL 14-8 was developed by introgressing type IV leaf glandular trichomes and secretion of acylsucroses from the wild tomato Solanum pimpinellifolium accession TO-937 into the genetic background of the whitefly- and virus-susceptible tomato cultivar Moneymaker. Results of preference bioassays with ABL 14-8 versus Moneymaker indicated that presence of type IV glandular trichomes and the production of acylsucrose deterred the landing and settling of B. tabaci on ABL 14-8. Moreover, electrical penetration graph studies indicated that B. tabaci adults spent more time in nonprobing activities and showed a reduced ability to start probing. Such behavior resulted in a reduced ability to reach the phloem. The superficial type of resistance observed in ABL 14-8 against B. tabaci probing significantly reduced primary and secondary spread of TYLCV. PMID:21615206

Rodríguez-López, M J; Garzo, E; Bonani, J P; Fereres, A; Fernández-Muñoz, R; Moriones, E

2011-10-01

106

A developmentally regulated lipocalin-like gene is overexpressed in Tomato yellow leaf curl virus-resistant tomato plants upon virus inoculation, and its silencing abolishes resistance.  

PubMed

To discover genes involved in tomato resistance to Tomato yellow leaf curl virus (TYLCV), we previously compared cDNA libraries from susceptible (S) and resistant (R) tomato lines. Among the genes preferentially expressed in R plants and upregulated by TYLCV infection was a gene encoding a lipocalin-like protein. This gene was termed Solanum lycopersicum virus resistant/susceptible lipocalin (SlVRSLip). The SlVRSLip structural gene sequence of R and S plants was identical. SlVRSLip was expressed in leaves during a 15-day window starting about 40 days after sowing (20 days after planting). SlVRSLip was upregulated by Bemisia tabaci (the TYLCV vector) feeding on R plant leaves, and even more strongly upregulated following whitefly-mediated TYLCV inoculation. Silencing of SlVRSLip in R plants led to the collapse of resistance upon TYLCV inoculation and to a necrotic response along the stem and petioles accompanied by ROS production. Contrary to previously identified tomato lipocalin gene DQ222981, SlVRSLip was not regulated by cold, nor was it regulated by heat or salt. The expression of SlVRSLip was inhibited in R plants in which the hexose transporter gene LeHT1 was silenced. In contrast, the expression of LeHT1 was not inhibited in SlVRSLip-silenced R plants. Hence, in the hierarchy of the gene network conferring TYLCV resistance, SlVRSLip is downstream of LeHT1. Silencing of another gene involved in resistance, a Permease-I like protein, did not affect the expression of SlVRSLip and LeHT1; expression of the Permease was not affected by silencing SlVRSLip or LeHT1, suggesting that it does not belong to the same network. The triple co-silencing of SlVRSLip, LeHT1 and Permease provoked an immediate cessation of growth of R plants upon infection and the accumulation of large amounts of virus. SlVRSLip is the first lipocalin-like gene shown to be involved in resistance to a plant virus. PMID:22843056

Sade, Dagan; Eybishtz, Assaf; Gorovits, Rena; Sobol, Iris; Czosnek, Henryk

2012-07-29

107

Squash operator and symmetry  

SciTech Connect

This article begins with a simple proof of the existence of squash operators compatible with the Bennett-Brassard 1984 (BB84) protocol that suits single-mode as well as multimode threshold detectors. The proof shows that, when a given detector is symmetric under cyclic group C{sub 4}, and a certain observable associated with it has rank two as a matrix, then there always exists a corresponding squash operator. Next, we go on to investigate whether the above restriction of 'rank two' can be eliminated; i.e., is cyclic symmetry alone sufficient to guarantee the existence of a squash operator? The motivation behind this question is that, if this were true, it would imply that one could realize a device-independent and unconditionally secure quantum key distribution protocol. However, the answer turns out to be negative, and moreover, one can instead prove a no-go theorem that any symmetry is, by itself, insufficient to guarantee the existence of a squash operator.

Tsurumaru, Toyohiro [Mitsubishi Electric Corporation, Information Technology R and D Center, 5-1-1 Ofuna, Kamakura-shi, Kanagawa, 247-8501 Japan (Japan)

2010-01-15

108

Faithful Squashed Entanglement  

NASA Astrophysics Data System (ADS)

Squashed entanglement is a measure for the entanglement of bipartite quantum states. In this paper we present a lower bound for squashed entanglement in terms of a distance to the set of separable states. This implies that squashed entanglement is faithful, that is, it is strictly positive if and only if the state is entangled. We derive the lower bound on squashed entanglement from a lower bound on the quantum conditional mutual information which is used to define squashed entanglement. The quantum conditional mutual information corresponds to the amount by which strong subadditivity of von Neumann entropy fails to be saturated. Our result therefore sheds light on the structure of states that almost satisfy strong subadditivity with equality. The proof is based on two recent results from quantum information theory: the operational interpretation of the quantum mutual information as the optimal rate for state redistribution and the interpretation of the regularised relative entropy of entanglement as an error exponent in hypothesis testing. The distance to the set of separable states is measured in terms of the LOCC norm, an operationally motivated norm giving the optimal probability of distinguishing two bipartite quantum states, each shared by two parties, using any protocol formed by local quantum operations and classical communication (LOCC) between the parties. A similar result for the Frobenius or Euclidean norm follows as an immediate consequence. The result has two applications in complexity theory. The first application is a quasipolynomial-time algorithm solving the weak membership problem for the set of separable states in LOCC or Euclidean norm. The second application concerns quantum Merlin-Arthur games. Here we show that multiple provers are not more powerful than a single prover when the verifier is restricted to LOCC operations thereby providing a new characterisation of the complexity class QMA.

Brandão, Fernando G. S. L.; Christandl, Matthias; Yard, Jon

2011-09-01

109

Ectopic Expression of BraYAB1-702, a Member of YABBY Gene Family in Chinese Cabbage, Causes Leaf Curling, Inhibition of Development of Shoot Apical Meristem and Flowering Stage Delaying in Arabidopsis thaliana  

PubMed Central

YABBY gene family plays an important role in the polarity development of lateral organs. We isolated the BraYAB1-702 gene, a member of the YABBY gene family, from young leaves of Chinese cabbage line 06J45. The full-length gene has a 937 bp CDNA sequence and contains an open reading frame (ORF) of 702 bp. The subcellular localization analysis showed that the expression product of the gene was localized in the nucleus. Ectopic expression of BraYAB1-702 in Arabidopsis thaliana caused leaf curling from the adaxial epidermises to abaxial epidermises; the partial abaxialization of the adaxial epidermises of leaves; leaf trichomes and stomata numbers being significantly increased; the plants being severely stunted; the flowering stage being remarkably delayed and inhibiting the development of shoot apical meristem (SAM) with the down-regulation of the expression of SHOOT MERISTEMLESS (STM), Brevipedicellus (BP) and KNAT2 which were related to the development of shoot apical meristem. These results from the present research help to reveal the molecular mechanism of BraYAB1-702 gene in the establishment of adaxial–abaxial polarity of the lateral organs in Chinese cabbage.

Zhang, Xin-Ling; Yang, Ze-Ping; Zhang, Jing; Zhang, Lu-Gang

2013-01-01

110

First report of Pepper leaf curl Bangladesh virus strain associated with bitter gourd ( Momordica charantia L.) yellow mosaic disease in India  

Microsoft Academic Search

A severe yellow mosaic disease with a significant disease incidence was observed on bitter gourd (Momordica charantia L.) during a survey of different locations around Gorakhpur, Uttar Pradesh, India in 2008. Polymerase chain reaction (PCR)\\u000a was carried out using total DNA isolated from infected leaf samples and a pair of begomovirus-specific primers. The expected\\u000a size (?1300 bp) amplicon was detected

S. K. RajA; S. K. SnehiA; M. S. KhanA; A. K. TiwariB; G. P. RaoB

2010-01-01

111

Squash(ed): Craniofacial and vertebral injury from collision on squash court  

PubMed Central

Squash is a popular racquet sport not usually associated with severe head or spinal injury. The incidence of squash-related injury ranges from 35.5 to 80.9 per 100,000 players, with the most common sites being the lower-limbs and eyes. We present a case of extensive traumatic craniomaxillofacial and vertebral injury resulting from collision on a squash court, without use of protective gear. The patient sustained fractures of the frontal bone, orbits, maxillae, zygomas, the first and second cervical vertebrae and the spinous process of the seventh cervical vertrebra. This is the first case of squash-related injury with such extensive craniofacial and vertebral involvement. This unique case required multiple surgical procedures as well as an extensive admission to the intensive care unit and highlights the risk of significant craniomaxillofacial trauma in sports not usually associated with such injuries.

Atik, Alp; Krilis, Matthew; Parker, Geoffrey

2012-01-01

112

First curl, then wrinkle.  

PubMed

The excellent properties of elastomers are exploited to trigger wrinkling instabilities in curved shells. Micro- and nano-fibres are produced by electrospinning and UV irradiated: each fibre consists of a soft core and a stiff outer half-shell. Upon solvent de-swelling, the fibres curl because the shell and the core have different natural lengths. Wrinkling only starts after the fibre has attained a well-defined helical shape. A simple analytical model is proposed to find the curling curvature and wrinkle wavelength, as well as the transition between the "curling" and "wrinkling" regimes. This new instability resembles that found in the tendrils of climbing plants as they dry and lignify. PMID:23959824

Trindade, Ana C; Canejo, João P; Teixeira, Paulo I C; Patrício, Pedro; Godinho, Maria H

2013-08-19

113

Discovering host genes involved in the infection by the Tomato Yellow Leaf Curl Virus complex and in the establishment of resistance to the virus using Tobacco Rattle Virus-based post transcriptional gene silencing.  

PubMed

The development of high-throughput technologies allows for evaluating gene expression at the whole-genome level. Together with proteomic and metabolomic studies, these analyses have resulted in the identification of plant genes whose function or expression is altered as a consequence of pathogen attacks. Members of the Tomato yellow leaf curl virus (TYLCV) complex are among the most important pathogens impairing production of agricultural crops worldwide. To understand how these geminiviruses subjugate plant defenses, and to devise counter-measures, it is essential to identify the host genes affected by infection and to determine their role in susceptible and resistant plants. We have used a reverse genetics approach based on Tobacco rattle virus-induced gene silencing (TRV-VIGS) to uncover genes involved in viral infection of susceptible plants, and to identify genes underlying virus resistance. To identify host genes with a role in geminivirus infection, we have engineered a Nicotiana benthamiana line, coined 2IRGFP, which over-expresses GFP upon virus infection. With this system, we have achieved an accurate description of the dynamics of virus replication in space and time. Upon silencing selected N. benthamiana genes previously shown to be related to host response to geminivirus infection, we have identified eighteen genes involved in a wide array of cellular processes. Plant genes involved in geminivirus resistance were studied by comparing two tomato lines: one resistant (R), the other susceptible (S) to the virus. Sixty-nine genes preferentially expressed in R tomatoes were identified by screening cDNA libraries from infected and uninfected R and S genotypes. Out of the 25 genes studied so far, the silencing of five led to the total collapse of resistance, suggesting their involvement in the resistance gene network. This review of our results indicates that TRV-VIGS is an exquisite reverse genetics tool that may provide new insights into the molecular mechanisms underlying plant infection and resistance to infection by begomoviruses. PMID:23524390

Czosnek, Henryk; Eybishtz, Assaf; Sade, Dagan; Gorovits, Rena; Sobol, Iris; Bejarano, Eduardo; Rosas-Díaz, Tábata; Lozano-Durán, Rosa

2013-03-22

114

Tomato yellow leaf curl virus infection of a resistant tomato line with a silenced sucrose transporter gene LeHT1 results in inhibition of growth, enhanced virus spread, and necrosis.  

PubMed

To identify genes involved in resistance of tomato to Tomato yellow leaf curl virus (TYLCV), cDNA libraries from lines resistant (R) and susceptible (S) to the virus were compared. The hexose transporter LeHT1 was found to be expressed preferentially in R tomato plants. The role of LeHT1 in the establishment of TYLCV resistance was studied in R plants where LeHT1 has been silenced using Tobacco rattle virus-induced gene silencing (TRV VIGS). Following TYLCV inoculation, LeHT1-silenced R plants showed inhibition of growth and enhanced virus accumulation and spread. In addition, a necrotic response was observed along the stem and petioles of infected LeHT1-silenced R plants, but not on infected not-silenced R plants. This response was specific of R plants since it was absent in infected LeHT1-silenced S plants. Necrosis had several characteristics of programmed cell death (PCD): DNA from necrotic tissues presented a PCD-characteristic ladder pattern, the amount of a JNK analogue increased, and production of reactive oxygen was identified by DAB staining. A similar necrotic reaction along stem and petioles was observed in LeHT1-silenced R plants infected with the DNA virus Bean dwarf mosaic virus and the RNA viruses Cucumber mosaic virus and Tobacco mosaic virus. These results constitute the first evidence for a necrotic response backing natural resistance to TYLCV in tomato, confirming that plant defense is organized in multiple layers. They demonstrate that the hexose transporter LeHT1 is essential for the expression of natural resistance against TYLCV and its expression correlates with inhibition of virus replication and movement. PMID:19946703

Eybishtz, Assaf; Peretz, Yuval; Sade, Dagan; Gorovits, Rena; Czosnek, Henryk

2009-11-28

115

Discovering Host Genes Involved in the Infection by the Tomato Yellow Leaf Curl Virus Complex and in the Establishment of Resistance to the Virus Using Tobacco Rattle Virus-based Post Transcriptional Gene Silencing  

PubMed Central

The development of high-throughput technologies allows for evaluating gene expression at the whole-genome level. Together with proteomic and metabolomic studies, these analyses have resulted in the identification of plant genes whose function or expression is altered as a consequence of pathogen attacks. Members of the Tomato yellow leaf curl virus (TYLCV) complex are among the most important pathogens impairing production of agricultural crops worldwide. To understand how these geminiviruses subjugate plant defenses, and to devise counter-measures, it is essential to identify the host genes affected by infection and to determine their role in susceptible and resistant plants. We have used a reverse genetics approach based on Tobacco rattle virus-induced gene silencing (TRV-VIGS) to uncover genes involved in viral infection of susceptible plants, and to identify genes underlying virus resistance. To identify host genes with a role in geminivirus infection, we have engineered a Nicotiana benthamiana line, coined 2IRGFP, which over-expresses GFP upon virus infection. With this system, we have achieved an accurate description of the dynamics of virus replication in space and time. Upon silencing selected N. benthamiana genes previously shown to be related to host response to geminivirus infection, we have identified eighteen genes involved in a wide array of cellular processes. Plant genes involved in geminivirus resistance were studied by comparing two tomato lines: one resistant (R), the other susceptible (S) to the virus. Sixty-nine genes preferentially expressed in R tomatoes were identified by screening cDNA libraries from infected and uninfected R and S genotypes. Out of the 25 genes studied so far, the silencing of five led to the total collapse of resistance, suggesting their involvement in the resistance gene network. This review of our results indicates that TRV-VIGS is an exquisite reverse genetics tool that may provide new insights into the molecular mechanisms underlying plant infection and resistance to infection by begomoviruses.

Czosnek, Henryk; Eybishtz, Assaf; Sade, Dagan; Gorovits, Rena; Sobol, Iris; Bejarano, Eduardo; Rosas-Diaz, Tabata; Lozano-Duran, Rosa

2013-01-01

116

How wet paper curls  

Microsoft Academic Search

When a piece of tracing paper is placed gently on the surface of a bath of water, it rapidly curls up from one edge and rolls up due to the swelling of the side in contact with water. With time, as the swelling front propagates through the thickness of the paper, the paper gradually uncurls itself and eventually straightens out.

E. Reyssat; L. Mahadevan

2011-01-01

117

Disease Control for Squash in Florida  

Microsoft Academic Search

Summer and winter squash are grown commercially throughout the state of Florida. In the middle of the winter, southern Florida is the primary supplier of fresh squash for the produce departments of supermarkets all over the nation. In 1997-1998, squash was harvested from 12,500 acres in the state with a total value of $54.5 million. Several diseases must be controlled

Pam Roberts; Ken Pernezny

2001-01-01

118

Squashed black holes in Goedel universes  

SciTech Connect

We investigate five-dimensional rotating and charged black holes with squashed horizons in Goedel universes. The general solution was recently derived by applying a squashing transformation on the general nonextremal charged and rotating black hole in the Goedel universe found by Wu. We give a discussion of the squashed geometry and also consider its lift to ten dimensions and discuss the T-dual geometry. Finally, using the counterterms method we compute its conserved charges and explore its thermodynamics.

Stelea, Cristian; Schleich, Kristin; Witt, Donald [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1 (Canada)

2008-12-15

119

Cestrum yellow leaf curling virus promoters  

US Patent & Trademark Office Database

This invention describes novel DNA sequences that function as promoters of transcription of associated nucleotide sequences. More specifically, this invention describes DNA sequences conferring constitutive expression to an associated nucleotide sequence. The invention also describes recombinant sequences containing such promoter sequences. The said recombinant DNA sequences may be used to create transgenic plants, but especially plants expressing a nucleotide sequence of interest at all times and in most tissues and organs.

Hohn; Thomas (Arlesheim, CH); Stavolone; Livia (Zurich, CH); De Haan; Petrus Theodorus (Oegstgeest, NL); Ligon; Hope Thompson (Apex, NC); Kononova; Maria (Raleigh, NC)

2007-01-23

120

Distributional geometry of squashed cones  

NASA Astrophysics Data System (ADS)

A regularization procedure developed by D. V. Fursaev and S. N. Solodukhin, [Phys. Rev. D 52, 2133 (1995)PRVDAQ0556-2821] for the integral curvature invariants on manifolds with conical singularities is generalized to the case of squashed cones. In general, the squashed conical singularities do not have rotational O(2) symmetry in a subspace orthogonal to a singular surface ? so that the surface is allowed to have extrinsic curvatures. A new feature of the squashed conical singularities is that the surface terms in the integral invariants, in the limit of a small angle deficit, now depend also on the extrinsic curvatures of ?. A case of invariants which are quadratic polynomials of the Riemann curvature is elaborated in different dimensions and applied to several problems related to entanglement entropy. The results are in complete agreement with computations of the logarithmic terms in entanglement entropy of 4D conformal theories [S. N. Solodukhin, Phys. Lett. B 665, 305 (2008)PYLBAJ0370-2693]. Among other applications of the suggested method are logarithmic terms in entanglement entropy of nonconformal theories and a holographic formula for entanglement entropy in theories with gravity duals.

Fursaev, Dmitri V.; Patrushev, Alexander; Solodukhin, Sergey N.

2013-08-01

121

Energy Requirements of Squash and Racquetball.  

ERIC Educational Resources Information Center

Oxygen consumption and heart rate were monitored in 32 male adults playing racquetball and squash. Results indicated that energy expenditure in racquetball was only slightly less than for squash, suggesting that either sport is appropriate for developing and maintaining fitness in healthy adults. (Author/CB)

Montpetit, Richard R.; And Others

1987-01-01

122

Squash vein yellowing virus, a novel ipomovirus, isolated from squash and watermelon in Florida  

Technology Transfer Automated Retrieval System (TEKTRAN)

A novel whitefly-transmitted member of the family Potyviridae was isolated from a squash plant (Cucurbita pepo) with vein yellowing symptoms in Florida. The virus, for which the name Squash vein yellowing virus (SqVYV) is proposed, has flexuous rod-shaped particles of ~840 nm in length. SqVYV was ...

123

Shear velocity profiles associated with auroral curls  

Microsoft Academic Search

Optical observations using high-resolution television cameras frequently show that auroral curls are associated with shear velocities in the apparent optical flow. The present study examines in detail one particular curl system event which happened to yield sufficient resolution to determine the fine structure of velocity and vorticity profiles by means of a new analysis technique. Those observations of curl system

J. Vogt; H. U. Frey; G. Haerendel; H. Höfner; J. L. Semeter

1999-01-01

124

Prediction of moisture curling of concrete slab  

Microsoft Academic Search

Moisture curling occurs due to non-uniform moisture distribution in a concrete slab. The curled geometry and self-weight of\\u000a the slab induce undesirable high stress region near the drying surface, and may cause cracks when external wheel loadings\\u000a are applied. Therefore, alleviating the degree of curling is an important issue in pavement design, and a proper prediction\\u000a scheme is essential in

Chang Joon Lee; David A. Lange; Yi-Shi Liu

2011-01-01

125

Audience Effects on Squash Players' Performance  

Microsoft Academic Search

In an unobtrusive field study of audience effects, the performance of 20 expert and 20 novice squash players was assessed under three randomly varied conditions: no audience, male audience, and female audience. It was expected that in accordance with Zajonc's nonspecific drive hypothesis, the performance of expert players would improve and that of novice players would deteriorate when observed by

Joseph P. Forgas; Greg Brennan; Susan Howe; John F. Kane; Shirley Sweet

1980-01-01

126

Swept Away: Exploring the Physics of Curling  

ERIC Educational Resources Information Center

|Studying the Olympic sport of curling is a fun and engaging way to learn about the concepts of friction, forces, momentum, and Newton's laws. Each winter, the author takes her eighth-grade physical science class on a field trip to experience curling firsthand. This field trip has become a favorite of the eighth graders at Capitol Hill Day School…

Esser, Liza

2011-01-01

127

Modelling curling as a Markov process  

Microsoft Academic Search

Markov processes have been used to model a variety of sports such as football, jai alai and baseball. Curling has a scoring system similar to baseball; both progress on an inning by inning basis. This suggests that curling could also be modeled as a Markov process. We will develop such a model and compare some basic strategies.

Kent J. Kostuk; Keith A. Willoughby; Anton P. H. Saedt

2001-01-01

128

Swept Away: Exploring the Physics of Curling  

ERIC Educational Resources Information Center

Studying the Olympic sport of curling is a fun and engaging way to learn about the concepts of friction, forces, momentum, and Newton's laws. Each winter, the author takes her eighth-grade physical science class on a field trip to experience curling firsthand. This field trip has become a favorite of the eighth graders at Capitol Hill Day School…

Esser, Liza

2011-01-01

129

Resistance to Cucurbit Leaf Crumple Virus in Melon  

Technology Transfer Automated Retrieval System (TEKTRAN)

Cucurbit leaf crumple virus (CuLCrV) is a geminivirus common in melons (Cucumis melo L.) planted from July through September in the desert southwest U.S.A. Symptoms include chlorotic leaf spots and terminal buds, leaf curling and crumpling and interveinal yellowing, and plants may be stunted in size...

130

Reduction of type IIB on squashed Sasaki-Einstein manifolds  

NASA Astrophysics Data System (ADS)

We present a consistent truncation of type IIB supergravity on squashed Sasaki-Einstein manifolds, leading to half-maximal gauged supergravity in five dimensions. We comment on the holographic picture of consistency.

Cassani, D.

2011-07-01

131

[Effects of root exudates of squash grafted with cucumber shoot on seed germination].  

PubMed

Cucumber (Cucumis statirus L.) is commonly cultivated by grafting on squash (Cucurbita moschata) in commercial production. The effects of root exudates of squash grafted with cucumber on seed germination rate of cucumber and squash were tested. In this study, the exudates of cucumber-grafted squash roots were continuously collected with XAD-4 resin, and were further diluted with distilled water to make 5%, 10%, 20% and 40% concentrations. Cucumber and squash seeds were used for bioassay. The seeds were germinated in glass petri dishes with 2 filter papers at bottoms and containing 5 mL the diluted root exudates. The results showed that the exudates of cucumber-grafted squash roots significantly inhibit germination rate, radicel and hypocotyl elongation in cucumber and squash, and the inhibitory rate positively correlate with the concentration of the grafted cucumber root exudates. So grafted cucumber still have allelopathy. The exudates of cucumber-grafted squash roots significantly stimulated IAA oxidase activity in cucumber and squash. As a result, they decrease IAA level in cucumber and squash, and restrained their growth. The exudates of cucumber-grafted squash roots also decrease significantly the activities of amylase and alpha-amylase in cucumber and squash, and this decrease effects were strengthening with the increasing of the concentration of the grafted cucumber root exudates. So the exudates of cucumber-grafted squash roots can inhibit the hydrolysis and utilization of starch in cucumber and squash, and thereby suppress germination and seedling growth. PMID:15840942

Qi, Jian-Hua; Liang, Yin-Li; Liang, Zong-Suo

2005-04-01

132

What do adult squash players think about protective eyewear?  

PubMed Central

OBJECTIVE: To determine the attitudes of adult squash players towards protective eyewear. METHODS: A survey of 197 competition and social squash players from seven squash centres in the outer eastern suburbs of Melbourne, Australia was conducted in September to October 1995. Information about participation in squash, previous injuries, use of protective eyewear, barriers towards eyewear use, and attitudes towards protective eyewear was obtained by a self report questionnaire. RESULTS: Squash is a popular sport in Australia. Of the players surveyed, 6% played in junior competitions, 67% in senior competitions, and 27% were social players. Most had been playing for more than ten years. Some 15% of players had previously suffered an eye injury, most commonly caused by a racquet. Less than 10% of players reported that they wore protective eyewear when they played squash, and 35% of these wore prescriptive lenses which they considered to be protective. The major reason for not wearing protective eyewear was the perception that it was unnecessary. Poor vision and a lack of comfort were also stated as reasons by a significant number of players. More than half (57%) of the respondents agreed that more players should wear protective eyewear, yet only 16% thought it should be compulsory for all players. There was considerable support for protective eyewear use by junior players, however. CONCLUSIONS: The rate of protective eyewear use is low among competition and social squash players in Melbourne. The major areas that need to be addressed are the ignorance of the need for protective eyewear among social and experienced players and the mistaken belief that prescription lenses provide adequate protection on a squash court. ???

Finch, C.; Vear, P.

1998-01-01

133

7 CFR 319.56-48 - Conditions governing the entry of baby squash and baby courgettes from Zambia.  

Code of Federal Regulations, 2010 CFR

...of baby squash and baby courgettes from Zambia. 319.56-48 Section 319.56-48...of baby squash and baby courgettes from Zambia. Baby squash (Curcurbita maxima ...into the continental United States from Zambia only under the conditions...

2009-01-01

134

7 CFR 319.56-48 - Conditions governing the entry of baby squash and baby courgettes from Zambia.  

Code of Federal Regulations, 2010 CFR

...of baby squash and baby courgettes from Zambia. 319.56-48 Section 319.56-48...of baby squash and baby courgettes from Zambia. Baby squash (Curcurbita maxima ...into the continental United States from Zambia only under the conditions...

2010-01-01

135

The Motion of Rapidly Rotating Curling Rocks  

Microsoft Academic Search

We present a physical model that accounts for the motion of rapidly rotating curling rocks. By rapidly rotating we mean that the rotational speed of the contact annulus of the rock about the centre of mass is large compared with the translational speed of the centre of mass. The principal features of the model are: (i) that the kinetic friction

Mark R. A. Shegelski; Ross Niebergall B

1999-01-01

136

Preparation of Curled Microfibers by Electrospinning with Tip Collector  

NASA Astrophysics Data System (ADS)

We report on curled polyvinylpyrrolidone (PVP) microfibers fabricated by a modified electrospinning with a small nail as the tip collector. PVP (45 wt%) ethanol solution is electrospun under different working voltages ranging from 10 to 15, 20, 30 and 40 kV. It is found that with the increase of working voltage, the proportion of the curled fibers increases and the uniformity of the curled fibers improves, as well as the repeat distance of the curled structures reducing. Particularly, some curled fibers develop into helical structures under relatively high voltages. Further analyses indicate that the formation mechanism for the curled polymer fibers can be ascribed to electrical driven bending instability and/or mechanical jet buckling when hitting the collector surface. This modified electrospinning technique may be a cost-effective approach for the mass production of curled microfibers.

Tang, Cheng-Chun; Chen, Jun-Chi; Long, Yun-Ze; Yin, Hong-Xing; Sun, Bin; Zhang, Hong-Di

2011-05-01

137

Validation Studies of the The Short Questionnaire to assess Health–enhancing Physical activity (SQUASH)  

Cancer.gov

Validation Studies of the The Short Questionnaire to assess Health–enhancing Physical activity (SQUASH) Wendel-Vos et al. 2003 See reference #65 Methods Relationship between SQUASH and CSA Activity Monitor (Spearman correlations) Sample 36 men and 14

138

Squashed embedding of E-R schemas in hypercubes  

SciTech Connect

The authors have been investigating an approach to parallel database processing based on treating entity-relationship (E-R) schema graphs as dataflow graphs. A prerequisite is to find appropriate embeddings of the schema graphs into a processor graph, in this case a hypercube. This paper studies a class of adjacency preserving embeddings that map a node in the schema graph into a subcube (relaxed squashed or RS embeddings) or into adjacent subcubes (relaxed extended squashed or RES embeddings) of a hypercube. The mapping algorithm is motivated by the technique used for state assignment in asynchronous sequential machines. In general, the dimension of the cube required for squashed embedding of a graph is called the weak cubical dimension or WCD of the graph.

Baru, C.K.; Goel, P. (Advanced Computer Architecture Lab., Dept. of Electrical Engineering and Computer Science, Univ. of Michigan, Ann Arbor, MI (US))

1990-04-01

139

Expression of Ascorbic Acid Oxidase in Zucchini Squash (Cucurbita pepo L.) 1  

PubMed Central

The expression of ascorbic acid oxidase was studied in zucchini squash (Cucurbita pepo L.), one of the most abundant natural sources of the enzyme. In the developing fruit, specific activity of ascorbic acid oxidase was highest between 4 and 6 days after anthesis. Protein and mRNA levels followed the same trend as enzyme activity. Highest growth rate of the fruit occurred before 6 days after anthesis. Within a given fruit, ascorbic acid oxidase activity and mRNA level were highest in the epidermis, and lowest in the central placental region. In leaf tissue, ascorbic acid oxidase activity was higher in young leaves, and very low in old leaves. Within a given leaf, enzyme activity was highest in the fast-growing region (approximately the lower third of the blade), and lowest in the slow-growing region (near leaf apex). High expression of ascorbic acid oxidase at a stage when rapid growth is occurring (in both fruits and leaves), and localization of the enzyme in the fruit epidermis, where cells are under greatest tension during rapid growth in girth, suggest that ascorbic acid oxidase might be involved in reorganization of the cell wall to allow for expansion. Based on the known chemistry of dehydroascorbic acid, the end product of the ascorbic acid oxidase-catalyzed reaction, we have proposed several hypotheses to explain how dehydroascorbic acid might cause cell wall “loosening.” ImagesFigure 3Figure 4Figure 5

Lin, Liang-Shiou; Varner, Joseph E.

1991-01-01

140

Game analysis and energy requirements of elite squash.  

PubMed

The aim of this study was to describe the game characteristics and energy requirement in elite squash. Seven players (ranked 1-25 in their national federation, including the world number 1) performed a squash-specific incremental test to volitional exhaustion and 3 squash games simulating competition. Pulmonary gas exchanges, heart rate (HR), and blood lactate concentration ([LA]) were recorded by portable analyzers. Energy expenditure (EE(VO(2))) was evaluated by indirect calorimetry. Temporal structure was determined from video recordings. The mean oxygen uptake (VO(2)), HR, EE(VO(2)), and [LA] were 54.4 +/- 4.8 ml x min(-1) x kg(-1) (86 +/- 9% of VO(2)max reached in the incremental squash test), 177 +/- 10 beats x min(-1) (92 +/- 3% of HRmax), 4,933 +/- 620 kJ x h(-1), and 8.3 +/- 3.4 mmol x L(-1), respectively. Time spent >90% of VO(2)max and HRmax was 24 +/- 29% and 69 +/- 18% of the total match duration, respectively. [LA] was correlated (R = 0.87; p = 0.01) with time spent >90% of VO(2)max. The mean rally duration yielded 18.6 +/- 4.6 s, and 34.6% of the rallies were <10 s, and 32.6% were >21 s. The effective playing time was 69.7 +/- 4.7%. World-standard squash is predominantly a high-intensity aerobic activity with great emphasize on the anaerobic energy systems and a high uncertainty in the course of match play. To improve squash results, coaches should plan training according to the characteristics of the sport. By showing the contribution of the different energy pathways and variables easily controllable during training sessions (e.g., HR, rally duration, lactate), the accurate prescription of conditioning session is improved. PMID:17685699

Girard, Olivier; Chevalier, Renaud; Habrard, Mickael; Sciberras, Paul; Hot, Philippe; Millet, Grégoire P

2007-08-01

141

Squash bug: Vector of cucurbit yellow vine disease pathogen  

Technology Transfer Automated Retrieval System (TEKTRAN)

Cucurbits, especially watermelon and cantaloupe, are important crops in the South Central region of the U.S. and are affected by a variety of insect and disease complexes. Prominent among these are the squash bug, Anasa tristis (DeGeer) and a destructive vine decline, cucurbit yellow vine disease (...

142

Geodetic precession in squashed Kaluza-Klein black hole spacetimes  

SciTech Connect

We investigate the geodetic precession effect of a parallelly transported spin vector along a circular geodesic in five-dimensional squashed Kaluza-Klein black hole spacetime. Then we derive the higher-dimensional correction of the precession angle to general relativity. We find that the correction is proportional to the square of (size of extra dimension)/(gravitational radius of central object)

Matsuno, Ken; Ishihara, Hideki [Department of Mathematics and Physics, Graduate School of Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585 (Japan)

2009-11-15

143

Preceramic Adoption of Peanut, Squash, and Cotton in Northern Peru  

Microsoft Academic Search

The early development of agriculture in the New World has been assumed to involve early farming in settlements in the Andes, but the record has been sparse. Peanut (Arachis sp.), squash (Cucurbita moschata), and cotton (Gossypium barbadense) macrofossils were excavated from archaeological sites on the western slopes of the northern Peruvian Andes. Direct radiocarbon dating indicated that these plants grew

Tom D. Dillehay; Jack Rossen; Thomas C. Andres; David E. Williams

2007-01-01

144

Spatial ability in highly skilled women squash players.  

PubMed

13 women international squash players, 13 players of low ability, and 13 non-players were administered the Space Relations Form T of the Differential Aptitude Tests, a test of spatial ability. The data, analyzed by3 a one-way analysis of variance, yielded no significant differences among groups. PMID:7402881

Graydon, J

1980-06-01

145

H(curl) Auxiliary Mesh Preconditioning  

SciTech Connect

This paper analyzes a two-level preconditioning scheme for H(curl) bilinear forms. The scheme utilizes an auxiliary problem on a related mesh that is more amenable for constructing optimal order multigrid methods. More specifically, we analyze the case when the auxiliary mesh only approximately covers the original domain. The latter assumption is important since it allows for easy construction of nested multilevel spaces on regular auxiliary meshes. Numerical experiments in both two and three space dimensions illustrate the optimal performance of the method.

Kolev, T V; Pasciak, J E; Vassilevski, P S

2006-08-31

146

Third-order Nedelec curl-conforming finite element  

Microsoft Academic Search

Summary form only given. Curl-conforming elements approximate the unknown vector field along the boundary of the finite element in terms of the tangential component of the field over the boundary by means of vectorial basis functions. Thus, they are appropiate for the approximation of the magnetic (or electric) field. Among the curl-conforming elements in the literature, it is worth mentioning

L. E. Garcia-Castillo; A. J. Ruiz-Genoves; M. Salazar-Palma; T. K. Sarkar

2002-01-01

147

The Curl of a Vector Field: Beyond the Formula  

ERIC Educational Resources Information Center

|It has been widely acknowledged that there is some discrepancy in the teaching of vector calculus in mathematics courses and other applied fields. The curl of a vector field is one topic many students can calculate without understanding its significance. In this paper, we explain the origin of the curl after presenting the standard mathematical…

Burch, Kimberly Jordan; Choi, Youngna

2006-01-01

148

Comparative fitness of a wild squash species and three generations of hybrids between wild x virus-resistant transgenic squash.  

PubMed

We compared some fitness components of the wild squash species Cucurbita pepo spp. ovifera var. texana (C. texana) and three generations of hybrids (F1, BC1, and BC2) between C. texana and commercial transgenic squash CZW-3 over three consecutive years under field conditions of low (LDP) and high disease pressure (HDP) by Cucumber mosaic virus (CMV), Zucchini yellow mosaic virus (ZYMV) and Watermelon mosaic virus (WMV). Transgenic squash CZW-3 expresses the coat protein (CP) genes of CMV, ZYMV, and WMV, and is resistant to these three aphid-borne viruses. Across all HDP trials, transgenic BC1 and BC2 hybrids expressing the three CP genes grew more vigorously, displayed resistance to CMV, ZYMV, and WMV, and produced a greater number of mature fruits and viable seeds than nontransgenic hybrid segregants and C. texana. Transgenic F1 hybrids behaved similarly to BC1 and BC2 hybrids but grew less vigorously than C. texana. In contrast, across all LDP trials, C. texana outperformed the transgenic and nontransgenic hybrid segregants. Further, only one back cross was necessary to recover individuals with most of the C. texana characteristics and yet maintain virus resistance. Our data suggest that C. texana acquiring CP transgenes upon hybridization and introgression could have a selective advantage if CMV, ZYMV, and WMV are severely limiting the growth and reproductibility of wild squash populations. PMID:15612352

Fuchs, Marc; Chirco, Ellen M; McFerson, Jim R; Gonsalves, Dennis

149

EFFECT OF LEAF EXPLANTS ORIENTATION ON ADVENTITIOUS SHOOT REGENERATION OF PEAR  

Technology Transfer Automated Retrieval System (TEKTRAN)

The literature on adventitious shoot regeneration is contradictory with respect to the effect of orientation of leaf explants with regard to the medium surface. Few studies have compared both adaxial and abaxial surfaces. The tendency of leaf explants to expand, curl, and lose complete contact wit...

150

Racquet Sports: Tennis, Badminton, Squash, Racquetball, and Handball  

Microsoft Academic Search

\\u000a Racquet sports make up an eclectic group of court activities that can be quite diverse. In this chapter we focus on the following\\u000a racquet sports: tennis, badminton, squash, racquetball, and handball. Though it is beyond the scope of this chapter, it is\\u000a paramount that readers become acquainted with certain background information on each of these individual sports including\\u000a developmental history,

Richard T. Bouché

151

Simulation of Curl Compensation in MEMS Micromirror  

NASA Astrophysics Data System (ADS)

This paper reports a design to compensate overlapping area reduction in MEMS Micromirror. The electromechanical behavior of a 300x300 m mirror actuated by electrostatic comb drive is simulated by CoventorWareTM. The interdigitated fingers are 240 µm long and 20 µm wide separated by 20 µm gap. The displacement of the mirror is compared when the frame of stator is released and fixed. The simulation shows that released-frame stator produces more displacement in z direction than fixed-frame stator by the factor of 3 when 50V DC voltage is applied. The improvement in micromirror actuation is as a result of the increase of overlapping area provided by curl compensation with released-frame approach. Therefore, the released-frame design is a promising method to reduce input voltage and enhance efficiency of electrostatic comb drive micromirror.

Tuantranont, Adisorn; Hemarat, Karawik; Wisitsoraat, Anurat

2006-04-01

152

Physical curl forces: dipole dynamics near optical vortices  

NASA Astrophysics Data System (ADS)

The force on a particle with complex electric polarizability is known to be not derivable from a potential, so its curl is non-zero. This ‘curl force’ is studied in detail for motion near an anisotropic optical vortex of arbitrary strength. Fundamental questions are raised by the fact that although the curl force requires the polarizability to have a non-zero imaginary part, reflecting absorption or scattering (‘dissipation’) in the internal dipole dynamics, the particle motion that it generates is non-dissipative (volume-preserving in the position-velocity state space).

Berry, M. V.; Shukla, Pragya

2013-10-01

153

Cucurbit leaf crumple virus detected in green beans in southwest Florida  

Technology Transfer Automated Retrieval System (TEKTRAN)

Cucurbit leaf crumple virus (CuLCrV) was recently reported infecting various cucurbit crops, including squash and watermelon, in Florida. In December 2007, CuLCrV was identified for the first time in green beans in southwest Florida. Although CuLCrV has previously been reported to infect beans in ...

154

7 CFR 319.56-36 - Watermelon, squash, cucumber, and oriental melon from the Republic of Korea.  

Code of Federal Regulations, 2010 CFR

...Watermelon, squash, cucumber, and oriental melon from the Republic of Korea. 319.56-36...Watermelon, squash, cucumber, and oriental melon from the Republic of Korea. Watermelon...cucumber (Cucumis sativus ), and oriental melon (Cucumis melo ) may be imported...

2010-01-01

155

7 CFR 319.56-36 - Watermelon, squash, cucumber, and oriental melon from the Republic of Korea.  

Code of Federal Regulations, 2010 CFR

...Watermelon, squash, cucumber, and oriental melon from the Republic of Korea. 319.56-36...Watermelon, squash, cucumber, and oriental melon from the Republic of Korea. Watermelon...cucumber (Cucumis sativus ), and oriental melon (Cucumis melo ) may be imported...

2009-01-01

156

7 CFR 319.56-36 - Watermelon, squash, cucumber, and oriental melon from the Republic of Korea.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 2013-01-01 false Watermelon, squash, cucumber, and oriental...Vegetables § 319.56-36 Watermelon, squash, cucumber, and oriental...from the Republic of Korea. Watermelon (Citrullus lanatus ),...

2013-01-01

157

The Sports Science of Curling: A Practical Review  

PubMed Central

Curling is a sport played on ice in which two teams each deliver 8 granite stones towards a target, or ‘house’. It is the only sport in which the trajectory of the projectile can be influenced after it has been released by the athlete. This is achieved by sweeping the ice in front of the stone to change the stone-ice friction and thereby enable to stone to travel further, curl more or stay straight. Hard sweeping is physically demanding. Different techniques of sweeping can also have different effects on the stone. This paper will review the current research behind sweeping a curling stone, outline the physiological demands of sweeping, the associated performance effects and suggest potential strategies of sweeping that can be used by both coaches and curling teams. Key points Sweeping a curling stone can be highly physically demanding. Effective sweeping requires a combination of downward force and brush head speed, determined by the stone velocity. Sweeping on the left or right of a stone can help the stone to remain straight or curl more depending on the rotation of the stone. This can lead to the development of sweeping and playing tactics and contribute to team selection.

Bradley, John L.

2009-01-01

158

Development of Mass Rearing Methods, and Novel Methods For Control of the Squash Bug, Anasa Tristis (De Geer) (Heteroptera: Coreidae)  

Technology Transfer Automated Retrieval System (TEKTRAN)

The Squash bug, Anasa tristis (De Geer), a major pest of squash, pumpkin, watermelon, cucumber and cantaloupe, uses piercing-sucking mouthparts to imbibe plant fluids. The severity of plant damage resulting from squash bug feeding causes extensive damage to stems resulting in wilting, fruit discolo...

159

Effect of temperature preconditioning on catalase, peroxidase, and superoxide dismutase in chilled zucchini squash  

Microsoft Academic Search

The development of chilling injury symptoms in zucchini squash (Cucurbita pepo L., cv. ‘Elite’) stored at 5 °C was delayed by preconditioning the fruit at a temperature of 15 °C for two days. This temperature preconditioning treatment suppressed the increase in peroxidase activity and reduced the decline of catalase activity in squash during subsequent storage at 5 °C. The superoxide

Chien Yi Wang

1995-01-01

160

Artificial feeding system for the squash bug, anasa tristis (de geer)(heteroptera: coreidae)  

Technology Transfer Automated Retrieval System (TEKTRAN)

Squash bugs, Anasa tristis, did not feed on liquid diet-filled sachets used tradionally for homopterans, or on pouchlike artificial feed source (AFS) containing a meridic diet developed for rearing the western tarnished plant bug. However, excised cubes of squash fruit, vacuum infiltrated with a su...

161

Local and Systemic Changes in Squash Gene Expression in Response to Silverleaf Whitefly Feeding  

PubMed Central

Squash genes (SLW1 and SLW3) induced systemically after silverleaf whitefly feeding were identified. Differences in the local and systemic expression of SLW1 and SLW3 after feeding by the closely related silverleaf and sweetpotato whiteflies were observed. Temporal and spatial studies showed that SLW1 and SLW3 were induced when second, third, and fourth nymphal instars were feeding. Although only barely detected after wounding and bacterial infection, SLW1 and SLW3 RNAs were abundant during water-deficit stress. Treatments with wound/defense signal molecules showed that SLW1 RNAs accumulated in response to methyl jasmonate and ethylene, whereas SLW3 was not regulated by known wound/defense signals, suggesting utilization of a novel mechanism for defense signal transduction. SLW1 RNAs accumulated during floral and fruit development, whereas SLW3 RNAs were not detected during vegetative or reproductive development. The potential roles of SLW1, an M20b peptidase–like protein, and SLW3, a ?-glucosidase–like protein, in defense and the leaf-silvering disorder are discussed.

van de Ven, Wilhelmina T. G.; LeVesque, Cynthia S.; Perring, Thomas M.; Walling, Linda L.

2000-01-01

162

Universal squash model for optical communications using linear optics and threshold detectors  

SciTech Connect

Transmission of photons through open-air or optical fibers is an important primitive in quantum-information processing. Theoretical descriptions of this process often consider single photons as information carriers and thus fail to accurately describe experimental implementations where any number of photons may enter a detector. It has been a great challenge to bridge this big gap between theory and experiments. One powerful method for achieving this goal is by conceptually squashing the received multiphoton states to single-photon states. However, until now, only a few protocols admit a squash model; furthermore, a recently proven no-go theorem appears to rule out the existence of a universal squash model. Here we show that a necessary condition presumed by all existing squash models is in fact too stringent. By relaxing this condition, we find that, rather surprisingly, a universal squash model actually exists for many protocols, including quantum key distribution, quantum state tomography, Bell's inequality testing, and entanglement verification.

Fung, Chi-Hang Fred; Chau, H. F. [Department of Physics and Center of Computational and Theoretical Physics, University of Hong Kong, Pokfulam Road (Hong Kong); Lo, Hoi-Kwong [Center for Quantum Information and Quantum Control, Department of Physics and Department of Electrical and Computer Engineering, University of Toronto, Toronto, Ontario, M5S 3G4 (Canada)

2011-08-15

163

Physiological profiles and sport specific fitness of Asian elite squash players.  

PubMed Central

There is a scarcity of descriptive data on the physiological characteristics of elite Asian squash players. The purpose of this study was to evaluate the physiological profile and sports specific fitness of Hong Kong elite squash players. It was conducted before the selection of the Hong Kong national squash team for the 1992 Asian Squash Championship. Ten elite squash players were selected as subjects for the study. Maximum oxygen uptake was measured using a continuous treadmill running test. A sports specific field test was performed in a squash court. The following means (s.d.) were observed: height 172.6(4.3) cm; weight 67.7(6.9) kg; body fat 7.4(3.4)%; forced vital capacity (FVC) 5.13(0.26) litres; maximum oxygen uptake (VO2max) 61.7(3.4) ml.kg-1.min-1; anaerobic threshold (AT) 80.2(3.3)% of VO2max; alactic power index 15.5(1.8) W.kg-1; lactic work index 323.5(29.4) J.kg-1, peak isokinetic dominant knee extensor and flexor strengths 3.11(0.29) Nm.kg-1 and 1.87(0.18) Nm.kg-1. The results show that the Hong Kong squash players have relatively high cardiorespiratory sports specific fitness and muscle strength which may be one of the key factors that contributed to the success of the Hong Kong team in the Asian Championship.

Chin, M K; Steininger, K; So, R C; Clark, C R; Wong, A S

1995-01-01

164

Evaluating the Effect of Slab Curling on IRI for South Carolina Concrete Pavements.  

National Technical Information Service (NTIS)

Concrete pavements are known to curl due to a temperature gradient within the concrete caused by both daily and seasonal temperature variations. This research project measured the magnitude of concrete pavement slab curling of two newly constructed jointe...

A. M. Johnson B. C. Smith L. W. Gibson W. H. Johnson

2010-01-01

165

Finite length and solvent analysis effects on the squash mode of single walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

Nanotube diameters (d) are usually characterized using the radial breathing mode d-1 the squash mode frequency (f) however is predicted to vary as d-2. We demonstrate using the MM+ forcefield that for lengths <9 nm the symmetric squash mode (SSM) and asymmetric squash mode (ASM) ((10,0) SWNT (single wall carbon nanotubes)) are non-degenerate with ?f <= 55 cm-1. In solution, the SWNT-water interaction upshifts the ASM by 20 cm-1 and the SSM by 10 cm-1. Such asymmetries could be used to simultaneously characterize the length and diameter of short nanotubes for applications including nanoresonators and biomedical probes.

de Fréin, C.; Quirke, N.; Zerulla, D.

2013-10-01

166

Computation of Surface Integrals of Curl Vector Fields  

ERIC Educational Resources Information Center

|This article presents a way of computing a surface integral when the vector field of the integrand is a curl field. Presented in some advanced calculus textbooks such as [1], the technique, as the author experienced, is simple and applicable. The computation is based on Stokes' theorem in 3-space calculus, and thus provides not only a means to…

Hu, Chenglie

2007-01-01

167

The sports science of curling: A practical review  

Microsoft Academic Search

Curling is a sport played on ice in which two teams each deliver 8 granite stones towards a target, or 'house'. It is the only sport in which the trajectory of the projectile can be influenced after it has been released by the athlete. This is achieved by sweeping the ice in front of the stone to change the stone-ice

John L. Bradley

168

Leaf Margins  

NSDL National Science Digital Library

This illustrated guide is designed to help students recognize and learn the difference between entire and toothed leaf margins. The single Web page can be easily printed for use at field sites. Both leaf margin illustrations identify the leaf blade and the petiole.

169

Heavy metals in summer squash fruits grown in soil amended with municipal sewage sludge.  

PubMed

The increasing awareness of the value of vegetables and fruits in the human diet requires monitoring of heavy metals in food crops. The effects of amending soil with compost made from municipal sewage sludge (MSS) and MSS mixed with yard waste (MSS-YW) on Cd, Cr, Mo, Cu, Zn, Pb, and Ni concentrations in soil and the potential bioaccumulation of heavy metals in squash fruits at harvest were investigated. A field study was conducted in a silty-loam soil at Kentucky State University Research Farm. Eighteen plots of 22 x 3.7 m each were separated using metal borders and the soil in six plots was mixed with MSS at 15 t acre(-1), six plots were mixed with MSS-YW at 15 t acre(-1) (on dry weight basis), and six unamended plots (no-mulch) were used for comparison purposes. Plots were planted with summer squash and heavy metals were analyzed in soil and mature fruits at harvest. Analysis of heavy metals in squash fruits was conducted using inductively coupled plasma spectrometry. Zinc and Cu concentrations in soil mixed with MSS were extremely high compared to other metals. In squash fruits, concentrations of Zn were generally greater than Cu. Total squash marketable yield was greatest in MSS-YW and MSS treatments compared to no-mulch conventional soil. Concentrations of Cd and Pb in soil amended with MSS averaged 0.1 and 1.4 mg kg(-1), respectively. These levels were much lower than the limits in the U.S. guidelines for using MSS in land farming. Data revealed that maximum concentrations of Cd and Pb in squash fruits were 0.03 and 0.01 microg g(-1) dry fruit, respectively. Nickel concentration in squash fruits fluctuated among harvest dates reaching a maximum of 2.5 microg g(-1) dry fruit. However, these concentrations were far below their permissible limits in edible fruits. PMID:20390947

Antonious, George F; Snyder, John C; Dennis, Sam O

2010-02-01

170

Cosmic shear of the microwave background: The curl diagnostic  

SciTech Connect

Weak-lensing distortions of the cosmic-microwave-background (CMB) temperature and polarization patterns can reveal important clues to the intervening large-scale structure. The effect of lensing is to deflect the primary temperature and polarization signal to slightly different locations on the sky. Deflections due to density fluctuations, gradient-type for the gradient of the projected gravitational potential, give a direct measure of the mass distribution. Curl-type deflections can be induced by, for example, a primordial background of gravitational waves from inflation or by second-order effects related to lensing by density perturbations. Whereas gradient-type deflections are expected to dominate, we show that curl-type deflections can provide a useful test of systematics and serve to indicate the presence of confusing secondary and foreground non-Gaussian signals.

Cooray, Asantha [Department of Physics and Astronomy, 4129 Frederick Reines Hall, University of California, Irvine, California 92697 (United States); Kamionkowski, Marc [Mail Code 130-33, California Institute of Technology, Pasadena, California 91125 (United States); Caldwell, Robert R. [Department of Physics and Astronomy, Dartmouth College, 6127 Wilder Laboratory, Hanover, New Hampshire 03755 (United States)

2005-06-15

171

Full-sky lensing reconstruction of gradient and curl modes from CMB maps  

NASA Astrophysics Data System (ADS)

We present a method of lensing reconstruction on the full sky, by extending the optimal quadratic estimator proposed by Okamoto & Hu (2003) to the case including the curl mode of deflection angle. The curl mode is induced by the vector and tensor metric perturbations, and the reconstruction of the curl mode would be a powerful tool to not only check systematics in the estimated gradient mode but also probe any vector and tensor sources. We find that the gradient and curl modes can be reconstructed separately, thanks to the distinctive feature in the parity symmetry between the gradient and curl modes. We compare our estimator with the flat-sky estimator proposed by Cooray et al (2005). Based on the new formalism, the expected signal-to-noise ratio of the curl mode produced by the primordial gravitational-waves and a specific model of cosmic strings are estimated, and prospects for future observations are discussed.

Namikawa, Toshiya; Yamauchi, Daisuke; Taruya, Atsushi

2012-01-01

172

CURL: A Searchable CUrricular Resources Library of Earth and Environmental Science Websites  

Microsoft Academic Search

A searchable web-based Curricular Resources Library (CURL) has been developed by earth and environmental science faculty from four New England schools (Dartmouth College, Connecticut College, Trinity College, and Wesleyan University) in conjunction with Wesleyan's Information Technology Services (ITS) and librarians. The site (http:\\/\\/www.wesleyan.edu\\/curl\\/) provides access to pre-selected earth and environmental science material. CURL sites are identified by faculty who provide

S. O'Connell; T. Klassen; M. Roy; M. Glynn

2001-01-01

173

Gourd and squash artifacts yield starch grains of feasting foods from preceramic Peru.  

PubMed

In a study of residues from gourd and squash artifacts, we recovered starch grains from manioc (Manihot esculenta), potato (Solanum sp.), chili pepper (Capsicum spp.), arrowroot (Maranta arundinacea), and algarrobo (Prosopis sp.) from feasting contexts at the Buena Vista site, a central Peruvian preceramic site dating to approximately 2200 calendar years B.C. This study has implications for the study of plant food use wherever gourds or squashes are preserved, documents the earliest evidence for the consumption of algarrobo and arrowroot in Peru, and provides insights into foods consumed at feasts. PMID:19633184

Duncan, Neil A; Pearsall, Deborah M; Benfer, Robert A

2009-07-24

174

Gourd and squash artifacts yield starch grains of feasting foods from preceramic Peru  

PubMed Central

In a study of residues from gourd and squash artifacts, we recovered starch grains from manioc (Manihot esculenta), potato (Solanum sp.), chili pepper (Capsicum spp.), arrowroot (Maranta arundinacea), and algarrobo (Prosopis sp.) from feasting contexts at the Buena Vista site, a central Peruvian preceramic site dating to ?2200 calendar years B.C. This study has implications for the study of plant food use wherever gourds or squashes are preserved, documents the earliest evidence for the consumption of algarrobo and arrowroot in Peru, and provides insights into foods consumed at feasts.

Duncan, Neil A.; Pearsall, Deborah M.; Benfer, Robert A.

2009-01-01

175

FIRST REPORT OF BACTERIAL LEAF SPOT ON LEAFY BRASSICA GREENS CAUSED BY PSEUDOMONAS SYRINGAE PV. MACULICOLA IN SOUTH CAROLINA  

Technology Transfer Automated Retrieval System (TEKTRAN)

As of 2001, South Carolina ranked second in the United States in acreage of turnip greens (Brassica rapa) and collard (B. oleracea) and third in acreage of mustard (B. juncea). In June 2001, a leaf disease was found on turnip greens (cv. Alamo), mustard (cv. Southern Giant Curled and Florida Broadl...

176

Out with the Sit-Up, in with the Curl-Up!  

ERIC Educational Resources Information Center

|Explains why physical education teachers should discourage full sit-ups and describes the Robertson Modified Curl-Up Test as a recommended alternative test of abdominal muscular strength. Curl-up test administration guidelines are included with some preliminary norms from adult groups. (SM)|

MacFarlane, Pamela A.

1993-01-01

177

A high speed profiler based slab curvature index for jointed concrete pavement curling and warping analysis  

Microsoft Academic Search

One of the biggest gaps of missing knowledge between accurate structural modeling of concrete pavement slab behavior and real pavement behavior is accounting for slab warping (locked-in curvature and moisture gradient effects) and curling (temperature gradient effects). Curling and warping are curvatures that can be present in a PCC slab that can cause corners and edges, or mid panel, of

Christopher Ronald Byrum

2001-01-01

178

A bioeconomic decision model comparing composted and fresh litter for winter squash  

Microsoft Academic Search

Decision aids are needed to identify management strategies for complex agricultural problems affecting numerous stakeholders. Our objective was to develop a bioeconomic decision aid examining poultry litter application to winter squash, Cucurbita maxima, on the basis of multiple goals: enhancing environmental and soil quality, maximizing waste recycling, and maximizing net revenues. Because farm-level decisions about waste management may conflict with

S. S. Andrews; L. Lohr; M. L. Cabrera

1999-01-01

179

Measurement error associated with the SAGIT\\/Squash computer tracking software  

Microsoft Academic Search

The velocities and distances covered by players during competition serve as a basis for planning fitness regimes according to the specific demand of the sport. The techniques used to calculate these movement parameters have ranged from human judgements to technological solutions such as GPS and computer vision. This paper evaluates the accuracy of a computerized motion tracking system (SAGIT\\/Squash) that

Goran Vu?kovi?; Janez Perš; Nic James; Mike Hughes

2010-01-01

180

Physical and sensory changes during the development and storage of buttercup squash  

Microsoft Academic Search

Changes in composition and sensory quality of buttercup squash (Cucurbita maxima Duch. ‘Delica') during fruit development and postharvest temperature and humidity conditions simulating shipment to Japan were studied at three representative growing sites in New Zealand. Fruit of a known setting date were harvested at 10?day intervals and data were collected on heat accumulation, days after flowering, flesh colour, seed

W. J. Harvey; D. G. Grant; J. P. Lammerink

1997-01-01

181

Long-term unilateral loading and bone mineral density and content in female squash players  

Microsoft Academic Search

We examined 19 female Finnish national level squash players and 19 healthy female controls with a dual energy x-ray absorptiometric (DXA) scanner for the determination of the association between long-term unilateral activity and bone mineral density (BMD) and content (BMC) of the upper extremities. In players, the BMDs and the BMCs were significantly higher in each bone site of the

H. Haapasalo; P. Kannus; H. Sievänen; A. Heinonen; P. Oja; I. Vuori

1994-01-01

182

Radiation and water use efficiencies of greenhouse zucchini squash in relation to different climate parameters  

Microsoft Academic Search

In the Mediterranean region, zucchini squash (Cucurbita pepo L.) is widely grown under unheated greenhouse conditions for off-season production. Climatic conditions affecting both radiation and water use are mainly determined by the planting dates. Elucidating the relationship between the radiation and the water use with climate variables is important for the quantification of crop productivity and for improving water use

Youssef Rouphael; Giuseppe Colla

2005-01-01

183

Tennis-Badminton-Squash Guide with Official Rules. June 1972 - June 1974.  

ERIC Educational Resources Information Center

|Rules in tennis, badminton, and squash for girls and women from June 1972 - June 1974 are discussed. Standards in the sports are detailed along with the Division for Girls and Women's Sports (DGWS) statement of beliefs. Specific articles dealing with teaching techniques, officiating techniques, and rules for tennis and badminton are presented.…

Knight, Martha, Ed.; And Others

184

Use of 1-methylcyclopropene to complement refrigeration and ameliorate chilling injury symptoms in summer squash  

Microsoft Academic Search

To elucidate the role of ethylene in summer squash [Cucurbita maxima var. Zapallito (Carr.) Millan] postharvest responses, harvested fruit was treated with the inhibitor of ethylene action 1-methylcyclopropene (1-MCP, 1 ?L L) and stored at 10 or 0?°C for 14 or 19 days, respectively. Deterioration, chilling injury (CI), weight loss, surface color, firmness, respiration rate, acidity, sugars, and antioxidants were determined.

Juan F. Massolo; Analía Concellón; Alicia R. Chaves; Ariel R. Vicente

2012-01-01

185

Transgenic approaches for the Control of Tomato Yellow Leaf Curl Virus  

Microsoft Academic Search

Management of TYLCV and other begomoviruses is very difficult and expensive. The least expensive and most practical control\\u000a of TYLCV and many other begomoviruses is the use of resistant cultivars. Begomovirus-resistant tomato cultivars would greatly\\u000a reduce the use of insecticides for whitefly control, which would reduce production costs and chemical contamination of the\\u000a environment. Conventional breeding of TYLCV-resistant tomato lines

JANE E. POLSTON; Ernest Hiebert

186

Management of Tomato yellow leaf curl virus: US and Israel Perspectives  

Microsoft Academic Search

Over the last 15 years, TYLCV has been a serious problem for tomato production in many parts of the world. The virus has been\\u000a known in Israel for over 40 years and in Florida since 1997 (Cohen & Nitzany, 1966; Polston et al., 1997). In Israel, tomato\\u000a crops are severely affected by epidemics of TYLCV and despite almost daily spraying

JANE E. POLSTON; Moshe Lapidot

187

Genetic Variability of Natural Populations of Cotton Leaf Curl Geminivirus, a Single-Stranded DNA Virus  

Microsoft Academic Search

.   Reports on the genetic variability and evolution of natural populations of DNA viruses are scarce in comparison with the\\u000a abundant information on the variability of RNA viruses. Geminiviruses are plant viruses with circular ssDNA genomes that are\\u000a replicated by the host plant DNA polymerases. Whitefly-transmitted geminiviruses (WTG) are the agents of important diseases\\u000a of crop plants and best exemplify

Ana I. Sanz; Aurora Fraile; Jesus M. Gallego; Jose M. Malpica; Fernando García-Arenal

1999-01-01

188

Leaf Identification  

NSDL National Science Digital Library

This straightforward tutorial on leaf identification comes from the Department of Horticulture at Penn State University. Simple diagrams, helpful photos, and clear explanations make short work of learning the basics of leaf identification. The website even includes a section on why anyone should bother learning this skill (i.e. it's not just for dedicated horticulturists and botanists). The tutorial covers leaf structure, blade shape, margins, venation, and so on. The self-testing component appears to be unavailable at this time, but this site as a whole is definitely worth a look.

189

Leaf Development  

PubMed Central

The shoot system is the basic unit of development of seed plants and is composed of a leaf, a stem, and a lateral bud that differentiates into a lateral shoot. The most specialized organ in angiosperms, the flower, can be considered to be part of the same shoot system since floral organs, such as the sepal, petal, stamen, and carpel, are all modified leaves. Scales, bracts, and certain kinds of needle are also derived from leaves. Thus, an understanding of leaf development is critical to an understanding of shoot development. Moreover, leaves play important roles in photosynthesis, respiration and photoperception. Thus, a full understanding of leaves is directly related to a full understanding of seed plants. The details of leaf development remain unclear. The difficulties encountered in studies of leaf development, in particular in dicotyledonous plants such as Arabidopsis thaliana (L.) Henyn., are derived from the complex process of leaf development, during which the division and elongation of cells occur at the same time and in the same region of the leaf primordium (Maksymowych, 1963; Poethig and Sussex, 1985). Thus, we cannot divide the entire process into unit processes in accordance with the tenets of classical anatomy. Genetic approaches in Arabidopsis, a model plant (Meyerowitz and Pruitt, 1985), have provided a powerful tool for studies of mechanisms of leaf development in dicotyledonous plants, and various aspects of the mechanisms that control leaf development have been revealed in recent developmental and molecular genetic studies of Arabidopsis (for reviews, see Tsukaya, 1995 and 1998; Van Lijsebettens and Clarke, 1998; Sinha, 1999; Van Volkenburgh, 1999; Tsukaya, 2000; Byrne et al., 2001; Dengler and Kang, 2001; Dengler and Tsukaya, 2001; Tsukaya, 2001). In this review, we shall examine the information that is currently available about various mechanisms of leaf development in Arabidopsis. Vascular patterning is also an important factor in the determination of leaf shape, and this topic is reviewed in this resource by Turner (see also Dengler and Kang, 2001). The interested reader is also referred to work on the basic characterization of the vascular patterning in foliage leaves of Arabidopsis has been carried out by Candela et al. (1999) and Semiarti et al. (2001). For terminology, see Fig. 1.

Tsukaya, Hirokazu

2002-01-01

190

Modeling moisture diffusivity, activation energy and specific energy consumption of squash seeds in a semi fluidized and fluidized bed drying  

Microsoft Academic Search

This study investigated thin layer drying of squash seeds under semi fluidized and fluidized bed conditions with initial moisture\\u000a content about 83.99% (d.b.). An experimental fluidized bed dryer was also used in this study. Air temperature levels of 50,\\u000a 60, 70 and 80 °C were applied in drying samples. To estimate the drying kinetic of squash seed, seven mathematical models\\u000a were

Reza Amiri Chayjan; Kamran Salari; Qasem Abedi; Ali Akbar Sabziparvar

191

Why no shear in ``Div, grad, curl, and all that''?  

NASA Astrophysics Data System (ADS)

Are there good reasons for the absence of shear and gradients of vectors in the undergraduate curriculum, or have we simply been negligent by not explicitly introducing students to these concepts early on? In this paper, we (i) remind the reader that div and curl are not the entire story when it comes to vector derivatives and (ii) ask the reader to consider whether the missing information--shear or the more general vector gradient--should be included in the undergraduate curriculum. In an attempt to address this last point, we give a list of hypothetical responses to the question ``Why no shear?,'' along with some arguments both for and against teaching it. We leave it to the readers to choose among these reasons or to come up with one of their own when deciding whether or not to include shear and vector gradients in their undergraduate teaching.

Romano, Joseph D.; Price, Richard H.

2012-06-01

192

Leaf development.  

PubMed

Leaves are the most important organs for plants. Without leaves, plants cannot capture light energy or synthesize organic compounds via photosynthesis. Without leaves, plants would be unable perceive diverse environmental conditions, particularly those relating to light quality/quantity. Without leaves, plants would not be able to flower because all floral organs are modified leaves. Arabidopsis thaliana is a good model system for analyzing mechanisms of eudicotyledonous, simple-leaf development. The first section of this review provides a brief history of studies on development in Arabidopsis leaves. This history largely coincides with a general history of advancement in understanding of the genetic mechanisms operating during simple-leaf development in angiosperms. In the second section, I outline events in Arabidopsis leaf development, with emphasis on genetic controls. Current knowledge of six important components in these developmental events is summarized in detail, followed by concluding remarks and perspectives. PMID:23864837

Tsukaya, Hirokazu

2013-06-07

193

PCR and ELISA-based virus surveys of banana, papaya and cucurbit crops in Vietnam  

Microsoft Academic Search

Between 1998 and 2002, we conducted PCR-based plant virus disease surveys throughout Vietnam, on banana, papaya, and several cucurbit crops, namely pumpkin, cucumber, gourds and loofa. Banana bunchy top virus in banana and Papaya ringspot virus in both papaya and cucurbits were widespread. Squash leaf curl virus-Vietnam and Cucumber mosaic virus were also widespread, predominantly infecting pumpkin and cucumber respectively.

P. A. Revill; C. V. Ha; R. E. Lines; K. E. Bell; M. T. Vu; J. L. Dale

2004-01-01

194

Role of intraoperative squash smear cytology as a diagnostic modality in lipoma of quadrigeminal cistern.  

PubMed

Quadrigeminal lipoma is a rare tumor that has been categorized as developmental malformation rather than a hamartoma or true neoplasm, due to its origin from abnormal persistence and mal-differentiation of meninx primitiva during the development of the subarachnoid cisterns. Reported admixture of adipose tissue with heterotopic elements also supports a developmental origin. Quadrigeminal lipomas are frequently asymptomatic and detected incidentally. Though a favorable clinical course is usually expected, recurrences may occur due to partial removal of lesions in close relation to vital structure. We describe the role of intraoperative squash smear cytology as a diagnostic aid in quadrigeminal cistern lipoma and an alternative to frozen sections that are technically difficult to obtain due to presence of lobules of fibro-adipose tissue. With radiological correlation, squash cytology can be an economical method for intraoperative diagnosis, pending subsequent histopathological confirmation. PMID:23546355

Majumdar, Kaushik; Saran, Ravindra Kumar; Tyagi, Ila; Shankar, Ravi; Singh, Daljit

2013-01-01

195

POLYTENE CHROMOSOME SQUASH METHODS FOR STUDYING TRANSCRIPTION AND EPIGENETIC CHROMATIN MODIFICATION IN DROSOPHILA USING ANTIBODIES  

PubMed Central

The giant polytene chromosomes from Drosophila third instar larval salivary glands provide an important model system for studying the architectural changes in chromatin morphology associated with the process of transcription initiation and elongation. Especially, analysis of the heat shock response has proved useful in correlating chromatin structure remodeling with transcriptional activity. An important tool for such studies is the labeling of polytene chromosome squash preparations with antibodies to the enzymes, transcription factors, or histone modifications of interest. However, in any immunohistochemical experiment there will be advantages and disadvantages to different methods of fixation and sample preparation, the relative merits of which must be balanced. Here we provide detailed protocols for polytene chromosome squash preparation and discuss their relative pros and cons in terms of suitability for reliable antibody labeling and preservation of high resolution chromatin structure.

Johansen, Kristen M.; Cai, Weili; Deng, Huai; Bao, Xiaomin; Zhang, Weiguo; Girton, Jack; Johansen, J?rgen

2009-01-01

196

Role of intraoperative squash smear cytology as a diagnostic modality in lipoma of quadrigeminal cistern  

PubMed Central

Quadrigeminal lipoma is a rare tumor that has been categorized as developmental malformation rather than a hamartoma or true neoplasm, due to its origin from abnormal persistence and mal-differentiation of meninx primitiva during the development of the subarachnoid cisterns. Reported admixture of adipose tissue with heterotopic elements also supports a developmental origin. Quadrigeminal lipomas are frequently asymptomatic and detected incidentally. Though a favorable clinical course is usually expected, recurrences may occur due to partial removal of lesions in close relation to vital structure. We describe the role of intraoperative squash smear cytology as a diagnostic aid in quadrigeminal cistern lipoma and an alternative to frozen sections that are technically difficult to obtain due to presence of lobules of fibro-adipose tissue. With radiological correlation, squash cytology can be an economical method for intraoperative diagnosis, pending subsequent histopathological confirmation.

Majumdar, Kaushik; Saran, Ravindra Kumar; Tyagi, Ila; Shankar, Ravi; Singh, Daljit

2013-01-01

197

The gravity dual of supersymmetric gauge theories on a biaxially squashed three-sphere  

NASA Astrophysics Data System (ADS)

We present the gravity dual to a class of three-dimensional N=2 supersymmetric gauge theories on a biaxially squashed three-sphere, with a non-trivial background gauge field. This is described by a 1/2 BPS Euclidean solution of four-dimensional N=2 gauged supergravity, consisting of a Taub-NUT-AdS metric with a non-trivial instanton for the graviphoton field. The holographic free energy of this solution agrees precisely with the large N limit of the free energy obtained from the localized partition function of a class of Chern-Simons quiver gauge theories. We also discuss a different supersymmetric solution, whose boundary is a biaxially squashed Lens space S3/Z2 with a topologically non-trivial background gauge field. This metric is of Eguchi-Hanson-AdS type, although it is not Einstein, and has a single unit of gauge field flux through the S2 cycle.

Martelli, Dario; Sparks, James

2013-01-01

198

Effects of High Temperature Treatment on Curl And Microstructure of Heavily Boron Doped Silicon.  

National Technical Information Service (NTIS)

An experimental study was performed to investigate the effects of high temperature treatment on the microstructure and curling behavior of heavily boron-doped silicon structures. Cantilever structures were created from p++ boron diffused silicon wafers. T...

D. M. Bruce

1997-01-01

199

Cytological detection of Wolbachia in squashed and paraffin embedded insect tissues.  

PubMed

Wolbachia localization in situ is essential for accurate analysis of the infection and its consequences. Whole cell hybridization is proposed as an easy and rapid method for detecting Wolbachia cells in paraffin embedded tissues or testis squashes of Chorthippus parallelus (Orthoptera). Wolbachia is found in whole gonads and other adjacent tissues. A higher bacterial density, however, is observed in ovarioles and testis. Small independent bacteria with strictly cytoplasmic distribution are displayed. Bacterial density differences among individuals are also revealed. PMID:19384745

Martínez, P; Del Castillo, P; Bella, J L

2009-12-01

200

Nitrate Reductase from Squash: cDNA Cloning and Nitrate Regulation  

Microsoft Academic Search

The assimilation of nitrate in plants involves the reduction of nitrate to ammonia in two steps. The first step requires nitrate reductase, a nitrate-inducible enzyme. When seedlings of squash (Cucurbita maxima L.) were treated with nitrate, both nitrate reductase activity and protein were induced in the cotyledons. Poly(A)+ RNA was prepared from cotyledons of nitrate-treated seedlings and was used to

Nigel M. Crawford; Wilbur H. Campbell; Ronald W. Davis

1986-01-01

201

Strong gravitational lensing in a squashed Kaluza-Klein black hole spacetime  

SciTech Connect

We investigate the strong gravitational lensing in a Kaluza-Klein black hole with squashed horizons. We find the size of the extra dimension imprints in the radius of the photon sphere, the deflection angle, the angular position, and magnification of the relativistic images. Supposing that the gravitational field of the supermassive central object of the Galaxy can be described by this metric, we estimated the numerical values of the coefficients and observables for gravitational lensing in the strong field limit.

Liu Yue; Chen Songbai; Jing Jiliang [Institute of Physics and Department of Physics, Hunan Normal University, Changsha, Hunan 410081 (China) and Key Laboratory of Low Dimensional Quantum Structures and Quantum Control (Hunan Normal University), Ministry of Education (China)

2010-06-15

202

SHAPESET: A process to reduce sidewall curl springback in high-strength steel rails  

Microsoft Academic Search

High-strength steel rails for structural members can reduce vehicle weight, but sidewall curl springback in these rails causes\\u000a assembly difficulties with adjacent parts. A process to greatly reduce curl springback, known as SHAPESET, was investigated\\u000a for a variety of high-strength steels, including two dual-phase steels. Gridded blanks were stamped by the two-step SHAPESET\\u000a process and by conventional methods. The SHAPESET

R. A. Ayres

1984-01-01

203

Variability of wind stress curl over the Indian Ocean during years 1970-1995  

Microsoft Academic Search

Climatological and interannual variability aspects of monthly mean pseudo-stress curl over the Indian Ocean for the pe- riod 1970-1995 are explored. A harmonic analysis of the curl fields finds most of the variance of the northern basins domi- nated by semi-annual variability. In particular the coastal areas of Somalia and south\\/southwestern India have large contri- butions from this harmonic. In

A. D. Rao

2002-01-01

204

Effects of Corn Hybrid and Growth Environment on Corn Curl and Pet Food Extrudates 1  

Microsoft Academic Search

Cereal Chem. 76(5):625-628 The effects of corn growth environment and hybrid on properties of corn curl and pet food extrudates were studied. Extrusion runs were conducted using a twin-screw extruder. Both corn curl and pet food extrudates were affected significantly by the corn growth environment (location) and corn hybrid. Corn hybrids grown at Creston, IA, produced extrudates with sig- nificantly

J. M. Mathew; R. C. Hoseney; J. M. Faubion

1999-01-01

205

Self reported injury patterns among competitive curlers in the United States: a preliminary investigation into the epidemiology of curling injuries  

PubMed Central

Methods: Participants at two curling championship events were asked to complete injury history questionnaires. Results: 76 curlers (39%) participated; 79% of these reported curling related musculoskeletal pain, most commonly involving the knee (54%), back (33%), and shoulder (20%). Sweeping and delivering the stone were most likely to provoke symptoms. Time loss injuries were estimated to occur at a rate of 2 per 1000 athlete exposures. Conclusions: Curling appears to be a relatively safe winter sport. Prospective studies are needed to confirm these preliminary findings and to further define the risk factors for curling related injuries.

Reeser, J; Berg, R

2004-01-01

206

EFFECTS OF METHYL JASMONATE AND SUPERATMOSPHERIC OXYGEN LEVELS ON ALTERNATIVE OXIDASE IN LOW TEMPERATURE STORED GREEN PEPPER (CAPSICUM ANNUUM L.) AND ZUCCHINI SQUASH (CUCURBITA PEPO L.)  

Technology Transfer Automated Retrieval System (TEKTRAN)

Quality was improved in the cold-stored green pepper and zucchini squash following treatments with methyl jasmonate and superatmospheric levels of oxygen. Green pepper and zucchini squash are sensitive to chilling temperatures. However, the severity of chilling injury in these commodities was redu...

207

Antidiabetic II drug metformin in plants: uptake and translocation to edible parts of cereals, oily seeds, beans, tomato, squash, carrots, and potatoes.  

PubMed

Residues of pharmaceuticals present in wastewater and sewage sludge are of concern due to their transfer to aquatic and terrestrial food chains and possible adverse effects on nontargeted organisms. In the present work, uptake and translocation of metformin, an antidiabetic II medicine, by edible plant species cultivated in agricultural soil have been investigated in greenhouse experiment. Metformin demonstrated a high uptake and translocation to oily seeds of rape ( Brassica napus cv. Sheik and Brassica rapa cv. Valo); expressed as an average bioconcentration factor (BCF, plant concentration over initial concentration in soil, both in dry weight), BCF values as high as 21.72 were measured. In comparison, BCFs for grains of the cereals wheat, barley, and oat were in the range of 0.29-1.35. Uptake and translocation to fruits and vegetables of tomato (BCFs 0.02-0.06), squash (BCFs 0.12-0.18), and bean (BCF 0.88) were also low compared to rape. BCFs for carrot, potato, and leaf forage B. napus cv. Sola were similar (BCF 1-4). Guanylurea, a known degradation product of metformin by microorganisms in activated sludge, was found in barley grains, bean pods, potato peel, and small potatoes. The mechanisms for transport of metformin and guanidine in plants are still unknown, whereas organic cation transporters (OCTs) in mammals are known to actively transport such compounds and may guide the way for further understanding of mechanisms also in plants. PMID:22712757

Eggen, Trine; Lillo, Cathrine

2012-07-05

208

The validity of recent curl-up tests in young adults.  

PubMed

The validity of 2 field tests of abdominal endurance was examined in a sample of 22 male and 22 female college students. Scores on the modified trunk-curl (7) and the 90-second bench trunk-curl (22) were correlated with isometric trunk flexor strength and endurance measured on a Cybex TEF machine. There were no significant correlations (-0.21 < r < 0.36) between the field tests and abdominal strength. Only the bench trunk-curl was significantly correlated (rmale = 0.50 and rfemale = 0.46, p < 0.05) with abdominal muscular endurance. The nonsignificant association with the modified curl-up was likely due to a ceiling effect created by the ease of the test. The weak correlations between field tests of abdominal endurance and isometric abdominal endurance (about 25% common variance) and a recent longitudinal study (17) suggest that the curl-ups scores and their hypothesized health-related fitness standards should be interpreted with caution. PMID:11708712

Knudson, D

2001-02-01

209

Wheat curl mite (Acari: Eriophyidae) dispersal and its relationship with kernel red streaking in maize.  

PubMed

Wheat curl mites, Aceria tosichella Keifer, dispersing from wheat (Triticum spp.) to nearby corn (Zea mays L.) fields play a role in the development of kernel red streaking in corn. These studies were undertaken to verify the relationship of wheat curl mite to kernel red streaking, to determine whether wheat is the main source of curl mites dispersing into corn and to determine whether planting corn in temporal or spatial isolation of wheat is a valid management strategy. These studies were conducted on farm fields using sticky traps to monitor mites, followed by sampling mature grain for kernel streaking in southwestern Ontario from 1999 to 2002. The dominant source mites were winter wheat. Mite dispersal occurred during the first 3 wk of winter wheat maturation after the wheat had reached Zadoks stage 87. Mite dispersal corresponded to prevailing winds in the area with the lowest number of mites and the lowest severity of kernel red streaking occurring 60 m from wheat fields planted to the north, south, and east of cornfields and 90 m from wheat fields planted to the west of cornfields. The severity of kernel red streaking was positively correlated with the density of wheat curl mites in corn; however, the correlation was weak and kernel red streaking was still high in many cornfields when few or no mites were present. These findings suggest that wheat curl mite migration into corn is not entirely predictive of the incidence and severity of kernel red streaking. PMID:16334327

Liu, J; Lee, E A; Sears, M K; Schaafsma, A W

2005-10-01

210

Curling and local shape changes of red blood cell membranes driven by cytoskeletal reorganization.  

PubMed

Human red blood cells (RBCs) lack the actin-myosin-microtubule cytoskeleton that is responsible for shape changes in other cells. Nevertheless, they can display highly dynamic local deformations in response to external perturbations, such as those that occur during the process of apical alignment preceding merozoite invasion in malaria. Moreover, after lysis in divalent cation-free media, the isolated membranes of ruptured ghosts show spontaneous inside-out curling motions at the free edges of the lytic hole, leading to inside-out vesiculation. The molecular mechanisms that drive these rapid shape changes are unknown. Here, we propose a molecular model in which the spectrin filaments of the RBC cortical cytoskeleton control the sign and dynamics of membrane curvature depending on whether the ends of the filaments are free or anchored to the bilayer. Computer simulations of the model reveal that curling, as experimentally observed, can be obtained either by an overall excess of weakly-bound filaments throughout the cell, or by the flux of such filaments toward the curling edges. Divalent cations have been shown to arrest the curling process, and Ca2+ ions have also been implicated in local membrane deformations during merozoite invasion. These effects can be replicated in our model by attributing the divalent cation effects to increased filament-membrane binding. This process converts the curl-inducing loose filaments into fully bound filaments that arrest curling. The same basic mechanism can be shown to account for Ca2+-induced local and dynamic membrane deformations in intact RBCs. The implications of these results in terms of RBC membrane dynamics under physiological, pathological, and experimental conditions is discussed. PMID:20682258

Kabaso, Doron; Shlomovitz, Roie; Auth, Thorsten; Lew, Virgilio L; Gov, Nir S

2010-08-01

211

Cytopatholologic features of gliosarcoma with areas of primitive neuroepithelial differentiation of the brain in squash smears.  

PubMed

Gliosarcoma with areas of primitive neuroepithelial differentiation (GSPNED) is an extremely rare neoplasm. A case is presented here in which squash smears of a left temporal lobe tumor in a 76-year-old male demonstrated two distinct and easily recognizable cellular populations, i.e., densely hyperchromatic cells of a primitive nature in a fibrillary background and pleomorphic spindle-shaped cells. Occasional pseudo-rosette formations and nuclear cannibalism suggestive of neuroendocrine differentiation were also found. A cytologic diagnosis of a malignant tumor was suggested, and histochemical and immunohistochemical studies were conducted on formalin-fixed, paraffin-embedded material. Reticulin stain highlighted increased intercellular collagen and reticulin deposition within the spindled regions, whereas nodules with primitive cells were reticulin-poor. There was a diffuse and strong reactivity to neuron specific enolase, synaptophysin and CD56 immunostains. A stain for glial fibrillary acidic protein and S-100 protein demonstrated a subset of tumor cells including elongated cytoplasmic processes. The spindled component was positive for vimentin and smooth muscle actin, whereas the primitive-appearing tumor cells were negative. The diagnosis of GSPNED was confirmed based on cytopathologic, histopathological and immunohistochemical results. The cytomorphologic features of this distinctive tumor are illustrated, and the adjunctival value of squash smears for frozen-section diagnosis is also discussed. This is the first presentation of a cytopathologic analysis that provides an important clue to an accurate diagnosis of GSPNED. PMID:19582814

Hayashi, Toshitetsu; Kushida, Yoshio; Kadota, Kyuichi; Katsuki, Naomi; Bando, Kenji; Miyai, Yumi; Funamoto, Yasunobu; Haba, Reiji

2009-12-01

212

Synthesis, Salvage, and Catabolism of Uridine Nucleotides in Boron-Deficient Squash Roots 1  

PubMed Central

Previous work has provided evidence that plants may require boron to maintain adequate levels of pyrimidine nucleotides, suggesting that the state of boron deficiency may actually be one of pyrimidine starvation. Since the availability of pyrimidine nucleotides is influenced by their rates of synthesis, salvage, and catabolism, we compared these activities in the terminal 3 centimeters of roots excised from boron-deficient and -sufficient squash plants (Cucurbita pepo L.). Transferring 5-day-old squash plants to a boron-deficient nutrient solution resulted in cessation of root elongation within 18 hours. However, withholding boron for up to 30 hours did not result in either impaired de novo pyrimidine biosynthesis or a change in the sensitivity of the de novo pathway to regulation by end product inhibition. Boron deprivation had no significant effect on pyrimidine salvage or catabolism. These results provide evidence that boron-deficient plants are not starved for uridine nucleotides collectively. Whether a particular pyrimidine nucleotide or derivative is limiting during boron deprivation remains to be examined.

Lovatt, Carol J.; Albert, Luke S.; Tremblay, George C.

1981-01-01

213

Squash vein yellowing virus detection using nested polymerase chain reaction demonstrates Momordica charantia is a reservoir host  

Technology Transfer Automated Retrieval System (TEKTRAN)

Squash vein yellowing virus (SqVYV) is a recently described ipomovirus from cucurbits in Florida that induces the relatively unusual symptoms in watermelon of plant death and fruit rind necrosis and discoloration, commonly known in Florida as watermelon vine decline. In this report, we demonstrate ...

214

Evaluation of plant growth-promoting rhizobacteria for control of Phytophthora blight on squash under greenhouse conditions  

Microsoft Academic Search

Phytophthora blight caused by Phytophthora capsici is a serious threat to vegetable production worldwide. Currently, no single method provides adequate control of P. capsici. Greenhouse studies were conducted to evaluate the potential of the use of bacilli plant growth-promoting rhizobacteria (PGPR) for control of Phytophthora blight on squash. PGPR strains were applied as a soil drench 1 and 2weeks after

Shouan Zhang; Thomas L. White; Miriam C. Martinez; John A. McInroy; Joseph W. Kloepper; Waldemar Klassen

2010-01-01

215

Geostatistical analysis of spatial virus spread overtime provides new insights into the environmental safety of commercial virus-resistant squash  

Technology Transfer Automated Retrieval System (TEKTRAN)

This is a review of a journal article published in 2006. The spatial and temporal patterns of aphid-vectored spread of Zucchini yellow mosaic virus (ZYMV) and Watermelon mosaic virus (WMV) were monitored over two consecutive years in plantings of nontransgenic and transgenic squash ZW-20H (commerci...

216

Squashing the Millennium Bug: A Year 2000 Compliance Guide for Elementary/Secondary Schools and School Districts.  

ERIC Educational Resources Information Center

This guide was developed to assist the nation's elementary and secondary schools and school districts address their Year 2000 (Y2K) problem. The guide is divided into three sections: Squashing the Millennium Bug Step-by-Step; Remediating Specific Types of Systems; and Appendix. The first chapter presents the following steps for tackling the Year…

Root, Mark; Carlson, Robert; Dexter, David; Karinch, Samantha; Kaplan, Heather

217

The effects of ankle guards and taping on joint motion before, during, and after a squash match  

Microsoft Academic Search

The effects of ankle guards and taping on joint motion before, during, and after exercise were studied. Twelve league squash players played two matches, each last ing 1 hour. Two different ankle guards, and two types of tape applied by the same method, served as sup ports. A specially designed goniometer with electronic digital display (accuracy 1 °) was used

Kathryn H. Myburgh; Christopher L. Vaughan; Sedic K. Isaacs

1984-01-01

218

Transcript levels of antioxidative genes and oxygen radical scavenging enzyme activities in chilled zucchini squash in response to superatmospheric oxygen  

Technology Transfer Automated Retrieval System (TEKTRAN)

The transcript levels of antioxidative genes including Mn-superoxide dismutase (Mn-SOD), Cu/Zn SOD, ascorbate peroxidise (APX), and catalase (CAT) do not vary significantly during storage at 5 °C with high oxygen treatment in freshly harvested zucchini squash (Cucurbita pepo L. cv. Elite). However, ...

219

Note on transformation to general curvilinear coordinates for Maxwell's curl equations  

Microsoft Academic Search

Maxwell's curl equations are formulated in curvilinear non-orthogonal coordinates in three dimensions in a manner that enables to preserve conventional Cartesian mesh for the finite-difference schemes by means of mere redefinition of the permittivity and permeability coefficients. It is highlighted that in the previous works on this subject [Ward and Pendry 1996 J. Modern Opt. 43 773; 1998 Phys. Rev.

Dzmitry M. Shyroki

2003-01-01

220

Curling's Ulcer in Children: A 12-Year Review of 63 Cases.  

National Technical Information Service (NTIS)

Case reports of 63 children with Curling's ulcer treated at the United States Army Institute of Surgical Research during the 12-year period 1959-1971 are discussed. The incidence of this complication was 13% and the mortality 84% during this study period....

B. A. Pruitt H. M. Bruck

1972-01-01

221

Identification of the Wheat Curl Mite as the Vector of Triticum Mosaic Virus  

Technology Transfer Automated Retrieval System (TEKTRAN)

Triticum mosaic virus (TriMV) is a newly discovered virus found infecting wheat (Triticum aestivum L.) in Kansas. This study was conducted to determine if the wheat curl mite (WCM, Aceria tosichella Keifer) and the bird cherry oat aphid (Rhopalosiphum padi L. ) could transmit TriMV. Using diffe...

222

CURL: A Searchable CUrricular Resources Library of Earth and Environmental Science Websites  

NASA Astrophysics Data System (ADS)

A searchable web-based Curricular Resources Library (CURL) has been developed by earth and environmental science faculty from four New England schools (Dartmouth College, Connecticut College, Trinity College, and Wesleyan University) in conjunction with Wesleyan's Information Technology Services (ITS) and librarians. The site (http://www.wesleyan.edu/curl/) provides access to pre-selected earth and environmental science material. CURL sites are identified by faculty who provide information about the site in the following nine fields: Annotation (description), Discipline, Keywords, Origin of Site, Reason for Submission, Submitted By, URL, URL Title, URL Type. Subject Headings conform to those developed by the Library of Congress. These are determined by the Wesleyan University science librarian who enters them into the database. The Curl database can be searched three ways: 1) Browsing alphabetically by Subject Heading (e.g. remote sensing but not satellite pictures), 2) Keyword search which will look for an exact match of a term in any of the designated fields (e.g. URL type, origin of site, discipline), and 3) Advanced search, which allows you to combine terms from any of ten different fields in a single search. Results are displayed in alphabetical order and include the URL title, the URL, and a brief annotation that describes the website. There is an active link to the URL. A web link checker accesses sites to identify broken links. After several unsuccessful attempts, the submitter is contacted and asked to update or delete the site. Between 200 and 250 earth and environmental sites are presently catalogued through CURL. This format could be used by any academic discipline and future plans allow for web resources to span collections.

O'Connell, S.; O'Connell, S.; Klassen, T.; Roy, M.; Glynn, M.

2001-05-01

223

Conservative management of a case of medial epicondylosis in a recreational squash player  

PubMed Central

Objective: This case study was conducted to evaluate the treatment and management of a patient presenting with medial elbow pain diagnosed as medial epicondylosis. Case: A 35 year old male presented with medial elbow pain of 4–6 weeks duration that worsened after playing squash. Treatment: A course of fascial stripping techniques was initiated, including: cross friction massage, instrument assisted fascial stripping to the medial epicondyle area and over the belly of the pronator teres muscle, ischemic compression of a trigger point in the pronator teres, active assisted compressions to the trigger point noted in the pronator teres, and mobilizations of the carpals, specifically the scaphoid. Instructions were given to the patient regarding icing the elbow and daily eccentric exercises. At a one year follow up, the patient reported complete resolution of symptoms with no recurrence. Conclusion: Conservative management, including eccentric exercises, mobilizations, and fascial stripping appear to be beneficial in the treatment of medial epicondylosis.

Hudes, Karen

2011-01-01

224

Fermions and D = 11 supergravity on squashed Sasaki-Einstein manifolds  

NASA Astrophysics Data System (ADS)

We discuss the dimensional reduction of fermionic modes in a recently found class of consistent truncations of D = 11 supergravity compactified on squashed seven-dimensional Sasaki-Einstein manifolds. Such reductions are of interest, for example, in that they have (2 + 1)-dimensional holographic duals, and the fermionic content and their interactions with charged scalars are an important aspect of their applications. We derive the lower-dimensional equations of motion for the fermions and exhibit their couplings to the various bosonic modes present in the truncations under consideration, which most notably include charged scalar and form fields. We demonstrate that our results are consistent with the expected supersymmetric structure of the lower dimensional theory, and apply them to a specific example which is relevant to the study of (2 + 1)-dimensional holographic superconductors.

Bah, Ibrahima; Faraggi, Alberto; Jottar, Juan I.; Leigh, Robert G.; Pando Zayas, Leopoldo A.

2011-02-01

225

Thermodynamics of five-dimensional static three-charge STU black holes with squashed horizons  

NASA Astrophysics Data System (ADS)

We present a new expression for the five-dimensional static Kaluza-Klein black hole solution with squashed S3 horizons and three different charge parameters. This black hole solution belongs to D=5, N=2 supergravity theory, its spacetime is locally asymptotically flat and has a spatial infinity R×S1?S2. The form of the solution is extraordinary simple and permits us very conveniently to calculate its conserved charges by using the counterterm method. It is further shown that our thermodynamical quantities perfectly obey both the differential and the integral first laws of black hole thermodynamics if the length of the compact extra-dimension can be viewed as a thermodynamical variable.

Wu, Shuang-Qing; Wen, Dan; Jiang, Qing-Quan; Yang, Shu-Zheng

2013-10-01

226

Monoclonal antibody-based immunoaffinity chromatography for purifying corn and squash NADH: nitrate reductases. Evidence for an interchain disulfide bond in nitrate reductase  

Microsoft Academic Search

NADH: nitrate reductase (EC 1.6.6.1) (NR) is present in small amounts in plant tissues and its polypeptide in inherently labile. Consequently, NR is difficult to purify. We have generated 20 monoclonal antibodies (McAb) for corn and squash NR and selected two for use in immunoaffinity chromatography. Squash McAb CM 15(11) and corn McAb ZM 2(69)9, which both bind corn and

Gregory E. Hyde; Julie A. Wilberding; Annette L. Meyer; Ellen R. Campbell; Wilbur H. Campbell

1989-01-01

227

Solution of the Div-Curl Problem in Generalized Curvilinear Coordinates  

Microsoft Academic Search

We propose a method for solving the div-curl problem on a structured nonorthogonal curvilinear grid. The differential operators are discretized using a MAC-scheme for the unknowns in such a way that the discrete counterparts of the usual vector analysis relations are satisfied. The derived discrete problem is then solved by performing a Helmholtz-type decomposition of the unknown vector field. This

F. Bertagnolio; O. Daube

1997-01-01

228

Electromyographic muscle activity in curl-up exercises with different positions of upper and lower extremities.  

PubMed

The purpose of the study was to evaluate the electromyographic (EMG) activity of muscles in curl-up exercises depending on the position of the upper and lower extremities. From the perspective of biomechanics, different positions of the extremities result in shifting the center of gravity and changing muscular loads in abdominal strength exercises. The subjects of the research were 3 healthy students (body mass 53-56 kg and height 163-165 cm) with no history of low back pain or abdominal surgery. Subjects completed 18 trials for each of the 9 exercises (static curl-up with 3 positions of the upper and 3 position of the lower extremities). The same experiment with the same subjects was conducted on the next day. The EMG activity of rectus abdominis (RA), erector spinae (ES), and quadriceps femoris-long head (rectus femoris [RF]) was examined during the exercises. The surface electrical activity was recorded for the right and left sides of each muscle. The raw data for each muscle were rectified and integrated. The statistical analysis showed that changing the position of upper extremities in the examined exercises affects the EMG activity of RA and ES but does not significantly affect the EMG activity of RF. Additionally, it was found that curl-up exercises with the upper extremities extended behind the head and the lower extremities flexed at 90° in the hip and knee joints involve RA with the greatest intensity, whereas curl-up exercises with the upper extremities extended along the trunk and the lower extremities flexed at 90° in the hip and knee joints involve RA with the lowest intensity. PMID:20940638

Rutkowska-Kucharska, Alicja; Szpala, Agnieszka

2010-11-01

229

Volume-Surface Integral Equations with hybrid curl-conforming and divergence-conforming basis functions  

Microsoft Academic Search

In this paper, the VSIE solved by a hybrid curl-conforming and divergence-conforming basis functions is presented. In this method, new EFIEs are formed first. Then curlconforming edge basis functions are used for the VIE with the electric field as the unknowns and divergence-conforming edge basis functions are used for the SIE on PEC surfaces with the surface electric current as

Xiande Cao; Cai-Cheng Lu

2010-01-01

230

Chopping of near- and mid-infrared radiation using a curled electrostatic MEMS actuator  

NASA Astrophysics Data System (ADS)

An electrostatic MEMS actuator known as the "Artificial Eyelid" can be used as a micromechanical chopper for IR detectors. The actuator structure consists of a curled polymer/metal film stack which is microfabricated and released from an IR transparent substrate. The film stack is uncurled by applying an electric field between the curled film and the transparent fixed electrode on the substrate. These flexible film actuators can act as IR choppers, providing transmission of radiation to the sensor elements when open (curled) and reflection when closed (uncurled). Arrays of actuators were fabricated on ITO-coated glass substrates and ranged in size from 4 x 4 mm to 7.5 x 15 mm with individual elements ranging from 250 to 500 ?m on a side. Actuation for devices with average radius of curvature of 120 ? was consistently achieved at 150-170 V operation with 98-100% of the elements functioning and long lifetimes. IR chopper characteristics were measured using a blackbody source and pyroelectric detector by applying sine and square wave voltage to the actuators at a frequency of 30 Hz. The capability of the artificial eyelid for chopping near- and mid-IR radiation, including future fabrication of devices using NiCo2O4 or NiRh2O4 films for IR transparent electrodes, will be discussed.

Dausch, David E.; Goodwin, Scott H.; Exarhos, Gregory J.

2003-09-01

231

Competition between curls and plectonemes near the buckling transition of stretched supercoiled DNA  

NASA Astrophysics Data System (ADS)

Recent single-molecule experiments have observed that formation of a plectonemically supercoiled region in a stretched, twisted DNA proceeds via abrupt formation of a small plectonemic “bubble.” A detailed mesoscopic model is presented for the formation of plectonemic domains, including their positional entropy, and the influence of small chiral loops or “curls” along the extended DNA. Curls begin to appear just before plectoneme formation, and are more numerous at low salt concentrations (<20 mM univalent ions) and at low forces (<0.5 pN). However, plectonemic domains quickly become far more stable slightly beyond the transition to supercoiling at moderate forces and physiological salt conditions. At the supercoiling transition, for shorter DNAs (2 kb) only one supercoiled domain appears, but for longer DNAs at lower forces (<0.5 pN) positional entropy favors formation of more than one plectonemic domain; a similar effect occurs for low salt. Although they are not the prevalent mode of supercoiling, curls are a natural transition state for binding of DNA-loop-trapping enzymes; we show how addition of loop-trapping enzymes can modify the supercoiling transition. The behavior of DNA torque is also discussed, including the effect of the measurement apparatus torque stiffness, which can play a role in determining how large the torque “overshoot” is at the buckling transition.

Marko, John F.; Neukirch, Sébastien

2012-01-01

232

A biomechanical assessment of the sliding motion of curling delivery in elite and subelite curlers.  

PubMed

The present study examined the technical characteristics of sliding performance from push-off until stone release in curling delivery. Five elite performance level curlers (> 7 years experience) and five subelite level curlers (< 3 years experience) were analyzed during the action of delivery of a curling stone. The joint angles, angular velocities, and moments of the body center of mass (COM) were determined based on three-dimensional kinematic data. The plantar pressure data were measured using a validated in-shoe system. The results indicated that the gliding time and horizontal velocity of the mass center of the body during the sliding phase were not significantly different between the elite and subelite groups. However, there were significant differences in the gliding distance and the rate of changes in velocity profiles of body COM between the two groups. The moment of the body COM from its relative position to the ankle of the support limb in the anterior/posterior direction was positive in elite curlers and negative in subelite curlers. In addition, larger ankle dorsiflexion and greater contact area of the sliding foot were observed in elite curlers. These data suggest a superior ability of elite curlers to maintain a regulated movement speed and balance control during the performance of a curling stone delivery. PMID:22661127

Yoo, Kyoung-Seok; Kim, Hyun-Kyung; Park, Jin-Hoon

2012-05-10

233

Mapping leaf surface landscapes.  

PubMed Central

Leaf surfaces provide the ecologically relevant landscapes to those organisms that encounter or colonize the leaf surface. Leaf surface topography directly affects microhabitat availability for colonizing microbes, microhabitat quality and acceptability for insects, and the efficacy of agricultural spray applications. Prior detailed mechanistic studies that examined particular fungi-plant and pollinator-plant interactions have demonstrated the importance of plant surface topography or roughness in determining the outcome of the interactions. Until now, however, it has not been possible to measure accurately the topography--i.e., the three-dimensional structure--of such leaf surfaces or to record precise changes in patterns of leaf surface elevation over time. Using contact mode atomic force microscopy, we measured three-dimensional coordinates of upper leaf surfaces of Vaccinium macrocarpon (cranberry), a perennial plant, on leaves of two age classes. We then produced topographic maps of these leaf surfaces, which revealed striking differences between age classes of leaves: old leaves have much rougher surfaces than those of young leaves. Atomic force microscope measurements were analyzed by lag (1) autocorrelation estimates of leaf surfaces by age class. We suggest that the changes in topography result from removal of epicuticular lipids and that the changes in leaf surface topography influence phylloplane ecology. Visualizing and mapping leaf surfaces permit detailed investigations into leaf surface-mediated phenomena, improving our understanding of phylloplane interactions. Images Fig. 1

Mechaber, W L; Marshall, D B; Mechaber, R A; Jobe, R T; Chew, F S

1996-01-01

234

Movement of Soil-Applied Imidacloprid and Thiamethoxam into Nectar and Pollen of Squash (Cucurbita pepo)  

PubMed Central

There has been recent interest in the threat to bees posed by the use of systemic insecticides. One concern is that systemic insecticides may translocate from the soil into pollen and nectar of plants, where they would be ingested by pollinators. This paper reports on the movement of two such systemic neonicotinoid insecticides, imidacloprid and thiamethoxam, into the pollen and nectar of flowers of squash (Cucurbita pepo cultivars “Multipik,” “Sunray” and “Bush Delicata”) when applied to soil by two methods: (1) sprayed into soil before seeding, or (2) applied through drip irrigation in a single treatment after transplant. All insecticide treatments were within labeled rates for these compounds. Pollen and nectar samples were analyzed using a standard extraction method widely used for pesticides (QuEChERS) and liquid chromatography mass spectrometric analysis. The concentrations found in nectar, 10±3 ppb (mean ± s.d) for imidacloprid and 11±6 ppb for thiamethoxam, are higher than concentrations of neonicotinoid insecticides in nectar of canola and sunflower grown from treated seed, and similar to those found in a recent study of neonicotinoids applied to pumpkins at transplant and through drip irrigation. The concentrations in pollen, 14±8 ppb for imidacloprid and 12±9 ppb for thiamethoxam, are higher than those found for seed treatments in most studies, but at the low end of the range found in the pumpkin study. Our concentrations fall into the range being investigated for sublethal effects on honey bees and bumble bees.

Stoner, Kimberly A.; Eitzer, Brian D.

2012-01-01

235

Fermions and type IIB supergravity on squashed Sasaki-Einstein manifolds  

NASA Astrophysics Data System (ADS)

We discuss the dimensional reduction of fermionic modes in a recently found class of consistent truncations of type IIB supergravity compactified on squashed five-dimensional Sasaki-Einstein manifolds. We derive the lower dimensional equations of motion and effective action, and comment on the supersymmetry of the resulting theory, which is consistent with N = 4 gauged supergravity in d = 5, coupled to two vector multiplets. We compute fermion masses by linearizing around two AdS 5 vacua of the theory: one that breaks N = 4 down to N = 2 spontaneously, and a second one which preserves no supersymmetries. The truncations under consideration are noteworthy in that they retain massive modes which are charged under the U(1) R-symmetry, a feature that makes them interesting for applications to condensed matter phenomena via gauge/gravity duality. In this light, as an application of our general results we exhibit the coupling of the fermions to the type IIB holographic superconductor, and find a consistent further truncation of the fermion sector that retains a single spin-1/2 mode.

Bah, Ibrahima; Faraggi, Alberto; Jottar, Juan I.; Leigh, Robert G.

2011-01-01

236

Tactical use of the T area in squash by players of differing standard.  

PubMed

The importance of dominating the T in squash is recognized by coaches and players but there has been little formal investigation of this aspect of tactical play. Consequently, the aim of this research was to analyse player occupancy of a T area, to establish whether there are differences between winners and losers of games at different playing standards. An automated player-tracking system, with operator supervision and intervention, captured players' movements during matches at the World Team Championships (n = 11), the Slovenian National Championships (n = 11), and a local tournament (n = 15). Frequency of occupying the T area at the moment opponents played their shot best discriminated playing standard. Winners spent a greater proportion of total playing time in the T area than losers (P < 0.001), except during closely contested games. The results suggest that time in the T area indicates dominance of rallies. Future studies need to consider both between-group (playing standard) and within-game (individual player standard) differences, as both were shown to influence the time players spent in the T area. PMID:19551552

Vuckovi?, Goran; Pers, Janez; James, Nic; Hughes, Mike

2009-06-01

237

The geminivirus BL1 movement protein is associated with endoplasmic reticulum-derived tubules in developing phloem cells.  

PubMed Central

Plant viruses encode movement proteins that are essential for systemic infection of their host but dispensable for replication and encapsidation. BL1, one of the two movement proteins encoded by the bipartite geminivirus squash leaf curl virus, was immunolocalized to unique approximately 40-nm tubules that extended up to and across the walls of procambial cells in systemically infected pumpkin leaves. These tubules were not found in procambial cells from pumpkin seedlings inoculated with BL1 mutants that are defective in movement. The tubules also specifically stained with antisera to binding protein (BiP), indicating that they were derived from the endoplasmic reticulum. Independent confirmation of this endoplasmic reticulum association was obtained by subcellular fractionation studies in which BL1 was localized to fractions that contained both endoplasmic reticulum membranes and BiP. Thus, squash leaf curl virus appears to recruit the endoplasmic reticulum as a conduit for cell-to-cell movement of the viral genome.

Ward, B M; Medville, R; Lazarowitz, S G; Turgeon, R

1997-01-01

238

Leaf Pack Network  

NSDL National Science Digital Library

The Leaf Pack Network (LPN) is a network of teachers and students investigating their local stream ecosystems by participating in the leaf pack experiment, which involves creating an artificial leaf pack (dry leaves in a mesh bag), immersing it in a stream for 3-4 weeks, and examining it for signs of aquatic insects as indicators of stream health. Participating classrooms share their data through the internet. This activity highlights the connection between streamside forests and the ecology of rivers and streams.

239

Nod factor-induced root hair curling: continuous polar growth towards the point of nod factor application.  

PubMed

A critical step in establishing a successful nitrogen-fixing symbiosis between rhizobia and legume plants is the entrapment of the bacteria between root hair cell walls, usually in characteristic 180 degrees to 360 degrees curls, shepherd's crooks, which are formed by the host's root hairs. Purified bacterial signal molecules, the nodulation factors (NFs), which are lipochitooligosaccharides, induce root hair deformation in the appropriate host legume and have been proposed to be a key player in eliciting root hair curling. However, for curling to occur, the presence of intact bacteria is thought to be essential. Here, we show that, when spot applied to one side of the growing Medicago truncatula root hair tip, purified NF alone is sufficient to induce reorientation of the root hair growth direction, or a full curl. Using wild-type M. truncatula containing the pMtENOD11::GUS construct, we demonstrate that MtENOD11::GUS is expressed after spot application. The data have been incorporated into a cell biological model, which explains the formation of shepherd's crook curls around NF-secreting rhizobia by continuous tip growth reorientation. PMID:12913154

Esseling, John J; Lhuissier, Franck G P; Emons, Anne Mie C

2003-08-01

240

The Geminivirus BR1 Movement Protein Binds Single-Stranded DNA and Localizes to the Cell Nucleus  

Microsoft Academic Search

Plant viruses encode movement proteins that are essential for infection of the host but are not required for viral replica- tion or encapsidation. Squash leaf curl virus (SqLCV), a bipartite geminivirus with a single-stranded DNA genome, encodes two movement proteins, BR1 and BL1, that have been implicated in separate functions in viral movement. To further eluci- date these functions, we

Erica Pascal; Anton A. Sanderfoot; Brian M. Ward; Richard Medville; Robert Turgeon; Sondra G. Lazarowitz

1994-01-01

241

Sequence-Specific lnteraction with the Vira1 ALI Protein ldentifies a Geminivirus DNA Replication Origin  

Microsoft Academic Search

The bipartite geminiviruses such as tomato golden mosaic virus (TGMV) and squash leaf curl virus (SqLCV) have two single-stranded circular genomic DNAs, the A and B components, thought to be replicated from double-stranded circular DNA intermediates. Although it has been presumed that the origin sequences for viral replication are located in the highly conserved 200-nucleotide common region (CR) present in

Sondra G. Lazarowitz; Leeju C. WU; Stephen G. Rogerqb; J. Scott Elmerb

1992-01-01

242

Opto-Curling Probe for Simultaneous Monitoring of Optical Emission and Electron Density in Reactive Plasmas  

NASA Astrophysics Data System (ADS)

An advanced robust probe called opto-curling probe (OCP) is presented, which enables the simultaneous monitoring of electron density and optical emission of reactive plasma. The electron density is obtained from the microwave resonance frequency of a small antenna set on the probe surface while the optical emission spectra are observed through an optical fiber tip located at the probe surface. The ratio of the measured optical emission intensity to the electron density readily provides the radical density without relying on actinometry. The usefulness of OCP was experimentally demonstrated in the oxygen plasma cleaning of a carbonized wall with endpoint detection.

Pandey, Anil; Nakamura, Keiji; Sugai, Hideo

2013-05-01

243

Leaf cutter ants  

NSDL National Science Digital Library

There is much diversity between ants. Leaf cutter ants use their mandibles to cut leaf fragments and take them back to their home. They don't eat the leaves, but instead use them to grow fungus on. They then eat the fungus.

N/A N/A (None;)

2007-12-15

244

Radionuclide concentrations in pinto beans, sweet corn, and zucchini squash grown in Los Alamos Canyon at Los Alamos National Laboratory  

SciTech Connect

Pinto beans, sweet corn, and zucchini squash (Cucurbita pepo var. black beauty) were grown in a randomized complete-block field/pot experiment at a site that contained the highest observed levels of surface gross gamma radioactivity within Los Alamos Canyon (LAC) at Los Alamos National Laboratory. Soils as well as washed edible and nonedible crop tissues were analyzed for various radionuclides and heavy metals . Most radionuclides, with the exception of {sup 3}H and {sup tot}U, in soil from LAC were detected in significantly higher concentrations (p <0.01) than in soil collected from regional background (RBG) locations. Similarly, most radionuclides in edible crop portions of beans, squash, and corn were detected in significantly higher (p <0.01 and 0.05) concentrations than RBG. Most soil-to-plant concentration ratios for radionuclides in edible and nonedible crop tissues from LAC were within the default values given by the Nuclear Regulatory Commission and Environmental Protection Agency. All heavy metals in soils, as well as edible and nonedible crop tissues grown in soils from LAC, were within RBG concentrations. Overall, the total maximum net positive committed effective dose equivalent (CEDE)--the CEDE plus two sigma for each radioisotope minus background and then all positive doses summed--to a hypothetical 50-year resident that ingested 160 kg of beans, corn, and squash in equal proportions, was 74 mrem y{sup -1}. This dose was below the International Commission on Radiological Protection permissible dose limit (PDL) of 100 mrem y{sup -1} from all pathways; however, the addition of other internal and external exposure route factors may increase the overall dose over the PDL. Also, the risk of an excess cancer fatality, based on 74 mrem y{sup -1}, was 3.7 x 10{sup -5} (37 in a million), which is above the Environmental Protection Agency`s (acceptable) guideline of one in a million. 31 refs., 15 tabs.

Fresquez, P.R.; Mullen, M.A.; Naranjo, L. Jr.; Armstrong, D.R.

1997-05-01

245

Estimation of the squashing degree within a three-dimensional domain  

NASA Astrophysics Data System (ADS)

Context. The study of the magnetic topology of magnetic fields aims at determining the key sites for the development of magnetic reconnection. Quasi-separatrix layers (QSLs), regions of strong connectivity gradients, are topological structures where intense-electric currents preferentially build-up, and where, later on, magnetic reconnection occurs. Aims: QSLs are volumes of intense squashing degree, Q; the field-line invariant quantifying the deformation of elementary flux tubes. QSL are complex and thin three-dimensional (3D) structures difficult to visualize directly. Therefore Q maps, i.e. 2D cuts of the 3D magnetic domain, are a more and more common features used to study QSLs. Methods: We analyze several methods to derive 2D Q maps and discuss their analytical and numerical properties. These methods can also be used to compute Q within the 3D domain. Results: We demonstrate that while analytically equivalent, the numerical implementation of these methods can be significantly different. We derive the analytical formula and the best numerical methodology that should be used to compute Q inside the 3D domain. We illustrate this method with two twisted magnetic configurations: a theoretical case and a non-linear force free configuration derived from observations. Conclusions: The representation of QSL through 2D planar cuts is an efficient procedure to derive the geometry of these structures and to relate them with other quantities, e.g. electric currents and plasma flows. It will enforce a more direct comparison of the role of QSL in magnetic reconnection.

Pariat, E.; Démoulin, P.

2012-05-01

246

Inoculation of plants with begomoviruses by particle bombardment without cloning: Using rolling circle amplification of total DNA from infected plants and whiteflies.  

PubMed

A new system for inoculation of plants with begomoviral DNA without cloning or the use insect vectors is described. Total DNA extracted from begomovirus-infected plants was amplified by rolling circle amplification (RCA) using the bacteriophage phi29 DNA polymerase, and inoculated to plants by particle bombardment. Infection rates of up to 100% were obtained using this technique. This technique successfully inoculated all the begomoviruses evaluated: five bipartite (Bean golden yellow mosaic virus, Cabbage leaf curl virus, Squash leaf curl virus, Tomato mottle virus, Watermelon chlorotic stunt virus) as well as one monopartite (Tomato yellow leaf curl virus). The success of the technique was not dependent upon plant species. Four species from three plant families [Phaseolus vulgaris (bean), Solanum lycopersicum (tomato), Cucurbita pepo (squash), and Citrullus lanatus (watermelon)], could all be inoculated by this technique. The success of the method was not dependent upon either the type or the age of the source of virus. Infectious DNA was obtained successfully from fresh, freeze-dried or desiccated plant material, from squashes of plant leaves on FTA cards, as well as from the insect vector. Plant material collected and dried as long as 25 years ago yielded infectious DNA by this method. In summary, this method can be used to obtain infectious DNA of single-stranded circular DNA viruses that can be activated for purposes of completing Koch's postulates, for preservation of pure virus cultures, and for many other applications where infectious DNA is required. PMID:20447420

Guenoune-Gelbart, Dana; Sufrin-Ringwald, Tali; Capobianco, Heather; Gaba, Victor; Polston, Jane E; Lapidot, Moshe

2010-05-04

247

In-situ Observation of Current-Pulse-Induced Curling of Graphene Edges and Carbon-Cages Production  

NASA Astrophysics Data System (ADS)

We found a new cage transformation process where Joule heating with a cyclic current pulse strongly triggered the curling of graphene edge, and enhanced the transformation of the cages feeding with a source of amorphous carbon that adhered on the graphene sheet. Here the cyclic thermal stress seems to play an important role to induce the curling of the graphene edges. We also found that internal stress induced by a mechanical vibration strongly enhanced the transformation to larger carbon-cages and multi-walled graphitic onions that was never appeared in the current pulse induction.

Nishijima, Takuya; Ueki, Ryuichi; Kano, Emi; Fujita, Jun-ichi

2012-06-01

248

Estimating Near-Infrared Leaf Reflectance from Leaf Structural Characteristics  

Microsoft Academic Search

The relationship between near-infrared reflectance at 800 nm (NIRR) from leaves and characteristics of leaf structure known to affect photosynthesis was investigated in 48 species of alpine angiosperms. This wavelength was selected to discriminate the effects of leaf structure vs. chemical or water content on leaf reflectance. A quantitative model was first constructed correlating NIRR with leaf structural characteristics for

Michele R. Slaton; E. Raymond Hunt; William K. Smith

2001-01-01

249

Four-Leaf Clover  

NSDL National Science Digital Library

Scientist-in-training Summer Praetorius has an unusual skillâshe is really, really good at spotting four-leaf clovers (Trifolium repens L.). A single gene causes the normally three-leafed clover to produce a fourth, supposedly lucky, leaf. As it turns out, good science depends on both close observationâa skill Praetorius uses to spot tiny shelled animals called foraminiferaâand a little bit of luck. Ari Daniel Shapiro explains. Also included is a Learn More section that provides background information on the scientists recorded in the podcast, lessons, images, and cool facts.

2009-01-01

250

Scolicidal effects of squash (Corylus spp) seeds, hazel (Curcurbia spp) nut and garlic (Allium sativum) extracts on hydatid cyst protoscolices  

PubMed Central

Background: Because there is no effective drug therapy for hydatid cyst yet, assessment and finding of some new agents especially from herbal origin with a desired scolicidal effect attracts great attention for treatment and pre-surgical use to prevent the hydatid cyst recurrence. Hazelnut, squash seeds and garlic chloroformic and hydro-alcoholic extracts’ scolicidal effects were examined. Materials and Methods: Suspension of protoscolices was obtained from infected liver and or lung of sheep and goats from Ziyaran abattoir. The chloroformic and hydro-alcoholic extracts from hazelnut, squash seeds and garlic were extracted using the succilate method. Scolicidal effect of each extract assessed in different concentrations and effected time using microscopy and 0.1% eosin solution stained only killed protoscolices. Results: Present study showed that garlic had more potent scolicidal effects among all the 3 plants and the chloroformic extract of garlic was the most potent protoscolicid among all of the extracts and killed 98% of protoscolices in 50 mg/ml on a minimum of 20 minutes exposure. Conclusion: Garlic chloroformic extract is a safe and potent protoscolicid and might be used in hydatid cyst treatment and pre-surgery to prevent secondary cyst recurrence.

Eskandarian, Abbas Ali

2012-01-01

251

Do Leaf Breakdown Rates Actually Measure Leaf Disappearance from Streams?  

Microsoft Academic Search

Abstract Wemeasured leaf input, leaf breakdown, and benthic leaf standing stock in Hugh White Creek, a second-order, Appalachian Mountain stream in North Carolina, U. S. A. Leaf input and leaf breakdown data were used in a ,computer ,model to predict standing stocks. Predicted standing stocks were then compared,with measured,values. Once the model was modified to include leaves in four breakdown,rate

J. R. Webster; E. F. Benfield; J. J. Hutchens; J. L. Tank; S. W. Golladay; J. C. Adams

2001-01-01

252

The wetting of leaf surfaces  

Microsoft Academic Search

Recent advances in the area of the wetting of leaf areas are reviewed with particular emphasis on their relation to agrochemical application. Areas reviewed include leaf wax composition, leaf wetting and superhydrophobicity, agrochemical deposit formation and spray retention. It is thought that most progress has been made in the area of leaf wetting through the work on lotus leaves. In

Philip Taylor

2011-01-01

253

The Effect of Court Location and Available Time on the Tactical Shot Selection of Elite Squash Players  

PubMed Central

No previous research in squash has considered the time between shots or the proximity of the ball to a wall, which are two important variables that influence shot outcomes. The aim of this paper was to analyse shot types to determine the extent to which they are played in different court areas and a more detailed analysis to determine whether the time available had an influence on the shot selected. Ten elite matches, contested by fifteen of the world’s top right handed squash players (age 27 ± 3.2, height 1.81 ± 0.06 m, weight 76.3 ± 3.7 kg), at the men’s World Team Championships were processed using the SAGIT/Squash tracking system with shot information manually added to the system. Results suggested that shot responses were dependent upon court location and the time between shots. When these factors were considered repeatable performance existed to the extent that one of two shots was typically played when there was limited time to play the shot (< 1.20s). For example, it was clear that when players did not have a lot of time to hit the ball (low time i.e. < 1.06s, and mid time i.e. 1.06 - 1.20s) in the front left corner close to the side wall, the crosscourt lob was used frequently (44.30% and 36.31% respectively) whereas when there was more time this shot was seldom used (13.64%). Consequently variant and invariant behaviour were shown to exist in elite squash although for the first time it was suggested that the availability of time to play a shot contributed to which of these behaviours was evident. This analysis could be extended by adopting a case study approach to see how individual differences in strategy and tactics affect shot selections. Key points Previous research has suggested that a playing strategy, elements decided in advance of the match, may be evident for elite players by examining court location and preceding shot type, however these parameters alone are unlikely to be sufficient predictors. At present there is no known analysis in squash, or indeed in any of the racket sports, that has quantified the time available to respond to different shot types. An understanding of the time interval between shots and the movement characteristics of the player responding to different shots according to the court positions might facilitate a better understanding of the dynamics that determine shot selection. Some elements of a general playing strategy were evident e.g. predominately hitting to the back left of the court, but tactical differences in shot selection were also evident on the basis of court location and time available to play a shot.

Vuckovic, Goran; James, Nic; Hughes, Mike; Murray, Stafford; Sporis, Goran; Pers, Janez

2013-01-01

254

Electronic Leaf Project  

NSDL National Science Digital Library

This article demonstrates the benefits of a direct application of technology into a science classroom by transferring a traditional activity, such as leaf identification, into an electronic format. The new dynamic medium possesses attributes that can enha

Houston, Carolyn; Hargis, Jace

2000-05-01

255

Leaf Absorbance and Photosynthesis.  

National Technical Information Service (NTIS)

The absorption spectrum of a leaf is often thought to contain some clues to the photosynthetic action spectrum of chlorophyll. Of course, absorption of photons is needed for photosynthesis, but the reverse, photosynthesis when there is absorption, is not ...

K. Schurer

1994-01-01

256

Leaf to Landscape  

Microsoft Academic Search

\\u000a Temporal dynamics and structural complexity of plant canopies strongly affect light harvesting, generating variable spatio-temporal\\u000a distributions of the irradiance on leaf area (Baldocchi and Collineau 1994). Leaf light interception scales linearly with\\u000a incident irradiance, but plant photosynthesis and photomorphogenesis typically exhibit a saturating response to light. Because\\u000a of the inherent nonlinearity in light responses, estimates of the photosynthetic rate at

Alessandro Cescatti; Ülo Niinemets

257

Leaf to Landscape  

Microsoft Academic Search

\\u000a One fundamental “problem” for maximizing carbon gain at the leaf and higher organizational levels entails the link between\\u000a light capture and leaf energy budgets. The balance between the two processes, however, depends on the environment. For example,\\u000a shade environments limit carbon gain due to low light levels, and so we would expect plants to display traits that maximize\\u000a light interception

Stanley D. Smith; Elke Naumburg; ÜLo Niinemets; Matthew J. Germino

258

Numerical investigation on strength design and curling effect of mechanically fastened joints in cold-formed austenitic stainless steel  

Microsoft Academic Search

A variety of parametric studies utilizing the finite element analysis (FEA) have been performed by Kim et al in order to predict the mechanical behavior (ultimate strength) of single shear bolted joints in cold-formed (thin-walled) stainless steel sheet. Strength equations considering the strength reduction by curling effect in bolted joint with long end distance and edge distance have been suggested.

Tae Soo Kim; Hitoshi Kuwamura

2011-01-01

259

Stimulation of ROS-scavenging systems in squash ( Cucurbita pepo L.) plants by compost supplementation under normal and low temperature conditions  

Microsoft Academic Search

The beneficial effect of compost, the final product of aerobic biodegradation of organic matter, on growth, lipid peroxidation [as malondialdehyde (MDA], hydrogen peroxide (H2O2) and superoxide anion (O2•?), activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR), as well as reduced ascorbate (ASC) and glutathione (GSH) and their oxidized forms was investigated in squash (Cucurbita

Kamel A. H. Tartoura; Sahar A. Youssef

2011-01-01

260

Effect of living (buckwheat) and UV reflective mulches with and without imidacloprid on whiteflies, aphids and marketable yields of zucchini squash  

Microsoft Academic Search

The silverleaf whitefly, B biotype of the sweetpotato whitefly, Bemisia tabaci Gennadius also known as B. argentifolii Bellows and Perring, and the melon aphid, Aphis gossypii Glover, are key pests of zucchini squash in Florida. The use of mulches, living or synthetic, is one of the tactics that could be used to suppress whitefly and aphid populations and their associated

T. W. Nyoike; O. E. Liburd

2010-01-01

261

Effects of cooking on the cell walls (dietary fiber) of 'Scarlet Warren' winter squash ( Cucurbita maxima ) studied by polysaccharide linkage analysis and solid-state (13)C NMR.  

PubMed

Cell wall polysaccharides of 'Scarlet Warren' winter squash ( Cucurbita maxima ) were investigated before and after thermal processing. Linkage analysis of polysaccharides was done by gas chromatography coupled to mass spectrometry (GC-MS). The linkage analysis showed the cell wall polysaccharide compositions of raw and cooked squash were similar. The total pectic polysaccharides (galacturonan, rhamnogalacturonan, arabinan, and arabinogalactan) contents of the cell walls of both raw and cooked squash were 39 mol %. The amounts of pectic polysaccharides and xyloglucan in the cell walls of squash showed little alteration on heating. The cellulose content of the raw and cooked cell walls was relatively high at 47 mol %, whereas the xyloglucan content was low at 4 mol %. Solid-state (13)C nuclear magnetic resonance (NMR) spectroscopy techniques were used to examine the molecular motion of the polysaccharides in the cell walls. The mobility of highly flexible galactan depends on the water content of the sample, but no difference was seen between raw and cooked samples. Likewise, the mobility of semimobile pectic polysaccharides was apparently unaltered by cooking. No change was detected in the rigid cellulose microfibrils on cooking. PMID:21604813

Ratnayake, R M Sunil; Sims, Ian M; Newman, Roger H; Melton, Laurence D

2011-06-20

262

Deer predation on leaf miners via leaf abscission  

NASA Astrophysics Data System (ADS)

The evergreen oak Quercus gilva Blume sheds leaves containing mines of the leaf miner Stigmella sp. (Lepidoptera: Nepticulidae) earlier than leaves with no mines in early spring in Nara, central Japan. The eclosion rates of the leaf miner in abscised and retained leaves were compared in the laboratory to clarify the effects of leaf abscission on leaf miner survival in the absence of deer. The leaf miner eclosed successfully from both fallen leaves and leaves retained on trees. However, sika deer ( Cervus nippon centralis Kishida) feed on the fallen mined leaves. Field observations showed that deer consume many fallen leaves under Q. gilva trees, suggesting considerable mortality of leaf miners due to deer predation via leaf abscission. This is a previously unreported relationship between a leaf miner and a mammalian herbivore via leaf abscission.

Yamazaki, Kazuo; Sugiura, Shinji

2008-03-01

263

Cleared Leaf Collection  

NSDL National Science Digital Library

The University of California-Berkeley Museum of Paleontology has recently launched this online database of the Daniel I. Axelrod and the Berkeley leaf collections, which contain over 2000 modern leaf specimens bleached and stained to make their venation patterns more visible. Data records for both collections are now online, and images (including a higher resolution mode) will eventually become available for each specimen beginning with those in the Axelrod collection. Using the database is somewhat tricky, but a detailed help page is provided.

264

Ramularia Leaf Spot  

Technology Transfer Automated Retrieval System (TEKTRAN)

Ramularia leaf spot of sugar beet, a disease caused by Ramularia beticola, is a sporadic problem in the United States, particularly in seed production. It is a more common problem in parts of Europe. Symptoms include light brown, angular spots on the leaves and can cause death of leaves. Epidemiol...

265

Leaf area index measurements  

Microsoft Academic Search

Leaf area index (LAI) is a key structural characteristic of forest ecosystems because of the role of green leaves in controlling many biological and physical processes in plant canopies. Accurate LA1 estimates are required in studies of ecophysiology , atmosphere-ecosystem interactions, and global change. The objective of this paper is to evaluate LA1 values obtained by several research teams using

Jing M. Chen; Paul Steven Plummer; M. Rich; Stith T. Gower; John M. Norman

1997-01-01

266

A high speed profiler based slab curvature index for jointed concrete pavement curling and warping analysis  

NASA Astrophysics Data System (ADS)

One of the biggest gaps of missing knowledge between accurate structural modeling of concrete pavement slab behavior and real pavement behavior is accounting for slab warping (locked-in curvature and moisture gradient effects) and curling (temperature gradient effects). Curling and warping are curvatures that can be present in a PCC slab that can cause corners and edges, or mid panel, of the slab to lift off of the ground resulting in relatively high deflection and stress in the system. The least understood type of curvature in slabs is apparent locked-in curvature, which can become excessive and control the overall behavior of the pavement system. This project is focused on quantifying slab curvatures and the effects of apparent locked-in curvature on the behavior and long-term performance of pavement systems. A high-speed profile analysis technique for detecting the amount of slab curvatures along pavement wheel paths is described. This signal processing technique can detect relatively small curvature variations in high-speed pavement elevation profiles obtained at normal highway operating speeds using special vehicles. A resulting curvature detection algorithm is applied to the Federal Highway Administration (FHWA) Long Term Pavement Performance (LTPP) database high-speed pavement profiles for jointed concrete pavements. The range and nature of slab curvatures detected in the profiles is described. The calculated locked-in curvature at the various pavement sites is compared to LTPP database information to evaluate curvature effects on pavement deterioration rates and the relation between site parameters and locked-in curvature. The significance of slab curvature is shown through statistics and predictive models developed for various pavement distress modes. It is shown that the amount of curvature locked into concrete slabs is one of the strongest factors in the FHWA LTPP data correlated to deterioration of pavements. This study shows that preventing locked-in slab curvature should be a top priority for PCC slabs in highway applications. The profile analysis routine and distress prediction models developed will be valuable tools for pavement designers, managers, and researchers.

Byrum, Christopher Ronald

267

Macro-scale observation of curl-free vector potential: A manifestation of quantum modulation of the de Broglie wave  

NASA Astrophysics Data System (ADS)

Experimental results are presented here reporting the detection of a curl-free vector potential on the macro-scale as contrasted with the detection on the micro-scale à la Aharonov-Bohm. Such a detection is attributed to the `quantum modulation' of the plane wave state of the guiding centre motion of a charged particle in a magnetic field, which is generated concomitantly with the excitation of its Landau levels in a scattering episode, through the mechanism of quantum entanglement between the parallel and perpendicular degrees of freedom of the particle. Such a `quantum modulation' is also a matter wave, but on the macro-scale, and leads to the `sensing' of the curl-free vector potential on the macro-scale. Thus while the Aharonov-Bohm effect is attributed to the sensing of the curl-free vector potential by the de Broglie wave, its sensing on the macro-scale is attributed to the modulation of the de Broglie wave.

Varma, R. K.; Banerjee, S. B.; Ambastha, A.

2012-02-01

268

PFB coal-fired combined-cycle development program. Test evaluation report: CURL test series  

SciTech Connect

Under contract to the United States Department of Energy, the General Electric Company participated in the NCB/CURL 10 x 100 hour test at Leatherhead, England, in order to investigate corrosion and erosion of candidate gas turbine blade alloys for service in a Pressurized Fluidized Bed (PFB) combined-cycle power plant. The tests also permitted an evaluation of hot gas cleanup equipment. The results are encouraging, indicating that it is possible to provide materials which can withstand the erosive/corrosive PFB environment. Further, it was found that the reduction of particulate efflux via cyclones was sufficient to eliminate excessive erosion of gas turbine components in the stationary cascades tested. The tests also demonstrated the great care required to obtain accurate and consistent data measurement in certain areas. In particular, effluent characterization techniques require significant sophistication. Particle size distribution data indicated a high consistency of operation. On the other hand, difficulties were encountered in obtaining accurate and reliable indication of the alkali content of the exhaust gas. This was disappointing, since this is an important factor related to the tolerance levels of conventional gas turbine materials. Future testing efforts are recommended and defined.

Not Available

1980-01-01

269

Signal transduction in leaf senescence.  

PubMed

Leaf senescence is a complex developmental phase that involves both degenerative and nutrient recycling processes. It is characterized by loss of chlorophyll and the degradation of proteins, nucleic acids, lipids, and nutrient remobilization. The onset and progression of leaf senescence are controlled by an array of environmental cues (such as drought, darkness, extreme temperatures, and pathogen attack) and endogenous factors (including age, ethylene, jasmonic acid, salicylic acid, abscisic acid, and cytokinin). This review discusses the major breakthroughs in signal transduction during the onset of leaf senescence, in dark- and drought-mediated leaf senescence, and in various hormones regulating leaf senescence achieved in the past several years. Various signals show different mechanisms of controlling leaf senescence, and cross-talks between different signaling pathways make it more complex. Key senescence regulatory networks still need to be elucidated, including cross-talks and the interaction mechanisms of various environmental signals and internal factors. PMID:23096425

Zhang, Haoshan; Zhou, Chunjiang

2012-10-25

270

The worldwide leaf economics spectrum.  

PubMed

Bringing together leaf trait data spanning 2,548 species and 175 sites we describe, for the first time at global scale, a universal spectrum of leaf economics consisting of key chemical, structural and physiological properties. The spectrum runs from quick to slow return on investments of nutrients and dry mass in leaves, and operates largely independently of growth form, plant functional type or biome. Categories along the spectrum would, in general, describe leaf economic variation at the global scale better than plant functional types, because functional types overlap substantially in their leaf traits. Overall, modulation of leaf traits and trait relationships by climate is surprisingly modest, although some striking and significant patterns can be seen. Reliable quantification of the leaf economics spectrum and its interaction with climate will prove valuable for modelling nutrient fluxes and vegetation boundaries under changing land-use and climate. PMID:15103368

Wright, Ian J; Reich, Peter B; Westoby, Mark; Ackerly, David D; Baruch, Zdravko; Bongers, Frans; Cavender-Bares, Jeannine; Chapin, Terry; Cornelissen, Johannes H C; Diemer, Matthias; Flexas, Jaume; Garnier, Eric; Groom, Philip K; Gulias, Javier; Hikosaka, Kouki; Lamont, Byron B; Lee, Tali; Lee, William; Lusk, Christopher; Midgley, Jeremy J; Navas, Marie-Laure; Niinemets, Ulo; Oleksyn, Jacek; Osada, Noriyuki; Poorter, Hendrik; Poot, Pieter; Prior, Lynda; Pyankov, Vladimir I; Roumet, Catherine; Thomas, Sean C; Tjoelker, Mark G; Veneklaas, Erik J; Villar, Rafael

2004-04-22

271

Isoperimetric problems for the helicity of vector fields and the Biot-Savart and curl operators  

NASA Astrophysics Data System (ADS)

The helicity of a smooth vector field defined on a domain in three-space is the standard measure of the extent to which the field lines wrap and coil around one another. It plays important roles in fluid mechanics, magnetohydrodynamics, and plasma physics. The isoperimetric problem in this setting is to maximize helicity among all divergence-free vector fields of given energy, defined on and tangent to the boundary of all domains of given volume in three-space. The Biot-Savart operator starts with a divergence-free vector field defined on and tangent to the boundary of a domain in three-space, regards it as a distribution of electric current, and computes its magnetic field. Restricting the magnetic field to the given domain, we modify it by subtracting a gradient vector field so as to keep it divergence-free while making it tangent to the boundary of the domain. The resulting operator, when extended to the L2 completion of this family of vector fields, is compact and self-adjoint, and thus has a largest eigenvalue, whose corresponding eigenfields are smooth by elliptic regularity. The isoperimetric problem for this modified Biot-Savart operator is to maximize its largest eigenvalue among all domains of given volume in three-space. The curl operator, when restricted to the image of the modified Biot-Savart operator, is its inverse, and the isoperimetric problem for this restriction of the curl is to minimize its smallest positive eigenvalue among all domains of given volume in three-space. These three isoperimetric problems are equivalent to one another. In this paper, we will derive the first variation formulas appropriate to these problems, and use them to constrain the nature of any possible solution. For example, suppose that the vector field V, defined on the compact, smoothly bounded domain ?, maximizes helicity among all divergence-free vector fields of given nonzero energy, defined on and tangent to the boundary of all such domains of given volume. We will show that (1) |V| is a nonzero constant on the boundary of each component of ? (2) all the components of ?? are tori; and (3) the orbits of V are geodesics on ??. Thus, among smooth simply connected domains, none are optimal in the above sense. In principal, one could have a smooth optimal domain in the shape, say, of a solid torus. However, we believe that there are no smooth optimal domains at all, regardless of topological type, and that the true optimizer looks like the singular domain presented in this paper, which we can think of either as an extreme apple, in which the north and south poles have been pressed together, or as an extreme solid torus, in which the hole has been shrunk to a point. A computational search for this singular optimal domain and the helicity-maximizing vector field on it is at present under way, guided by the first variation formulas in this paper.

Cantarella, Jason; Deturck, Dennis; Gluck, Herman; Teytel, Mikhail

2000-08-01

272

Functional and Neuromuscular Changes in the Hamstrings After Drop Jumps and Leg Curls  

PubMed Central

The purpose of this study was to use a holistic approach to investigate changes in jumping performance, kinaesthesia, static balance, isometric strength and fast stepping on spot during a 5-day recovery period, following an acute bout of damaging exercise consisted of drop jumps and leg curls, where specific emphasis was given on the hamstring muscles. Eleven young healthy subjects completed a series of highly intensive damaging exercises for their hamstring muscles. Prior to the exercise, and during the 5-day recovery period, the subjects were tested for biochemical markers (creatine kinase, aspartate aminotransferase, and lactate dehydrogenase), perceived pain sensation, physical performance (squat jump, counter movement jump, maximal frequency leg stamping, maximal isometric torque production and maximally explosive isometric torque production), kinaesthesia (active torque tracking) and static balance. We observed significant decreases in maximal isometric knee flexion torque production, the rate of torque production, and majority of the parameters for vertical jump performance. No alterations were found in kinaesthesia, static balance and fast stepping on spot. The highest drop in performance and increase in perceived pain sensation generally occurred 24 or 48 hours after the exercise. Damaging exercise substantially alters the neuromuscular functions of the hamstring muscles, which is specifically relevant for sports and rehabilitation experts, as the hamstrings are often stretched to significant lengths, in particular when the knee is extended and hip flexed. These findings are practically important for recovery after high-intensity trainings for hamstring muscles. Key Points Hamstring function is significantly reduced following specifically damaging exercise. It fully recovers 120 hours after the exercise. Prevention of exercise-induced muscle damage is cruicial for maintaining normal training regime.

Sarabon, Nejc; Panjan, Andrej; Rosker, Jernej; Fonda, Borut

2013-01-01

273

Functional and neuromuscular changes in the hamstrings after drop jumps and leg curls.  

PubMed

The purpose of this study was to use a holistic approach to investigate changes in jumping performance, kinaesthesia, static balance, isometric strength and fast stepping on spot during a 5-day recovery period, following an acute bout of damaging exercise consisted of drop jumps and leg curls, where specific emphasis was given on the hamstring muscles. Eleven young healthy subjects completed a series of highly intensive damaging exercises for their hamstring muscles. Prior to the exercise, and during the 5-day recovery period, the subjects were tested for biochemical markers (creatine kinase, aspartate aminotransferase, and lactate dehydrogenase), perceived pain sensation, physical performance (squat jump, counter movement jump, maximal frequency leg stamping, maximal isometric torque production and maximally explosive isometric torque production), kinaesthesia (active torque tracking) and static balance. We observed significant decreases in maximal isometric knee flexion torque production, the rate of torque production, and majority of the parameters for vertical jump performance. No alterations were found in kinaesthesia, static balance and fast stepping on spot. The highest drop in performance and increase in perceived pain sensation generally occurred 24 or 48 hours after the exercise. Damaging exercise substantially alters the neuromuscular functions of the hamstring muscles, which is specifically relevant for sports and rehabilitation experts, as the hamstrings are often stretched to significant lengths, in particular when the knee is extended and hip flexed. These findings are practically important for recovery after high-intensity trainings for hamstring muscles. Key PointsHamstring function is significantly reduced following specifically damaging exercise.It fully recovers 120 hours after the exercise.Prevention of exercise-induced muscle damage is cruicial for maintaining normal training regime. PMID:24149148

Sarabon, Nejc; Panjan, Andrej; Rosker, Jernej; Fonda, Borut

2013-09-01

274

Salt allocation during leaf development and leaf fall in mangroves  

Microsoft Academic Search

By taking samples along individual branches and measuring leaf size, thickness and Na+ and K+ concentrations, we have shown in Bruguiera cylindrica, Avicennia rumphiana and Avicennia marina that there are two phases of salt accumulation by leaves. This is confirmed by re-analysis of published data for other species. The first phase is a rapid increase in leaf content as it

John W. Cram; Peter G. Torr; Derek A. Rose

2002-01-01

275

Mass Spectrometric Quantification of Indole-3-Acetic Acid in Rhizobium Culture Supernatants: Relation to Root Hair Curling and Nodule Initiation  

PubMed Central

Indole-3-acetic acid (IAA) has been unequivocally identified in culture supernatants of Rhizobium strains by gas chromatography-mass spectrometry. A method for accurately quantitating IAA in bacterial culture supernatants, employing deuterium-labeled IAA as an internal standard, has been developed. Similar IAA concentrations were found in culture supernatants of chosen Rhizobium mutants (defective in nodule formation) and their corresponding parent strains. Since some of the mutants are known to adhere to root hairs, it can be concluded that root hair curling is not simply a consequence of IAA production by rhizobia.

Badenoch-Jones, Jane; Summons, R. E.; Djordjevic, M. A.; Shine, J.; Letham, D. S.; Rolfe, B. G.

1982-01-01

276

The artificial leaf.  

PubMed

To convert the energy of sunlight into chemical energy, the leaf splits water via the photosynthetic process to produce molecular oxygen and hydrogen, which is in a form of separated protons and electrons. The primary steps of natural photosynthesis involve the absorption of sunlight and its conversion into spatially separated electron-hole pairs. The holes of this wireless current are captured by the oxygen evolving complex (OEC) of photosystem II (PSII) to oxidize water to oxygen. The electrons and protons produced as a byproduct of the OEC reaction are captured by ferrodoxin of photosystem I. With the aid of ferrodoxin-NADP(+) reductase, they are used to produce hydrogen in the form of NADPH. For a synthetic material to realize the solar energy conversion function of the leaf, the light-absorbing material must capture a solar photon to generate a wireless current that is harnessed by catalysts, which drive the four electron/hole fuel-forming water-splitting reaction under benign conditions and under 1 sun (100 mW/cm(2)) illumination. This Account describes the construction of an artificial leaf comprising earth-abundant elements by interfacing a triple junction, amorphous silicon photovoltaic with hydrogen- and oxygen-evolving catalysts made from a ternary alloy (NiMoZn) and a cobalt-phosphate cluster (Co-OEC), respectively. The latter captures the structural and functional attributes of the PSII-OEC. Similar to the PSII-OEC, the Co-OEC self-assembles upon oxidation of an earth-abundant metal ion from 2+ to 3+, may operate in natural water at room temperature, and is self-healing. The Co-OEC also activates H(2)O by a proton-coupled electron transfer mechanism in which the Co-OEC is increased by four hole equivalents akin to the S-state pumping of the Kok cycle of PSII. X-ray absorption spectroscopy studies have established that the Co-OEC is a structural relative of Mn(3)CaO(4)-Mn cubane of the PSII-OEC, where Co replaces Mn and the cubane is extended in a corner-sharing, head-to-tail dimer. The ability to perform the oxygen-evolving reaction in water at neutral or near-neutral conditions has several consequences for the construction of the artificial leaf. The NiMoZn alloy may be used in place of Pt to generate hydrogen. To stabilize silicon in water, its surface is coated with a conducting metal oxide onto which the Co-OEC may be deposited. The net result is that immersing a triple-junction Si wafer coated with NiMoZn and Co-OEC in water and holding it up to sunlight can effect direct solar energy conversion via water splitting. By constructing a simple, stand-alone device composed of earth-abundant materials, the artificial leaf provides a means for an inexpensive and highly distributed solar-to-fuels system that employs low-cost systems engineering and manufacturing. Through this type of system, solar energy can become a viable energy supply to those in the non-legacy world. PMID:22475039

Nocera, Daniel G

2012-04-04

277

The worldwide leaf economics spectrum  

Microsoft Academic Search

Bringing together leaf trait data spanning 2,548 species and 175 sites we describe, for the first time at global scale, a universal spectrum of leaf economics consisting of key chemical, structural and physiological properties. The spectrum runs from quick to slow return on investments of nutrients and dry mass in leaves, and operates largely independently of growth form, plant functional

Ian J. Wright; Peter B. Reich; Mark Westoby; David D. Ackerly; Zdravko Baruch; Frans Bongers; Jeannine Cavender-Bares; Terry Chapin; Johannes H. C. Cornelissen; Matthias Diemer; Jaume Flexas; Eric Garnier; Philip K. Groom; Javier Gulias; Kouki Hikosaka; Byron B. Lamont; Tali Lee; William Lee; Christopher Lusk; Jeremy J. Midgley; Marie-Laure Navas; Ülo Niinemets; Jacek Oleksyn; Noriyuki Osada; Pieter Poot; Lynda Prior; Vladimir I. Pyankov; Catherine Roumet; Sean C. Thomas; Mark G. Tjoelker; Erik J. Veneklaas; Rafael Villar

2004-01-01

278

Leaf retention and cassava productivity  

Microsoft Academic Search

Increased longevity of leaves, or improved leaf retention, has been suggested as a possible means to increase productivity of cassava (Manihot esculenta Crantz). This study evaluated variation in leaf retention and its relation to cassava productivity under irrigated and stressed conditions. In the first trial 1350 clones were evaluated on the North Coast of Colombia with a 5-month dry period

J. I. Lenis; F. Calle; G. Jaramillo; J. C. Perez; H. Ceballos; J. H. Cock

2006-01-01

279

Simulating Leaf Appearance in Rice  

Microsoft Academic Search

Most rice (Oryza sativa L.) simulation models assume that only temperature aff ects leaf appearance rate (LAR). Th is assumption ignores results from controlled environment studies that show that LAR in rice is not constant with time (calendar days) under constant temperature. Th e Streck model, which takes into account age eff ects on LAR, improved the prediction of leaf

Nereu Augusto Streck; Leosane Cristina Bosco; Isabel Lago

2008-01-01

280

Effects of Irrigation Treatments and Rates of Nitrogen Fertilization on Young Hass Avocado Trees. II. Relation to Leaf Tipburn, Tree Sunburn, Shoot Dieback, Leaf Scorch, Leaf Color, Leaf Size, Tree Vigor, and Leaf Moisture Deficits  

Microsoft Academic Search

Periodic observations were made during the years 1955 and 1956. The presence and extent of leaf tipburn, tree sunburn, shoot dieback, leaf scorch, leaf color, leaf size, and tree vigor were noted. Leal: moisture deficits were determined during part of the 1956 irrigation season. LEAF TIPBURN Leaf tipburn, due to the accumulation of Cl and SO4 in mature leaves, is

P. W. Moore; S. J. Richards

281

Novel inhibitors of human leukocyte elastase and cathepsin G. Sequence variants of squash seed protease inhibitor with altered protease selectivity  

SciTech Connect

Novel peptide inhibitors of human leukocyte elastase (HLE) and cathepsin G (CG) were prepared by solid-phase peptide synthesis of P1 amino acid sequence variants of Curcurbita maxima trypsin inhibitor III (CMTI-III), a 29-residue peptide found in squash seed. A systematic study of P1 variants indicated that P1, Arg, Lys, Leu, Ala, Phe, and Met inhibit trypsin; P1, Val, Ile, Gly, Leu, Ala, Phe, and Met inhibit HLE; P1 Leu, Ala, Phe, and Met inhibit CG and chymotrypsin. Variants with P1, Val, Ile, or Gly were selective inhibitors of HLE, while inhibition of trypsin required P1 amino acids with an unbranched {beta} carbon. Studies of Val-5-CMTI-III (P1 Val) inhibition of HLE demonstrated a 1:1 binding stoichiometry with a (K{sub i}){sub app} of 8.7 nM. Inhibition of HLE by Gly-5-CMTI-III indicated a significant role for reactive-site structural moieties other than the P1 side chain. Val-5-CMTI-III inhibited both HLE and human polymorphonuclear leukocyte (PMN) proteolysis of surface-bound {sup 125}I-labeled fibronectin. Val-5-CMTI-III was more effective at preventing turnover of a peptide p-nitroanilide substrate than halting dissolution of {sup 125}I-labeled fibronectin. It was about as effective as human serum {alpha}{sub 1}-proteinase inhibitor in preventing PMN degradation of the connective tissue substrate. In addition to providing interesting candidates for controlling inflammatory cell proteolytic injury, the CMTI-based inhibitors are ideal for studying molecular recognition because of their small size, their ease of preparation, and the availability of sensitive and quantitative assays for intermolecular interactions.

McWherter, C.A.; Walkenhorst, W.F.; Glover, G.I. (Monsanto Company, St. Louis, MO (USA)); Campbell, E.J. (Jewish Hospital at Washington Univ. School of Medicine, ST. Louis, MO (USA))

1989-07-11

282

Agrobacterium mediated genetic transformation of summer squash ( Cucurbita pepo L. cv. Australian green) with cbf-1 using a two vector system  

Microsoft Academic Search

Efficient plant regeneration via shoot tip provided a basis for the optimization of the genetic transformation protocol. Therefore,\\u000a experiments were conducted to establish an efficient in vitro regeneration protocol in summer squash for genetic co-transformation.\\u000a 6-benzylaminopurine at 0.05 mg l?l was found to be optimum concentration of direct regeneration from shoot tip. Effective root system was induced in shootlets\\u000a in indole-3-aceticacid 0.5 mg l?l.

Pramila Shah; N. K. Singh; Neeraj Khare; Meenal Rathore; S. Anandhan; M. Arif; Rupesh Kumar Singh; S. C. Das; Z. Ahmed; Narendra Kumar

2008-01-01

283

Variability of sea surface temperature in the Japan Sea and its relationship to the wind-curl field  

NASA Astrophysics Data System (ADS)

The variability of sea surface temperature (SST) in the Japan Sea is investigated using the complex EOF analysis of daily data produced at Tohoku University, Japan (New Generation SST; 2002-2006). The relationship with the wind field is investigated from the daily NCEP/NCAR reanalysis data with a 1° spatial resolution. Anomalies in the SST (SSTAs) are calculated by subtracting the basin-average annual variation estimated as a leading mode of temperature. The leading mode of an SSTA represents a adjustment to the annual mean variation, most significant in December in the zone of subtropical waters entering the sea through the Korean Strait and in the northwestern sea, over which a cyclonic wind curl develops in the cold period. The semiannual variability mode is identified, which is characterized by the largest temperature increase (decrease) in the western branch of the subarctic front (in the Tatar Strait), which lags by two months behind the semiannual changes in wind curl over the sea. An episodic SSTA movement is detected in the northern part of the sea, which moves from east to west along the western branch of the Tsushima Warm Current with a speed corresponding in magnitude to an advective scale.

Trusenkova, O. O.; Lobanov, V. B.; Kaplunenko, D. D.

2008-08-01

284

The in vitro neurotoxic and myotoxic effects of the venom from the Suta genus (curl snakes) of elapid snakes.  

PubMed

Australia has a tremendous diversity of elapid snakes, including many unique smaller sized species of this venomous snake family. However, little if anything is known about the majority of the venoms of these lesser studied snakes. In the current study, the venoms of Suta suta (curl snake) and Suta punctata (spotted-curl snake) were examined for in vitro activity using a skeletal muscle preparation (i.e. chick biventer cervicis nerve-muscle preparation). Both venoms caused concentration-dependent (3-10 microg/ml) inhibition of nerve-mediated twitches, and inhibited responses to exogenous acetylcholine and carbachol, indicating the presence of postsynaptic neurotoxins. These effects were prevented by prior addition of CSL Ltd. polyvalent snake antivenom (5 units/ml) but only partially reversed by the addition of antivenom (5 units/ml) at the t(90) time-point (i.e. time at which twitches were inhibited by 90%). Suta punctata venom (10 microg/ml) was also myotoxic as indicated by the inhibition of direct twitches of the chick biventer cervicis nerve-muscle preparation. This effect was not reversed by antivenom (5 units/ml). This study highlights the danger of underestimating the potential severe clinical effects posed by these small but highly venomous snakes. PMID:18028104

Kuruppu, Sanjaya; Robinson, Stephanie; Hodgson, Wayne C; Fry, Bryan G

2007-12-01

285

The presence of tomato leaf curl Kerala virus AC3 protein enhances viral DNA replication and modulates virus induced gene-silencing mechanism in tomato plants  

Microsoft Academic Search

Background  Geminiviruses encode few viral proteins. Most of the geminiviral proteins are multifunctional and influence various host cellular\\u000a processes for the successful viral infection. Though few viral proteins like AC1 and AC2 are well characterized for their\\u000a multiple functions, role of AC3 in the successful viral infection has not been investigated in detail.\\u000a \\u000a \\u000a \\u000a \\u000a Results  We performed phage display analysis with the purified

Kalyan K Pasumarthy; Sunil K Mukherjee; Nirupam R Choudhury

2011-01-01

286

The presence of tomato leaf curl Kerala virus AC3 protein enhances viral DNA replication and modulates virus induced gene-silencing mechanism in tomato plants  

PubMed Central

Background Geminiviruses encode few viral proteins. Most of the geminiviral proteins are multifunctional and influence various host cellular processes for the successful viral infection. Though few viral proteins like AC1 and AC2 are well characterized for their multiple functions, role of AC3 in the successful viral infection has not been investigated in detail. Results We performed phage display analysis with the purified recombinant AC3 protein with Maltose Binding Protein as fusion tag (MBP-AC3). Putative AC3 interacting peptides identified through phage display were observed to be homologous to peptides of proteins from various metabolisms. We grouped these putative AC3 interacting peptides according to the known metabolic function of the homologous peptide containing proteins. In order to check if AC3 influences any of these particular metabolic pathways, we designed vectors for assaying DNA replication and virus induced gene-silencing of host gene PCNA. Investigation with these vectors indicated that AC3 enhances viral replication in the host plant tomato. In the PCNA gene-silencing experiment, we observed that the presence of functional AC3 ORF strongly manifested the stunted phenotype associated with the virus induced gene-silencing of PCNA in tomato plants. Conclusions Through the phage display analysis proteins from various metabolic pathways were identified as putative AC3 interacting proteins. By utilizing the vectors developed, we could analyze the role of AC3 in viral DNA replication and host gene-silencing. Our studies indicate that AC3 is also a multifunctional protein.

2011-01-01

287

Leaf death and decomposition during pasture regrowth  

Microsoft Academic Search

Data are presented that describe the pattern of leaf death per ramet and per unit area. Leaf death per ramet was influenced by the number of leaves that died and the weight of the dead leaves. Leaf weight was important in determining differences in seasonal and species death rate per ramet.Leaf death rates reached a maximum of 56 lb D.M.

W. F. Hunt

1971-01-01

288

Healing the Wounds of War and More: An Integrative Approach to Peace--The Work of Adam Curle and Others with Mir i dobro in Zupanja, Croatia.  

ERIC Educational Resources Information Center

Examines practical implications of Curle's approach to psychological aspects of conflict and peacemaking as evidenced in the Mir i dobro project in Zupanja, taking into consideration some of the current debates concerning treatment of psychological trauma, including validity of the diagnosis of posttraumatic stress disorder and use of so-called…

Mitchels, Barbara

2003-01-01

289

Force-free magnetic fields, curl eigenfunctions, and the sphere in transform space, with applications to fluid dynamics and electromagnetic theory  

Microsoft Academic Search

The mathematical foundation of a new description of force free magnetic fields (FFMF's) is given, using Moses' curl eigenfunctions, in preparation for an investigation of solar magnetic clouds and their interaction with the Earth's magnetosphere and perturbation of the radiation belts. Constant-alpha FFMF's are defined completely on the unit hemisphere in Fourier transform space. This reduces the three-dimensional physical space

Malcolm A. MacLeod

1993-01-01

290

1 Comparison of Wind Stress Algorithms and Their Influence on Wind Stress Curl Using Buoy Measurements over the Shelf off Bodega Bay, California  

Microsoft Academic Search

The main objectives of this study were to compare three wind stress algorithms of varying intricacy and estimate the extent to which each method altered computed wind stress curl. The algorithms included (1) a simple bulk formula for neutral conditions that is dependent only on wind velocity components; (2) a formula that in addition to dependence on wind components includes

Adam Kochanski; E. Dorman

291

Comparison of wind-stress algorithms and their influence on wind-stress curl using buoy measurements over the shelf off Bodega Bay, California  

Microsoft Academic Search

The main objectives of this study were to compare three wind-stress algorithms of varying intricacy and estimate the extent to which each method altered computed wind-stress curl. The algorithms included (1) a simple bulk formula for neutral conditions that is dependent only on wind velocity components; (2) a formula that in addition to dependence on wind components includes a simplified

Adam Kochanski; Darko Koracin; Clive E. Dorman

2006-01-01

292

Application of Failure Mode and Effect Analysis (FMEA), Cause and Effect Analysis, and Pareto Diagram in Conjunction with HACCP to a Corn Curl Manufacturing Plant  

Microsoft Academic Search

The Failure Mode and Effect Analysis (FMEA) model has been applied for the risk assessment of corn curl manufacturing. A tentative approach of FMEA application to the snacks industry was attempted in an effort to exclude the presence of GMOs in the final product. This is of crucial importance both from the ethics and the legislation (Regulations EC 1829\\/2003; EC

Theodoros H. Varzakas; Ioannis S. Arvanitoyannis

2007-01-01

293

Counting Microfiche: The Utilization of the Microform Section of the ANSI Standard Z39.7-1983 "Library Statistics"; Microfiche Curl; and "Poly" or "Cell"?  

ERIC Educational Resources Information Center

|The first of three articles describes procedures for using ANSI statistical methods for estimating the number of pieces in large homogeneous collections of microfiche. The second discusses causes of curl, its control, and measurement, and the third compares the advantages and disadvantages of cellulose acetate and polyester base for microforms.…

Caldwell-Wood, Naomi; And Others

1987-01-01

294

Why do leaf-tying caterpillars abandon their leaf ties?  

PubMed Central

Leaf-tying caterpillars act as ecosystem engineers by building shelters between overlapping leaves, which are inhabited by other arthropods. Leaf-tiers have been observed to leave their ties and create new shelters (and thus additional microhabitats), but the ecological factors affecting shelter fidelity are poorly known. For this study, we explored the effects of resource limitation and occupant density on shelter fidelity and assessed the consequences of shelter abandonment. We first quantified the area of leaf material required for a caterpillar to fully develop for two of the most common leaf-tiers that feed on white oak, Quercus alba. On average, Psilocorsis spp. caterpillars consumed 21.65 ± 0.67 cm2 leaf material to complete development. We also measured the area of natural leaf ties found in a Maryland forest, to determine the distribution of resources available to caterpillars in situ. Of 158 natural leaf ties examined, 47% were too small to sustain an average Psilocorsis spp. caterpillar for the entirety of its development. We also manipulated caterpillar densities within experimental ties on potted trees to determine the effects of cohabitants on the likelihood of a caterpillar to leave its tie. We placed 1, 2, or 4 caterpillars in ties of a standard size and monitored the caterpillars twice daily to track their movement. In ties with more than one occupant, caterpillars showed a significantly greater propensity to leave their tie, and left sooner and at a faster rate than those in ties as single occupants. To understand the consequences of leaf tie abandonment, we observed caterpillars searching a tree for a site to build a shelter in the field. This is a risky behavior, as 17% of the caterpillars observed died while searching for a shelter site. Caterpillars that successfully built a shelter traveled 110 ± 20 cm and took 28 ± 7 min to find a suitable site to build a shelter. In conclusion, leaf-tying caterpillars must frequently abandon their leaf tie due to food limitation and interactions with other caterpillars, but this is a costly behavior.

Sliwinski, Michelle

2013-01-01

295

Stem-and-Leaf Plots  

NSDL National Science Digital Library

This lesson is designed to introduce students to stem-and-leaf plots as a graphical way to represent a data set. The lesson also reviews measures of central tendency. This lesson provides links to discussions and activities related to stem-and-leaf plots as well as suggested ways to integrate them into the lesson. Finally, the lesson provides links to follow-up lessons designed for use in succession with the current one.

2010-01-01

296

Analysis of factors that influence the maximum number of repetitions in two upper-body resistance exercises: curl biceps and bench press.  

PubMed

The purpose of this study was to analyze the influence of exercise type, set configuration, and relative intensity load on relationship between 1 repetition maximum (1RM) and maximum number of repetitions (MNR). Thirteen male subjects, experienced in resistance training, were tested in bench press and biceps curl for 1RM, MNR at 90% of 1RM with cluster set configuration (rest of 30s between repetitions) and MNR at 70% of 1RM with traditional set configuration (no rest between repetitions). A lineal encoder was used for measuring displacement of load. Analysis of variance analysis revealed a significant effect of load (p<0.01) and a tendency in exercise factor (p=0.096), whereas the interaction effect was not significant. MNR at 70% of 1RM was lower for biceps curl (16.31+/-2.59 vs. 8.77+/-3 in bench press and biceps curl, respectively; p<0.05) and at 90% of 1RM (21.85+/-11.06 vs. 18.54+/-12.84 in bench press and biceps curl, respectively; p>0.05). Correlation between 1RM and MNR was significant for medium-intensity in biceps curl (r=-0.574; p<0.05) and between MNR and 1RM/body mass (r=-0.574; p<0.05). Neither 1RM nor 1RM/body mass correlated with velocity along set, so velocity seems to be similar at a same relative intensity for subjects with differences in maximum strength levels. From our results, we suggest the employment of MNR rather than % of 1RM for training monitoring. Furthermore, we suggest the introduction of cluster set configuration for upper-body assessment of MNR and for upper-body muscular endurance training at high-intensity loads, as it seems an efficient approach in looking for sessions with greater training volumes. This could be an interesting approach for such sports as wrestling or weightlifting. PMID:20508460

Iglesias, Eliseo; Boullosa, Daniel A; Dopico, Xurxo; Carballeira, Eduardo

2010-06-01

297

Leaf exsertion, leaf elongation, and leaf senescence in Eriophorum vaginatum and Carex Bigelowii  

SciTech Connect

Most of the common sedges of arctic vegetation show a pattern of leaf production in which the exsertion and elongation of new leaves is more or less simultaneous with the senescence of old leaves. The present study was designed to increase our understanding of the variability sequential leaf production by arctic sedges, and to determine some of the controls on that variability. We did this in two ways: first, we compared the sequential patterns of leaf growth and senescence in E. vaginatum with those of Carex Bigelowii Torr. at two tussock tundra sites near Toolik Lake on the North Slope of Alaska. Second, we compared the responses of leaf growth in these species in control and fertilized plots and in two microenvironments thought to differ sharply in nutrient availability and total productivity. 29 refs., 28 figs., 2 tabs.

Shaver, G.R.; Yandow, T.; Laundre, J.

1990-01-01

298

Identification of a Rhizobium meliloti pSym2011 region controlling the host specificity of root hair curling and nodulation.  

PubMed

In Rhizobium meliloti 2011 nodulation genes (nod) required to nodulate specifically alfalfa are located on a pSym megaplasmid. Nod- derivatives carrying large pSym deletions were isolated. By complementation of these strains with in vivo- and in vitro-constructed episomes containing pSym of sequences and introduction of these episomes into Agrobacterium tumefaciens, we show (i) that from a region of pSym of about 360 kilobases, genes required for specific alfalfa nodulation are clustered in a DNA fragment of less than 30 kilobases and (ii) that a nod region located between nifHDK and the common nod genes is absolutely required for alfalfa nodulation and controls the specificity of root hair curling and nodule organogenesis initiation. PMID:4066612

Truchet, G; Debellé, F; Vasse, J; Terzaghi, B; Garnerone, A M; Rosenberg, C; Batut, J; Maillet, F; Dénarié, J

1985-12-01

299

NON-DESTRUCTIVE ASSESSMENT OF ARUNDO DONAX (POACEAE) LEAF QUALITY.  

Technology Transfer Automated Retrieval System (TEKTRAN)

Leaf quality information (i.e., leaf C content, leaf N content, leaf C:N ratio) is especially useful for understanding plant-herbivore interactions and may be important in developing control methods for the invasive riparian plant Arundo donax L. We measured leaf C content, leaf N content, leaf C:N ...

300

Estimating leaf biochemistry using the PROSPECT leaf optical properties model  

Microsoft Academic Search

The biophysical, biochemical, and optical properties of 63 fresh leaves and 58 dry leaves were measured to investigate the potential of remote sensing to estimate the leaf biochemistry from space. Almost 2000 hemispherical reflectance and transmittance spectra were acquired from 400 nm to 2500 nm using a laboratory spectrophotometer. The amount of chlorophyll, water, protein, cellulose, hemicellulose, lignin, and starch

S. Jacquemoud; S. L. Ustin; J. Verdebout; G. Schmuck; G. Andreoli; B. Hosgood

1996-01-01

301

7 CFR 30.2 - Leaf tobacco.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 2013-01-01 false Leaf tobacco. 30.2 Section 30.2 Agriculture...STANDARDS AND STANDARD CONTAINER REGULATIONS TOBACCO STOCKS AND STANDARDS Classification of Leaf Tobacco Covering Classes, Types and Groups of...

2013-01-01

302

7 CFR 29.3648 - Thin Leaf (C Group).  

Code of Federal Regulations, 2013 CFR

...tolerance. C2F Fine Quality Medium-brown Thin Leaf. ...injury tolerance. C3F Good Quality Medium-brown Thin Leaf. ...injury tolerance. C3G Good Quality Green Thin Leaf. Underripe, medium body, firm leaf...

2013-01-01

303

Localization of Boron in Cell Walls of Squash and Tobacco and Its Association with Pectin (Evidence for a Structural Role of Boron in the Cell Wall).  

PubMed Central

B deficiency results in a rapid inhibition of plant growth, and yet the form and function of B in plants remains unclear. In this paper we provide evidence that B is chemically localized and structurally important in the cell wall of plants. The localization and chemical fractionation of B was followed in squash plants (Curcurbita pepo L.) and cultured tobacco cells (Nicotiana tabacum) grown in B-replete or B-deficient medium. As squash plants and cultured tobacco cells became deficient, an increasingly large proportion of cellular B was found to be localized in the cell wall. Cytoplasmic B concentrations were reduced to essentially zero as plants became deficient, whereas cell wall B concentration remained at or above 10 [mu]g B/g cell wall dry weight in all experiments. Chemical and enzymic fractionation studies suggest that the majority of cell B is associated with pectins within the cell wall. Physical analysis of B-deficient tissue indicates that cell wall plastic extensibility is greatly reduced under B deficiency, and anatomical observations indicate that B deficiency impairs normal cell elongation in growing plant tissue. In plants in which B deficiency had inhibited all plant growth, tissues remained green and did not show any additional visible symptoms for at least 1 week with no additional B. This occurred even though cytoplasmic B had been reduced to extremely low levels (<0.2 [mu]g/g). This suggests that B in these species is largely associated with the cell wall and that any cytoplasmic role for B is satisfied by very low concentrations of B. The localization of B in the cell wall, its association with cell wall pectins, and the contingent effects of B on cell wall extensibility suggest that B plays a critical, although poorly defined, role in the cell wall structure of higher plants.

Hu, H.; Brown, P. H.

1994-01-01

304

Deciduous leaf drop reduces insect herbivory  

Microsoft Academic Search

Deciduous leaf fall is thought to be an adaptation that allows plants living in seasonal environments to reduce water loss\\u000a and damage during unfavorable periods while increasing photosynthetic rates during favorable periods. Observations of natural\\u000a variation in leaf shedding suggest that deciduous leaf fall may also allow plants to reduce herbivory. I tested this hypothesis\\u000a by experimentally manipulating leaf retention

Richard Karban

2007-01-01

305

Application of Failure Mode and Effect Analysis (FMEA), cause and effect analysis, and Pareto diagram in conjunction with HACCP to a corn curl manufacturing plant.  

PubMed

The Failure Mode and Effect Analysis (FMEA) model has been applied for the risk assessment of corn curl manufacturing. A tentative approach of FMEA application to the snacks industry was attempted in an effort to exclude the presence of GMOs in the final product. This is of crucial importance both from the ethics and the legislation (Regulations EC 1829/2003; EC 1830/2003; Directive EC 18/2001) point of view. The Preliminary Hazard Analysis and the Fault Tree Analysis were used to analyze and predict the occurring failure modes in a food chain system (corn curls processing plant), based on the functions, characteristics, and/or interactions of the ingredients or the processes, upon which the system depends. Critical Control points have been identified and implemented in the cause and effect diagram (also known as Ishikawa, tree diagram, and the fishbone diagram). Finally, Pareto diagrams were employed towards the optimization of GMOs detection potential of FMEA. PMID:17457722

Varzakas, Theodoros H; Arvanitoyannis, Ioannis S

2007-01-01

306

Leaf Photosynthesis Under Drought Stress  

Microsoft Academic Search

The photosynthetic apparatus is resistant to drought. Net CO2 uptake of a leaf submitted to a mild desiccation decreases because of stomatal closure. As aresult, CO2 concentration in the chloroplast decreases in plants exposed to water shortage. This drop in the chloroplast CO2 concentration causes: (i) a decrease in photochemical yield of open PS II centers and, consequently, an increase

Gabriel Cornic; Angelo Massacci

307

CORN LEAF CHLOROPHYLL STATUS FROM HYPERSPECTRAL IMAGES  

Technology Transfer Automated Retrieval System (TEKTRAN)

Leaf chlorophyll concentration is an indicator of plant N status. Subtle differences in canopy reflectance due to changes in leaf chlorophyll concentration are often overwhelmed by the large changes in reflectance associated with soil brightness and leaf area index (LAI). Our objective was to devel...

308

7 CFR 29.2278 - Leaf structure.  

Code of Federal Regulations, 2010 CFR

...2 2010-01-01 2010-01-01 false Leaf structure. 29.2278 Section 29.2278 Agriculture ...Fire-Cured Tobacco (u.s. Type 21) § 29.2278 Leaf structure. The cell development of a leaf as indicated by its...

2010-01-01

309

7 CFR 29.2278 - Leaf structure.  

Code of Federal Regulations, 2010 CFR

...2 2009-01-01 2009-01-01 false Leaf structure. 29.2278 Section 29.2278 Agriculture ...Fire-Cured Tobacco (u.s. Type 21) § 29.2278 Leaf structure. The cell development of a leaf as indicated by its...

2009-01-01

310

Leaf litter decomposition in three Adirondack lakes  

Microsoft Academic Search

Decomposition of terrestrial leaf litter in three Adirondack lakes with water pH values approximately 5, 6, and 7 was studied. Litter bags containing leaves of American beech, sugar maple, red maple, leather leaf, and red spruce were placed in the lakes. Samples were removed periodically over a 3-year period and analyzed for loss in weight, changes in leaf surface area,

A. J. Francis; H. L. Quinby; G. R. Hendrey; C. G. Hoogendyk

1983-01-01

311

Malate Dehydrogenases in the Rusted Bean Leaf.  

PubMed

Rust growth in the bean leaf was accompanied by the appearance of one new malate dehydrogenase isozyme and continuation of one otherwise lost during the development of the healthy leaf. The new isozyme was contributed by the fungus, the other by the leaf. Both enzymes were cytoplasmic proteins. Rusting caused the loss of a mitochondrial isozyme. PMID:17802172

Staples, R C; Stahmann, M A

1963-06-21

312

Contents of isoflavones and effect of isoflavones on root hair curling in non-nodulating- Rj1Rj1) soybean plant  

Microsoft Academic Search

Leguminous plants form symbiotic nitrogen-fixing nodules with specific bacterial species of Rhizobium or Bradyrhizobium. This symbiosis takes place by interaction of both partners. The non-nodulating mutants of the host plants are useful materials for physiological and genetical analyses of plant function in nodule formation. In a Rj1 non-nodulating mutant of soybean, root hair curling was greatly reduced, whereas bacterial adhesion

Norio Suganuma; Sadako Satoh

1991-01-01

313

Promising genetic resources for resistance to wheat streak mosaic virus and the wheat curl mite in wheat- Thinopyrum partial amphiploids and their derivatives  

Microsoft Academic Search

Wheat streak mosaic virus (WSMV), vectored by the wheat curl mite (WCM),Aceria tosichella Keifer, is one of the most destructive viral diseases of wheat found in many wheat producing areas of the world. Host resistance is the most effective method for controlling this disease and its vector. Symptomatological analysis and enzyme-linked immunosorbent assay (ELISA) were used to characterize WSMV-resistance in

Hongjie Li; Robert L. Conner; Qin Chen; Robert J. Graf; André Laroche; F. Ahmad; A. D. Kuzyk

2005-01-01

314

Single leaf area estimation models based on leaf weight of eucalyptus in southern China  

Microsoft Academic Search

Leaf area is an important parameter for modeling tree growth and physiological processes of trees. The single young and mature\\u000a leaf area estimation models of eucalyptus were developed based on leaf fresh weight. In total, leaf area and leaf weight were\\u000a measured from 455 fresh leaves of 25 trees of eucalyptus in southern China. The majority of the data (80%)

Jun Diao; Xiang-dong Lei; Ling-xia Hong; Jian-tao Rong; Qiang Shi

2010-01-01

315

Habitat Complexity of Stream Leaf Packs: Effects on Benthic Macroinvertebrates and Leaf Litter Breakdown  

NASA Astrophysics Data System (ADS)

We investigated two attributes of leaf-pack complexity (i.e., leaf-pack mass and leaf surface area) on fish predation, colonization of benthic macroinvertebrates, and leaf breakdown rates in a coldwater Michigan stream. We manipulated three factors using a factorial design: fish (exclusion or control cage), leaf-pack mass (1, 3, or 5 g dry mass), and leaf surface area (<7, 7-10, or >10 cm leaf width). Acer leaves were fastened into leaf packs. Exclusion cages had mesh on all sides; control cages lacked mesh on two sides to provide access to fishes. Two replicate leaf packs were randomly collected after 25-31 d from two sections of the stream (n = 4). Common shredders were Gammarus, Pycnopsyche, and Lepidostoma. We did not detect a significant effect of fish predation on benthic macroinvertebrates or leaf breakdown (i.e., mass loss). Colonization of benthic macroinvertebrates appeared proportional to leaf-pack mass but was unaffected by the surface area of leaves. Leaf breakdown was more rapid among leaf packs with fewer leaves (i.e., leaves with large surface area and leaf packs with low mass) and greater numbers of shredders. We suspect that physical fragmentation is the primary mechanism for higher breakdown rates among leaf packs with fewer leaves.

Ruetz, C. R.; Vanhaitsma, D. L.; Breen, M. J.

2005-05-01

316

The dosimetric impact of leaf interdigitation and leaf width on VMAT treatment planning in Pinnacle: comparing Pareto fronts  

Microsoft Academic Search

To evaluate in an objective way the effect of leaf interdigitation and leaf width on volumetric modulated arc therapy plans in Pinnacle. Three multileaf collimators (MLCs) were modeled: two 10 mm leaf width MLCs, with and without interdigitating leafs, and a 5 mm leaf width MLC with interdigitating leafs. Three rectum patients and three prostate patients were used for the

Z van Kesteren; T M Janssen; E Damen; C van Vliet-Vroegindeweij

2012-01-01

317

A randomised clinical trial of the efficacy of drop squats or leg extension/leg curl exercises to treat clinically diagnosed jumper's knee in athletes: pilot study  

PubMed Central

Objectives—To compare the therapeutic effect of two different exercise protocols in athletes with jumper's knee. Methods—Randomised clinical trial comparing a 12 week programme of either drop squat exercises or leg extension/leg curl exercises. Measurement was performed at baseline and after six and 12 weeks. Primary outcome measures were pain (visual analogue scale 1–10) and return to sport. Secondary outcome measures included quadriceps and hamstring moment of force using a Cybex II isokinetic dynamometer at 30°/second. Differences in pain response between the drop squat and leg extension/curl treatment groups were assessed by 2 (group) x 3 (time) analysis of variance. Two by two contingency tables were used to test differences in rates of return to sport. Analysis of variance (2 (injured versus non-injured leg) x 2 (group) x 3 (time)) was also used to determine differences for secondary outcome measures. Results—Over the 12 week intervention, pain diminished by 2.3 points (36%) in the leg extension/curl group and 3.2 points (57%) in the squat group. There was a significant main effect of both exercise protocols on pain (p<0.01) with no interaction effect. Nine of 10 subjects in the drop squat group returned to sporting activity by 12 weeks, but five of those subjects still had low level pain. Six of nine of the leg extension/curl group returned to sporting activity by 12 weeks and four patients had low level pain. There was no significant difference between groups in numbers returning to sporting activity. There were no differences in the change in quadriceps or hamstring muscle moment of force between groups. Conclusions—Progressive drop squats and leg extension/curl exercises can reduce the pain of jumper's knee in a 12 week period and permit a high proportion of patients to return to sport. Not all patients, however, return to sport by that time. Key Words: knee; patellar tendon; tendinopathy; tendinosis; eccentric strengthening; strength training

Cannell, L; Taunton, J; Clement, D; Smith, C; Khan, K

2001-01-01

318

Relation between the wind stress curl in the North Atlantic and the Atlantic inflow to the Nordic Seas  

NASA Astrophysics Data System (ADS)

In this study an isopycnic coordinate ocean model has been used to investigate the relationships between the North Atlantic wind stress curl (WSC) and the inflow of Atlantic water to the Nordic Seas. For the period 1995-2001, there is a maximum in the correlation between the zonally averaged WSC at 55°N and the inflow with a 15-month time lag, capturing a relation already found in observational data. In the model this relation is linked to the mixing along the western flank of the Rockall Bank (56°N, 15°W). For the period 1995-2001 the atmospheric forcing in the northeastern North Atlantic is relatively weak, and the depth of the mixed layer is shallower than the sill depths of the Greenland-Scotland Ridge (GSR). Slowly moving, baroclinic disturbances caused by anomalies in the wind forcing will then be transmitted into the Nordic Seas where they are recorded as anomalous volume transports in the Norwegian Atlantic Current. In contrast, for the pentad prior to this period the atmospheric forcing is much more intense, and generates mixing well below sill depths of the GSR for all winters. Baroclinic disturbances forced by variations in the atmospheric forcing will then tend to follow f/H contours that do not enter the Nordic Seas, and the 15-month lagged relations between the wind and the volume transports will vanish. Recent observational data support this view.

Sandø, A. B.; Furevik, T.

2008-06-01

319

Non-euclidean stress-free configuration of arteries accounting for curl of axial strips sectioned from vessels.  

PubMed

It is well known that arteries are subject to residual stress. In earlier studies, the residual stress in the arterial ring relieved by a radial cut was considered in stress analysis. However, it has been found that axial strips sectioned from arteries also curled into arcs, showing that the axial residual stresses were relieved from the arterial walls. The combined relief of circumferential and axial residual stresses must be considered to accurately analyze stress and strain distributions under physiological loading conditions. In the present study, a mathematical model of a stress-free configuration of artery was proposed using Riemannian geometry. Stress analysis for arterial walls under unloaded and physiologically loaded conditions was performed using exponential strain energy functions for porcine and human common carotid arteries. In the porcine artery, the circumferential stress distribution under physiological loading became uniform compared with that without axial residual strain, whereas a gradient of axial stress distribution increased through the wall thickness. This behavior showed almost the same pattern that was observed in a recent study in which approximate analysis accounting for circumferential and axial residual strains was performed, whereas the circumferential and axial stresses increased from the inner surface to the outer surface under a physiological condition in the human common carotid artery of a two-layer model based on data of other recent studies. In both analyses, Riemannian geometry was appropriate to define the stress-free configurations of the arterial walls with both circumferential and axial residual strains. PMID:24008313

Takamizawa, Keiichi; Nakayama, Yasuhide

2013-11-01

320

Kettlebell swing targets semitendinosus and supine leg curl targets biceps femoris: an EMG study with rehabilitation implications.  

PubMed

BACKGROUND: The medial hamstring muscle has the potential to prevent excessive dynamic valgus and external rotation of the knee joint during sports. Thus, specific training targeting the medial hamstring muscle seems important to avoid knee injuries. OBJECTIVE: The aim was to investigate the medial and lateral hamstring muscle activation balance during 14 selected therapeutic exercises. STUDY DESIGN: The study design involved single-occasion repeated measures in a randomised manner. Sixteen female elite handball and soccer players with a mean (SD) age of 23 (3) years and no previous history of knee injury participated in the present study. Electromyographic (EMG) activity of the lateral (biceps femoris - BF) and medial (semitendinosus - ST) hamstring muscle was measured during selected strengthening and balance/coordination exercises, and normalised to EMG during isometric maximal voluntary contraction (MVC). A two-way analysis of variance was performed using the mixed procedure to determine whether differences existed in normalised EMG between exercises and muscles. RESULTS: Kettlebell swing and Romanian deadlift targeted specifically ST over BF (?17-22%, p<0.05) at very high levels of normalised EMG (73-115% of MVC). In contrast, the supine leg curl and hip extension specifically targeted the BF over the ST (? 20-23%, p<0.05) at very high levels of normalised EMG (75-87% of MVC). CONCLUSION: Specific therapeutic exercises targeting the hamstrings can be divided into ST dominant or BF dominant hamstring exercises. Due to distinct functions of the medial and lateral hamstring muscles, this is an important knowledge in respect to prophylactic training and physical therapist practice. PMID:22736206

Zebis, Mette Kreutzfeldt; Skotte, Jørgen; Andersen, Christoffer H; Mortensen, Peter; Petersen, Maria Højland; Viskær, Tine C; Jensen, Tanja L; Bencke, Jesper; Andersen, Lars L

2012-07-01

321

7 CFR 28.466 - Leaf Grade 6.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 2013-01-01 false Leaf Grade 6. 28.466 Section 28.466 Agriculture Regulations of the Department of Agriculture...for the Leaf Grade of American Upland Cotton § 28.466 Leaf Grade 6. Leaf Grade 6 is leaf which is...

2013-01-01

322

7 CFR 29.1162 - Leaf (B Group).  

Code of Federal Regulations, 2013 CFR

...firm leaf structure, medium body, rich in oil...10 percent. B3LâGood Quality Lemon Leaf Ripe, firm leaf structure, medium body, oily, strong...firm leaf structure, medium body, stringy. Uniformity...percent waste. B3SâGood Quality Slick Leaf...

2013-01-01

323

7 CFR 29.3647 - Heavy Leaf (B Group).  

Code of Federal Regulations, 2013 CFR

...Medium-brown Heavy Leaf. Ripe, medium body, open leaf structure...injury tolerance. B3F Good Quality Medium-brown Heavy Leaf. Mature...injury tolerance. B3M Good Quality Mixed Heavy Leaf. Mature, medium body, firm leaf...

2013-01-01

324

Deep oceanic zonal jets constrained by fine-scale wind stress curls in the South Pacific Ocean: A high-resolution coupled GCM study  

NASA Astrophysics Data System (ADS)

Oceanic alternating zonal jets at depth have been detected ubiquitously in observations and ocean general circulation models (GCMs). Such oceanic jets are generally considered as being generated by purely oceanic processes. Here we explore a possible air-sea interaction induced by surface signatures of the deep zonal jets using an eddy-permitting coupled atmosphere-ocean GCM (CGCM). The 23-year CGCM integration reproduces bands of latitudinally-narrow alternating jets in the Southeast Pacific. They extend from the sea surface to well below the main thermocline and are embedded in the large-scale westward-flowing South Equatorial Current, the latter mostly confined above the thermocline. These jets generate fine-scale sea surface temperature (SST) anomalies through the advection of zonal temperature gradients. The atmospheric boundary layer appears to respond thermally to this fine-scale SST field, which induces fine-scale wind stress anomaly through atmospheric pressure adjustment, as indicated by a good spatial correlation between the SST Laplacian field and the fine-scale wind stress curl. A Sverdrup calculation on the wind stress field of the CGCM predicts fine-scale zonal currents driven by the meridional gradient of the fine-scale wind stress curl. The positions of these Sverdrup currents are generally coincident with those of the original zonal jets and the Sverdrup prediction explains roughly half of the amplitudes of the jets. While the original cause of the deep zonal jets simulated in our CGCM is unidentified, this analysis suggests that there is likely a positive air-sea feedback: the jets generate fine-scale wind stress curl that reinforces themselves through the Sverdrup dynamics.

Taguchi, B.; Furue, R.; Komori, N.; Kuwano-Yoshida, A.; Nonaka, M.; Sasaki, H.; Ohfuchi, W.

2012-04-01

325

The effect of experimental warming on leaf functional traits, leaf structure and leaf biochemistry in Arabidopsis thaliana  

Microsoft Academic Search

BACKGROUND: The leaf is an important plant organ, and how it will respond to future global warming is a question that remains unanswered. The effects of experimental warming on leaf photosynthesis and respiration acclimation has been well studied so far, but relatively little information exists on the structural and biochemical responses to warming. However, such information is very important to

Biao Jin; Li Wang; Jing Wang; Ke-Zhen Jiang; Yang Wang; Xiao-Xue Jiang; Cheng-Yang Ni; Yu-Long Wang; Nian-Jun Teng

2011-01-01

326

Leaf emergence in relation to leaf traits in temperate woody species in East-Chinese Quercus fabri forests  

NASA Astrophysics Data System (ADS)

To determine the effect of leaf traits on leaf emergence phenology, timing of leaf emergence, leaf expansion rate, durations of leaf emergence and expansion, leaf mass per area (LMA) and leaf size were investigated for 48 woody species from 25 families in two closed Chinese white oak ( Quercus fabri) forests of eastern China. Cross-species regression and phylogenetic regression were employed to examine the relationship between leaf phenology and leaf traits. Leaf area, LMA, and leaf expansion rate were found to be significantly greater in canopy trees than in understory shrubs in the oak forests. However, there was no significant difference in timing of leaf emergence and durations of leaf emergence and expansion between canopy and understory species. The large-LMA species leafed out earlier than the species with small LMA. The small-leaved species leafed out earlier than the species with large leaves, but the large-leaved species were greater in leaf expansion rate than their counterparts. Leaf expansion rate was positively correlated with leaf area and timing of leaf emergence, but no significant relationship was found between leaf size and leaf expansion period. These results suggest that large- and small-leaved species possibly employed different strategies to minimize herbivory damage, i.e. early leafing to avoid defoliator damage in small-leaved species and fast expanding and thereby shortening vulnerable time to herbivores in large-leaved species. It could be inferred that the species with small leaves and large-LMA leafed out early in the oak forests, thereby permitting less energy loss than their counterparts under the influence of frost in early spring. In general, early leaf emergence is of significance for high LMA species to increase carbon gain in temperate broad-leaved forests, but it is not related to plant height. Leaf size and leaf expansion period are not necessarily correlated.

Sun, Shucun; Jin, Dongmei; Li, Rongjin

2006-09-01

327

"Breath figures" on leaf surfaces-formation and effects of microscopic leaf wetness.  

PubMed

"Microscopic leaf wetness" means minute amounts of persistent liquid water on leaf surfaces which are invisible to the naked eye. The water is mainly maintained by transpired water vapor condensing onto the leaf surface and to attached leaf surface particles. With an estimated average thickness of less than 1 ?m, microscopic leaf wetness is about two orders of magnitude thinner than morning dewfall. The most important physical processes which reduce the saturation vapor pressure and promote condensation are cuticular absorption and the deliquescence of hygroscopic leaf surface particles. Deliquescent salts form highly concentrated solutions. Depending on the type and concentration of the dissolved ions, the physicochemical properties of microscopic leaf wetness can be considerably different from those of pure water. Microscopic leaf wetness can form continuous thin layers on hydrophobic leaf surfaces and in specific cases can act similar to surfactants, enabling a strong potential influence on the foliar exchange of ions. Microscopic leaf wetness can also enhance the dissolution, the emission, and the reaction of specific atmospheric trace gases e.g., ammonia, SO2, or ozone, leading to a strong potential role for microscopic leaf wetness in plant/atmosphere interaction. Due to its difficult detection, there is little knowledge about the occurrence and the properties of microscopic leaf wetness. However, based on the existing evidence and on physicochemical reasoning it can be hypothesized that microscopic leaf wetness occurs on almost any plant worldwide and often permanently, and that it significantly influences the exchange processes of the leaf surface with its neighboring compartments, i.e., the plant interior and the atmosphere. The omission of microscopic water in general leaf wetness concepts has caused far-reaching, misleading conclusions in the past. PMID:24167510

Burkhardt, Juergen; Hunsche, Mauricio

2013-10-24

328

"Breath figures" on leaf surfaces--formation and effects of microscopic leaf wetness  

PubMed Central

“Microscopic leaf wetness” means minute amounts of persistent liquid water on leaf surfaces which are invisible to the naked eye. The water is mainly maintained by transpired water vapor condensing onto the leaf surface and to attached leaf surface particles. With an estimated average thickness of less than 1 ?m, microscopic leaf wetness is about two orders of magnitude thinner than morning dewfall. The most important physical processes which reduce the saturation vapor pressure and promote condensation are cuticular absorption and the deliquescence of hygroscopic leaf surface particles. Deliquescent salts form highly concentrated solutions. Depending on the type and concentration of the dissolved ions, the physicochemical properties of microscopic leaf wetness can be considerably different from those of pure water. Microscopic leaf wetness can form continuous thin layers on hydrophobic leaf surfaces and in specific cases can act similar to surfactants, enabling a strong potential influence on the foliar exchange of ions. Microscopic leaf wetness can also enhance the dissolution, the emission, and the reaction of specific atmospheric trace gases e.g., ammonia, SO2, or ozone, leading to a strong potential role for microscopic leaf wetness in plant/atmosphere interaction. Due to its difficult detection, there is little knowledge about the occurrence and the properties of microscopic leaf wetness. However, based on the existing evidence and on physicochemical reasoning it can be hypothesized that microscopic leaf wetness occurs on almost any plant worldwide and often permanently, and that it significantly influences the exchange processes of the leaf surface with its neighboring compartments, i.e., the plant interior and the atmosphere. The omission of microscopic water in general leaf wetness concepts has caused far-reaching, misleading conclusions in the past.

Burkhardt, Juergen; Hunsche, Mauricio

2013-01-01

329

7 CFR 29.2438 - Thin Leaf (C Group).  

Code of Federal Regulations, 2013 CFR

...and specifications C1L Choice Light-brown Thin Leaf. Thin to medium body, mature to ripe...Light-brown Thin Leaf. Thin to medium body, mature to ripe...percent injury tolerance. Choice Medium-brown Thin Leaf....

2013-01-01

330

7 CFR 29.1162 - Leaf (B Group).  

Code of Federal Regulations, 2010 CFR

...Ripe, firm leaf structure, medium body, lean in oil, weak color intensity, narrow...Ripe, firm leaf structure, medium body, lean in oil, weak color intensity, stringy... Ripe, firm leaf structure, fleshy, lean in oil, weak color intensity,...

2009-01-01

331

7 CFR 29.1162 - Leaf (B Group).  

Code of Federal Regulations, 2010 CFR

...Ripe, firm leaf structure, medium body, lean in oil, weak color intensity, narrow...Ripe, firm leaf structure, medium body, lean in oil, weak color intensity, stringy... Ripe, firm leaf structure, fleshy, lean in oil, weak color intensity,...

2010-01-01

332

7 CFR 28.471 - Below Leaf Grade Cotton.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 false Below Leaf Grade Cotton. 28.471 Section 28.471 Agriculture...STANDARDS AND STANDARD CONTAINER REGULATIONS COTTON CLASSING, TESTING, AND STANDARDS Standards Below Leaf Grade Cotton § 28.471 Below Leaf Grade...

2013-01-01

333

7 CFR 29.2437 - Heavy Leaf (B Group).  

Code of Federal Regulations, 2013 CFR

...injury tolerance. B3F Good Medium-brown Heavy Leaf. ...injury tolerance. B3M Good Mixed Color Heavy Leaf. Medium to heavy body, mature...injury tolerance. B3G Good Green Heavy Leaf. Medium to heavy body,...

2013-01-01

334

7 CFR 29.2662 - Heavy Leaf (B Group).  

Code of Federal Regulations, 2013 CFR

...injury tolerance. B3F Good Medium-brown Heavy Leaf. Medium...injury tolerance. B3VF Good Greenish Medium-brown Heavy Leaf. Medium...injury tolerance. B3G Good Green Heavy Leaf. Medium to heavy body,...

2013-01-01

335

Automobile leaf springs from composite materials  

Microsoft Academic Search

The automobile industry has shown increased interest in the replacement of steel springs with fiberglass reinforced composite leaf springs. Therefore, the aim of this paper is to present a general study on the analysis, design and fabrication of composite springs. From this viewpoint, the suspension spring of a compact car, “a jeep” was selected as a prototype.A single leaf, variable

H. A. Al-Qureshi

2001-01-01

336

Identification of Plant Using Leaf Image Analysis  

NASA Astrophysics Data System (ADS)

The trees are basically identified by their leaves. There are different varieties of trees grown throughout the world. Some are important cash crop. Some are used in medicine. The tree identification is very important in day to day life. Their identifications had been studied using various laboratory methods. The morphological and genetically characteristics were employed to classify different leafs. However, the presence of wide morphological varieties through evolution among the various leaf cultivars made it more complex and difficult to classify them. Therefore manual identification as well as classification of these leaves is a tedious task. During the last few decades computational biologists have studied various diversities among leaf due to huge number of evolutionary changes. Leaf structures play a very crucial role in determining the characteristics of a plant. The broad and narrow shaped leaves, leaf arrangement, leaf margin characteristics features which differentiate various leaf of a tree. This project proposed the methods to identify the leaf using an image analysis based approach.

Pramanik, Subhra; Bandyopadhyay, Samir Kumar; Bhattacharyya, Debnath; Kim, Tai-Hoon

337

Leaf Litter Decomposition in Three Adirondack Lakes.  

National Technical Information Service (NTIS)

Decomposition of terrestrial leaf litter in three Adirondack lakes with water pH values approximately 5, 6, and 7 was studied. Litter bags containing leaves of American beech, sugar maple, red maple, leather leaf, and red spruce were placed in the lakes. ...

A. J. Francis H. L. Quinby G. R. Hendrey C. G. Hoogendyk

1983-01-01

338

Photovoltaic Leaf Area Meter Development and Testing  

Microsoft Academic Search

Photovoltaic (PV) panel was used to develop a simple and practical leaf area meter. Components of the developed PV leaf area meter include a PV panel as sensor, a wooden cabinet as enclosure, a flashlight as light source, and a commercial digital multimeter for voltage measurement. The principle of projected area measurement is the voltage generated by the PV panel

C. Igathinathane; B. Chennakesavulu; K. Manohar; A. R. Womac; L. O. Pordesimo

2008-01-01

339

[Photoprotective mechanisms of leaf anthocyanins: research progress].  

PubMed

Anthocyanin is widely distributed in plant organs such as root, stem, leaf, flower and fruit, being a kind of secondary metabolites generated in plant morphogenesis or for stress response. Leaf anthocyanin has special chemical structure and spectral properties, playing important roles in plant photoprotection, and becomes a hotspot in plant photosynthetic physiological ecology. This paper summarized the recent research progress in the effects of leaf anthocyanin on plant photosynthesis, including the distribution of leaf anthocyanin, its spectral properties, and its relationships with photosynthetic pigments, with the focus on the potential mechanisms of anthocyanins photoprotection, including light absorption, antioxidation, and osmotic regulation. The further research directions on the effects of leaf anthocyanin on photoprotection were proposed. PMID:22720633

Wang, Liang-Zai; Hu, Yan-Bo; Zhang, Hui-Hui; Xu, Nan; Zhang, Xiu-Li; Sun, Guang-Yu

2012-03-01

340

Trends and variability in the sea surface height, sea surface temperature and wind stress curl in the South Atlantic ocean  

NASA Astrophysics Data System (ADS)

Altimetry sea level anomalies (SLA), sea surface temperatures anomalies (SSTA) and wind stress curl (WSC) were analyzed and had their trends calculated and their variability studied for the South Atlantic ocean using the last 19 years of SALTO/DUACS altimeter data, ERSST data and ERA-INTERIM data. All data had their temporal resolution adjusted to the one of altimeter data. The trends were calculated between January, 1st 1993 and December, 31th 2011. The stronger and positive SLA trends occurred in the region of the Zapiola Ridge (14 mm/year) and in some places in the Drake Passage (10 mm/year). Negative trends were observed in the Southern part of Argentinian basin (-4 mm/year), next to the Confluence Brazil Malvinas (-8 mm/year) and to the southwest of the African coast (-6 mm/year). The SST trends were positive North of 40°S, and negative south of 60°S. They were also negative along the Argentinean continental slope along the path of the Malvinas Current. The WSC trend was also negative along the Argentine continental slope. In the Southeast Atlantic, the WSC trend had a zonal distribution with alternate signs. To understand the processes responsible for the trend patterns in the South Atlantic ocean, the high and the low frequencies were obtained applying successively a 25 week band pass filter followed by a 37 week band pass filter. The percentage of explained variance by the high frequency, low frequency and seasonal signals (hf/lf/ss) were compared for SLA, SSTA and WSC. The variance of SLA in the Southwestern Atlantic was explained by the proportion of (80%, 15%,5%), except along the Argentinean continental slope (15%, 50%, 35%), the inner part of the ZR (10%,65%,25%). The central part of the South Atlantic showed dominant low frequency variance (proportions of 15%, 80% and 5% (hf/lf/ss), respectively). The SSTA variance was dominated by the high frequency in the Uruguayan coast, around ZR, in the Drake Passage and in the Agulhas Leakage (60-80%), low frequency variability responds to 55-75% of the total variability away from the continental borders. The seasonal frequency is important in the CBM region and in the inner of ZR (25%, 40%, 35%). The WSC variance was mostly explained by high frequencies (70%), low frequencies explained between 10% and 15%, at latitudes lower than 20°S, in the Argentinean continental slope and in the Agulhas Leakage. The EOF analysis were performed on the high and low frequencies components of each variable. The results will be presented in the poster.

Porto da Silveira, Isabel; Ponzi Pezzi, Luciano; Buss de Souza, Ronald; Sennéchael, Nathalie; Provost, Christine

2013-04-01

341

A model for leaf initiation  

PubMed Central

A biophysical model is proposed for how leaf primordia are positioned on the shoot apical
meristem in both spiral and whorl phyllotaxes. Primordia are initiated by signals that propagate
in the epidermis in both azimuthal directions away from the cotyledons or the most recently
specified primordia. The signals are linear waves as inferred from the spatial periodicity of the
divergence angle and a temporal periodicity. The periods of the waves, which represent actively
transported auxin, are much smaller than the plastochron interval. Where oppositely directed
waves meet at one or more angular positions on the periphery of the generative circle, auxin
concentration builds and as in most models this stimulates local movement of auxin to
underlying cells, where it promotes polarized cell division and expansion. For higher order
spirals the wave model requires asymmetric function of auxin transport; that is, opposite wave
speeds differ. An algorithm for determination of the angular positions of leaves in common leaf
phyllotaxic configurations is proposed. The number of turns in a pattern repeat, number of leaves
per level and per pattern repeat, and divergence angle are related to speed of auxin transport and
radius of the generative circle. The rule for composition of Fibonacci or Lucas numbers
associated with some phyllotaxes is discussed. A subcellular model suggests how the shoot
meristem might specify either symmetric or asymmetric transport of auxin away from the
forming primordia that produce it. Biological tests that could make or break the mathematical
and molecular hypotheses are proposed.

Abraham-Shrauner, Barbara; Pickard, Barbara G

2011-01-01

342

Curling And Inertia  

NSDL National Science Digital Library

The following resource is from Lessonopoly, which has created student activities and lesson plans to support the video series, Science of the Olympic Winter Games, created by NBC Learn and the National Science Foundation. Featuring exclusive footage from NBC Sports and contributions from Olympic athletes and NSF scientists, the series will help teach your students valuable scientific concepts. Through class discussion and a fun demonstration, students will review what they know about inertia. Students will then set up collisions with marbles and a stationary cup to explore the relationship between mass and inertia.

2010-01-01

343

Why so strong for the lotus leaf?  

NASA Astrophysics Data System (ADS)

The authors discussed the potential reasons why the lotus leaf is so strong by means of scanning electron microscopy (SEM). The results showed that the good mechanical properties of lotus leaf should be attributed to its architecture, such as paralleled microtubes structure, umbrellalike structure, and hierarchically layered hexagon structure. The important observation from this work is that the surface of the rear face of the lotus leaf seems to be constituted by the layers of hexagons whose hierarchical pilling up of size decreases as we go deeper from surface. This is a typical fractal-like phenomenon.

Guo, Zhiguang; Liu, Weimin; Su, Bao-Lian

2008-11-01

344

Key Proliferative Activity in the Junction between the Leaf Blade and Leaf Petiole of Arabidopsis1[W][OA  

PubMed Central

Leaves are the most important, fundamental units of organogenesis in plants. Although the basic form of a leaf is clearly divided into the leaf blade and leaf petiole, no study has yet revealed how these are differentiated from a leaf primordium. We analyzed the spatiotemporal pattern of mitotic activity in leaf primordia of Arabidopsis (Arabidopsis thaliana) in detail using molecular markers in combination with clonal analysis. We found that the proliferative zone is established after a short interval following the occurrence of a rod-shaped early leaf primordium; it is separated spatially from the shoot apical meristem and seen at the junction region between the leaf blade and leaf petiole and produces both leaf-blade and leaf-petiole cells. This proliferative region in leaf primordia is marked by activity of the ANGUSTIFOLIA3 (AN3) promoter as a whole and seems to be differentiated into several spatial compartments: activities of the CYCLIN D4;2 promoter and SPATULA enhancer mark parts of it specifically. Detailed analyses of the an3 and blade-on-petiole mutations further support the idea that organogenesis of the leaf blade and leaf petiole is critically dependent on the correct spatial regulation of the proliferative region of leaf primordia. Thus, the proliferative zone of leaf primordia is spatially differentiated and supplies both the leaf-blade and leaf-petiole cells.

Ichihashi, Yasunori; Kawade, Kensuke; Usami, Takeshi; Horiguchi, Gorou; Takahashi, Taku; Tsukaya, Hirokazu

2011-01-01

345

Antagonistic roles of SEPALLATA3, FT and FLC genes as targets of the polycomb group gene CURLY LEAF.  

PubMed

In Arabidopsis, mutations in the Pc-G gene CURLY LEAF (CLF) give early flowering plants with curled leaves. This phenotype is caused by mis-expression of the floral homeotic gene AGAMOUS (AG) in leaves, so that ag mutations largely suppress the clf phenotype. Here, we identify three mutations that suppress clf despite maintaining high AG expression. We show that the suppressors correspond to mutations in FPA and FT, two genes promoting flowering, and in SEPALLATA3 (SEP3) which encodes a co-factor for AG protein. The suppression of the clf phenotype is correlated with low SEP3 expression in all case and reveals that SEP3 has a role in promoting flowering in addition to its role in controlling floral organ identity. Genetic analysis of clf ft mutants indicates that CLF promotes flowering by reducing expression of FLC, a repressor of flowering. We conclude that SEP3 is the key target mediating the clf phenotype, and that the antagonistic effects of CLF target genes masks a role for CLF in promoting flowering. PMID:22363474

Lopez-Vernaza, Manuel; Yang, Suxin; Müller, Ralf; Thorpe, Frazer; de Leau, Erica; Goodrich, Justin

2012-02-17

346

Antagonistic Roles of SEPALLATA3, FT and FLC Genes as Targets of the Polycomb Group Gene CURLY LEAF  

PubMed Central

In Arabidopsis, mutations in the Pc-G gene CURLY LEAF (CLF) give early flowering plants with curled leaves. This phenotype is caused by mis-expression of the floral homeotic gene AGAMOUS (AG) in leaves, so that ag mutations largely suppress the clf phenotype. Here, we identify three mutations that suppress clf despite maintaining high AG expression. We show that the suppressors correspond to mutations in FPA and FT, two genes promoting flowering, and in SEPALLATA3 (SEP3) which encodes a co-factor for AG protein. The suppression of the clf phenotype is correlated with low SEP3 expression in all case and reveals that SEP3 has a role in promoting flowering in addition to its role in controlling floral organ identity. Genetic analysis of clf ft mutants indicates that CLF promotes flowering by reducing expression of FLC, a repressor of flowering. We conclude that SEP3 is the key target mediating the clf phenotype, and that the antagonistic effects of CLF target genes masks a role for CLF in promoting flowering.

Lopez-Vernaza, Manuel; Yang, Suxin; Muller, Ralf; Thorpe, Frazer; de Leau, Erica; Goodrich, Justin

2012-01-01

347

NbPHAN, a MYB transcriptional factor, regulates leaf development and affects drought tolerance in Nicotiana benthamiana.  

PubMed

MYB transcriptional factors, characterized by the presence of conserved DNA-binding domains (BDs) (MYB domain), are involved in diverse processes including plant growth, development, metabolic and stress responses. In this study, a new R2R3-type MYB gene, NbPHAN (Nicotiana benthamiana PHANTASTICA), was identified in N. benthamiana. The NbPHAN encodes a protein of 362 amino acids and shares high sequence identities with the AS1-RS2-PHANs (ARPs) from other plant species. The NbPHAN protein targets to and forms homodimers in the nucleus. The MYB domain and C-terminal region of NbPHAN determine its subcellular localization and homodimerization, respectively. Using virus-induced gene silencing, we showed that the NbPHAN-silenced leaves exhibited severe downward curling and abnormal growth of blades along the main veins through suppressing the expression of the NTH20 gene. In addition, we found NbPHAN plays an important role in drought tolerance. The NbPHAN-silenced plants exhibited severe wilting and increased rate of water loss than that found in the non-silenced plants when growing under the water deficit condition. Although abscisic acid accumulation was not altered in the NbPHAN-silenced plants as compared with that in the non-silenced plants, several other stress-inducible genes were clearly repressed under the water deficit condition. Our results provide strong evidence that other than controlling leaf development, the ARP genes can also regulate plant tolerance to drought stress. PMID:23387304

Huang, Changjun; Hu, Gaojie; Li, Fangfang; Li, Yunqin; Wu, Jianxiang; Zhou, Xueping

2013-03-15

348

Global leaf trait relationships: mass, area, and the leaf economics spectrum.  

PubMed

The leaf economics spectrum (LES) describes multivariate correlations that constrain leaf traits of plant species primarily to a single axis of variation if data are normalized by leaf mass. We show that these traits are approximately distributed proportional to leaf area instead of mass, as expected for a light- and carbon dioxide-collecting organ. Much of the structure in the mass-normalized LES results from normalizing area-proportional traits by mass. Mass normalization induces strong correlations among area-proportional traits because of large variation among species in leaf mass per area (LMA). The high LMA variance likely reflects its functional relationship with leaf life span. A LES that is independent of mass- or area-normalization and LMA reveals physiological relationships that are inconsistent with those in global vegetation models designed to address climate change. PMID:23539179

Osnas, Jeanne L D; Lichstein, Jeremy W; Reich, Peter B; Pacala, Stephen W

2013-03-28

349

Curl-free vector potential observation on the macro-scale for charged particles in a magnetic field compared with that on the micro-scale: the Aharonov-Bohm effect  

NASA Astrophysics Data System (ADS)

The recently reported curl-free vector potential observation (Varma et al 2012 Eur. Phys. J. D 66 38) in relation to a system of charged particles in a magnetic field points to the existence of a new state of the electron—a quantum modulated state—which arises through a scattering-induced transition across Landau levels. This quantum modulated state has been shown to account for some very unusual effects on the macro-scale, which are distinct from the ones which can be understood in terms of a ‘classical electron’ and also from the ones which can be understood in terms of a ‘quantum electron’ on the micro-scale characterized by the Planck quantum. This quantum modulated state has been shown to account for the observation of a static curl-free vector potential on the macro-scale alluded to above, as well as other matter wave manifestations on the macro-scale. The macro-scale curl-free vector potential observation differs fundamentally from the corresponding micro-scale effect—the well-known Aharonov-Bohm effect. These two effects—on the macro-scale and the macro-scale—are compared and contrasted to each other here in their manner of detection of the static curl-free vector potential. Such a comparative study helps gain a deeper understanding of the nature of the quantum modulated state and the macro-scale matter wave it represents.

Varma, Ram K.

2012-10-01

350

Relationships between specific leaf weight and mineral concentration among genotypes  

Microsoft Academic Search

Physiological functions are usually expressed on a leaf area basis, whereas leaf mineral concentrations are often expressed on a dry matter basis. If specific leaf weight (SLW; g DM m?2 leaf) differs among genotypes then variability in mineral concentration may depend on the basis of expression. Data from experiments with peanut (Arachis hypogaea L.) and pearl millet [Pennisetum glaucum (L.)

R. Harold Brown; George T. Byrd

1997-01-01

351

Simulating Leaf Area of Corn Plants at Contrasting Water Status  

Technology Transfer Automated Retrieval System (TEKTRAN)

An exponential decay function was fitted with literature data to describe the decrease in leaf expansion rate as leaf water potential decreases. The fitted function was then applied to modify an existing leaf area simulation module in a soil-plant-atmosphere continuum model in order to simulate leaf...

352

Calibration of the Minolta SPAD502 leaf chlorophyll meter  

Microsoft Academic Search

Use of leaf meters to provide an instantaneous assessment of leaf chlorophyll has become common, but calibration of meter output into direct units of leaf chlorophyll concentration has been difficult and an understanding of the relationship between these two parameters has remained elusive. We examined the correlation of soybean (Glycine max) and maize (Zea mays L.) leaf chlorophyll concentration, as

John Markwell; John C. Osterman; Jennifer L. Mitchell

1995-01-01

353

7 CFR 29.2663 - Thin Leaf (C Group).  

Code of Federal Regulations, 2013 CFR

...injury tolerance. C3F Good Medium-brown Thin Leaf...tolerance. C3VF Good Greenish Medium-brown Thin Leaf... C5VF Low Greenish Medium-brown Thin Leaf...injury tolerance. C3G Good Green Thin Leaf....

2013-01-01

354

Assessing the generality of global leaf trait relationships  

Microsoft Academic Search

Summary • Global-scale quantification of relationships between plant traits gives insight into the evolution of the world's vegetation, and is crucial for parameterizing vegetation- climate models. • A database was compiled, comprising data for hundreds to thousands of species for the core 'leaf economics' traits leaf lifespan, leaf mass per area, photosynthetic capacity, dark respiration, and leaf nitrogen and phosphorus

Ian J. Wright; Peter B. Reich; Johannes H. C. Cornelissen; Daniel S. Falster; Eric Garnier; Kouki Hikosaka; Byron B. Lamont; William Lee; C. H. Lusk; J. Oleksyn; N. Osada; R. Villar; D. I. Warton; M. Westoby

2005-01-01

355

Elevated COâ and leaf shape: Are dandelions getting toothier?  

Microsoft Academic Search

Heteroblastic leaf development in Taraxacum officinale is compared between plants grown under ambient (350 ppm) vs. elevated (700 ppm) COâ levels. Leaves of elevated COâ plants exhibited more deeply incised leaf margins and relatively more slender leaf laminae than leaves of ambient COâ plants. These differences were found to be significant in allometric analyses that controlled for differences in leaf

S. C. Thomas; F. A. Bazzaz

1996-01-01

356

RFLP tagging of QTLs conditioning specific leaf weight and leaf size in soybean  

Microsoft Academic Search

Selection for high specific leaf weight (SLW) in soybean [Glycine max (L) Merr.] may increase apparent photosynthetic rate per unit leaf area (AP), which in turn may improve seed yield. In general,\\u000a the SLW and leaf size are negatively correlated in soybean. To maximize total photosynthetic performance, and perhaps the\\u000a seed yield, of a soybean cultivar, it would be necessary

M. A. R. Mian; R. Wells; T. E. Carter Jr.; D. A. Ashley; H. R. Boerma

1998-01-01

357

Effect of Image Processing of a Leaf Photograph on the Calculated Fractal Dimension of Leaf Veins  

Microsoft Academic Search

Digital photography is a promised method for estimating the fractal characteristics of leaf veins. In this study, the effects\\u000a of different threshold levels and image processing methods using Adobe Photoshop software on the fractal dimension values\\u000a were examined from a digital photo of nectarine leaf. The results showed that the nectarine leaf vein has typical fractal\\u000a characteristics and its fractal

Yun Kong; Shaohui Wang; Chengwei Ma; Baoming Li; Yuncong Yao

2007-01-01

358

Characterization of Rhynchosia yellow mosaic Yucatan virus, a new recombinant begomovirus associated with two fabaceous weeds in Yucatan, Mexico.  

PubMed

Rhynchosia minima (L.) DC. (Fabaceae) plants exhibiting bright golden mosaic symptoms were previously associated with begomovirus infection in Yucatan, México [1]. To characterize the begomovirus infecting these plants, the complete bipartite genome was cloned and sequenced. Sequence comparisons indicated that the virus was distinct from all other begomoviruses known to date, including those previously identified from symptomatic R. minima, and the name Rhynchosia yellow mosaic Yucatan virus (RhYMYuV) is proposed. Pairwise comparisons indicated that RhYMYuV DNA-A [2,597 nt, (EU021216)] and DNA-B [2,542 nt, (FJ792608)] components shared the highest nt sequence identity with Cabbage leaf curl virus (CaLCuV), 87% for component A and 71% for component B. Phylogenetic analysis indicated that both components of RhYMYuV are most closely related to other New World begomoviruses, having as closest relatives immediate outliers to the major Squash leaf curl virus (SLCV) clade. Recombination analysis of the RhYMYuV genome indicated that the DNA-A component has arisen through intermolecular recombination. R. minima plants inoculated with the monomeric clones developed a bright yellow mosaic similar to symptoms observed in naturally infected plants, confirming that the clones were infectious. Nicotiana benthamiana plants biolistically inoculated with monomeric clones developed curling and chlorosis in the newly emerging leaves. RhYMYuV was also detected in symptomatic Desmodium sect. Scorpiurus Benth. (Fabaceae) that were collected near the RhYMYuV-infected plants. PMID:20574644

Hernández-Zepeda, C; Brown, J K; Moreno-Valenzuela, O A; Argüello-Astorga, G; Idris, A M; Carnevali, G; Rivera-Bustamante, R F

2010-06-24

359

Leaf Decomposition in a Tropical Rainforest Stream.  

National Technical Information Service (NTIS)

Fungi play an important part in leaf litter decomposition in terrestrial ecosystems in both temperate and tropical regions. There are few published reports dealing with decomposition in running waters, and no work has been done in tropical streams. Result...

D. E. Padgett

1975-01-01

360

Monitoring Air Quality with Leaf Yeasts.  

ERIC Educational Resources Information Center

|Proposes that leaf yeast serve as quick, inexpensive, and effective techniques for monitoring air quality. Outlines procedures and provides suggestions for data analysis. Includes results from sample school groups who employed this technique. (ML)|

Richardson, D. H. S.; And Others

1985-01-01

361

Guava leaf extract and topical haemostasis.  

PubMed

The effects of guava leaf extract on the bleeding time and the three main mechanisms of haemostasis: vasoconstriction, platelet aggregation and blood coagulation, were investigated. The water extract of guava leaves did not shorten bleeding times in rats. Guava leaf extract potentiated the vascular muscle contraction induced in rabbits by phenylephrine, and when given alone it stimulated human platelet aggregation in vitro in a dose-dependent manner. On the other hand, it significantly prolonged blood coagulation; activated partial thromboplastin time (APTT) test (p < 0.05). The higher the concentration of the extract, the longer APTT was observed. Thus, a water extract of guava leaves showed ambiguous effects on the haemostatic system. Guava leaf extract did not affect bleeding times, it stimulated vasoconstriction and platelet aggregation but it inhibited blood coagulation. Therefore, guava leaf extract is not recommended as a haemostatic agent. PMID:10925412

Jaiarj, P; Wongkrajang, Y; Thongpraditchote, S; Peungvicha, P; Bunyapraphatsara, N; Opartkiattikul, N

2000-08-01

362

Photosynthesis and Respiration in Leaf Slices.  

ERIC Educational Resources Information Center

|Demonstrates how leaf slices provide an inexpensive material for illustrating several fundamental points about the biochemistry of photosynthesis and respiration. Presents experiments that illustrate the effects of photon flux density and herbicides and carbon dioxide concentration. (DDR)|

Brown, Simon

1998-01-01

363

Leaf Senescence: Gene Expression and Regulation  

Microsoft Academic Search

\\u000a Each autumn leaf senescence leaves its mark on the planet in the form of dramatic changes in color that can be seen from space.\\u000a Annually, leaf senescence mediates the breakdown of 300 million tons of chlorophyll while changing green forests and fields\\u000a to yellow and orange (1). The drama of these color changes is matched by the dramatic nature of

Louis M. Weaver; Edward Himelblau; Richard M. Amasino

364

Leaf Impressions: A Model for Carbonization  

NSDL National Science Digital Library

In this activity students make leaf impressions on paper to illustrate how carbonization works. They use the leaf press method to demonstrate staining as a model for carbonization, when living tissue leaves a carbon film in sediment and rock. The students will discover that many plant fossils are preserved through carbonization and that soft parts of animals including skin and fur have also been preserved as fossils through the process of carbonization.

Greb, Stephen

365

Somatic embryogenesis from leaf cultures of potato  

Microsoft Academic Search

An efficient procedure has been developed for inducing somatic embryogenesis from leaf cultures of potato cv. Jyothi. Leaf sections were initially cultured on 2,4-dichlorophenoxyacetic acid (2,4-D) + benzyladenine (BA) and a-naphthaleneacetic acid (NAA) + BA supplemented Murashige and Skoog (MS) media. Nodular embryogenic callus developed from the cut ends of explants on media containing 2,4-D and BA, whereas compact callus

T. JayaSree; U. Pavan; M. Ramesh; A. V. Rao; K. Jagan Mohan Reddy; A. Sadanandam

2001-01-01

366

Relationship between hydraulic resistance and leaf morphology in broadleaf Quercus species: a new interpretation of leaf lobation  

Microsoft Academic Search

We investigated the relationship between leaf shape and leaf hydraulic resistance in a set of broadleaf Quercus tree species (Q. cerris, Q. frainetto, Q. petraea, Q. pyrenaica, Q. robur, Q. rubra, Q. velutina). Seedlings of all the studied species were grown under uniform environmental conditions. A new high-pressure flowmeter was designed to measure leaf-blade hydraulic resistance. Leaf shape was characterised

S. Sisó; J. J. Camarero; Eustaquio Gil-Pelegrín

2001-01-01

367

Leaf morphology shift linked to climate change  

PubMed Central

Climate change is driving adaptive shifts within species, but research on plants has been focused on phenology. Leaf morphology has demonstrated links with climate and varies within species along climate gradients. We predicted that, given within-species variation along a climate gradient, a morphological shift should have occurred over time due to climate change. We tested this prediction, taking advantage of latitudinal and altitudinal variations within the Adelaide Geosyncline region, South Australia, historical herbarium specimens (n = 255) and field sampling (n = 274). Leaf width in the study taxon, Dodonaea viscosa subsp. angustissima, was negatively correlated with latitude regionally, and leaf area was negatively correlated with altitude locally. Analysis of herbarium specimens revealed a 2 mm decrease in leaf width (total range 1–9 mm) over 127 years across the region. The results are consistent with a morphological response to contemporary climate change. We conclude that leaf width is linked to maximum temperature regionally (latitude gradient) and leaf area to minimum temperature locally (altitude gradient). These data indicate a morphological shift consistent with a direct response to climate change and could inform provenance selection for restoration with further investigation of the genetic basis and adaptive significance of observed variation.

Guerin, Greg R.; Wen, Haixia; Lowe, Andrew J.

2012-01-01

368

Chemistry and Biology of Plant Leaf Movements.  

PubMed

The leaves of Mimosa pudica L. are well known for their rapid movement when touched. Recently, we were able to isolate an excitatory substance in small quantities from this plant, which consists of three different components (potassium L-malate, magnesium trans-aconitate, and dimethylammonium salt). Many plants close their leaves in the evening, as if to sleep, and open them early in the morning (nyctinastic leaf movement). This circadian rhythm is known to be controlled by the biological clock of such plants. Extensive studies on other nyctinastic plants led to the isolation of a variety of leaf-opening substances (LOSs) and leaf-closing substances (LCSs). Based on our experiments on these bioactive substances, we found that the circadian rhythmic leaf movement of these plants is initiated by the regulated balance of LOSs and LCSs. The balance of concentration between the two leaf-movement factors (LMFs) is inversed during the day. The glycoside-type LMF is hydrolyzed with beta-glucosidase, the activity of which is regulated by the biological clock. The circadian rhythm observed in the leaf movement is introduced by activation of beta-glucosidase regulated by the biological clock. PMID:10777626

Ueda; Yamamura

2000-04-01

369

Ginseng leaf-stem: bioactive constituents and pharmacological functions  

Microsoft Academic Search

Ginseng root is used more often than other parts such as leaf stem although extracts from ginseng leaf-stem also contain similar active ingredients with pharmacological functions. Ginseng's leaf-stems are more readily available at a lower cost than its root. This article reviews the pharmacological effects of ginseng leaf-stem on some diseases and adverse effects due to excessive consumption. Ginseng leaf-stem

Hongwei Wang; Dacheng Peng; Jingtian Xie

2009-01-01

370

Decline of leaf hydraulic conductance with dehydration: relationship to leaf size and venation architecture.  

PubMed

Across plant species, leaves vary enormously in their size and their venation architecture, of which one major function is to replace water lost to transpiration. The leaf hydraulic conductance (K(leaf)) represents the capacity of the transport system to deliver water, allowing stomata to remain open for photosynthesis. Previous studies showed that K(leaf) relates to vein density (vein length per area). Additionally, venation architecture determines the sensitivity of K(leaf) to damage; severing the midrib caused K(leaf) and gas exchange to decline, with lesser impacts in leaves with higher major vein density that provided more numerous water flow pathways around the damaged vein. Because xylem embolism during dehydration also reduces K(leaf), we hypothesized that higher major vein density would also reduce hydraulic vulnerability. Smaller leaves, which generally have higher major vein density, would thus have lower hydraulic vulnerability. Tests using simulations with a spatially explicit model confirmed that smaller leaves with higher major vein density were more tolerant of major vein embolism. Additionally, for 10 species ranging strongly in drought tolerance, hydraulic vulnerability, determined as the leaf water potential at 50% and 80% loss of K(leaf), was lower with greater major vein density and smaller leaf size (|r| = 0.85-0.90; P < 0.01). These relationships were independent of other aspects of physiological and morphological drought tolerance. These findings point to a new functional role of venation architecture and small leaf size in drought tolerance, potentially contributing to well-known biogeographic trends in leaf size. PMID:21511989

Scoffoni, Christine; Rawls, Michael; McKown, Athena; Cochard, Hervé; Sack, Lawren

2011-04-21

371

Pulvinus activity, leaf movement and leaf water-use efficiency of bush bean ( Phaseplus vulgaris L.) in a hot environment  

Microsoft Academic Search

Pulvinus activity of Phaseolus species in response to environmental stimuli plays an essential role in heliotropic leaf movement. The aims of this study\\u000a were to monitor the continuous daily pulvinus movement and pulvinus temperature, and to evaluate the effects of leaf movements,\\u000a on a hot day, on instantaneous leaf water-use efficiency (WUEi), leaf gas exchange, and leaf temperature. Potted plants

Mahmoud Raeini-Sarjaz; Vida Chalavi

2008-01-01

372

Leaf patterns, leaf size and ecologically related traits in high Mediterranean mountain on the Moroccan High Atlas  

Microsoft Academic Search

Leaf traits functional relationship is particularly important in plant ecological strategies, but few data are available from\\u000a Mediterranean high-altitude environments. We analysed leaf general patterns and leaf trait relationships in 84 perennial species\\u000a on the High Atlas, Morocco. We examined the correlation amongst leaf size, leaf width and length, plant height and seed size,\\u000a analysed multi-trait relationships using Structural Equation

Teresa Navarro; Jalal El Oualidi; Mohammed Sghir Taleb; Virginia Pascual; Baltasar Cabezudo; Rubén Milla

2010-01-01

373

Leaf miner-induced changes in leaf transmittance cause variations in insect respiration rates  

Microsoft Academic Search

Very little is known about alterations in microclimate when an herbivore feeds on host plant. Modifications of leaf transmittance properties induced by feeding activity of the leaf miner Phyllonorycter blancardella F. were measured using a spectrometer. Their effects on the herbivore's body temperature and respiration rate have been determined under controlled conditions and varying radiation level employing an infrared gas

Sylvain Pincebourde; Jérôme Casas

2006-01-01

374

Leaf alkaloids, phenolics, and coffee resistance to the leaf miner Leucoptera coffeella (Lepidoptera: Lyonetiidae).  

PubMed

Coffee (Coffea spp.) alkaloids (caffeine and related methylxanthines) and phenolics (caffeic and chlorogenic acids) have recognized pestistatic/pesticidal activity and mediate insect-plant interactions. The present investigation assessed the resistance of 12 coffee genotypes to the leaf miner Leucoptera (= Perileucoptera) coffeella (Guérin-Méneville & Perrottet) (Lepidoptera: Lyonetiidae) and correlated such results with the leaf content of coffee alkaloids and phenolics that probably play a role in the interaction between coffee and this leaf miner. The levels of chlorogenic and caffeic acid, caffeine, and related methylxanthines were measured and quantified in leaf extracts of these genotypes before and 7 d after their infestation by the leaf miner. Some coffee genotypes (Coffea canephora L. and Coffea racemosa Lour. and its hybrids with Coffea arabica L.) exhibited high pesticidal activity (100% mortality) toward the L. coffeella, indicating their antibiosis resistance. However, there was no correlation between this activity and the leaf levels of coffee alkaloids and phenolics. Curiously, infestation by L. coffeella leads to a nearly four-fold decline in the leaf levels of chlorogenic acid, which does not affect this pest species but may affect other generalist species. Indeed, chlorogenic acid sprayed on coffee leaves stimulated locomotory activity of the green scale Coccus viridis (Green) (Hemiptera: Coccidae), thus minimizing their feeding in contrast with the absence of this polyphenol. Therefore, reduction of chlorogenic acid levels in coffee leaves due to leaf miner infestation seems to also favor infestation by generalist insects, such as the green scale. PMID:20857759

Magalhães, S T V; Fernandes, F L; Demuner, A J; Picanço, M C; Guedes, R N C

2010-08-01

375

Does leaf manipulation affect leaf appearance in italian ryegrass (Lolium multiflorum Lam.)  

Technology Transfer Automated Retrieval System (TEKTRAN)

Mechanical stimuli such as rubbing, shaking, or flexing plants can alter their growth rates and morphologies. Plant response to mechanical stress can result in delayed plant growth, reduced leaf size, shorten and thicken stems, and reduced yields. Repeated measurements, such as leaf counting or me...

376

Relationships between sclerophylly, leaf biomechanical properties and leaf anatomy in some Australian heath and forest species  

Microsoft Academic Search

A previous study of 19 south-east Australian heath and forest species with a range of leaf textures showed that they varied considerably in leaf biomechanical properties. By using an index of sclerophylly derived from botanists' rankings (botanists' sclerophylly index, BSI) we determined that leaves considered by botanists to be sclerophyllous generally had both high strength and work to fracture (particularly

Cheryl Edwards; Gordon D. Sanson; Nuvan Aranwela; Jennifer Read

2000-01-01

377

Leaf endophyte load and fungal garden development in leaf-cutting ants  

Technology Transfer Automated Retrieval System (TEKTRAN)

Previous work has shown that leaf-cutting ants prefer to cut leaf material that is relatively low in fungal endophyte content. Such a preference suggests that fungal endophytes exact a cost on the ants or on the development of their colonies. We hypothesized that endophytes may play a role in thei...

378

SPECIFIC LEAF AREA AND LEAF DRY MATTER CONTENT OF PLANTS GROWING IN SAND DUNES  

Technology Transfer Automated Retrieval System (TEKTRAN)

We investigated variations in specific leaf area (SLA) and leaf dry matter content (LDMC) of 20 species (10 annuals and 10 perennials) that have different distributional patterns in Kerqin sandy land in northern China. The main purpose of our study was to determine if SLA and/or LDMC could be used ...

379

The Scaling Relationships between Leaf Mass and Leaf Area of Vascular Plant Species Change with Altitude  

PubMed Central

The scaling relationship between leaf dry mass and leaf surface area has important implications for understanding the ability of plants to harvest sunlight and grow. Whether and how the scaling relationships vary across environmental gradients are poorly understood. We analyzed the scaling relationships between leaf mass and leaf area of 121 vascular plant species along an altitudinal gradient in a subtropical monsoon forest. The slopes increased significantly with altitude, it varied from less than 1 at low altitude to more than 1 at high altitude. This means that plants growing at high altitude allocate proportionately more biomass to support tissues in larger leaves and less in smaller leaves, whereas the reverse is true at low altitude. This pattern can be explained by different leaf strategies in response to environmental pressure and constrains.

Pan, Sha; Liu, Chao; Zhang, Weiping; Xu, Shanshan; Wang, Nan; Li, Yan; Gao, Jing; Wang, Yang; Wang, Genxuan

2013-01-01

380

The Scaling Relationships between Leaf Mass and Leaf Area of Vascular Plant Species Change with Altitude.  

PubMed

The scaling relationship between leaf dry mass and leaf surface area has important implications for understanding the ability of plants to harvest sunlight and grow. Whether and how the scaling relationships vary across environmental gradients are poorly understood. We analyzed the scaling relationships between leaf mass and leaf area of 121 vascular plant species along an altitudinal gradient in a subtropical monsoon forest. The slopes increased significantly with altitude, it varied from less than 1 at low altitude to more than 1 at high altitude. This means that plants growing at high altitude allocate proportionately more biomass to support tissues in larger leaves and less in smaller leaves, whereas the reverse is true at low altitude. This pattern can be explained by different leaf strategies in response to environmental pressure and constrains. PMID:24146938

Pan, Sha; Liu, Chao; Zhang, Weiping; Xu, Shanshan; Wang, Nan; Li, Yan; Gao, Jing; Wang, Yang; Wang, Genxuan

2013-10-11

381

In vitro response of leaf tissues from Lolium multiflorum — a comparison with leaf segment position, leaf age and in vivo mitotic activity  

Microsoft Academic Search

Immature gramineous leaves provide a convenient system for comparing the response of cells in culture with their state of differentiation. Callusing frequency is compared with leaf segment position, leaf age and in vivo mitotic activity in Lolium multiflorum. (1) In a succession of one millimeter sections from the immature leaf base, callus was formed from the first and second sections

O. I. Joarder; N. H. Joarder; P. J. Dale

1986-01-01

382

Leaf Water Repellency as an Adaptation to Cloud Forest Environments  

NASA Astrophysics Data System (ADS)

Fog persistency and high precipitation totals contribute to the unique ecohydrology of tropical montane cloud forests. The persistence of water droplets on leaf surfaces in cloud forests inhibits photosynthetic carbon exchange because carbon dioxide diffuses slower in water than air. Adaptations that reduce water retention on leaf surfaces may increase photosynthetic capacity of cloud forests. The hypothesis of this study was that 12 cloud forest species from the Sierra de las Minas, Guatemala have a higher degree of leaf water repellency than 12 species from tropical dry forests in Chiquimula, Guatemala and 12 species from foothills-grassland vegetation in Colorado (USA). Leaf water repellency was measured as the contact angle between the leaf surface and the line tangent to the water droplet passing through the point of contact between the droplet and the leaf surface. Leaf water repellency was significantly different between the three study areas; however, leaf water repellency of 12 species in the Sierra de las Minas was lower than 12 species in Chiquimula and 12 species in Colorado. Leaf water repellency of abaxial surfaces of all species in the cloud forest was greater than leaf water repellency of adaxial surfaces. The low values of leaf water repellency in cloud forest species may be influenced by presence of epiphylls or the loss of epicuticular wax on the leaf surfaces because of high precipitation totals and longer leaf life-span. High leaf water repellency in dry climates may be an adaptation to increase hydrological inputs underneath the canopy.

Holder, C. D.

2006-12-01

383

How do leaf veins influence the worldwide leaf economic spectrum? Review and synthesis.  

PubMed

Leaf vein traits are implicated in the determination of gas exchange rates and plant performance. These traits are increasingly considered as causal factors affecting the 'leaf economic spectrum' (LES), which includes the light-saturated rate of photosynthesis, dark respiration, foliar nitrogen concentration, leaf dry mass per area (LMA) and leaf longevity. This article reviews the support for two contrasting hypotheses regarding a key vein trait, vein length per unit leaf area (VLA). Recently, Blonder et al. (2011, 2013) proposed that vein traits, including VLA, can be described as the 'origin' of the LES by structurally determining LMA and leaf thickness, and thereby vein traits would predict LES traits according to specific equations. Careful re-examination of leaf anatomy, published datasets, and a newly compiled global database for diverse species did not support the 'vein origin' hypothesis, and moreover showed that the apparent power of those equations to predict LES traits arose from circularity. This review provides a 'flux trait network' hypothesis for the effects of vein traits on the LES and on plant performance, based on a synthesis of the previous literature. According to this hypothesis, VLA, while virtually independent of LMA, strongly influences hydraulic conductance, and thus stomatal conductance and photosynthetic rate. We also review (i) the specific physiological roles of VLA; (ii) the role of leaf major veins in influencing LES traits; and (iii) the role of VLA in determining photosynthetic rate per leaf dry mass and plant relative growth rate. A clear understanding of leaf vein traits provides a new perspective on plant function independently of the LES and can enhance the ability to explain and predict whole plant performance under dynamic conditions, with applications towards breeding improved crop varieties. PMID:24123455

Sack, Lawren; Scoffoni, Christine; John, Grace P; Poorter, Hendrik; Mason, Chase M; Mendez-Alonzo, Rodrigo; Donovan, Lisa A

2013-10-01

384

Role of chloroplastidial proteases in leaf senescence  

PubMed Central

In this report the effect of hydrogen peroxide (H2O2) on peroxidase (POD) activity during leaf senescence was studied with and without phenylmethylsulfonyl fluoride (PMSF) pre-treatment in detached neem (Azadirachta indica A. juss) leaf chloroplasts. Increased POD activity was detected in natural and H2O2-promoted senescent leaf chloroplasts compared to untreated control mature green leaf chloroplasts. However, under H2O2 POD activity markedly increased at 1 day, and then significantly decreased until 4 days. In the presence of H2O2, PMSF, the induction of POD activity was alleviated at 1 day, whereas reduced after 4 days. In contrast, in the presence of H2O2, cycloheximide (CX), the induction of POD activity was reduced at 1 day, whereas alleviated after 4 days. The was a partial reduction in H2O2-induced POD activity with PMSF and CX, indicating the presence of pre-existing inactive PODs in chloroplasts. We also propose a new role for chloroplastidial proteases as activators of pre-existing inactive PODs during leaf senescence.

Goud, Prashanth B

2011-01-01

385

Role of chloroplastidial proteases in leaf senescence.  

PubMed

In this report the effect of hydrogen peroxide (H2O2) on peroxidase (POD) activity during leaf senescence was studied with and without phenylmethylsulfonyl fluoride (PMSF) pre-treatment in detached neem (Azadirachta indica A. juss) leaf chloroplasts. Increased POD activity was detected in natural and H2O2-promoted senescent leaf chloroplasts compared to untreated control mature green leaf chloroplasts. However, under H2O2 POD activity markedly increased at 1 day, and then significantly decreased until 4 days. In the presence of H2O2, PMSF, the induction of POD activity was alleviated at 1 day, whereas reduced after 4 days. In contrast, in the presence of H2O2, cycloheximide (CX), the induction of POD activity was reduced at 1 day, whereas alleviated after 4 days. The was a partial reduction in H2O2-induced POD activity with PMSF and CX, indicating the presence of pre-existing inactive PODs in chloroplasts. We also propose a new role for chloroplastidial proteases as activators of pre-existing inactive PODs during leaf senescence. PMID:22024830

Goud, Prashanth B; Kachole, Manvendra S

2011-09-01

386

A Polygalacturonase from Citrus Leaf Explants  

PubMed Central

The relationship between polygalacturonase activity and abscission of citrus leaf explants was studied. Determination of polygalacturonase activity in citrus tissues requires concentration of the enzyme, use of a proper assay method, and inhibition of an oxidase present in the extracts which oxidizes the reaction products of the polygalacturonase. The polygalacturonase from citrus leaf explants is an exopolygalacturonase and appears to be a soluble enzyme. Polygalacturonase activity increased during abscission of citrus leaf explants and was localized in the separation layer. Ethylene accelerated the increase in polygalacturonase activity, but its effect was evident only after at least an 8-hour lag period. 2,4-Dichlorophenoxyacetic acid and cycloheximide inhibited abscission and polygalacturonase activity. It is concluded that polygalacturonase, in addition to cellulase, plays a role in abscission. Images

Riov, J.

1974-01-01

387

Physiological Studies with Isolated Leaf Cells  

PubMed Central

A number of plants have been surveyed with respect to isolation by mild grinding in large quantities of leaf cells. The extent of recovery of mesophyll cells per unit leaf area was found to vary with plant species and the method of grinding. Greater than 70% recovery was obtained from the leaves of Canna indica L., Crotalaria Laburnifolia L., and Thunbergia grandiflora Roxb. By pulse-chase time course experiments, the photosynthetically fixed primary carbon compounds of bean leaf cells were not converted into the ethanol-insoluble fraction. About 25% of total 14C-photoassimilates were found to leak out into the incubation medium. In contrast, Euglena and Chlorella cells incorporated their primary photosynthetic products into cellular macromolecules and the amount of “leak” was very little. 14C-Leucine supplied to the bean cells was absorbed readily and incorporated into the trichloroacetic acid insoluble fraction. Images

Kulandaivelu, G.; Gnanam, A.

1974-01-01

388

Leaf Stomata as Bioindicators of Environmental Change  

NSDL National Science Digital Library

Leaf stomatal densities can be determined by a simple laboratory technique and yet have wide application in understanding environmental change. Several researchers have evidence which indicates that stomatal densities change in response to changing atmospheric levels of carbon dioxide. Stomata may also vary in response to the amount of annual rainfall in different localities. Because this investigation involves climatic variations, it requires that many geographically dispersed sites collect and share data. In this experiment, leaves from two species of trees will be collected and the stomatal index on the upper and lower epidermis of each leaf will be determined.

Steve Case (University of Kansas REV)

1994-07-30

389

Autophagic degradation of leaf starch in plants.  

PubMed

Autophagy is an evolutionarily conserved process in eukaryotic cells that functions to degrade cytoplasmic components in the vacuole or lysosome. Previous research indicates that the core molecular machinery of autophagosome formation works well in plants, and plant autophagy plays roles in diverse biological processes such as nutrient recycling, development, immunity and responses to a variety of abiotic stresses. Recently, we reported that autophagy contributed to leaf starch degradation, which had been thought to be a process confined to chloroplasts. This finding demonstrated a previously unidentified pathway of leaf starch depletion and a new role of basal autophagy in plants. PMID:23722252

Wang, Yan; Liu, Yule

2013-05-29

390

Molecular Models of Leaf Extracts  

NSDL National Science Digital Library

Our Featured Molecules this month come from the paper by Pelter et. al. on the analysis of leaf extracts by thin-layer chromatography (1). As the authors discuss, their experiment may be used in courses at various levels of the curriculum. The molecules discussed in the paper are also of wide interest both for their structural properties and their wide-ranging appearance in both natural and synthetic substances. Included in the molecule collection are all of the isomers for the molecules pictured in the text with the exception of menthyl acetate, for which only one structure is given (see below). All of these molecules have been optimized at the HF/631-G(d) level. The menthol family enantiomeric pairs of menthol, isomenthol, neomenthol and neoisomenthol provide a rich yet coherent group of molecules on which to base discussion of chirality, enantiomers and diastereomers. Treadwell and Black have described some of the differences in physical properties of four members of this family, and several other experiments using one or more menthols have been published in this Journal (2, 3). I have created a Web page in which the eight molecules are embedded in no particular order, and with no rational file names. This is being used in at least one of our organic sections to give students experience at identifying enantiomers, and diastereomers, and in applying R/S notation (4). As access to computational software becomes more common, and as efforts are being made to incorporate more relevant modeling experiments into all levels of the curriculum, the menthols again present some interesting possibilities. While students at the organic level know about enantiomers differing in their optical rotation, and about chiral molecules interacting with chiral and achiral environments, it is instructive for them to think of other ways in which enantiomers and diastereomers are the same or different. Three useful ways of checking to see whether two structures are truly enantiomers is to compute their total energies, vibrational spectra, and dipole moments. These calculations are available in most common computational packages. Figure 1 shows the results of energy calculations on optimized structures of the eight isomers. The enantiomeric pairs have, as expected, exactly the same total energy, while the various diastereomers differ in energy. The computation of the vibrational spectra is a very sensitive probe to determine whether two structures are optimized and enantiomeric or not. Structures that are almost enantiomeric, but not quite optimized, may exhibit similar energies, but the low frequency vibrations will be sensitive to any deviation from optimization. If two supposedly enantiomeric structures do not have the same computed vibrations, or if either shows a negative frequency, the structures need to be optimized more carefully. As with the vibrational frequencies, enantiomers should show identical dipole moments. Only one structure of the eight isomers in the menthyl acetate family is included in the collection, giving students the chance to build the other seven and verify their computed properties. Because of the central role that chirality plays in chemistry, and particularly in biochemistry, it seems appropriate to introduce some of these visualization and modeling exercises early in the curriculum, and in courses designed for students majoring in other areas. Students in various courses could pursue other aspects of these same molecules including odor and cooling properties, and green chemistry approaches to synthesizing menthols.

391

Leaf Abscisic Acid Accumulation in Response To Substrate Water Content: Linking Leaf Gas Exchange Regulation with Leaf Abscisic Acid Concentration  

Microsoft Academic Search

ADDITIONAL INDEX WORDS. stomatal conductance, drought tolerance, genotype variation ABSTRACT. Quantitative differences in leaf abscisic acid (ABAL) among four cultivars of red maple (Acer rubrum L.) and one freeman maple (Acer ×freemanii E. Murray) cultivar were investigated. This study tested the hypothesis that ABAL concentration can be used to compare the effects of water stress on the gas exchange response

William L. Bauerle; William W. Inman; Jerry B. Dudley

2006-01-01

392

7 CFR 29.2437 - Heavy Leaf (B Group).  

Code of Federal Regulations, 2010 CFR

...show no ground injury. Choice- and fine-quality...specifications B1F Choice Medium-brown Heavy Leaf...Medium-brown Heavy Leaf. Medium body, mature, close...injury tolerance. B1D Choice Dark-brown Heavy...

2010-01-01

393

7 CFR 29.2437 - Heavy Leaf (B Group).  

Code of Federal Regulations, 2010 CFR

...show no ground injury. Choice- and fine-quality...specifications B1F Choice Medium-brown Heavy Leaf...Medium-brown Heavy Leaf. Medium body, mature, close...injury tolerance. B1D Choice Dark-brown Heavy...

2009-01-01

394

Assessment of Leaf Surface Residues for Selected Organophosphorus Insecticides.  

National Technical Information Service (NTIS)

The results of a study of leaf insecticide residues are presented. General methods used to collect data from study sites in Arizona, California, Florida, and Texas are reviewed, including procedures for insecticide application, sample collection, leaf sur...

J. L. Gehrich J. A. Burkart D. Y. Takade E. R. Turner S. D. Allen

1976-01-01

395

7 CFR 30.31 - Classification of leaf tobacco.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 false Classification of leaf tobacco. 30.31 Section 30.31 Agriculture...STANDARDS AND STANDARD CONTAINER REGULATIONS TOBACCO STOCKS AND STANDARDS Classification of Leaf Tobacco Covering Classes, Types and Groups of...

2013-01-01

396

DIGITAL IMAGE ANALYSIS OF ZOSTERA MARINA LEAF INJURY  

EPA Science Inventory

Current methods for assessing leaf injury in Zostera marina (eelgrass) utilize subjective indexes for desiccation injury and wasting disease. Because of the subjective nature of these measures, they are inherently imprecise making them difficult to use in quantifying complex leaf...

397

Coordination of leaf development via regulation of KNOX1 genes  

Microsoft Academic Search

Class I KNOTTED1-LIKE HOMEOBOX (KNOX1) genes are expressed in the shoot apical meristem (SAM) to effect its formation and maintenance. KNOX1 genes are also involved in leaf shape control throughout angiosperm evolution. Leaves can be classified as either simple\\u000a or compound, and KNOX1 expression patterns in leaf primordia are highly correlated with leaf shape; in most simple-leafed species, KNOX1 genes

Naoyuki Uchida; Seisuke Kimura; Daniel Koenig; Neelima Sinha

2010-01-01

398

Neutralization of Acid Droplets on Plant Leaf Surfaces  

Microsoft Academic Search

Sulfuric acid mist exposure of bush bean leaves at a low rate of precipitation suggested that acid on the leaf surface was neutralized by cations leached from leaf tissues and that Ca-S compounds were accumulated on the leaf surface (Kohno, 1994). This report summarizes visual observations of the neutralization process of acid on leaf surfaces as determined by a pH-imaging

Y. Kohno; R. Matsuki; S. Nomura; K. Mitsunari; M. Nakao

2001-01-01

399

Effect of Leaf Rust on Cereal Forage  

Microsoft Academic Search

FEW investigators have examined the effect of leaf rust on yield, chemical composition and nutritive value of cereal forage. This situation is unexpected in view of the large acreage of cereals devoted to sheep and cattle grazing in many countries. However, the reviews of Allen1 and of Chester2 indicate that invasion of a susceptible host by an obligate parasite such

A. F. Greenall

1957-01-01

400

Millimeter wave scattering model for a leaf  

Microsoft Academic Search

At millimeter wave frequencies a typical leaf is a significant fraction of a wavelength in thickness, and its nonuniform dielectric profile now affects the scattering. To provide a simple and efficient method for predicting the scattering, two types of physical optics approximations are examined. The first approximates the volume polarization current by the current which would exist in an infinite

K. Sarabandi; F. T. Ulaby; T. B. A. Senior

1990-01-01

401

THE WHEAT (TRITICUM AESTIVUM L.) LEAF PROTEOME  

Technology Transfer Automated Retrieval System (TEKTRAN)

The wheat leaf proteome was mapped and partially characterized to function as a comparative template for future wheat research. In total, 404 proteins were visualized, and 277 of these were selected for analysis based on reproducibility and relative quantity. Using a combination of protein and exp...

402

Winter leaf reddening in 'evergreen' species.  

PubMed

Leaf reddening during autumn in senescing, deciduous tree species has received widespread attention from the public and in the scientific literature, whereas leaf reddening in evergreen species during winter remains largely ignored. Winter reddening can be observed in evergreen herbs, shrubs, vines and trees in Mediterranean, temperate, alpine, and arctic regions, and can persist for several months before dissipating with springtime warming. Yet, little is known about the functional significance of this colour change, or why it occurs in some species but not others. Here, the biochemistry, physiology and ecology associated with winter leaf reddening are reviewed, with special focus on its possible adaptive function. Photoprotection is currently the favoured hypothesis for winter reddening, but alternative explanations have scarcely been explored. Intraspecific reddening generally increases with sunlight incidence, and may also accompany photosynthetic inferiority in photosynthetically 'weak' (e.g. low-nitrogen) individuals. Red leaves tend to show symptoms of shade acclimation relative to green, consistent with a photoprotective function. However, winter-red and winter-green species often cohabitate the same high-light environments, and exhibit similar photosynthetic capacities. The factors dictating interspecific winter leaf colouration therefore remain unclear. Additional outstanding questions and future directions are also highlighted, and possible alternative functions of winter reddening discussed. PMID:21375534

Hughes, Nicole M

2011-03-04

403

An Outbreak of Foxglove Leaf Poisoning  

Microsoft Academic Search

Comfrey (Symphytum officinale) leaves resemble those of foxglove (Digitalis purpurea) when the plant is not in bloom and, therefore, cardiac glycoside poisoning may occur when people confuse foxglove with comfrey. We report an outbreak of foxglove leaf poisoning following the use of alleged \\

Chun-Chi Lin; Chen-Chang Yang; Dong-Haur Phua; Jou-Fang Deng; Li-Hua Lu

2010-01-01

404

Leaf Stomata as Bioindicators: Stimulating Student Research  

ERIC Educational Resources Information Center

|Stomata are the pores on leaves through which carbon dioxide, oxygen, and water vapor are exchanged with the atmosphere. Researchers have found that leaf stomatal densities change in response to several environmental variables, including humidity, light intensity, and atmospheric levels of carbon dioxide, a greenhouse gas (Van Der Burgh, Dilcher,…

Case, Steven B.

2006-01-01

405

Physicochemical properties of cotton-leaf peroxidase  

Microsoft Academic Search

The physicochemical properties of peroxidase isolated from cotton leaves were investigated. The optimal pH value for exhibiting activity was 4.7; temperature, 30°C. The Michaelis constant was 2.3 mM. Cotton-leaf peroxidase has a very high affinity for benzidine.

A. A. Akhunov; Z. Golubenko; Yu. V. Beresneva; F. A. Ibragimov; N. A. Abdurashidova; E. Ch. Mustakimova; N. R. Khashimova; G. O. Akbarova

2004-01-01

406

Leaf protein: a beneficiary of tribulation  

Microsoft Academic Search

In some cases, the protein content of the discarded haulm of crop plants may be as great as that of the harvested crop. After two false starts at the time of the Second World War, research on exploiting this and other sources of leaf protein may now be near to acceptance.

N. W. Pirie

1975-01-01

407

Planthopper transmission of Phormium yellow leaf phytoplasma  

Microsoft Academic Search

Phonnium yellow leaf (PYL) phytoplasma was transmitted from diseased to healthy New Zealand flax (Phormium tenax) by the native planthopper, Oliarus atkinsoni (Homoptera: Cixiidae). By contrast, transmission was not effected by the introduced passionvine hopper, Scolypopa australis (Homoptera: Ricaniidae). Successful transmission of PYL phytoplasma from New Zealand flax to New Zealand flax by O. atkinsoni was demonstrated by symptomatology and

L. W. Liefting; R. E. Beever; C. J. Winksc; M. N. Pearson; R. L. S. Forster

1997-01-01

408

TEMPORAL ANALYSIS OF LEAF GROWTH UNDER CLIMATE CHANGE SCENARIOS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Many of the cellular and molecular mechanisms that control leaf growth and expansion have yet to be examined, even though this information would be valuable for predicting leaf area throughout growth and could potentially be used to maximize leaf area index, which could increase canopy productivity ...

409

Mapping vineyard leaf area with multispectral satellite imagery  

Microsoft Academic Search

Vineyard leaf area is a key determinant of grape characteristics and wine quality. As is frequently the case in agriculture, available ground-based leaf area measurements employed by growers are not well suited to larger area mapping. In this study, IKONOS high spatial resolution, multispectral satellite imagery was used to map leaf area throughout two commercial wine grape vineyards (approximately 800

L. F. Johnson; D. E. Roczen; S. K. Youkhana; R. R. Nemani; D. F. Bosch

2003-01-01

410

Plant species identification using Elliptic Fourier leaf shape analysis  

Microsoft Academic Search

Elliptic Fourier (EF) and discriminant analyses were used to identify young soybean (Glycine max (L.) merrill), sunflower (Helianthus pumilus), redroot pigweed (Amaranthus retroflexus) and velvetleaf (Abutilon theophrasti Medicus) plants, based on leaf shape. Chain encoded, Elliptic Fourier harmonic functions were generated based on leaf boundary. A complexity index of the leaf shape was computed using the variation between consecutive EF

João Camargo Neto; George E. Meyer; David D. Jones; Ashok K. Samal

2006-01-01

411

Taste Sensitivity of Detritivorous Mosquito Larvae to Decomposed Leaf Litter  

Microsoft Academic Search

Dietary leaf litter chemistry is known to play an important ecotoxicological role in the plant–mosquito interaction in subalpine flooded areas surrounded by vegetation because of differential larvicidal effects of insoluble polyphenols formed during the leaf decaying process. This dietary interaction was investigated through comparative evaluation of the role of toxic\\/nontoxic leaf litter in both larval foraging and feeding behavior, by

Jean-Philippe David; André Ferran; Jacques Gambier; Jean-Claude Meyran

2002-01-01

412

On the Relevance and Control of Leaf Angle  

Microsoft Academic Search

Plants can have constitutive leaf angles that are fixed and do not vary much among different growth environments. Several species, however, have the ability to actively adjust their leaf angles. Active leaf repositioning can be functional in avoiding detrimental environmental conditions, such as avoidance of heat stress and complete submergence, or can be, for example, utilized to maximize carbon gain

M. van Zanten; T. L. Pons; J. A. M. Janssen; L. A. C. J. Voesenek; A. J. M. Peeters

2010-01-01

413

Leaf removal in cool seasons enhances ‘Pinot noir’ anthocyanins  

Technology Transfer Automated Retrieval System (TEKTRAN)

‘Pinot noir’ grapes were harvested from a control (no leaf removal) and three complete leaf removed cluster zone treatments, which were initiated at three separate pre-véraison growth stages (bloom, grain-pea size, and bunch closure). Control and leaf–removed treatments were monitored and maintained...

414

Leaf wetness: implications for agriculture and remote sensing  

Microsoft Academic Search

Information regarding leaf wetness duration (LWD) has been used in disease management schemes for decades by researchers in the plant disease and agricultural meteorology communities. LWD is currently measured predominantly by electronic leaf wetness sensors or through the use of a model that represents latent heat transfer. Studies have been conducted that examine the placement, orientation and treatment of leaf

Tracy L. Rowlandson

2011-01-01

415

Incomplete resistance to coffee leaf rust (Hemileia vastatrix)  

Microsoft Academic Search

Incomplete resistance to coffee leaf rust ( Hemileia vastatrix<\\/u> ) may be of value in obtaining durable resistance, which is of great importance for the perennial coffee crop. Methods were developed to assess incomplete resistance to coffee leaf rust by using illustrated scales ranging from 0 to 9 (Chapter 1). A laboratory screening method, which uses leaf disks, has been

T. K. A. B. Eskes

1983-01-01

416

REMOTE SENSING LEAF CHLOROPHYLL CONCENTRATION IN CORN FIELDS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Nitrogen (N) is frequently the major nutrient limiting crop growth. Variations in soil reflectance and leaf area index (LAI) often confound assessments of leaf chlorophyll concentrations by remote sensing techniques. Our objective was to develop a strategy for assessing leaf chlorophyll status of co...

417

A wheat canopy model linking leaf area and phenology  

Microsoft Academic Search

The accurate simulation of leaf area in wheat models is important because leaf area intercepts light and stores nitrogen, and the arrangement of leaves influences the transmission of foliar diseases and inter-species competition. In this paper, we report on the development and testing of a model that links a mechanistic phenological model that depends on the prediction of leaf appearance

C. Lawless; M. A. Semenova; P. D. Jamieson

2005-01-01

418

7 CFR 29.3153 - Leaf (B Group).  

Code of Federal Regulations, 2013 CFR

...injury tolerance. B3F Good Tan Leaf. Medium body, mature to ripe...injury tolerance. B3FL Good Tannish-buff Leaf Medium body, mature to ripe...injury tolerance. B3VF Good Greenish-tan Leaf. Medium body, underripe,...

2013-01-01

419

OKRA-LEAF AS A POTENTIAL FOR WHITEFLY CONTROL  

Technology Transfer Automated Retrieval System (TEKTRAN)

We compared smooth-leaf okra- and normal-leaf upland cotton (Gossypium hirsutum L.) cultivars for susceptibility to colonization by Bemisia tabaci (Gennadius) biotype B. Seven field studies were conducted, five at Holtville, CA and two at Maricopa, AZ during 1996 to 2000. Okra-leaf cultivars as a gr...

420

Diel leaf growth of soybean: a novel method to analyze two-dimensional leaf expansion in high temporal resolution based on a marker tracking approach (Martrack Leaf)  

PubMed Central

Background We present a novel method for quantitative analysis of dicot leaf expansion at high temporal resolution. Image sequences of growing leaves were assessed using a marker tracking algorithm. An important feature of the method is the attachment of dark beads that serve as artificial landmarks to the leaf margin. The beads are mechanically constricted to the focal plane of a camera. Leaf expansion is approximated by the increase in area of the polygon defined by the centers of mass of the beads surrounding the leaf. Fluctuating illumination conditions often pose serious problems for tracking natural structures of a leaf; this problem is circumvented here by the use of the beads. Results The new method has been used to assess leaf growth in environmental situations with different illumination conditions that are typical in agricultural and biological experiments: Constant illumination via fluorescent light tubes in a climate chamber, a mix of natural and artificial illumination in a greenhouse and natural illumination of the situation on typical summer days in the field. Typical features of diel (24h) soybean leaf growth patterns were revealed in all three conditions, thereby demonstrating the general applicability of the method. Algorithms are provided to the entire community interested in using such approaches. Conclusions The implementation Martrack Leaf presented here is a robust method to investigate diel leaf growth rhythms both under natural and artificial illumination conditions. It will be beneficial for the further elucidation of genotype x environment x management interactions affecting leaf growth processes.

2013-01-01

421

Disguising the Leaf Surface: The Use of Leaf Coatings for Plant Disease Control  

Microsoft Academic Search

The ability of fungal pathogens to develop resistance to fungicides and to overcome genetic resistance in their hosts, coupled\\u000a with growing public concern for the environment, means that there is an urgent need for novel methods of disease control.\\u000a The leaf surface provides the first barrier that fungi must overcome in order to gain access to the leaf, but it

Dale R. Walters

2006-01-01

422

Composition of speciose leaf litter alters stream detritivore growth, feeding activity and leaf breakdown.  

PubMed

Leaf litter derived from riparian trees can control secondary production of detritivores in forested streams. Species-rich assemblages of leaf litter reflect riparian plant species richness and represent a heterogeneous resource for stream consumers. Such variation in resource quality may alter consumer growth and thus the feedback on leaf breakdown rate via changes in feeding activity. To assess the consequences of this type of resource heterogeneity on both consumer growth and subsequent litter breakdown, we performed a laboratory experiment where we offered a leaf-shredding stream detritivore (the stonefly Tallaperla maria, Peltoperlidae) ten treatments of either single- or mixed-species leaf litter. We measured consumer growth rate, breakdown rate and feeding activity both with and without consumers for each treatment and showed that all three variables responded to speciose leaf litter. However, the number of leaf species was not responsible for these results, but leaf species composition explained the apparent non-additive effects. T. maria growth responded both positively and negatively to litter composition, and growth on mixed-litter could not always be predicted by averaging estimates of growth in single-species treatments. Furthermore, breakdown and feeding rates in mixed litter treatments could not always be predicted from estimates of single-species rates. Given that species richness and composition of senesced leaves in streams reflects riparian plant species richness, in-stream secondary production of detritivores and organic matter dynamics may be related to species loss of trees in the riparian zone. Loss of key species may be more critical to maintaining such processes than species richness per se. PMID:16425049

Swan, Christopher M; Palmer, Margaret A

2006-01-20

423

The use of leaf disk inoculations in assessing resistance to coffee leaf rust (Hemileia vastatrix)  

Microsoft Academic Search

The suitability of inoculations of leaf disks of 1.8 cm diameter in determining resistance of coffee toHemileia vastatrix, the causal agent of coffee leaf rust, was studied. Results obtained by this method were similar to those obtained by greenhouse tests with respect to reaction types of coffee plants with complete and\\/or major gene resistance. The efficacy of the method in

A. B. Eskes

1982-01-01

424

Optimal Leaf-to-Root Ratio and Leaf Nitrogen Content Determined by Light and Nitrogen Availabilities  

Microsoft Academic Search

Plants exhibit higher leaf-to-root ratios (L\\/R) and lower leaf nitrogen content (Narea) in low-light than in high-light environments, but an ecological significance of this trait has not been explained from a whole-plant perspective. This study aimed to theoretically and experimentally demonstrate whether these observed L\\/R and Narea are explained as optimal biomass allocation that maximize whole-plant relative growth rate (RGR).

Daisuke Sugiura; Masaki Tateno

2011-01-01

425

Leaf non-structural carbohydrates and leaf dry weight per area in three altitudinal populations of Espeletia schultzii WEDD  

Microsoft Academic Search

The leaf non-structural carbohydrate (NSC) content and total non-structural carbohydrate content (TNC) were measured on a\\u000a dry weight basis and on a leaf area basis in three altitudinal (3100, 3550 and 4200 m a.s.l.) populations ofE. schultzii. The values of leaf dry weight per area (LWA) increase with altitude. The leaf non-structural carbohydrate content (expressed\\u000a as g\\/kg dry weight) does

Marisol Castrillo; Milton Simoes

1997-01-01

426

Significance of leaf surface characteristics in plant responses to air pollution  

Microsoft Academic Search

Plant responses to air pollution were found to vary with type of leaf vesture. Considerable reduction in leaf area, leaf biomass, total plant biomass and chlorophyll content was observed in plants having pilose or pubescent leaf surface as compared to plants with glabrescent leaf surface. The study shows the importance of leaf vesture in determining response of plants to air

C. K. Varshney; K. K. Garg

1980-01-01

427

Xylem Cavitation in the Leaf of Prunus laurocerasus and Its Impact on Leaf Hydraulics1  

PubMed Central

This paper reports how water stress correlates with changes in hydraulic conductivity of stems, leaf midrib, and whole leaves of Prunus laurocerasus. Water stress caused cavitation-induced dysfunction in vessels of P. laurocerasus. Cavitation was detected acoustically by counts of ultrasonic acoustic emissions and by the loss of hydraulic conductivity measured by a vacuum chamber method. Stems and midribs were approximately equally vulnerable to cavitations. Although midribs suffered a 70% loss of hydraulic conductance at leaf water potentials of ?1.5 MPa, there was less than a 10% loss of hydraulic conductance in whole leaves. Cutting and sealing the midrib 20 mm from the leaf base caused only a 30% loss of conduction of the whole leaf. A high-pressure flow meter was used to measure conductance of whole leaves and as the leaf was progressively cut back from tip to base. These data were fitted to a model of hydraulic conductance of leaves that explained the above results, i.e. redundancy in hydraulic pathways whereby water can flow around embolized regions in the leaf, makes whole leaves relatively insensitive to significant changes in conductance of the midrib. The onset of cavitation events in P. laurocerasus leaves correlated with the onset of stomatal closure as found recently in studies of other species in our laboratory.

Nardini, Andrea; Tyree, Melvin T.; Salleo, Sebastiano

2001-01-01

428

Optimal use of leaf nitrogen explains seasonal changes in leaf nitrogen content of an understorey evergreen shrub  

PubMed Central

Background and Aims Understorey evergreen species commonly have a higher leaf nitrogen content in winter than in summer. Tested here is a hypothesis that such changes in leaf nitrogen content maximize nitrogen-use efficiency, defined as the daily carbon gain per unit nitrogen, under given temperature and irradiance levels. Methods The evergreen shrub Aucuba japonica growing naturally at three sites with different irradiance regimes in Japan was studied. Leaf photosynthetic characteristics, Rubisco and leaf nitrogen with measurements of temperature and irradiance monthly at each site were determined. Daily carbon gain was determined as a function of leaf nitrogen content to calculate the optimal leaf nitrogen content that maximized daily nitrogen-use efficiency. Key Results As is known, the optimal leaf nitrogen content increased with increasing irradiance. The optimal leaf nitrogen content also increased with decreasing temperature because the photosynthetic capacity per Rubisco decreased. Across sites and months, the optimal leaf nitrogen content was close to the actual leaf nitrogen content and explained the variation in actual leaf nitrogen by 64 %. Sensitivity analysis showed that the effect of temperature on optimal nitrogen content was similar in magnitude to that of irradiance. Conclusions Understorey evergreen species regulate leaf nitrogen content so as to maximize nitrogen-use efficiency in daily carbon gain under changing irradiance and temperature conditions.

Muller, Onno; Hirose, Tadaki; Werger, Marinus J. A.; Hikosaka, Kouki

2011-01-01

429

Living With Limited Water, Part II: Dynamics of Leaf Rolling, Leaf Water Homeostasis and Water Economy by Hybrid Rice  

Microsoft Academic Search

Change in leaf form or shape has often been enumerated as a potential means of reducing transpiration by plants experiencing water deficit. Because leaf rolling is the first and foremost visible physiological response to water deficit in rice plant, its dynamic nature and impact on leaf water homeostasis and water conservation were studied in hybrid rice (Oryza sativa L.) in

S. Singh; T. N. Singh; J. S. Chauhan

2011-01-01

430

Leaf-wax n-alkanes record the plant-water environment at leaf flush  

PubMed Central

Leaf-wax n-alkanes 2H/1H ratios are widely used as a proxy in climate reconstruction. Although the broad nature of the relationship between n-alkanes ?2H values and climate is appreciated, the quantitative details of the proxy remain elusive. To examine these details under natural environmental conditions, we studied a riparian broadleaf angiosperm species, Populus angustifolia, growing on water with a constant ?2H value and monitored the ?2H values of leaf-wax n-alkanes and of stem, leaf, stream, and atmospheric waters throughout the entire growing season. Here we found the ?2H values of leaf-wax n-alkanes recorded only a 2-wk period during leaf flush and did not vary for the 19 weeks thereafter when leaves remained active. We found ?2H values of leaf-wax n-alkanes of P. angustifolia record conditions earlier in the season rather than fully integrating the entire growing season. Using these data, we modeled precipitation ?2H values during the time of wax synthesis. We observed that the isotope ratios of this precipitation generally were 2H-enriched compared with mean annual precipitation. This model provides a mechanistic basis of the often-observed 2H-enrichment from the expected fractionation values in studies of broadleaf angiosperm leaf-wax ?2H. In addition, these findings may have implications for the spatial and temporal uses of n-alkane ?2H values in paleoapplications; when both plant community and growth form are known, this study allows the isolation of the precipitation dynamics of individual periods of the growing season.

Tipple, Brett J.; Berke, Melissa A.; Doman, Christine E.; Khachaturyan, Susanna; Ehleringer, James R.

2013-01-01

431

Nitrogen release pattern in decomposing leaf litter of banj oak and chir pine seedlings leaf under glass house condition.  

PubMed

Decomposition rate for leaf litter of banj oak (Quercus leucotrichophora) and chir pine (Pinus roxburghii), seedlings was studied over a period of one year, under glass house condition. The leaf litter of Quercus leucotrichophora decomposed faster as compared to Pinus roxburghii. Initially during 0-62 days of placement, the decomposition rate was slower for leaf litter of both species but after 123 days of placement it was 53% for Quercus leucotrichophora leaf litter and 33% for Pinus roxburghii leaf litter. The Quercus leucotrichophora leaf litter was completely decomposed after 11 months; however, 65% weight loss was recorded in Pinus roxburghii leaf litter after 12 months study. In Quercus leucotrichophora leaf litter the, initial (at the start of decomposition) nitrogen concentration was much higher (1.15%) than that of Pinus roxburghii leaf litter (1.41%), release of N was slower in chir pine leaf litter compared to banj oak leaf litter. Material with higher C/N ratio had longer duration of immobilization and in turn slower release phase. The concentration of N increased approximately linearly as a function of mass loss towards the end of annual cycle. Concentration of N was about 1.2 to 1.9 fold higher than the initial litter for seedlings of both the species. PMID:24006820

Usman, Samina

2013-01-01

432

Chemical control of maize grey leaf spot  

Microsoft Academic Search

Grey leaf spot, Cercospora zeae-maydis, has, in a relatively short period, caused significant annual grain yield losses in the maize industry of KwaZulu-Natal, South Africa. No commercial hybrids are resistant to the disease, and because alternative measures of control, such as crop rotations and tillage practices, have limited effects, fungicides are the main option available for control of the disease.

J. M. J. Ward; M. D. Laing; D. C. Nowell

1997-01-01

433

Science Nation: Leaf-cutter Ants  

NSDL National Science Digital Library

In established colonies, millions of leaf-cutter ants cut and carry sections of leaves larger than their own bodies as part of a well choreographed, highly functioning society. With support from the National Science Foundation (NSF),bacteriologist Cameron Currie and his team study ants and their complex, productive societies to help address some of human society's most pressing challenges, such as better drugs and cleaner energy.

434

[Leaf epidermis ultrastructure of Zeugites (Poaceae: Panicoideae)].  

PubMed

The genus Zeugites comprises eleven species of neotropical grasses and it is principally distributed in Mexico, with some species extending to the Caribbean region, Central and South America. In this work, leaf epidermis ultrastructure of 11 species is described by the use of scanning electron microscopy. At least three specimens per species, that included herbarium and collected specimens, were used. An identification key and specific descriptions are included, in which the distinctive epidermal features are highlighted. The taxonomic valuable characters found were the following: presence or absence of prickles and macrohairs, intercostals short cells form and silica body form. Based on leaf epidermis characteristics, Zeugites species can be arranged into three groups: (1) species that lack prickles (Z. americana, Z. mexicana, Z. pringlei, Z. munroana and Z. sagittata); and lack macro hairs, with the exception of Z. pringlei; (2) species that have prickles (Z. latifolia and Z. smilacifolia); (3) species that have both, prickles and macrohairs (Z. capillaris, Z. hackelii, Z. pittieri and Z. sylvatica). The morphological features of leaf epidermis, support the relationship between the tribes Centotheceae and Paniceae. PMID:21721228

Soriano, Ana María; Terrazas, Teresa; Dávila, Patricia

2011-06-01

435

VOC Emissions From Decomposing Leaf Litter  

NASA Astrophysics Data System (ADS)

The emission of VOCs from the biosphere has a profound effect on the oxidative capacity of the troposphere. Most studies of the flux of reactive carbon from the biosphere have focused on BVOC emissions at leaf and canopy scales with relatively few studies investigating BVOC emissions from soils. Here we present results describing the emissions of a suite of BVOCs from different litter types under different levels of nitrogen availability. To investigate these effects, three biochemically distinct litter types (Deschampsia sp., Acomostylis sp., and Rhododendron sp.) were coarsely ground and incubated in the dark for two months under different nitrogen regimes at optimal conditions for microbial activity. We used proton transfer reaction mass spectrometry and an infrared gas analyzer (IRGA) to monitor BVOC emissions and CO2 production rates throughout the course of the investigation. When different leaf litter types decomposed, they released distinctly different types and quantities of VOCs. However, varying nitrogen availability caused the VOC signature from some litters to change dramatically. We suggest that decomposition of leaf litter could provide a substantive source of reactive carbon to the atmosphere at local and regional scales and hypothesize that nitrogen deposition may play a role in attenuating the release of some reactive species.

Brown, E. M.; Wilkinson, M. J.; Fierer, N.; Monson, R. K.

2007-12-01

436

Quantification of uncertainties in fossil leaf paleoaltimetry: Does leaf size matter?  

NASA Astrophysics Data System (ADS)

The utility of multivariate foliar physiognomy, specifically the Climate Leaf Analysis Multivariate Program (CLAMP), to yield reliable estimates of enthalpy and, hence, paleoelevation has been demonstrated by comparison with other proxies, yet concerns have arisen regarding uncertainties arising from (1) apparent ambiguities in the scoring regime and (2) the way leaf size is scored. Regarding the first concern, scoring ambiguities are examined by reporting on scoring tests with novice users and interlaboratory comparisons. The uncertainties were found to be less than those arising from the statistical methodology underpinning CLAMP. In respect to the second concern, the effect of removing all size data both from modern test sites and fossil data was tested. Specifically, the effect of removing leaf size data from the 15 Ma Namling data set from south central Tibet was investigated. Removal of all size data from modern sites demonstrated that size data contributes little to estimates of mean annual temperature and enthalpy. Similarly, the removal of leaf size information from the Namling data set alone, but with calibration unchanged, and from both the Namling site and calibration sites, this time with recalibration, still yield paleoelevation estimates that have been independently matched by oxygen isotope techniques. Moreover, the removal of all leaf size information results in only small increases in uncertainty (±52 m).

Spicer, Robert A.; Yang, Jian

2010-12-01

437

Inferring Amazon leaf demography from satellite observations of leaf area index  

NASA Astrophysics Data System (ADS)

Seasonal and year-to-year variations in leaf cover imprint significant spatial and temporal variability on biogeochemical cycles, and affect land-surface properties related to climate. We develop a demographic model of leaf phenology based on the hypothesis that trees seek an optimal Leaf Area Index (LAI) as a function of available light and soil water, and fitted it to spaceborne observations of LAI over the Amazon Basin, 2001-2005. We find the model reproduces the spatial and temporal LAI distribution whilst also predicting geographic variation in leaf age from the basin center (2.1 ± 0.2 yr), through to the lowest values over the deciduous Eastern Amazon (6 ± 2 months). The model explains the observed increase in LAI during the dry season as a net addition of leaves in response to increased solar radiation. We anticipate our work to be a starting point from which to develop better descriptions of leaf phenology to incorporate into more sophisticated earth system models.

Caldararu, S.; Palmer, P. I.; Purves, D. W.

2011-10-01

438

Inferring Amazon leaf demography from satellite observations of leaf area index  

NASA Astrophysics Data System (ADS)

Seasonal and year-to-year variations in leaf cover imprint significant spatial and temporal variability on biogeochemical cycles, and affect land-surface properties related to climate. We develop a demographic model of leaf phenology based on the hypothesis that trees seek an optimal leaf area index (LAI) as a function of available light and soil water, and fit it to spaceborne observations of LAI over the Amazon basin, 2001-2005. We find the model reproduces the spatial and temporal LAI distribution whilst also predicting geographic variation in leaf age from the basin centre (2.1 ± 0.2 years), through to the lowest values over the deciduous eastern and southern Amazon (6 ± 2 months). The model explains the observed increase in LAI during the dry season as a net addition of leaves in response to increased solar radiation. We anticipate our work to be a starting point from which to develop better descriptions of leaf phenology to incorporate into more sophisticated earth system models.

Caldararu, S.; Palmer, P. I.; Purves, D. W.

2012-04-01

439

[Effects of leaf hair on leaf reflectance and hyperspectral vegetation indices].  

PubMed

Many hyperspectral vegetation indices have been used to estimate the biochemical contents such as pigment content, nondestructively. These reflectance indices are influenced by leaf hair, and the existence of the leaf hair affects the performance of the indices on the estimation of the biochemical contents. The present research studied the possible effects of the leaf hair on the reflectance of the same leaf before and after removal of leaf hair. The authors found that dehairing had decreased the reflectance between wavelength 400 and 1 000 nm, and the decrease depends on the wavelength. The changes of 39 hyperspectral indices before and after the hair removal were compared. The results revealed that some indices that only use visible wavebands or the near infrared wavebands such as CTR1: R695/R420, D740/D720, WBI: R900/R970, R860/(R550 x R708) and REP (Red-edge position) were not affected much by the dehairing process and are thought relatively robust to estimate the biochemical contents. PMID:22512186

Ge, Hao; Lu, Shan; Zhao, Yun-sheng

2012-02-01

440

Leaf morphological effects predict effective path length and enrichment of 18O in leaf water of different Eucalyptus species  

NASA Astrophysics Data System (ADS)

Stable isotopes have been a valuable tool to study water or carbon fluxes of plants and ecosystems. In particular oxygen isotopes (?18O) in leaf water or plant organic material are now beginning to be established as a simple and integrative measure for plant - water relations. Current ?18O models, however, are still limited in their application to a broad range of different species and ecosystems. It remains for example unclear, if species-specific effects such as different leaf morphologies need to be included in the models for a precise understanding and prediction of ?18O signals. In a common garden experiment (Currency Creek Arboretum, South Australia), where over 900 different Eucalyptus species are cultivated in four replicates, we tested effects of leaf morphology and anatomy on ?18O signals in leaf water of 25 different species. In particular, we determined for all species enrichment in 18O of mean lamina leaf water above source water (?18O) as related to leaf physiology as well as leaf thickness, leaf area, specific leaf area and weight and selected anatomical properties. Our data revealed that diurnal ?18O in leaf water at steady state was significantly different among the investigated species and with differences up to 10% at midday. Fitting factors (effective path length) of leaf water ?18O models were also significantly different among the investigated species and were highly affected by species-specific morphological parameters. For example, leaf area explained a high percentage of the differences in effective path length observed among the investigated species. Our data suggest that leaf water ?18O can act as powerful tool to estimate plant - water relations in comparative studies but that additional leaf morphological parameters need to be considered in existing ?18O models for a better interpretation of the observed ?18O signals.

Kahmen, A.; Merchant, A.; Callister, A.; Dawson, T. E.; Arndt, S. K.

2006-12-01

441

Regulation of leaf senescence and crop genetic improvement.  

PubMed

Leaf senescence can impact crop production by either changing photosynthesis duration, or by modifying the nutrient remobilization efficiency and harvest index. The doubling of the grain yield in major cereals in the last 50 years was primarily achieved through the extension of photosynthesis duration and the increase in crop biomass partitioning, two things that are intrinsically coupled with leaf senescence. In this review, we consider the functionality of a leaf as a function of leaf age, and divide a leaf's life into three phases: the functionality increasing phase at the early growth stage, the full functionality phase, and the senescence and functionality decreasing phase. A genetic framework is proposed to describe gene actions at various checkpoints to regulate leaf development and senescence. Four categories of genes contribute to crop production: those which regulate (I) the speed and transition of early leaf growth, (II) photosynthesis rate, (III) the onset and (IV) the progression of leaf senescence. Current advances in isolating and characterizing senescence regulatory genes are discussed in the leaf aging and crop production context. We argue that the breeding of crops with leaf senescence ideotypes should be an essential part of further crop genetic improvement. PMID:23131150

Wu, Xiao-Yuan; Kuai, Ben-Ke; Jia, Ji-Zeng; Jing, Hai-Chun

2012-12-01

442

Spatial and temporal variations in leaf area index, specific leaf area and leaf nitrogen of two co-occurring savanna tree species  

Microsoft Academic Search

Summary Foliage growth, mass- and area-based leaf nitro- gen concentrations (Nm and Na) and specific leaf area (SLA) were surveyed during a complete vegetation cycle for two co- occurring savanna tree species: Crossopteryx febrifuga (Afzel. ex G. Don) Benth. and Cussonia arborea A. Rich. The study was conducted in the natural reserve of Lamto, Ivory Coast, on isolated and clumped

GUILLAUME SIMIONI; JACQUES GIGNOUX; XAVIER LE ROUX; RAPHAËLLE APPÉ; DANIELE BENEST

443

Leaf photosynthetic traits of 14 tropical rain forest species in relation to leaf nitrogen concentration and shade tolerance.  

PubMed

Variability of leaf traits related to photosynthesis was assessed in seedlings from 14 tree species growing in the tropical rain forest of French Guiana. Leaf photosynthetic capacity (maximum rate of carboxylation and maximum rate of electron transport) was estimated by fitting a biochemical model of photosynthesis to response curves of net CO2 assimilation rate versus intercellular CO2 mole fraction. Leaf morphology described by leaf mass per unit leaf area (LMA), density and thickness, as well as area- and mass-based nitrogen (N) and carbon (C) concentrations, were recorded on the same leaves. Large interspecific variability was detected in photosynthetic capacity as well as in leaf structure and leaf N and C concentrations. No correlation was found between leaf thickness and density. The correlations between area- and mass-based leaf N concentration and photosynthetic capacity were poor. Conversely, the species differed greatly in relative N allocation to carboxylation and bioenergetics. Principal component analysis (PCA) revealed that, of the recorded traits, only the computed fraction of total leaf N invested in photosynthesis was tightly correlated to photosynthetic capacity. We also used PCA to test to what extent species with similar shade tolerances displayed converging leaf traits related to photosynthesis. No clear-cut ranking could be detected among the shade-tolerant groups, as confirmed by a one-way ANOVA. We conclude that the large interspecific diversity in photosynthetic capacity was mostly explained by differences in the relative allocation of N to photosynthesis and not by leaf N concentration, and that leaf traits related to photosynthetic capacity did not discriminate shade-tolerance ranking of these tropical tree species. PMID:15996956

Coste, Sabrina; Roggy, Jean-Christophe; Imbert, Pascal; Born, Céline; Bonal, Damien; Dreyer, Erwin

2005-09-01

444

The dominant developmental mutants of tomato, Mouse-ear and Curl, are associated with distinct modes of abnormal transcriptional regulation of a Knotted gene.  

PubMed Central

The Curl (Cu) and Mouse-ear (Me) mutations of tomato cause two seemingly unrelated developmental syndromes with a wide range of pleiotropic phenotypes. Yet, the distinct morphogenic alterations in shoots, leaves, and inflorescences conferred by the two mutations appear to be caused by unchecked meristematic activity that characterizes dominant mutations in Knotted1 (Kn1)-like genes of monocot plants. We have been unable to separate the two closely linked Cu and Me mutations, and they may lie in the same gene. A homeobox-containing class I Kn1-like gene, TKn2, also maps to the same location. Significantly, the dominant mutations are associated with two aberrant modes of TKn2 transcription. Overexpression of the two in-frame wild-type transcripts of TKn2 is associated with the Cu mutation, whereas misexpression of an abundant and oversized fusion mRNA is associated with the Me mutation. Available molecular evidence strongly suggests that the defective Me-TKn2 transcript is generated via a novel splicing event that merges transcripts of two closely linked genes. The translated fusion product is comprised of most of the 5' end of the adjacent PPi-dependent fructose 6-phosphate phosphotransferase (PFP) transcript spliced in-frame to coding position 64 of the TKn2 transcript, leaving the TKn2 homeobox intact. We suggest that class I Kn1-like genes were selected early during evolution to regulate basic programs of aerial meristems and that subtle alterations in their function may be the basis for the wide diversity in growth parameters of shoot systems, leaves, and inflorescences among plant species.

Parnis, A; Cohen, O; Gutfinger, T; Hareven, D; Zamir, D; Lifschitz, E

1997-01-01

445

Biotemplated hierarchical porous material: the positively charged leaf.  

PubMed

Addressing the problem of pathogenic bacteria in human health remains a great challenge. We have prepared MgO, replicated from the leaf template, for efficient bacterial removal. The synthesis method perfectly inherits the advantage of the hierarchical three-level micro-meso-macroporous structure from the leaf template. The final product has the integrated advantages of a positively charged property, hierarchical three-level micro-meso-macroporous microstructure and sterilization property so that it could be named "the positively charged leaf". The positively charged leaf with the microstructure, which is bestowed by Nature, could be utilized in water purification for dye removal and could be extended to pollutant removal, especially of harmful bacteria. The positively charged leaf, as the leaf shield, could be useful in protecting human health. The concept of this work could be applied to the synthesis of different functional metal oxides with hierarchical porous structures, and the products could be utilized in efficient bacterial removal. PMID:23471878

Yang, Dalong; Fan, Tongxiang; Zhang, Di; Zhu, Jun; Wang, Yun; Du, Bin; Yan, Yaxian

2013-03-07

446

Transcriptomic analysis of incised leaf-shape determination in birch.  

PubMed

Plant researchers have focused much attention on leaf shape because of its importance in the identification. To evaluate the impact of intraspecies leaf-shape variation on the transcriptome, a series of Betula pendula 'Dalecarlica' and B. pendula saplings were generated through tissue culture. The leaf shapes and transcriptomes of B. pendula 'Dalecarlica' clones were compared with those of B. pendula clones. The leaf shape of B. pendula 'Dalecarlica' was incised and that of B. pendula was ovate. Transcriptome data revealed numerous changes in gene expression between B. pendula 'Dalecarlica' and B. pendula, including upregulation of 8767 unigenes and downregulation of 8379 unigenes in B. pendula 'Dalecarlica'. A pathway analysis revealed that the transport and signal transduction of auxin were altered in 'Dalecarlica', which may have contributed to its altered leaf shape. These results shed light on variation in birch leaf shape and help identify important genes for the genetic engineering of birch trees. PMID:24013080

Mu, Huaizhi; Lin, Lin; Liu, Guifeng; Jiang, Jing

2013-09-05

447

Leaf nitrogen:phosphorus stoichiometry across Chinese grassland biomes  

Microsoft Academic Search

Leaf N and P stoichiometry covaries with many aspects of plant biology, yet the drivers of this trait at biogeographic scales\\u000a remain uncertain. Recently we reported the patterns of leaf C and N based on systematic census of 213 species over 199 research\\u000a sites in the grassland biomes of China. With the expanded analysis of leaf P, here we report

Jin-Sheng He; Liang Wang; Dan F. B. Flynn; Xiangping Wang; Wenhong Ma; Jingyun Fang

2008-01-01

448

Yield losses caused by leaf roll of potatoes  

Microsoft Academic Search

Summary  The data presented confirm the opinion that the healthy hills adjoined by leaf roll plants on one or on both sides, compensate,\\u000a in part, for the low yield of the leaf roll plants.\\u000a \\u000a The gain in yield of a healthy plant adjoined on both sides by leaf roll plants is approximately double the gain of such plants\\u000a adjoined by a

H. C. Kirkpatrick; F. M. Biodgett

1943-01-01

449

The dynamics of iron in the leaf apoplast  

Microsoft Academic Search

The leaf apoplast plays an important physiological role in nutrient transport and storage, however, its significance for the\\u000a iron (Fe) nutrition is not sufficiently understood. There are only few studies in the literature primarily on the mechanism\\u000a of Fe absorption by leaf cells; even less information is available on the mobility and binding forms of Fe in the leaf apoplast.

M. Nikolic; V. Römheld

450

Regeneration of peppermint and orange mint from leaf disks  

Microsoft Academic Search

Leaf disks from peppermint, spearmint, orange mint, lavender mint and Scotch spearmint were cultured on various Murashige-Skoog-based media in order to regenerate shoots. A significantly larger average number of orange mint leaf disks regenerated shoots on basal medium containing 44.4 µM benzyladenine (BA) and 250 ml l-1 coconut water (CW). Shoots regenerated from peppermint leaf disks cultured on basal medium

J. M. Van Eck; S. L. Kitto

1992-01-01

451

Generality of leaf trait relationships: A test across six biomes  

SciTech Connect

Convergence in interspecific leaf trait relationships across diverse taxonomic groups and biomes would have important evolutionary and ecological implications. Such convergence has been hypothesized to result from trade-offs that limit the combination of plant traits for any species. Here the authors address this issue by testing for biome differences in the slope and intercept of interspecific relationships among leaf traits: longevity, net photosynthetic capacity (A{sub max}), leaf diffusive conductance (G{sub S}), specific leaf area (SLA), and nitrogen (N) status, for more than 100 species in six distinct biomes of the Americas. The six biomes were: alpine tundra-subalpine forest ecotone, cold temperate forest-prairie ecotone, montane cool temperate forest, desert shrubland, subtropical forest, and tropical rain forest. Despite large differences in climate and evolutionary history, in all biomes mass-based leaf N (N{sub mass}), SLA, G{sub S}, and A{sub max} were positively related to one another and decreased with increasing leaf life span. The relationships between pairs of leaf traits exhibited similar slopes among biomes, suggesting a predictable set of scaling relationships among key leaf morphological, chemical, and metabolic traits that are replicated globally among terrestrial ecosystems regardless of biome or vegetation type. However, the intercept (i.e., the overall elevation of regression lines) of relationships between pairs of leaf traits usually differed among biomes. With increasing aridity across sites, species had greater A{sub max} for a given level of G{sub S} and lower SLA for any given leaf life span. Using principal components analysis, most variation among species was explained by an axis related to mass-based leaf traits (A{sub max}, N, and SLA) while a second axis reflected climate, G{sub S}, and other area-based leaf traits.

Reich, P.B. [Univ. of Minnesota, Saint Paul, MN (United States). Dept. of Forest Resources; Ellsworth, D.S. [Brookhaven National Lab., Upton, NY (United States). Dept. of Applied Science; Walters, M.B. [Michigan State Univ., East Lansing, MI (United States). Dept. of Forestry; Vose, J.M. [Forest Service, Otto, NC (United States). Coweeta Hydrological Lab.; Gresham, C. [Clemson Univ., Georgetown, SC (United States). Baruch Forest Inst.; Volin, J.C. [Florida Atlantic Univ., Davie, FL (United States). Div. of Science; Bowman, W.D. [Inst. of Arctic and Alpine Research, Boulder, CO (United States). Mountain Research Station]|[Univ. of Colorado, Boulder, CO (United States). Dept. of Evolutionary, Population, and Organismic Biology

1999-09-01

452

Changes in Pelagic Bacteria Communities Due to Leaf Litter Addition  

Microsoft Academic Search

In many limnetic systems, the input of allochthonous organic matter, e.g., leaf litter, is a substantial source of dissolved\\u000a organic carbon (DOC) for pelagic bacteria, especially in fall and winter when autochthonous DOC production is low. However,\\u000a relatively little is known about community changes of pelagic lake bacteria due to leaf litter input which includes both the\\u000a release of leaf

Kristine Michelle L. Hutalle-Schmelzer; Elke Zwirnmann; Angela Krüger; Hans-Peter Grossart

2010-01-01

453

Ozone-induced ethylene release from leaf surfaces  

SciTech Connect

Ozone-induced stress-ethylene emissions from the adaxial and abaxial leaf surfaces of four plant species (Glycine max (L) Merr. cv. Dare, Lycopersicon esculentum Mill cv. Roma VF, Eucalyptus globulus Labill. and Hedera helix L.) were studied to determine if the stress ethylene diffused through the stomata or cuticle. In plants not exposed to ozone, basal ethylene was detected above both the adaxial and abaxial leaf surfaces of all the plant species examined, indicating that some ethylene can diffuse across the leaf cuticle. Oxone-induced stress ethylene production in all species examined. These data indicate that ozone-induced stress ethylene primarily diffuses from the leaf via the stomata.

Rodecap, K.D.; Tingey, D.T.

1986-01-01

454