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1

Squash leaf curl virus (SLCV): a serious disease threatening cucurbits production in Palestine.  

PubMed

The incidence of squash leaf curl disease and molecular characterization of the Palestinian isolate of Squash leaf curl virus [SLCV-(PAL)] are described in this study. Symptomatic leaf samples obtained from squash (Cucurbita pepo), watermelon [Citrullus lanatus (Thunb.)], and cucumber (Cucumis sativus L.) plants were tested for SLCV-[PAL] infection by PCR and RCA. SLCV was also found to occur naturally in Chenopodium murale, Convolvulus sp, and Prosporis farcta which showed yellowing. The disease incidence was 85 % in samples collected from Nablus in summer season, while it was 98 % in samples collected from Qalqilia in autumn. On the other hand, SLCV incidence did not exceed 25 % in winter season. The full-length DNA-A and DNA-B genomes of SLCV-[PAL] were amplified and sequenced, and the sequences were deposited in the GenBank. Sequence analysis reveals that SLCV-[PAL] is closely related to other isolates from Lebanon (SLCV-LB2), Jordan (SLCV-JO), Israel (SLCV-IL), and Egypt (SLCV-EG). DNA-A of SLCV-[PAL] showed the highest nucleotide identity (99.4 %) with SLCV-JO, and SLCV-LB2, while DNA-B had the highest nucleotide identity (99.3 %) with SLCV-IL. However, following genome sequencing, it was found that due to two separate point mutations, two viral open reading frames (ORF) were altered in some SLCV Palestinian isolates. The AC2 ORF was extended by 141 nucleotides, while the AC4 ORF was extended by 36 nucleotides. PMID:24258392

Ali-Shtayeh, M S; Jamous, R M; Hussein, E Y; Mallah, O B; Abu-Zeitoun, S Y

2014-04-01

2

Detection and quantitation of the new world Squash leaf curl virus by TaqMan real-time PCR.  

PubMed

Squash leaf curl diseases are caused by distinct virus species that are separated into two major phylogenetic groups, western and eastern hemisphere groups. The western group includes the new world Squash leaf curl virus (SLCV) which causes major losses to cucurbit production and induces severe stunting and leaf curl in squash plants. A TaqMan-based real time polymerase chain reaction (qPCR) assay has been developed for detection and quantitation of SLCV. Designed primers and probe targeted the AV1 (coat protein) gene and in silico analysis showed that they detect a large number of SLCV isolates. The developed assay could detect the virus in 18fg of total nucleic acid and 30 genomic units. The qPCR assay was about 1000 times more sensitive than PCR and amplified successfully SLCV from a wide range of cucurbit hosts and from viruliferous whiteflies. The developed qPCR assay should be suitable for detection and quantitation purposes for all reported SLCV isolates of the western hemisphere. PMID:23583490

Abrahamian, Peter E; Abou-Jawdah, Yusuf

2013-07-01

3

Squash as a trap crop to protect tomato from whitefly-vectored tomato yellow leaf curl  

Microsoft Academic Search

The silverleaf whitefly, Bemisia argentifolii Bellows & Perring [also known as biotype B of the sweetpotato whitefly, B. tabaci (Gennadius)], is a key pest of tomato in southern Florida. Most damage by the whitefly is inflicted indirectly through the transmission of plant viruses, the most damaging of which is Tomato yellow leaf curl virus (TYLCV). Trap crops may be one

David J Schuster

2004-01-01

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

Chili leaf curl betasatellite is associated with a distinct recombinant begomovirus, Pepper leaf curl Lahore virus, in Capsicum in Pakistan.  

PubMed

Capsium spp. are an important vegetable crop cultivated through Pakistan. Leaf curl disease is the major disease of Capsicum spp. in Pakistan caused by viruses. The disease has previously been shown to be associated with begomoviruses and betasatellites. We have cloned and sequenced a begomovirus and its associated betasatellite from Capsicum originating from central Pakistan. The begomovirus isolated was distinct from all previously characterised viruses and we propose the name Pepper leaf curl Lahore virus (PepLCLV) for this new species. Comparison of the sequence of PepLCLV with previously characterised begomoviruses shows it likely to have resulted from recombination between Papaya leaf curl virus and Chili leaf curl virus (ChiLCV), two species that have previously been identified in Pakistan. The betasatellite associated with PepLCLV in Capsicum was identified as Chili leaf curl betasatellite (ChLCB). This is the first identification of a cognate begomovirus for ChLCB infecting Capsicum, although this betasatellite has been shown in association with ChiLCV infecting potato in Pakistan. PepLCLV is one of an increasing number of monopartite begomoviruses shown to be associated with a betasatellite and one of the numerous species that affect Capsicum. In view of their only having been identified in Pakistan, PepLCLV and ChLCB likely represent a geographically distinct, Capsicum adapted, begomovirus-betasatellite complex. PMID:20079779

Tahir, Muhammad; Haider, Muhammad Saleem; Briddon, Rob W

2010-04-01

6

Molecular evidence for association of Tomato leaf curl New Delhi virus with leaf curl disease of papaya ( Carica papaya L.) in India  

Microsoft Academic Search

Association ofTomato leaf curl New Delhi virus with leaf curl disease of papaya (Carica papaya L.) was detected by polymerase chain reaction using begomovirus-specific primers and confirmed by highest sequence similarities\\u000a and close phylogenetic relationships.

S. K. RajA; S. K. SnehiA; M. S. KhanA; R. SinghA; A. A. KhanB

2008-01-01

7

Tomato leaf curl Joydebpur virus: a monopartite begomovirus causing severe leaf curl in tomato in West Bengal.  

PubMed

A begomovirus was isolated from tomato plants showing leaf curl and stunting symptoms in farmers' fields near the district of Kalyani, West Bengal, India. Viral genomic components amplified by rolling-circle amplification were cloned and sequenced. The genome organization of this virus was found to be similar to those of Old World monopartite begomovirus, with DNA A and a betasatellite component. Neither alphasatellite nor DNA B component was detected. The begomovirus showed highest sequence identity of 93.6% to tomato leaf curl Joydebpur virus (ToLCJoV-[IN:Kal:Chi:06]) and was thus identified to be an isolate of ToLCJoV. The betasatellite isolated from these samples was identified as tomato leaf curl Joydebpur betasatellite. ToLCJoV-[IN:Kal:Tom:08] alone induced severe symptoms in Solanum lycopersicum, N. benthamiana and N. glutinosa plants, and its severity was enhanced when co-inoculated with the cognate betasatellite. ToLCJoV-[IN:Kal:Tom:08] trans-replicated four more non-cognate betasatellites and induced severe symptoms in N. benthamiana and tomato. Since DNA A replicated efficiently and caused systemic symptom expression, it is hypothesized that ToLCJoV is essentially a monopartite virus, which could have acquired a betasatellite from an unknown source. PMID:22918555

Tiwari, Neha; Singh, Veer B; Sharma, P K; Malathi, V G

2013-01-01

8

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

9

Genetics of resistance in Luffa cylindrica Roem. against Tomato leaf curl New Delhi virus  

Microsoft Academic Search

Sponge gourd is a popular vegetable grown throughout India. Tomato leaf curl New Delhi virus, the causal virus of tomato leaf curl disease, has recently been reported to be associated with sponge gourd, causing up\\u000a to 100% crop loss under epidemic conditions. We have collected 30 genotypically diverse genotypes of sponge gourd from different\\u000a parts of India, screened these for

Sabina Islam; A. D. Munshi; Bikash Mandal; Ravinder Kumar; T. K. Behera

2010-01-01

10

Transreplication of a Tomato yellow leaf curl Thailand virus DNA-B and replication of a DNAbeta component by Tomato leaf curl Vietnam virus and Tomato yellow leaf curl Vietnam virus.  

PubMed

The genomes of two tomato-infecting begomoviruses from Vietnam were cloned and sequenced. A new variant of Tomato leaf curl Vietnam virus (ToLCVV) consisting of a DNA-A component and associated with a DNAbeta molecule as well as an additional begomovirus tentatively named Tomato yellow leaf curl Vietnam virus (TYLCVV) consisting also of a DNA-A component were identified. To verify if monopartite viruses occurring in Vietnam and Thailand are able to transreplicate the DNA-B component of Tomato yellow leaf curl Thailand virus-[Asian Institute of Technology] (TYLCTHV-[AIT]) infectivity assays were performed via agroinoculation and mechanically. As result, the DNA-B component of TYLCTHV-[AIT] was transreplicated by different DNA-A components of viruses from Vietnam and Thailand in Nicotiana benthamiana and Solanum lycopersicum. Moreover, the TYLCTHV-[AIT] DNA-B component facilitated the mechanical transmission of monopartite viruses by rub-inoculation as well as by particle bombardment in N. benthamiana and tomato plants. Finally, defective DNAs ranging from 735 to 1457 nucleotides were generated in N. benthamiana from those combinations containing TYLCTHV-[AIT] DNA-B component. PMID:18550192

Blawid, R; Van, D T; Maiss, E

2008-09-01

11

Replication of tomato yellow leaf curl virus (TYLCV) DNA in agroinoculated leaf discs from selected tomato genotypes  

Microsoft Academic Search

The leaf disc agroinoculation system was applied to study tomato yellow leaf curl virus (TYLCV) replication in explants from susceptible and resistant tomato genotypes. This system was also evaluated as a potential selection tool in breeding programmes for TYLCV resistance. Leaf discs were incubated with a head-to-tail dimer of the TYLCV genome cloned into the Ti plasmid ofAgrobacterium tumefaciens. In

H. Czosnek; A. Kheyr-Pour; B. Gronenborn; E. Remetz; M. Zeidan; A. Altman; H. D. Rabinowitch; S. Vidavsky; N. Kedar; Y. Gafni; D. Zamir

1993-01-01

12

Supervirulent pseudorecombination and asymmetric synergism between genomic components of two distinct species of begomovirus associated with severe tomato leaf curl disease in India  

Microsoft Academic Search

Isolates of two distinct begomovirus species, the severe strain of the species Tomato leaf curl New Delhi virus (tomato leaf curl New Delhi virus-(India:New Delhi:Severe:1992); ToLCNDV-(IN:ND:Svr:92), bipartite) and the Varanasi strain of the species Tomato leaf curl Gujarat virus (tomato leaf curl Gujarat virus-(India:Varanasi:2001); ToLCGV-(IN:Var:01), mono\\/ bipartite) infect tomato (Lycopersicon esculentum) and cause severe yield losses in northern India. This

S. Chakraborty; R. Vanitharani; B. Chattopadhyay; C. M. Fauquet

2008-01-01

13

Multiple Introductions of the Old World Begomovirus Tomato yellow leaf curl virus into the New World?  

PubMed Central

A phylogenetic analysis of three genomic regions revealed that Tomato yellow leaf curl virus (TYLCV) from western North America is distinct from TYLCV isolated in eastern North America and the Caribbean. This analysis supports a second introduction of this Old World begomovirus into the New World, most likely from Asia.

Duffy, Siobain; Holmes, Edward C.

2007-01-01

14

Purification of Tomato leaf curl Bangalore virus and production of polyclonal antibodies  

Microsoft Academic Search

Tomato leaf curl Bangalore virus (ToLCBV) was suc- cessfully transmitted using viruliferous whiteflies ( Be- misia tabaci) to several tomato varieties and hybrids, viz. Arka vikas, Pusa ruby, Rashmi, Rakshitha and Swaraksha. Hybrid Rashmi took 100% uniform infection, which was selected for further propagation of the v irus. ToLCBV was also transmitted to Nicotiana bentha- miana; the rate of infection

Kirthi Narayanaswamy; H. S. Savithri; V. Muniyappa

15

Identification of Replication Specificity Determinants in Two Strains of Tomato Leaf Curl Virus from New Delhi  

Microsoft Academic Search

We used two strains of tomato leaf curl virus from New Delhi to investigate specificity in replication of their cognate genomes. The strains share 94% sequence identity and are referred to as severe and mild on the basis of symptoms on tomato and tobacco. Replication assays in tobacco protoplasts and plants showed that a single amino acid change, Asn10 to

ANJU CHATTERJI; MALLA PADIDAM; ROGER N. BEACHY; CLAUDE M. FAUQUET

16

The Nuclear Shuttle Protein of Tomato Leaf Curl New Delhi Virus Is a Pathogenicity Determinant  

Microsoft Academic Search

The role of the movement protein (MP) and nuclear shuttle protein (NSP) in the pathogenicity of Tomato leaf curl New Delhi virus (ToLCNDV), a bipartite begomovirus, was studied. Both genes were expressed in Nicotiana benthamiana, Nicotiana tabacum, and Lycopersicon esculentum plants with the Potato virus X (PVX) expression vector or by stable transformation of gene constructs under the control of

Mazhar Hussain; Shahid Mansoor; Shazia Iram; Ayesha Naureen Fatima; Yusuf Zafar

2005-01-01

17

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

18

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

19

Genetic diversity of sweet potato begomoviruses in the United States and identification of a natural recombinant between sweet potato leaf curl virus and sweet potato leaf curl Georgia virus  

Microsoft Academic Search

In the United States, two sweet potato begomoviruses, sweet potato leaf curl virus (SPLCV) and sweet potato leaf curl Georgia\\u000a virus (SPLCGV), were previously identified in Louisiana. In recent years, at least seven additional sweet potato begomoviruses\\u000a have been identified in other parts of the world. In an effort to determine the genetic diversity and distribution of sweet\\u000a potato begomoviruses

Shuo Cheng Zhang; Kai-Shu Ling

2011-01-01

20

Stability of cotton cultivars under leaf curl virus epidemic in Pakistan  

Microsoft Academic Search

Experiments were undertaken to assess the sensitivity of cotton cultivars to leaf curl virus and to select cultivars that possesses stability of performance under a wide range of environments to supplement for planting with resistant cultivars. Experiments were conducted with seven strains\\/cultivars over 13 locations for 3 years (1992–1994) and with eight testing strains\\/cultivars over 14 locations during 1995 and

Hafeez-ur-Rahman; W. S Khan; Munir-ud-Din Khan; M Kausar Nawaz Shah

2001-01-01

21

Cotton leaf curl disease is associated with multiple monopartite begomoviruses supported by single DNA ß  

Microsoft Academic Search

Summary For bipartite begomoviruses (family Geminiviridae) trans-replication of the DNA B component by the DNA A-encoded replication-associated protein (Rep) is achieved by virtue of a shared sequence, the “common region”, which contains repeated motifs (iterons) which are sequence-specific Rep binding sites and form part of the origin of replication. Recently cotton leaf curl disease (CLCuD), a major constraint to cotton

S. Mansoor; R. W. Briddon; S. E. Bull; I. D. Bedford; A. Bashir; M. Hussain; M. Saeed; Y. Zafar; K. A. Malik; C. Fauquet; P. G. Markham

2003-01-01

22

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

23

Complete sequences of tomato leaf curl Palampur virus isolates infecting cucurbits in Iran.  

PubMed

Tomato leaf curl disease (TLCD) and and tomato yellow leaf curl (TYLCD) is caused by a number of begomovirus species that collectively threaten tomato production worldwide. We report here that an ongoing TLCD and TYLCD epidemic in Iran is caused by variants of tomato leaf curl Palampur virus (ToLCPMV), a newly proposed begomovirus species previously only detected in India. Besides infecting tomatoes, we identified ToLCPMV as the causal agent of a cucurbit disease that has devastated greenhouse cucumber and melon farms in Jiroft, southeastern Iran. We found no convincing evidence that the ToLCPMV DNA-B sequences have been derived through inter-species recombination, however, all of the currently sampled ToLCPMV DNA-A sequences are descendents of a sequence that probably arose through recombination between a ToLCNDV isolate and a currently unsampled geminivirus species that falls outside the ToLCNDV-ToLCPMV cluster. The increasing incidence of ToLCPMV in different cultivated species throughout Iran may signal the emergence of a serious new threat to agricultural production throughout the Middle East. PMID:19424773

Heydarnejad, Jahangir; Mozaffari, Azadeh; Massumi, Hossain; Fazeli, Roya; Gray, Alistair J A; Meredith, Sandra; Lakay, Francisco; Shepherd, Dionne N; Martin, Darren P; Varsani, Arvind

2009-01-01

24

Molecular detection and partial characterization of Tomato Yellow Leaf Curl Virus in Sri Lanka.  

PubMed

Tomato Yellow Leaf Curl Virus (TYLCV) is an important plant virus on one of the economically most important vegetable crops; tomato (Lycopersicon esculentum Mill.). This had not been molecularly detected before, in Sri Lanka. TYLCV-GN-SL was isolated from apparently infected tomato plants using modified Cetyltrimethyl Ammonium Bromide (CTAB) method in Gannoruwa. Associated Begomoviruses were detected using Deng 541/Deng 540 and AV 494/AC 1048 primer pairs. TYLCV was detected for the first time in tomato in Sri Lanka using P1V/P4C, TYLCV specific primer pair. Nucleotide sequence of coat protein of isolated TYLCV-GN-SL proved that the Indian strain of ToLC virus was closely related to Tomato Leaf Curl Sri Lanka Virus (TLCV-SL: 97%) and Tomato leaf curl Geminivirus (TLCGV: 93%) through direct sequencing data. TLCV-SL was confirmed as TYLCV isolate. TYLCV was molecularly detected from major tomato growing districts like Badulla, Nuwara-Eliya, Kandy and Matale in Sri Lanka. PMID:24205755

Samarakoon, S A M C; Balasuriya, A; Rajapaksha, R G A S; Wickramarachchi, W A R T

2012-09-15

25

Characterization and distribution of tomato yellow margin leaf curl virus, a begomovirus from Venezuela.  

PubMed

A begomovirus causing mottling and leaf deformation in tomato from the State of Mérida was cloned and sequenced. The virus has a bipartite genome comprised of a DNA-A (2,572 nucleotides) and a DNA-B (2,543 nucleotides) with a genome organization typical of New World begomoviruses. Both components share a common region of 115 nucleotides with 98 % sequence identity. Phylogenetic analysis indicated that while no virus sequences were closely related, the A component was distantly related to those of two other tomato-infecting viruses, tomato leaf deformation virus and Merremia mosaic virus; and the DNA-B, to those of pepper huasteco yellow vein virus and Rhynchosia golden mosaic Yucatan virus. The DNA-A and DNA-B sequences were submitted to GenBank (accession no. AY508993 and AY508994, respectively) and later accepted by the International Committee on Taxonomy of Viruses as the genome of a member of a unique virus species with the name Tomato yellow margin leaf curl virus (TYMLCV). Tomato (Solanum lycopersicum L. 'Fl. Lanai') plants inoculated with cloned TYMLCV DNA-A and DNA-B became systemically infected and showed chlorotic margins and leaf curling. The distribution of TYMLCV in tomato-producing states in Venezuela was determined by nucleic acid spot hybridization analysis of 334 tomato leaf samples collected from ten states using a TYMLCV-specific probe and confirmed by PCR and sequencing of the PCR fragment. TYMLCV was detected in samples from the states of Aragua, Guárico, and Mérida, suggesting that TYMLCV is widely distributed in Venezuela. PMID:23064695

Nava, A; Londoño, A; Polston, J E

2013-02-01

26

Regional Changes in the Sequence of Cotton Leaf Curl Multan Betasatellite  

PubMed Central

Cotton leaf curl disease (CLCuD) in Pakistan and northwestern India is caused by monopartite begomoviruses in association with an essential, disease-specific satellite, Cotton leaf curl Multan betasatellite (CLCuMB). Following a recent upsurge in CLCuD problems in Sindh province (southern Pakistan), sequences of clones of CLCuMB were obtained from Sindh and Punjab province (central Pakistan), where CLCuD has been a problem since the mid-1980s. The sequences were compared to all sequences of CLCuMB available in the databases. Analysis of the sequences shows extensive sequence variation in CLCuMB, most likely resulting from recombination. The range of sequence variants differ between Sindh, the Punjab and northwestern India. The possible significance of the findings with respect to movement of the CLCuD between the three regions is discussed. Additionally, the lack of sequence variation within the only coding sequence of CLCuMB suggests that the betasatellite is not involved in resistance breaking which became a problem after 2001 in the Punjab and subsequently also in northwestern India.

Akhtar, Sohail; Tahir, Muhammad Nouman; Baloch, Ghulam Rasool; Javaid, Shaista; Khan, Ali Qaiser; Amin, Imran; Briddon, Rob W.; Mansoor, Shahid

2014-01-01

27

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

28

Regional changes in the sequence of cotton leaf curl multan betasatellite.  

PubMed

Cotton leaf curl disease (CLCuD) in Pakistan and northwestern India is caused by monopartite begomoviruses in association with an essential, disease-specific satellite, Cotton leaf curl Multan betasatellite (CLCuMB). Following a recent upsurge in CLCuD problems in Sindh province (southern Pakistan), sequences of clones of CLCuMB were obtained from Sindh and Punjab province (central Pakistan), where CLCuD has been a problem since the mid-1980s. The sequences were compared to all sequences of CLCuMB available in the databases. Analysis of the sequences shows extensive sequence variation in CLCuMB, most likely resulting from recombination. The range of sequence variants differ between Sindh, the Punjab and northwestern India. The possible significance of the findings with respect to movement of the CLCuD between the three regions is discussed. Additionally, the lack of sequence variation within the only coding sequence of CLCuMB suggests that the betasatellite is not involved in resistance breaking which became a problem after 2001 in the Punjab and subsequently also in northwestern India. PMID:24859342

Akhtar, Sohail; Tahir, Muhammad Nouman; Baloch, Ghulam Rasool; Javaid, Shaista; Khan, Ali Qaiser; Amin, Imran; Briddon, Rob W; Mansoor, Shahid

2014-05-01

29

Lamium amplexicaule (Lamiaceae): a weed reservoir for tomato yellow leaf curl virus (TYLCV) in Korea.  

PubMed

After the first identification of tomato yellow leaf curl virus (TYLCV) in the southern part of Korea in 2008, TYLCV has rapidly spread to tomato farms in most regions of Korea. From 2008 to 2010, a survey of natural weed hosts that could be reservoirs of TYLCV was performed in major tomato production areas of Korea. About 530 samples were collected and identified as belonging to 25 species from 11 families. PCR and Southern hybridization were used to detect TYLCV in samples, and replicating forms of TYLCV DNA were detected in three species (Achyranthes bidentata, Lamium amplexicaule, and Veronica persica) by Southern hybridization. TYLCV transmission mediated by Bemisia tabaci from TYLCV-infected tomato plants to L. amplexicaule was confirmed, and TYLCV-infected L. amplexicaule showed symptoms such as yellowing, stunting, and leaf curling. TYLCV from infected L. amplexicaule was also transmitted to healthy tomato and L. amplexicaule plants by B. tabaci. The rate of infection of L. amplexicaule by TYLCV was similar to that of tomato. This report is the first to show that L. amplexicaule is a reservoir weed host for TYLCV. PMID:24327090

Kil, Eui-Joon; Park, Jungan; Lee, Hyejung; Kim, Jaedeok; Choi, Hong-Soo; Lee, Kyeong-Yeoll; Kim, Chang-Seok; Lee, Sukchan

2014-06-01

30

Viral diseases causing the greatest economic losses to the tomato crop. II. The Tomato yellow leaf curl virus — a review  

Microsoft Academic Search

Tomato yellow leaf curl geminivirus (TYLCV), transmitted by the whitefly Bemisia tabaci (Gennadius) is one of the most devastating diseases of cultivated tomato (Lycopersicon esculentum Mill.). TYLCV causes economic losses up to 100% in tomato crop in many tropical and subtropical regions, and is spreading towards new areas. The increasing economic importance of TYLCV has resulted in the need for

Belén Picó; María José Díez; Fernando Nuez

1996-01-01

31

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

32

Cotton leaf curl Multan betasatellite as a plant gene delivery vector trans-activated by taxonomically diverse geminiviruses.  

PubMed

Cotton leaf curl Multan betasatellite (CLCuMB) replicates in tobacco, tomato and datura plants in the presence of the helper viruses tomato leaf curl virus-Australia, Iranian isolates of tomato yellow leaf curl virus, tomato leaf curl Karnataka virus, and beet severe curly top virus (BSCTV). Infectious recombinant CLCuMB constructs were made in which segments of either the CaMV 35S or the petunia ChsA promoter replaced the CLCuMB ?C1 ORF, and these were designated pBin??C1-35S and pBin??C1-ChsA, respectively. Inoculation of tobacco plants containing a functional 35S-GUS transgene with pBin??C1-35S, and normal petunia plants with pBin??C1-ChsA, in the presence of helper viruses resulted in silencing of GUS and ChsA activities in transgenic tobacco and non-transgenic petunia plants, respectively. Replication of CLCuMB with different geminiviruses, especially BSCTV, a curtovirus with a broad host range, makes it a valuable gene delivery vector to the large number of host plant species of geminiviruses that support CLCuMB. PMID:22476203

Kharazmi, S; Behjatnia, S A A; Hamzehzarghani, H; Niazi, A

2012-07-01

33

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

34

Molecular characterization of a new species of Begomovirus and betasatellite causing leaf curl disease of tomato in India.  

PubMed

A new tomato-infecting begomovirus and cognate betasatellite were characterized from the gangetic plain of northern India. Genome organization of this virus was found to be similar to those of other old world begomoviruses. The DNA-A molecule (2752nt) shared maximum (85.8%) identity with Tomato leaf curl Laos virus-[Laos] (ToLCLV-[LA]; AF195782) from Laos and betasatellite molecule (1349nt) shared maximum (75.8%) identity with Tomato leaf curl Joydebpur betasatellite (ToLCJoB-[BD:Gaz:05]; AJ966244) from Bangladesh. Interestingly, both these molecules showed less identity with known tomato-infecting begomoviruses and their satellites from India. The recombination detection program (RDP) revealed that these molecules are not an outcome of direct exchange of sequences between existing begomovirus species. According to International Committee on Taxonomy of viruses (ICTV) species/strains demarcations norms for viruses belonging to the family Geminiviridae, this is a new Begomovirus species and we named this virus as Tomato leaf curl Patna virus (ToLCPaV) and new beta species as Tomato leaf curl Patna betasatellite (ToLCPaB). Partial tandem repeats of ToLCPaV and ToLCPaB could induce typical leaf curl symptom on tomato (Solanum lycopersicum) and Nicotiana benthamiana. Although, DNA-A could alone infect tomato typical to a monopartite Begomovirus, co-inoculation of DNA-A and DNA-beta resulted more stunting and severe symptoms. Interestingly, association of ToLCPaB did not assist in increased ToLCPaV accumulation in systemic leaves. ToLCPaV neither transreplicate DNA-B of Tomato leaf curl New Delhi virus (ToLCNDV) nor of Tomato leaf curl Gujarat virus (ToLCGV), presumably due to difference in rep-binding sequences. However, ToLCPaB formed viable pseudorecombinant with mono-bipartite ToLCGV DNA-A infecting both N. benthamiana and tomato but could not cause systemic infection on natural host tomato when co-inoculated with ToLCNDV DNA-A, which is a bipartite Begomovirus. PMID:20540978

Kumari, Punam; Singh, Achuit K; Chattopadhyay, Brotati; Chakraborty, Supriya

2010-09-01

35

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

36

Genetic diversity, host range, and distribution of tomato yellow leaf curl virus in Iran.  

PubMed

Tomato yellow leaf curl virus (TYLCV) is considered one of the most important tomato pathogens in tropical and subtropical regions including Iran. During the years 2007 to 2009, a total number of 510 symptomatic and asymptomatic vegetable, ornamental and weed samples were collected from fields and greenhouses in ten provinces of Iran. Symptoms included stunting, yellowing, leaf curl and flower senescence. PCR with specific primers showed TYLCV infection in 184 samples (36%) such as cucumber, pepper, tomato and several weeds from seven provinces. Based on the geographical origin, host range and symptoms, twenty three representative isolates were selected for phylogenetic analysis. An amplicon with a size about 608 base pair (bp) comprising partial sequence of the coat (CP) and movement protein (MP) coding regions of the viral genome was sequenced and compared with the corresponding selected sequences available in GenBank for Iran and worldwide. Phylogenetic analyses on the basis of the nucleotide sequences indicated two geographically separated clades. Isolates collected from Hormozgan, Khuzestan and Kerman provinces were grouped together with other Iranian isolates including TYLCV-Ir2, TYLCV-Kahnooj, and an isolate from Oman. It was also revealed that isolates collected from Boushehr, Fars, Tehran, and Isfahan placed close to the Iranian isolate TYLCV-Abadeh and isolates from Israel and Egypt. No correlation was found between the genetic variation and the host species, but selected Iranian isolates were grouped on the basis of the geographical origins. Results of this study indicated a high genetic diversity among Iranian TYLCV isolates. Keywords: TYLCV; host; weed; genetic diversity; Iran. PMID:24957717

Shirazi, M; Mozafari, J; Rakhshandehroo, F; Shams-Bakhsh, M

2014-01-01

37

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

38

Resistance of tomato and sweet-pepper genotypes to Tomato leaf curl Bangalore virus and its vector Bemisia tabaci  

Microsoft Academic Search

The primary objective of this study was to identify sources of resistance to Tomato leaf curl Bangalore virus—Bangalore strain 4 (ToLCBV-[Ban4]) and its whitefly vector Bemisia tabaci (Gennadius) in tomato and sweet-pepper genotypes, because resistant cultivars did not exist. A total of 25 wild and cultivated tomato and nine sweet-pepper genotypes obtained from the Asian Vegetable Research and Development Centre,

MN Maruthi; V. Muniyappa; SK Green; J. Colvin; P. Hanson

2003-01-01

39

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

40

Genome Sequencing of the Plant Pathogen Taphrina deformans, the Causal Agent of Peach Leaf Curl  

PubMed Central

ABSTRACT Taphrina deformans is a fungus responsible for peach leaf curl, an important plant disease. It is phylogenetically assigned to the Taphrinomycotina subphylum, which includes the fission yeast and the mammalian pathogens of the genus Pneumocystis. We describe here the genome of T. deformans in the light of its dual plant-saprophytic/plant-parasitic lifestyle. The 13.3-Mb genome contains few identifiable repeated elements (ca. 1.5%) and a relatively high GC content (49.5%). A total of 5,735 protein-coding genes were identified, among which 83% share similarities with other fungi. Adaptation to the plant host seems reflected in the genome, since the genome carries genes involved in plant cell wall degradation (e.g., cellulases and cutinases), secondary metabolism, the hallmark glyoxylate cycle, detoxification, and sterol biosynthesis, as well as genes involved in the biosynthesis of plant hormones. Genes involved in lipid metabolism may play a role in its virulence. Several locus candidates for putative MAT cassettes and sex-related genes akin to those of Schizosaccharomyces pombe were identified. A mating-type-switching mechanism similar to that found in ascomycetous yeasts could be in effect. Taken together, the findings are consistent with the alternate saprophytic and parasitic-pathogenic lifestyles of T. deformans.

Cisse, Ousmane H.; Almeida, Joao M. G. C. F.; Fonseca, Alvaro; Kumar, Ajay Anand; Salojarvi, Jarkko; Overmyer, Kirk; Hauser, Philippe M.; Pagni, Marco

2013-01-01

41

Female-Biased Symbionts and Tomato Yellow Leaf Curl Virus Infections in Bemisia tabaci  

PubMed Central

The female-biased infection of facultative symbionts has been found in Bemisia tabaci; however, whether there are any differences in tomato yellow leaf curl virus (TYLCV) and obligate symbiont infection rates between females and males is unknown. Determining whether such differences exist would be very important for understanding the spread of the plant virus and of the symbionts. We compared both symbiont infection types, including obligate and facultative symbionts, and the rates of TYLCV infection in both sexes in five field populations from Jiangsu Province, China. The obligate symbiont Portiera aleyrodidarum was not found in every whitefly tested. In all tested populations, more females than males were found to harbor P. aleyrodidarum; and more females than males also harbored Hamiltonella defense, the most common facultative symbiont as well as Cardinium. In addition to female-biased symbiont infections, there were also female-biased TYLCV infections, and the infection frequencies of this plant virus in females were higher than those in males. Taken together, these results suggested that both the female-biased symbiont infections and female-biased TYLCV infections promoted the rapid spread of TYLCV in China.

Guo, Huifang; Qu, Yufeng; Liu, Xiangdong; Zhong, Wanfang; Fang, Jichao

2014-01-01

42

Female-biased symbionts and tomato yellow leaf curl virus infections in Bemisia tabaci.  

PubMed

The female-biased infection of facultative symbionts has been found in Bemisia tabaci; however, whether there are any differences in tomato yellow leaf curl virus (TYLCV) and obligate symbiont infection rates between females and males is unknown. Determining whether such differences exist would be very important for understanding the spread of the plant virus and of the symbionts. We compared both symbiont infection types, including obligate and facultative symbionts, and the rates of TYLCV infection in both sexes in five field populations from Jiangsu Province, China. The obligate symbiont Portiera aleyrodidarum was not found in every whitefly tested. In all tested populations, more females than males were found to harbor P. aleyrodidarum; and more females than males also harbored Hamiltonella defense, the most common facultative symbiont as well as Cardinium. In addition to female-biased symbiont infections, there were also female-biased TYLCV infections, and the infection frequencies of this plant virus in females were higher than those in males. Taken together, these results suggested that both the female-biased symbiont infections and female-biased TYLCV infections promoted the rapid spread of TYLCV in China. PMID:24465416

Guo, Huifang; Qu, Yufeng; Liu, Xiangdong; Zhong, Wanfang; Fang, Jichao

2014-01-01

43

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

44

Bemisia tabaci Q carrying tomato yellow leaf curl virus strongly suppresses host plant defenses.  

PubMed

The concurrence of tomato yellow leaf curl virus (TYLCV) with the spread of its vector Bemisia tabaci Q rather than B in China suggests a more mutualistic relationship between TYLCV and Q. Here, we investigated the hypothesis that viruliferous B and Q have different effects on plant defenses. We found the fecundity of nonviruliferous B, nonviruliferous Q, viruliferous Q and viruliferous B was 11.080, 12.060, 10.760, and 11.220 respectively on plants previously attacked by the other biotype, however, on their respective noninfested control leaves fecundity was 12.000, 10.880, 9.760, and 8.020 respectively. Only viruliferous B had higher fecundity on viruliferous Q-infested plants than on control plants. The longevity of viruliferous B showed the same phenomenon. At 1 d infestion, the jasmonic acid content in leaves noninfested and in leaves infested with nonviruliferous B, nonviruliferous Q, viruliferous B and viruliferous Q was 407.000, 281.333, 301.333, 266.667 and 134.000?ng/g FW, respectively. The JA content was lowest in viruliferous Q-infested leaves. The proteinase inhibitor activity and expression of JA-related upstream gene LOX and downstream gene PI II showed the same trend. The substantial suppression of host defenses by Q carrying TYLCV probably enhances the spread of Q and TYLCV in China. PMID:24912756

Shi, Xiaobin; Pan, Huipeng; Zhang, Hongyi; Jiao, Xiaoguo; Xie, Wen; Wu, Qingjun; Wang, Shaoli; Fang, Yong; Chen, Gong; Zhou, Xuguo; Zhang, Youjun

2014-01-01

45

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

2013-01-01

46

Bemisia tabaci Q carrying tomato yellow leaf curl virus strongly suppresses host plant defenses  

PubMed Central

The concurrence of tomato yellow leaf curl virus (TYLCV) with the spread of its vector Bemisia tabaci Q rather than B in China suggests a more mutualistic relationship between TYLCV and Q. Here, we investigated the hypothesis that viruliferous B and Q have different effects on plant defenses. We found the fecundity of nonviruliferous B, nonviruliferous Q, viruliferous Q and viruliferous B was 11.080, 12.060, 10.760, and 11.220 respectively on plants previously attacked by the other biotype, however, on their respective noninfested control leaves fecundity was 12.000, 10.880, 9.760, and 8.020 respectively. Only viruliferous B had higher fecundity on viruliferous Q-infested plants than on control plants. The longevity of viruliferous B showed the same phenomenon. At 1 d infestion, the jasmonic acid content in leaves noninfested and in leaves infested with nonviruliferous B, nonviruliferous Q, viruliferous B and viruliferous Q was 407.000, 281.333, 301.333, 266.667 and 134.000?ng/g FW, respectively. The JA content was lowest in viruliferous Q-infested leaves. The proteinase inhibitor activity and expression of JA-related upstream gene LOX and downstream gene PI II showed the same trend. The substantial suppression of host defenses by Q carrying TYLCV probably enhances the spread of Q and TYLCV in China.

Shi, Xiaobin; Pan, Huipeng; Zhang, Hongyi; Jiao, Xiaoguo; Xie, Wen; Wu, Qingjun; Wang, Shaoli; Fang, Yong; Chen, Gong; Zhou, Xuguo; Zhang, Youjun

2014-01-01

47

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

48

Characterization of a new begomovirus and a beta satellite associated with the leaf curl disease of French bean in northern India.  

PubMed

Begomoviruses are emerging as serious threat to many crops throughout the world particularly in tropical and sub-tropical regions. A leaf curl disease with symptoms typical of infection by many begomoviruses was observed in French bean (Phaseolus vulgaris) at Kanpur, India, during 2010-2012. The disease caused downward leaf curling and made the plants unproductive. The disease was transmitted from infected to healthy plants through whitefly (Bemisia tabaci). The products of five samples digested with EcoRI yielded DNA fragments of about 2.7 kb. The complete sequence of the Fb1 sample comprised 2,741 nucleotides with genome organization typical of begomoviruses having two ORFs in virion-sense and five ORFs in complementary-sense separated by an intergenic region with begomovirus conserved nonanucleotide sequence, TAATATTAC. The complete DNA-A sequence homology was most closely related to Cotton leaf curl Bangalore virus with 80 % nucleotide sequence identity. Based on the demarcation criteria for identifying a begomovirus species, Fb1 is considered as a distinct begomovirus species, named French bean leaf curl virus and designated as FbLCV-[IN:Knp:12]. The complete sequence of associated satellite DNA-? comprises 1,379 nucleotides with single ORF and has 80 % identity with Papaya leaf curl beta satellite. There was no evidence of recombination in DNA-A of FbLCV and associated beta satellite DNA molecule. PMID:23054434

Kamaal, Naimuddin; Akram, Mohammad; Pratap, Aditya; Yadav, Prashant

2013-02-01

49

Identification of a novel circular single-stranded DNA associated with cotton leaf curl disease in Pakistan.  

PubMed

Recent reports have suggested that cotton leaf curl virus (CLCuV), a geminivirus of the genus Begomovirus, may be responsible for cotton leaf curl disease in Pakistan. However, the causal agent of the disease remains unclear as CLCuV genomic components resembling begomovirus DNA A are unable to induce typical disease symptoms when reintroduced into plants. All attempts to isolate a genomic component equivalent to begomovirus DNA B have been unsuccessful. Here, we describe the isolation and characterisation of a novel circular single-stranded (ss) DNA associated with naturally infected cotton plants. In addition to a component resembling DNA A, purified geminate particles contain a smaller unrelated ssDNA that we refer to as DNA 1. DNA 1 was cloned from double-stranded replicative form of the viral DNA isolated from infected cotton plants. Blot hybridisation using probes specific for either CLCuV DNA or DNA 1 was used to demonstrate that both DNAs co-infect naturally infected cotton plants from different geographical locations. DNA 1 was detected in viruliferous Bemisia tabaci and in tobacco plants infected under laboratory conditions using B. tabaci, indicating that it is transmitted by whiteflies. Sequence analysis showed that DNA 1 is approximately half the size of CLCuV DNA but shares no homology, indicating that it is not a defective geminivirus component. DNA 1 has some homology to a genomic component of members of Nanoviridae, a family of DNA viruses that are normally transmitted by aphids or planthoppers. DNA 1 encodes a homologue of the nanovirus replication-associated protein (Rep) and has the capacity to autonomously replicate in tobacco. The data suggest that a nanovirus-like DNA has become whitefly-transmissible as a result of its association with a geminivirus and that cotton leaf curl disease may result from a mutually dependent relationship that has developed between members of two distinct DNA virus families that share a similar replication strategy. PMID:10364503

Mansoor, S; Khan, S H; Bashir, A; Saeed, M; Zafar, Y; Malik, K A; Briddon, R; Stanley, J; Markham, P G

1999-06-20

50

A multiplex PCR method discriminating between the TYLCV and TYLCV-Mld clades of tomato yellow leaf curl virus.  

PubMed

Tomato yellow leaf curl virus (TYLCV) is one of the causal agents of tomato yellow leaf curl disease (TYLCD) and can cause up to 100% yield losses in tomato fields. As TYLCV continues to spread, many isolates have been described in different parts of the world. Recently two closely related but distinct TYLCV clades, called TYLCV and TYLCV-Mld, have been identified. Isolates from those two clades differ mainly in the nucleotide sequences of their replication associated protein genes but do not display significantly different symptomatology. In order to improve monitoring of the rapidly expanding worldwide TYLCD epidemic, a multiplex polymerase chain reaction assay (mPCR) was developed. A set of three primers were designed to detect and characterize the TYLCV and TYLCV-Mld clade isolates. The specificity and sensitivity of the mPCR were validated on TYLCV infected tomato plants and Bemisia tabaci whiteflies. Being cheap, fast and highly sensitive this new diagnostic tool should greatly simplify efforts to trace the global spread of TYLCV. PMID:17485124

Lefeuvre, P; Hoareau, M; Delatte, H; Reynaud, B; Lett, J-M

2007-09-01

51

Reaction of some tomato cultivars to tomato leaf curl virus and evaluation of the endophytic colonisation with Beauveria bassiana on the disease incidence and its vector, Bemisia tabaci  

Microsoft Academic Search

Tomato line LA1478 and Pusa Ruby were resistant to tomato leaf curl virus (TLCV) disease. They registered higher plant height, number of branches, total phenol content and yield per plant than the other cultivars. Variety Peto 86 was tolerant to the disease while the other popular tomato cultivars, i.e. Ace, Early Pack, Money Maker, Prichard and Strain B were highly

Hatem Mohamed El-Deeb; Sirag Mohamed Lashin; Youssef Al-Saied Arab

2012-01-01

52

Identification of a disease complex involving a novel monopartite begomovirus with beta- and alphasatellites associated with okra leaf curl disease in Oman.  

PubMed

Okra leaf curl disease (OLCD) is an important viral disease of okra in tropical and subtropical areas. The disease is caused by begomovirus-satellite complexes. A begomovirus and associated betasatellite and alphasatellite were identified in symptomatic okra plants from Barka, in the Al-Batinah region of Oman. Analysis of the begomovirus sequences showed them to represent a new begomovirus most closely related to cotton leaf curl Gezira virus (CLCuGeV), a begomovirus of African origin. The sequences showed less than 85 % nucleotide sequence identity to CLCuGeV isolates. The name okra leaf curl Oman virus (OLCOMV) is proposed for the new virus. Further analysis revealed that the OLCOMV is a recombinant begomovirus that evolved by the recombination of CLCuGeV isolates with tomato yellow leaf curl virus-Oman (TYLCV-OM). An alpha- and a betasatellite were also identified from the same plant sample, which were also unique when compared to sequences available in the databases. However, although the betasatellite appeared to be of African origin, the alphasatellite was most closely related to alphasatellites originating from South Asia. This is the first report of a begomovirus-satellite complex infecting okra in Oman. PMID:24287711

Akhtar, Sohail; Khan, Akhtar J; Singh, Achuit S; Briddon, Rob W

2014-05-01

53

High similarity among the tomato yellow leaf curl virus isolates from the West Mediterranean Basin: the nucleotide sequence of an infectious clone from Spain  

Microsoft Academic Search

Summary An isolate of tomato yellow leaf curl geminivirus, from the first epidemic outbreaks that occurred in Murcia, Spain (TYLCV-M) in 1992, was cloned and its nucleotide sequence was determined. The circular single stranded DNA consisted of 2777 nucleotides. The genome organization resembled that of other TYLCV sequenced so far; regulatory signal sequences for bidirectional transcription and for polyadenylation of

E. Noris; E. Hidalgo; G. P. Accotto; E. Moriones

1994-01-01

54

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

PubMed

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. PMID:22253651

Peretz, Yuval; Eybishtz, Assaf; Sela, Ilan

2011-01-01

55

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

56

A distinct strain of chickpea chlorotic dwarf virus (genus Mastrevirus, family Geminiviridae) identified in cotton plants affected by leaf curl disease.  

PubMed

As part of a study to determine the diversity of whitefly-transmitted viruses (genus Begomovirus, family Geminiviridae) associated with cotton leaf curl disease in Pakistan, leaf samples from cotton plants showing typical leaf curl disease symptoms were collected in various locations of Punjab province. Sequence analysis of full-length virus clones (~2.7 kb) showed plants to be infected with the begomovirus cotton leaf curl Burewala virus, the only virus identified in cotton in the Punjab since 2001. Surprisingly, a second virus, the leafhopper-transmitted chickpea chlorotic dwarf virus (CpCDV) of the genus Mastrevirus (family Geminiviridae), was identified in a small number of plants. The sequences of four CpCDV isolates from cotton originating from geographically distinct areas in Punjab were obtained. Analysis of the sequences showed them to represent a distinct, newly identified strain of CpCDV with the highest levels of nucleotide sequence identity to isolates of CpCDV strains C and D that have been identified previously in Pakistan. CpCDV has not been identified previously in cotton. The significance of this finding is discussed. PMID:24212888

Manzoor, Muhammad Tariq; Ilyas, Muhammad; Shafiq, Muhammad; Haider, Muhammad Saleem; Shahid, Ahmad Ali; Briddon, Rob W

2014-05-01

57

Influence of plant age, whitefly population and cultivar resistance on infection of cotton plants by cotton leaf curl virus (CLCuV) in Pakistan  

Microsoft Academic Search

The effect of plant age, the whitefly Bemisia tabaci population levels, and cultivar resistance to cotton leaf curl virus disease was determined for 10 newly developed mutant lines (via radiation) and one resistant and two susceptible\\/tolerant control varieties, under natural inoculation by the vector whiteflies. All cotton mutant lines\\/varieties become increasingly resistant to CLCuV as plants aged. Expression of the

Khalid P Akhtar; M Hussain; Azeem I Khan; M Ahsanul Haq; M Mohsin Iqbal

2004-01-01

58

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

59

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

60

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  

Microsoft Academic Search

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

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

2009-01-01

61

Sequence Parameters That Determine Specificity of Binding of the Replication-Associated Protein to Its Cognate Site in Two Strains of Tomato Leaf Curl Virus–New Delhi  

Microsoft Academic Search

The DNA binding sites for the replication-associated protein (Rep) of two strains of tomato leaf curl virus from New Delhi (ToLCV-Nde) were identified using electrophoretic mobility shift assays (EMSAs). The Rep proteins of the two strains were found to exhibit sequence specificity in recognition of their cognate repeat motifs (iterons) in the origin, despite the fact that they share 91%

Anju Chatterji; Udayan Chatterji; Roger N. Beachy; Claude M. Fauquet

2000-01-01

62

Association of an alphasatellite with tomato yellow leaf curl virus and ageratum yellow vein virus in Japan is suggestive of a recent introduction.  

PubMed

Samples were collected in 2011 from tomato plants exhibiting typical tomato leaf curl disease symptoms in the vicinity of Komae, Japan. PCR mediated amplification, cloning and sequencing of all begomovirus components from two plants from different fields showed the plants to be infected by Tomato yellow leaf curl virus (TYLCV) and Ageratum yellow vein virus (AYVV). Both viruses have previously been shown to be present in Japan, although this is the first identification of AYVV on mainland Japan; the virus previously having been shown to be present on the Okinawa Islands. The plant harboring AYVV was also shown to contain the betasatellite Tomato leaf curl Java betasatellite (ToLCJaB), a satellite not previously shown to be present in Japan. No betasatellite was associated with the TYLCV infected tomato plants analyzed here, consistent with earlier findings for this virus in Japan. Surprisingly both plants were also found to harbor an alphasatellite; no alphasatellites having previously been reported from Japan. The alphasatellite associated with both viruses was shown to be Sida yellow vein China alphasatellite which has previously only been identified in the Yunnan Province of China and Nepal. The results suggest that further begomoviruses, and their associated satellites, are being introduced to Japan. The significance of these findings is discussed. PMID:24424499

Shahid, Muhammad Shafiq; Ikegami, Masato; Waheed, Abdul; Briddon, Rob W; Natsuaki, Keiko T

2014-01-01

63

Association of an Alphasatellite with Tomato Yellow Leaf Curl Virus and Ageratum Yellow Vein Virus in Japan is Suggestive of a Recent Introduction  

PubMed Central

Samples were collected in 2011 from tomato plants exhibiting typical tomato leaf curl disease symptoms in the vicinity of Komae, Japan. PCR mediated amplification, cloning and sequencing of all begomovirus components from two plants from different fields showed the plants to be infected by Tomato yellow leaf curl virus (TYLCV) and Ageratum yellow vein virus (AYVV). Both viruses have previously been shown to be present in Japan, although this is the first identification of AYVV on mainland Japan; the virus previously having been shown to be present on the Okinawa Islands. The plant harboring AYVV was also shown to contain the betasatellite Tomato leaf curl Java betasatellite (ToLCJaB), a satellite not previously shown to be present in Japan. No betasatellite was associated with the TYLCV infected tomato plants analyzed here, consistent with earlier findings for this virus in Japan. Surprisingly both plants were also found to harbor an alphasatellite; no alphasatellites having previously been reported from Japan. The alphasatellite associated with both viruses was shown to be Sida yellow vein China alphasatellite which has previously only been identified in the Yunnan Province of China and Nepal. The results suggest that further begomoviruses, and their associated satellites, are being introduced to Japan. The significance of these findings is discussed.

Shahid, Muhammad Shafiq; Ikegami, Masato; Waheed, Abdul; Briddon, Rob W.; Natsuaki, Keiko T.

2014-01-01

64

The infective cycle of Cabbage leaf curl virus (CaLCuV) is affected by CRUMPLED LEAF (CRL) gene in Arabidopsis thaliana  

PubMed Central

Background Geminiviruses are single-stranded DNA viruses that cause serious crop losses worldwide. Successful infection by these pathogens depends extensively on virus-host intermolecular interactions that allow them to express their gene products, to replicate their genomes and to move to adjacent cells and throughout the plant. Results To identify host genes that show an altered regulation in response to Cabbage leaf curl virus (CaLCuV) infection, a screening of transposant Arabidopsis thaliana lines was carried out. Several genes were identified to be virus responsive and one, Crumpled leaf (CRL) gene, was selected for further characterization. CRL was previously reported by Asano et al., (2004) to affect the morphogenesis of all plant organs and the division of plastids. We report here that CRL expression, during CaLCuV infection, shows a short but strong induction at an early stage (3-5 days post inoculation, dpi). To study the role of CRL in CaLCuV infection, CRL over-expressing and silenced transgenic plants were generated. We compared the replication, movement and infectivity of CaLCuV in transgenic and wild type plants. Conclusion Our results showed that CRL over-expressing plants showed an increased susceptibility to CaLCuV infection (as compared to wt plants) whereas CRL-silenced plants, on the contrary, presented a reduced susceptibility to viral infection. The possible role of CRL in the CaLCuV infection cycle is discussed.

Trejo-Saavedra, Diana L; Vielle-Calzada, Jean P; Rivera-Bustamante, Rafael F

2009-01-01

65

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

66

Functional Characterization of a Bidirectional Plant Promoter from Cotton Leaf Curl Burewala Virus Using an Agrobacterium-Mediated Transient Assay  

PubMed Central

The C1 promoter expressing the AC1 gene, and V1 promoter expressing the AV1 gene are located in opposite orientations in the large intergenic region of the Cotton leaf curl Burewala virus (CLCuBuV) genome. Agro-infiltration was used to transiently express putative promoter constructs in Nicotiana tabacum and Gossypium hirsutum leaves, which was monitored by a GUS reporter gene, and revealed that the bidirectional promoter of CLCuBuV transcriptionally regulates both the AC1 and AV1 genes. The CLCuBuV C1 gene promoter showed a strong, consistent transient expression of the reporter gene (GUS) in N. tabacum and G. hirsutum leaves and exhibited GUS activity two- to three-fold higher than the CaMV 35S promoter. The CLCuBuV bidirectional genepromoter is a nearly constitutive promoter that contains basic conserved elements. Many cis-regulatory elements (CREs) were also analyzed within the bidirectional plant promoters of CLCuBuV and closely related geminiviruses, which may be helpful in understanding the transcriptional regulation of both the virus and host plant.

Ashraf, Muhammad Aleem; Shahid, Ahmad Ali; Rao, Abdul Qayyum; Bajwa, Kamran Shehzad; Husnain, Tayyab

2014-01-01

67

Peach [Prunus persica (L.) Batsch] KNOPE1, a class 1 KNOX orthologue to Arabidopsis BREVIPEDICELLUS/KNAT1, is misexpressed during hyperplasia of leaf curl disease.  

PubMed

Class 1 KNOTTED-like (KNOX) transcription factors control cell meristematic identity. An investigation was carried out to determine whether they maintain this function in peach plants and might act in leaf curliness caused by the ascomycete Taphrina deformans. KNOPE1 function was assessed by overexpression in Arabidopsis and by yeast two-hybrid assays with Arabidopsis BELL proteins. Subsequently, KNOPE1 mRNA and zeatin localization was monitored during leaf curl disease. KNOPE1 and Arabidopsis BREVIPEDICELLUS (BP) proteins fell into the same phyletic group and recognized the same BELL factors. 35S:KNOPE1 Arabidopsis lines exhibited altered traits resembling those of BP-overexpressing lines. In peach shoot apical meristem, KNOPE1 was expressed in the peripheral and central zones but not in leaf primordia, identically to the BP expression pattern. These results strongly suggest that KNOPE1 must be down-regulated for leaf initiation and that it can control cell meristem identity equally as well as all class 1 KNOX genes. Leaves attacked by T. deformans share histological alterations with class 1 KNOX-overexpressing leaves, including cell proliferation and loss of cell differentiation. Both KNOPE1 and a cytokinin synthesis ISOPENTENYLTRANSFERASE gene were found to be up-regulated in infected curled leaves. At early disease stages, KNOPE1 was uniquely triggered in the palisade cells interacting with subepidermal mycelium, while zeatin vascular localization was unaltered compared with healthy leaves. Subsequently, when mycelium colonization and asci development occurred, both KNOPE1 and zeatin signals were scattered in sectors of cell disorders. These results suggest that KNOPE1 misexpression and de novo zeatin synthesis of host origin might participate in hyperplasia of leaf curl disease. PMID:18250078

Testone, Giulio; Bruno, Leonardo; Condello, Emiliano; Chiappetta, Adriana; Bruno, Alessandro; Mele, Giovanni; Tartarini, Andrea; Spanò, Laura; Innocenti, Anna Maria; Mariotti, Domenico; Bitonti, Maria Beatrice; Giannino, Donato

2008-01-01

68

Multiple Forms of Vector Manipulation by a Plant-Infecting Virus: Bemisia tabaci and Tomato Yellow Leaf Curl Virus  

PubMed Central

For many insect-vectored plant viruses, the relationship between feeding behavior and vector competence may prove integral to an understanding of the epidemiology of the resulting plant disease. While plant-infecting viruses are well known to change host plant physiology in a way that makes them more attractive to vectors, viral manipulation of the vectors themselves has only recently been reported. Previous research suggested that the rapid spread of Tomato yellow leaf curl virus (TYLCV) throughout China has been facilitated by its primary vector, the whitefly Bemisia tabaci. We conducted two experiments testing the impact of TYLCV infection of the host plant (tomato) and vector (B. tabaci biotypes B and Q) on whitefly feeding behavior. Whiteflies of biotypes B and Q both appeared to find TYLCV-infected plants more attractive, probing them more quickly and having a greater number of feeding bouts; this did not, however, alter the total time spent feeding. Viruliferous whiteflies fed more readily than uninfected whiteflies and spent more time salivating into sieve tube elements. Because vector salivation is essential for viral transmission, this virally mediated alteration of behavior should provide TYLCV a direct fitness benefit. This is the first report of such manipulation by a nonpropagative virus that belongs to an exclusively plant-infecting family of viruses (Geminiviridae). In the context of previous research showing that feeding on TYLCV-infected plants harms biotype B but helps biotype Q, the fact that both biotypes were equally affected by TYLCV also suggests that the virus may alter the biotype B-biotype Q competitive interaction in favor of biotype Q.

Liu, Baiming; Preisser, Evan L.; Chu, Dong; Pan, Huipeng; Xie, Wen; Wang, Shaoli; Wu, Qingjun

2013-01-01

69

Two new natural begomovirus recombinants associated with the tomato yellow leaf curl disease co-exist with parental viruses in tomato epidemics in Italy.  

PubMed

Two tomato geminivirus species co-exist in protected crops in Sicily, Tomato yellow leaf curl Sardinia virus (TYLCSV, found in 1989) and Tomato yellow leaf curl virus (TYLCV, found in 2002), and mixed infections have been detected. In a field survey conducted in 2004, the viral intergenic region (IR) was amplified from infected plants, and molecules apparently hybrid between the two species were found, but only in plants where one or both parental species were also present. Two of these hybrids, named 2/2 and 2/5, were isolated and infectious clones were obtained. They were both readily whitefly-transmitted to tomato plants; clone 2/5 produced symptoms typical of TYLCSV and TYLCV, while clone 2/2 produced more severe symptoms, with leaves showing downward curling and rugosity. Sequence analysis showed that both 2/2 and 2/5 are newly generated hybrids, with two recombination sites each. One site, common to both hybrids, is in the stem-loop of the IR. The other is close to the 3'-end of the CP ORF in 2/5 and within the Rep ORF in 2/2. Thus, the 2/2 hybrid virus has a hybrid Rep protein, with the 202 amino-terminal aa from TYLCV and the remaining 155 aa from TYLCSV. Replication assays in leaf disc indicated a lower replicative capacity with respect to parental viruses, a fact that might help to explain why plants infected only by a recombinant have not been found so far. PMID:19463717

Davino, Salvatore; Napoli, Chiara; Dellacroce, Chiara; Miozzi, Laura; Noris, Emanuela; Davino, Mario; Accotto, Gian Paolo

2009-07-01

70

Subcellular localization of V2 protein of Tomato leaf curl Java virus by using green fluorescent protein and yeast hybrid system  

Microsoft Academic Search

Tomato leaf curl Java virus-A (ToLCJV-A[ID]) from Southeast Asia is a new member of the emerging group of monopartite begomoviruses that require a betasatellite\\u000a component for symptom induction. Previously, we have elucidated the role of V1 ORF encoded by ToLCJV-A[ID] in cell-to-cell\\u000a movement. In this study, the role of V2 (PreCP) in localization was determined. Subcellular localization of ToLCJV-A[ID] V2

Pradeep Sharma; Rajarshi K. Gaur; Masato Ikegami

2011-01-01

71

Molecular detection and partial characterization of a begomovirus causing leaf curl disease of potato in sub-Himalayan West Bengal, India.  

PubMed

The characteristic disease symptoms of apical leaf curl, crinkled leaves and conspicuous mosaic were observed in potato plants grown in areas of Coochbehar, one of the distinct agroclimatic zones of sub-Himalayan West Bengal. Whitefly (Bemisia tabaci) population was also observed in and around the infected plants. The characteristic disease symptoms and presence of whitefly (Bemisia tabaci) population indicated the possibility of begomovirus infection. Total DNA was extracted from infected samples and PCR was carried out using begomovirus specific primers. PCR product of 1539 nucleotide long containing pre-coat protein, coat protein, AC5, AC3, AC2 and partial AC1 gene of DNA-Asegment and 1001 nucleotide long DNA-B containing BV1 and BC1 genes were submitted to the GenBank (accession numbers HQ597033 for DNA-A and JN390432 for DNA-B). The amplified DNA-A and DNA-B segment showed highest 98% and 99% nucleotide sequence similarity respectively with Tomato leaf curl New Delhi virus (ToLCNDV). In phylogenetic analysis also the virus sequence clustered with ToLCNDV isolates. The disease was successfully transmitted to healthy tomato plants using both whitefly vector, B. tabaci and mechanical sap inoculation using sap of infected potato leaves. It is the first record of begomovirus infection of cultivated potato in sub-Himalayan West Bengal of Eastern India. PMID:24813019

Saha, Aniruddha; Saha, Bikram; Saha, Dipanwita

2014-05-01

72

Effects of genetic changes to the begomovirus/betasatellite complex causing cotton leaf curl disease in South Asia post-resistance breaking.  

PubMed

Cotton leaf curl disease (CLCuD) has been a problem for cotton production across Pakistan and north-eastern India since the early 1990s. The appearance of the disease has been attributed to the introduction, and near monoculture of highly susceptible cotton varieties. During the intervening period the genetic make-up of the virus(es) causing the disease has changed dramatically. The most prominent of these changes has been in response to the introduction of CLCuD-resistant cotton varieties in the late 1990s, which provided a brief respite from the losses due to the disease. During the 1990s the disease was shown to be caused by multiple begomoviruses and a single, disease-specific betasatellite. Post-resistance breaking the complex encompassed only a single begomovirus, Cotton leaf curl Burewala virus (CLCuBuV), and a recombinant version of the betasatellite. Surprisingly CLCuBuV lacks an intact transcriptional-activator protein (TrAP) gene. The TrAP gene is found in all begomoviruses and encodes a product of ?134 amino acids that is important in virus-host interactions; being a suppressor of post-transcriptional gene silencing (host defence) and a transcription factor that modulates host gene expression, including microRNA genes. Recent studies have highlighted the differences between CLCuBuV and the earlier viruses that are part of on-going efforts to define the molecular basis for resistance breaking in cotton. PMID:24361351

Briddon, Rob W; Akbar, Fazal; Iqbal, Zafar; Amrao, Luqman; Amin, Imran; Saeed, Muhammad; Mansoor, Shahid

2014-06-24

73

Comparative transcriptome profiling of a resistant vs. susceptible tomato (Solanum lycopersicum) cultivar in response to infection by tomato yellow leaf curl virus.  

PubMed

Tomato yellow leaf curl virus (TYLCV) threatens tomato production worldwide by causing leaf yellowing, leaf curling, plant stunting and flower abscission. The current understanding of the host plant defense response to this virus is very limited. Using whole transcriptome sequencing, we analyzed the differential gene expression in response to TYLCV infection in the TYLCV-resistant tomato breeding line CLN2777A (R) and TYLCV-susceptible tomato breeding line TMXA48-4-0 (S). The mixed inoculated samples from 3, 5 and 7 day post inoculation (dpi) were compared to non-inoculated samples at 0 dpi. Of the total of 34831 mapped transcripts, 209 and 809 genes were differentially expressed in the R and S tomato line, respectively. The proportion of up-regulated differentially expressed genes (DEGs) in the R tomato line (58.37%) was higher than that in the S line (9.17%). Gene ontology (GO) analyses revealed that similar GO terms existed in both DEGs of R and S lines; however, some sets of defense related genes and their expression levels were not similar between the two tomato lines. Genes encoding for WRKY transcriptional factors, R genes, protein kinases and receptor (-like) kinases which were identified as down-regulated DEGs in the S line were up-regulated or not differentially expressed in the R line. The up-regulated DEGs in the R tomato line revealed the defense response of tomato to TYLCV infection was characterized by the induction and regulation of a series of genes involved in cell wall reorganization, transcriptional regulation, defense response, ubiquitination, metabolite synthesis and so on. The present study provides insights into various reactions underlining the successful establishment of resistance to TYLCV in the R tomato line, and helps in the identification of important defense-related genes in tomato for TYLCV disease management. PMID:24260487

Chen, Tianzi; Lv, Yuanda; Zhao, Tongming; Li, Nan; Yang, Yuwen; Yu, Wengui; He, Xin; Liu, Tingli; Zhang, Baolong

2013-01-01

74

Characterization of a New World Monopartite Begomovirus Causing Leaf Curl Disease of Tomato in Ecuador and Peru Reveals a New Direction in Geminivirus Evolution  

PubMed Central

All characterized whitefly-transmitted geminiviruses (begomoviruses) with origins in the New World (NW) have bipartite genomes composed of a DNA-A and DNA-B component. Recently, an NW begomovirus lacking a DNA-B component was associated with tomato leaf curl disease (ToLCD) in Peru, and it was named Tomato leaf deformation virus (ToLDeV). Here, we show that isolates of ToLDeV associated with ToLCD in Ecuador and Peru have a single, genetically diverse genomic DNA that is most closely related to DNA-A components of NW bipartite begomoviruses. Agroinoculation of multimeric clones of the genomic DNA of three ToLDeV genotypes (two variants and a strain) resulted in the development of tomato leaf curl symptoms indistinguishable from those of ToLCD in Ecuador and Peru. Biological properties of these ToLDeV genotypes were similar to those of Old World (OW) monopartite tomato-infecting begomoviruses, including lack of sap transmissibility, phloem limitation, a resistance phenotype in tomato germplasm with the Ty-1 gene, and functional properties of the V1 (capsid protein) and C4 genes. Differences in symptom phenotypes induced by the ToLDeV genotypes in tomato and Nicotiana benthamiana plants were associated with a highly divergent left intergenic region and C4 gene. Together, these results establish that ToLDeV is an emergent NW monopartite begomovirus that is causing ToLCD in Ecuador and Peru. This is the first report of an indigenous NW monopartite begomovirus, and evidence is presented that it emerged from the DNA-A component of a NW bipartite progenitor via convergent evolution and recombination.

Melgarejo, Tomas A.; Kon, Tatsuya; Rojas, Maria R.; Paz-Carrasco, Lenin; Zerbini, F. Murilo

2013-01-01

75

Comparative Transcriptome Profiling of a Resistant vs. Susceptible Tomato (Solanum lycopersicum) Cultivar in Response to Infection by Tomato Yellow Leaf Curl Virus  

PubMed Central

Tomato yellow leaf curl virus (TYLCV) threatens tomato production worldwide by causing leaf yellowing, leaf curling, plant stunting and flower abscission. The current understanding of the host plant defense response to this virus is very limited. Using whole transcriptome sequencing, we analyzed the differential gene expression in response to TYLCV infection in the TYLCV-resistant tomato breeding line CLN2777A (R) and TYLCV-susceptible tomato breeding line TMXA48-4-0 (S). The mixed inoculated samples from 3, 5 and 7 day post inoculation (dpi) were compared to non-inoculated samples at 0 dpi. Of the total of 34831 mapped transcripts, 209 and 809 genes were differentially expressed in the R and S tomato line, respectively. The proportion of up-regulated differentially expressed genes (DEGs) in the R tomato line (58.37%) was higher than that in the S line (9.17%). Gene ontology (GO) analyses revealed that similar GO terms existed in both DEGs of R and S lines; however, some sets of defense related genes and their expression levels were not similar between the two tomato lines. Genes encoding for WRKY transcriptional factors, R genes, protein kinases and receptor (-like) kinases which were identified as down-regulated DEGs in the S line were up-regulated or not differentially expressed in the R line. The up-regulated DEGs in the R tomato line revealed the defense response of tomato to TYLCV infection was characterized by the induction and regulation of a series of genes involved in cell wall reorganization, transcriptional regulation, defense response, ubiquitination, metabolite synthesis and so on. The present study provides insights into various reactions underlining the successful establishment of resistance to TYLCV in the R tomato line, and helps in the identification of important defense-related genes in tomato for TYLCV disease management.

Chen, Tianzi; Lv, Yuanda; Zhao, Tongming; Li, Nan; Yang, Yuwen; Yu, Wengui; He, Xin; Liu, Tingli; Zhang, Baolong

2013-01-01

76

Expression of stress gene networks in tomato lines susceptible and resistant to Tomato yellow leaf curl virus in response to abiotic stresses.  

PubMed

The defense response to several abiotic stresses has been compared in two tomato inbred lines issued from the same breeding program, one susceptible and the other resistant to Tomato yellow leaf curl virus (TYLCV) infection. The level of oxidative burst and the amounts of key regulatory stress proteins: pathogenesis-related proteins (PRs), heat shock proteins (HSPs) and mitogen-activated protein kinases (MAPKs) were appraised following treatments with NaCl, H(2)O(2), and ethanol. Significant differences in the response of the two tomato genotypes to these stresses have been found for HSPs and MAPKs patterns at the level of down-regulation but not activation. The higher abundance of HSPs and MAPKs in tomatoes resistant to TYLCV could result in enhanced defense capacity against abiotic stresses. PMID:18171620

Gorovits, Rena; Czosnek, Henryk

2008-04-01

77

Dynamics of defense-related components in two contrasting genotypes of tomato upon infection with Tomato Leaf Curl New Delhi Virus.  

PubMed

Tomato leaf curl virus (ToLCV) disease is a serious threat for tomato cultivation in the tropics and subtropics. Despite serious efforts no immune commercial varieties or F(1) hybrids are available till date. In this study, the interaction between Solanum lycopersicum and ToLCV was characterized on molecular and biochemical basis. RNA silencing mediated by short interfering RNA (siRNA) and reactive oxygen species (ROS) has been proposed as central components of plant adaptation to several stresses. A comparative RNA interference study between two contrasting tomato genotypes, LA1777 (tolerant) and 15SBSB (susceptible) infected with Tomato Leaf Curl New Delhi Virus (ToLCNDV) revealed relatively higher accumulation of siRNA in the leaves of tolerant genotype. In LA1777, ToLCNDV produced chlorotic as well as necrotic areas at the inoculation sites 5-10 days post-inoculation. Caspase-9- and caspase-3-like activities were significantly increased in response to ToLCNDV infection in LA1777 at inoculated region. Activities of antioxidant enzymes involved in the detoxification of ROS were examined in both systemic and localized area of infection, and their expression level was further validated through quantitative real-time PCR of the corresponding transcripts. Expression patterns of three genes encoding pathogenesis-related proteins showed higher accumulation in tolerant genotype. Tolerance against the ToLCNDV in LA1777 can be attributed to the higher siRNA accumulation, localized cell death, altered levels of antioxidant enzymes and activation of pathogenesis-related genes at different durations of virus infection. Based on these direct and indirect evidences, we have proposed a putative mechanism for ToLCNDV tolerance in the tolerant genotype. PMID:22161255

Sahu, Pranav Pankaj; Rai, Neeraj Kumar; Puranik, Swati; Roy, Anirban; Khan, Moinuddin; Prasad, Manoj

2012-10-01

78

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

79

Leaf curl diseases of two solanaceous species in Southwest Arabia are caused by a monopartite begomovirus evolutionarily most closely related to a species from the Nile Basin and unique suite of betasatellites.  

PubMed

The complete genome of 2780 bases was amplified using rolling circle amplification, and cloned, and sequenced for two distinct strains of the monopartite begomovirus Tomato leaf curl Sudan virus (ToLCSDV). The two strains shared 86-91% identity with the previously described ToLCSDV from the Nile Basin, and 90-91% identity with one another. One strain was cloned from symptomatic tomato plants from Tihamah (ToLCSDV-YE[YE:Tih:05]) while the other was cloned from symptomatic tobacco plants collected from Wadi Hadramaut (ToLCSDV-YE[YE:Had:89]). A distinct full-length betasatellite molecule (1352 bases) was cloned from the respective field-infected tomato and tobacco plants. Agro-inoculation of tomato and Nicotiana benthamiana plants with cloned partial tandem repeats of ToLCSDV-YE[YE:Tih11:05]) and the associated betasatellite, Tomato leaf curl Yemen betasatellite (ToLCYEB-[Tih:tom:137:05]), resulted in the reproduction of leaf curl disease symptoms in test plants like those observed in the field-infected plants. The betasatellite contributed to symptom severity in N. benthamiana test plants when it was co-inoculated with ToLCSDV-YE, compared to the milder symptoms that were observed in tobacco plants infected with the helper virus alone. PMID:22841489

Idris, Ali M; Abdullah, N M; Brown, J K

2012-10-01

80

Characterization of Pepper yellow leaf curl virus, a tentative new Polerovirus species causing a yellowing disease of pepper  

Microsoft Academic Search

Pepper (Capsicum annuum) is an important crop worldwide. In Israel, approximately 2,500 ha are grown all year round for the local and export markets.\\u000a Herein, we report the identification of a viral pathogen causing a new devastating disease in pepper crops. The disease syndrome\\u000a includes shortening of stem internodes, interveinal yellowing, and upward rolling of the leaf blade, accompanied by fruit

Aviv Dombrovsky; Eyal Glanz; Mali Pearlsman; Oded Lachman; Yehezkel Antignus

2010-01-01

81

RNA viruses and their silencing suppressors boost Abutilon mosaic virus, but not the Old World Tomato yellow leaf curl Sardinia virus.  

PubMed

Mixed viral infections can induce different changes in symptom development, genome accumulation and tissue tropism. These issues were investigated for two phloem-limited begomoviruses, Abutilon mosaic virus (AbMV) and Tomato yellow leaf curl Sardinia virus (TYLCSV) in Nicotiana benthamiana plants doubly infected by either the potyvirus Cowpea aphid-borne mosaic virus (CABMV) or the tombusvirus Artichoke mottled crinkle virus (AMCV). Both RNA viruses induced an increase of the amount of AbMV, led to its occasional egress from the phloem and induced symptom aggravation, while the amount and tissue tropism of TYLCSV were almost unaffected. In transgenic plants expressing the silencing suppressors of CABMV (HC-Pro) or AMCV (P19), AbMV was supported to a much lesser extent than in the mixed infections, with the effect of CABMV HC-Pro being superior to that of AMCV P19. Neither of the silencing suppressors influenced TYLCSV accumulation. These results demonstrate that begomoviruses differentially respond to the invasion of other viruses and to silencing suppression. PMID:21843560

Sardo, Luca; Wege, Christina; Kober, Sigrid; Kocher, Conny; Accotto, Gian Paolo; Noris, Emanuela

2011-11-01

82

Peptide Aptamers That Bind to Geminivirus Replication Proteins Confer a Resistance Phenotype to Tomato Yellow Leaf Curl Virus and Tomato Mottle Virus Infection in Tomato  

PubMed Central

Geminiviruses constitute a large family of single-stranded DNA viruses that cause serious losses in important crops worldwide. They often exist in disease complexes and have high recombination and mutation rates, allowing them to adapt rapidly to new hosts and environments. Thus, an effective resistance strategy must be general in character and able to target multiple viruses. The geminivirus replication protein (Rep) is a good target for broad-based disease control because it is highly conserved and required for viral replication. In an earlier study, we identified a set of peptide aptamers that bind to Rep and reduce viral replication in cultured plant cells. In this study, we selected 16 of the peptide aptamers for further analysis in yeast two-hybrid assays. The results of these experiments showed that all 16 peptide aptamers interact with all or most of the Rep proteins from nine viruses representing the three major Geminiviridae genera and identified two peptide aptamers (A22 and A64) that interact strongly with different regions in the Rep N terminus. Transgenic tomato lines expressing A22 or A64 and inoculated with Tomato yellow leaf curl virus or Tomato mottle virus exhibited delayed viral DNA accumulation and often contained lower levels of viral DNA. Strikingly, the effect on symptoms was stronger, with many of the plants showing no symptoms or strongly attenuated symptoms. Together, these results established the efficacy of using Rep-binding peptide aptamers to develop crops that are resistant to diverse geminiviruses.

Reyes, Maria Ines; Nash, Tara E.; Dallas, Mary M.; Ascencio-Ibanez, J. Trinidad

2013-01-01

83

In silico prediction of cotton (Gossypium hirsutum) encoded microRNAs targets in the genome of Cotton leaf curl Allahabad virus  

PubMed Central

Cotton leaf curl Allahabad virus (CLCuAV) belongs to genus Begomovirus, family Geminiviridae. It has single stranded monopartite DNA genome transmitted by whitefly (Bemisia tabaci). MicroRNAs (miRNAs) belong to class of endogeneous small RNAs which suppress expression of genes following cleavage or translational inhibition of target messenger RNAs. They are demonstrated to be involved in a number of plant processes such as, development, biotic and abiotic stresses. Employing in silico approach, high scoring miRNA-target pairs satisfying rules of minimum free energy and maximum complementarity were selected to investigate if they possess the potential to bind the genome CLCuAV. Our results revealed that miRNA species viz., ghr-miR2950 can target all the viral genes, ghr-miR408 targets overlapping transcripts of AC1 and AC2 genes; while ghr-miR394 and ghr-miR395a and miR395d could bind overlapping transcripts of AC1 and AC4 genes. This is the first report of prediction of cotton miRNAs which have the potential to target CLCuAV genes including AC1 and AC4, involved in viral replication and gene silencing suppression, respectively.

Shweta; Khan, Jawaid A

2014-01-01

84

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

85

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

2010-09-01

86

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

2009-09-01

87

The sex pheromones of mealy plum (Hyalopterus pruni) and leaf-curl plum (Brachycaudus helichrysi) aphids: identification and field trapping of male and gynoparous aphids in prune orchards.  

PubMed

Mealy plum, Hyalopterus pruni, and leaf-curl plum, Brachycaudus helichrysi, aphids are the primary arthropod pests in orchards that produce dried plums (i.e., prunes). The sexual stage of their respective lifecycles occurs on prune trees in the fall, during which time males respond to sex pheromones produced by oviparous females. Air-entrainment collections confirmed that oviparous H. pruni and B. helichrysi emitted combinations of (4aS, 7S, 7aR)-nepetalactone and (1R, 4aS, 7S, 7aR)-nepetalactol. The responses of H. pruni and B. helichrysi to these compounds in ratios of 1:0, 0:1, 1:1, 2.6:1, 3.4:1, 5:1, 7:1, and 0:0 (no-pheromone control) using water traps were determined in field experiments conducted in prune orchards during the fall. The greatest number of male H. pruni was caught in traps releasing a 1:1 ratio of (4aS, 7S, 7aR)-nepetalactone and (1R, 4aS, 7S, 7aR)-nepetalactol, while male B. helichrysi were caught in similar numbers in traps releasing any of the two-component ratios tested. There was no evidence that any of the pheromone treatments influenced trap catches of gynoparae of either species. Results suggest that addition of sex pheromone lures increases trap catches of male H. pruni and B. helichrysi, and that this approach may improve monitoring and management of these pests in prune orchards. Knowledge gained from this study contributes to the understanding of the ecology of insect pests in prune orchards. PMID:22549554

Symmes, Emily J; Dewhirst, Sarah Y; Birkett, Michael A; Campbell, Colin A M; Chamberlain, Keith; Pickett, John A; Zalom, Frank G

2012-05-01

88

The complete genomic sequence of pepper yellow leaf curl virus (PYLCV) and its implications for our understanding of evolution dynamics in the genus polerovirus.  

PubMed

We determined the complete sequence and organization of the genome of a putative member of the genus Polerovirus tentatively named Pepper yellow leaf curl virus (PYLCV). PYLCV has a wider host range than Tobacco vein-distorting virus (TVDV) and has a close serological relationship with Cucurbit aphid-borne yellows virus (CABYV) (both poleroviruses). The extracted viral RNA was subjected to SOLiD next-generation sequence analysis and used as a template for reverse transcription synthesis, which was followed by PCR amplification. The ssRNA genome of PYLCV includes 6,028 nucleotides encoding six open reading frames (ORFs), which is typical of the genus Polerovirus. Comparisons of the deduced amino acid sequences of the PYLCV ORFs 2-4 and ORF5, indicate that there are high levels of similarity between these sequences to ORFs 2-4 of TVDV (84-93%) and to ORF5 of CABYV (87%). Both PYLCV and Pepper vein yellowing virus (PeVYV) contain sequences that point to a common ancestral polerovirus. The recombination breakpoint which is located at CABYV ORF3, which encodes the viral coat protein (CP), may explain the CABYV-like sequences found in the genomes of the pepper infecting viruses PYLCV and PeVYV. Two additional regions unique to PYLCV (PY1 and PY2) were identified between nucleotides 4,962 and 5,061 (ORF 5) and between positions 5,866 and 6,028 in the 3' NCR. Sequence analysis of the pepper-infecting PeVYV revealed three unique regions (Pe1-Pe3) with no similarity to other members of the genus Polerovirus. Genomic analyses of PYLCV and PeVYV suggest that the speciation of these viruses occurred through putative recombination event(s) between poleroviruses co-infecting a common host(s), resulting in the emergence of PYLCV, a novel pathogen with a wider host range. PMID:23936244

Dombrovsky, Aviv; Glanz, Eyal; Lachman, Oded; Sela, Noa; Doron-Faigenboim, Adi; Antignus, Yehezkel

2013-01-01

89

Infection of tomato leaf curl New Delhi virus (ToLCNDV), a bipartite begomovirus with betasatellites, results in enhanced level of helper virus components and antagonistic interaction between DNA B and betasatellites.  

PubMed

Tomato leaf curl New Delhi virus (ToLCNDV) (Geminiviridae) is an important pathogen that severely affects tomato production. An extensive survey was carried out during 2003-2010 to study the diversity of begomoviruses found in tomato, potato, and cucurbits that showed symptoms of leaf puckering, distortion, curling, vein clearing, and yellow mosaic in various fields in different regions of India. Ten begomovirus isolates were cloned from infected samples and identified as belonging to the species ToLCNDV. A total of 44 % of the samples showed association of betasatellites, with CLCuMuB and LuLDB being the most frequent. The ToLCNDV cloned component DNA A and DNA B were agroinoculated on Nicotiana benthamiana and tomato (Solanum lycopersicum) plants with or without betasatellites, CLCuMuB or LuLDB. The viral genome levels were then monitored by real-time polymerase chain reaction at different time points of disease development. Plants co-inoculated with betasatellites showed enhanced symptom severity in both N. benthamiana and tomato, as well as increases in helper viral DNA A and DNA B levels. The DNA B and betasatellites acted antagonistically to each other, so that the level of DNA B was 16-fold greater in the presence of betasatellites, while accumulation of betasatellites, CLCuMuB and LuLDB, were reduced by 60 % in the presence of DNA B. DNA B-mediated symptoms predominated in CLCuMuB-inoculated plants, whereas betasatellite-mediated leaf abnormalities were prominent in LuLDB-co-inoculated plants. Inoculation with the cloned components will be a good biotechnological tool in resistance breeding program. PMID:23306645

Jyothsna, P; Haq, Q M I; Singh, Priyanka; Sumiya, K V; Praveen, Shelly; Rawat, Ramaveer; Briddon, Rob W; Malathi, V G

2013-06-01

90

Effect of a single amino acid substitution in the NLS domain of Tomato yellow leaf curl virus-Israel (TYLCV-IL) capsid protein (CP) on its activity and on the virus life cycle.  

PubMed

The capsid protein (CP) of Tomato yellow leaf curl virus-Israel (TYLCV-IL), encoded by the v1 gene, is the only known component of the viral capsid. Three point mutations introduced into the conserved NLS region of the CP were investigated. One mutant, in which the Arg at position 19 was converted to Leu, had the most significant effect on the CP-CP homotypic interaction as well as on CP's interaction with its nuclear receptor karyopherin ?1 and with the protein GroEL. The latter has been suggested to protect the virions in the insect vector hemolymph. These effects were first observed by yeast two-hybrid assay and then confirmed in tobacco protoplasts by measuring fluorescence resonance energy transfer (FRET) between YFP- and CFP-tagged proteins. Most importantly, when the point mutation converting Arg 19 to Leu was introduced into the full-length TYLCV genome, it disrupted its ability to cause symptoms. PMID:21376764

Yaakov, Noga; Levy, Yael; Belausov, Eduard; Gaba, Victor; Lapidot, Moshe; Gafni, Yedidya

2011-06-01

91

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

92

A 'Squashed' Heliosphere  

NASA Video Gallery

Number 2 in the Top 5 Solar Discoveries is the finding of the 'squashed' heliosphere when Voyager 1 and 2 crossed the bubble of solar wind at different distances from the sun. This led to a change ...

93

A geminiviral amplicon (VA) derived from Tomato leaf curl virus (ToLCV) can replicate in a wide variety of plant species and also acts as a VIGS vector  

PubMed Central

Background The Tomato leaf curl virus (ToLCV) belongs to the genus begomoviridae of the family Geminiviridae. The 2.7 kb DNA genome of the virus encodes all the information required for viral DNA replication, transcription and transmission across the plant cells. However, all of the genome sequences are not required for viral DNA replication. We attempted to reveal the minimal essential region required for DNA replication and stable maintenance. The phenomenon of Virus Induced Gene Silencing (VIGS) has recently been observed with several geminiviruses. We investigated whether the minimal replicating region was also capable of producing siRNAs in planta and a VIGS vector could be constructed using the same minimal sequences. Results We have constructed vectors containing various truncated portions of the Tomato leaf curl virus (ToLCV) genome and established that a segment spanning from common region (CR) to AC3 (ORF coding for a replication enhancer) was the minimal portion which could efficiently replicate in a variety of both monocot and dicot plants. A viral amplicon (VA) vector was constructed using this region that produced siRNAs from various sites of the vector, in a temporal manner in plants, and hence can be used as a VIGS vector. The tomato endogene PCNA was silenced using this vector. Introduction of a mutation in the ORF AC2 (a silencing suppressor) increased the silencing efficiency of the newly constructed vector several folds. Conclusion Our study reveals that the vector is capable of replicating in diverse plant species and is highly efficient in silencing endogenes like PCNA of the host plant, thus acting as a VIGS vector. We observed that the geminiviral ORF AC2 functioned as a silencing suppressor and a null mutation in this ORF increased the efficiency of silencing several fold. This is the first report of construction of improved VIGS vector by mutation of the resident silencing suppressor gene. The present study opens up the possibility of using such VIGS vectors in silencing the host genes in a broad range of plant hosts.

Pandey, Prerna; Choudhury, Nirupam R; Mukherjee, Sunil K

2009-01-01

94

Making a friend from a foe: expressing a GroEL gene from the whitefly Bemisia tabaci in the phloem of tomato plants confers resistance to tomato yellow leaf curl virus.  

PubMed

Some (perhaps all) plant viruses transmitted in a circulative manner by their insect vectors avoid destruction in the haemolymph by interacting with GroEL homologues, ensuring transmission. We have previously shown that the phloem-limited begomovirus tomato yellow leaf curl virus (TYLCV) interacts in vivo and in vitro with GroEL produced by the whitefly vector Bemisia tabaci. In this study, we have exploited this phenomenon to generate transgenic tomato plants expressing the whitefly GroEL in their phloem. We postulated that following inoculation, TYLCV particles will be trapped by GroEL in the plant phloem, thereby inhibiting virus replication and movement, thereby rendering the plants resistant. A whitefly GroEL gene was cloned in an Agrobacterium vector under the control of an Arabidopsis phloem-specific promoter, which was used to transform two tomato genotypes. During three consecutive generations, plants expressing GroEL exhibited mild or no disease symptoms upon whitefly-mediated inoculation of TYLCV. In vitro assays indicated that the sap of resistant plants contained GroEL-TYLCV complexes. Infected resistant plants served as virus source for whitefly-mediated transmission as effectively as infected non-transgenic tomato. Non-transgenic susceptible tomato plants grafted on resistant GroEL-transgenic scions remained susceptible, although GroEL translocated into the grafted plant and GroEL-TYLCV complexes were detected in the grafted tissues. PMID:17334947

Akad, F; Eybishtz, A; Edelbaum, D; Gorovits, R; Dar-Issa, O; Iraki, N; Czosnek, H

2007-01-01

95

Tomato Yellow Leaf Curl Sardinia Virus Rep-Derived Resistance to Homologous and Heterologous Geminiviruses Occurs by Different Mechanisms and Is Overcome if Virus-Mediated Transgene Silencing Is Activated  

PubMed Central

The replication-associated protein (Rep) of geminiviruses is involved in several biological processes brought about by the presence of distinct functional domains. Recently, we have exploited the multifunctional character of the Tomato yellow leaf curl Sardinia virus (TYLCSV) Rep to develop a molecular interference strategy to impair TYLCSV infection. We showed that transgenic expression of its N-terminal 210 amino acids (Rep-210) confers resistance to the homologous virus by inhibiting viral transcription and replication. We have now used biochemical and transgenic approaches to carry out a fuller investigation of the molecular resistance mechanisms in transgenic plants expressing Rep-210. We show that Rep-210 confers resistance through two distinct molecular mechanisms, depending on the challenging virus. Resistance to the homologous virus is achieved by the ability of Rep-210 to tightly inhibit C1 gene transcription, while that to heterologous virus is due to the interacting property of the Rep-210 oligomerization domain. Furthermore, we present evidence that in Rep-210-expressing plants, the duration of resistance is related to the ability of the challenging virus to shut off transgene expression by a posttranscriptional homology-dependent gene silencing mechanism. A model of Rep-210-mediated geminivirus resistance that takes transgene- and virus-mediated mechanisms into account is proposed.

Lucioli, Alessandra; Noris, Emanuela; Brunetti, Angela; Tavazza, Raffaela; Ruzza, Valentino; Castillo, Araceli G.; Bejarano, Eduardo R.; Accotto, Gian Paolo; Tavazza, Mario

2003-01-01

96

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

2013-10-01

97

Curled up pill bug  

NSDL National Science Digital Library

This pill bug, sometimes called a woodlouse, sow bug, or roly poley, is curled into a ball to protect itself. Pill bugs often do this as a defensive measure so that anything that might attack it has a harder time getting to its underside.

Joaquim Alves Gaspar (Portuguese Navy;)

2007-10-09

98

Curls of My Dreams.  

ERIC Educational Resources Information Center

Describes an art activity in which students draw ribbons (thin watercolor paper that, when torn, will stand up in a curling fashion). Explains in detail the assignment in which students used pencil rendering or charcoal pencil depending on the type of paper used for the assignment. (CMK)

Greenman, Geri

2001-01-01

99

Summer squash response to root restriction under different light regimes  

Microsoft Academic Search

Two week?old summer squash (Cucurbita pepo L.) were transplanted to container volumes of 0.35, 2.00, or 7.60 liters and were grown under full light or 47% shaded conditions to determine the growth and development responses of the crop relative to root and shoot stresses. Light regime had no apparent impact on plant leaf area production; however, leaf area of plants

D. S. NeSmith

1993-01-01

100

Squash operator and symmetry  

NASA Astrophysics Data System (ADS)

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 C4, 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

2010-01-01

101

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

102

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

103

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

104

Squash and Stretch  

NSDL National Science Digital Library

This online activity has you order multiple images of a bouncing ball to show how, in animation, an object appears to lengthen as it falls, flatten as it hits the ground, and lengthen as it bounces up. This technique is used to produce the exaggerated look of an animated cartoon, but follows the rules of physics in that the object elongates along its axis of acceleration (stretch) and contracts when it meets resistance (squash). If images are out of place, they can be moved, rather than starting all over.

Omsi

2005-01-01

105

Conductance Oscillations in Squashed Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

A combination of molecular dynamics and electrical conductance calculations are used to probe the electromechanical properties of squashed metallic carbon nanotubes. We find that the conductance and bandgap of armchair nanotubes show oscillations upon squashing. The physical origin of these oscillations is attributed to interaction of carbon atoms with a fourth neighbor. Squashing of armchair and zigzag nanotubes ultimately leads to metallic behavior.

Mehrez, H.; Anantram, M. P.; Svizhenko, A.

2003-01-01

106

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

107

Alteration of neuromuscular function in squash  

Microsoft Academic Search

The alteration in neuromuscular function of knee extensor muscles was characterised after a squash match in 10 trained players. Maximal voluntary contraction (MVC) and surface EMG activity of vastus lateralis (VL) and vastus medialis (VM) muscles were measured before and immediately after a 1-h squash match. M-wave and twitch contractile properties were analysed following single stimuli. MVC declined (280.5±46.8 vs.

Olivier Girard; Jean-Paul Micallef; Julien Noual; Grégoire P. Millet

2010-01-01

108

The squash family of serine proteinase inhibitors. Amino acid sequences and association equilibrium constants of inhibitors from squash, summer squash, zucchini, and cucumber seeds.  

PubMed

Six amino acid sequences for trypsin inhibitors isolated from squash, summer squash, zucchini, and cucumber seeds were determined. All these inhibitors along with the two previously sequenced squash inhibitors (1) form the squash inhibitor family. The striking characteristic of the family is that its member inhibitors are very small (29-32 residues, 3 disulfide bridges). The association equilibrium constants with bovine beta trypsin for 6 squash family inhibitors were determined and range from 5.9 X 10(10) to 9.5 X 10(11) M-1. PMID:3977882

Wieczorek, M; Otlewski, J; Cook, J; Parks, K; Leluk, J; Wilimowska-Pelc, A; Polanowski, A; Wilusz, T; Laskowski, M

1985-01-31

109

Pill bug curled up on back  

NSDL National Science Digital Library

Many pill bugs curl up in a ball to protect themselves. Pill bugs use their antennae to feel around their environment. They use their eyes to see where they are going. They use their legs to walk or crawl around.

Joaquim Alves Gaspar (Portuguese Navy;)

2008-02-09

110

A NONCONFORMING PENALTY METHOD FOR A TWO-DIMENSIONAL CURL–CURL PROBLEM  

Microsoft Academic Search

A nonconforming penalty method for a two-dimensional curl-curl problem is studied in this paper. It uses weakly con- tinuous P1 vector elds and penalizes the local divergence. Two consistency terms involving the jumps of the vector elds across element boundaries are also included to ensure the convergence of the scheme. Optimal convergence rates (up to an arbitrary posi- tive )

SUSANNE C. BRENNER; FENGYAN LI; LI-YENG SUNG

2009-01-01

111

Gene silencing of Tomato Yellow Leaf Curl Virus  

Microsoft Academic Search

The Geminiviridae family has received a great deal of attention in recent years and is becoming one of the most important and studied families\\u000a of plant viruses. Some reasons why so much effort has been dedicated to their study include the economic and social impact\\u000a of the diseases they cause (Palmer & Rybicki; 1998; Harrison & Robinson, 1999; Morales &

Ghandi Anfoka

112

Modeling competitive squash performance from quantitative analysis  

Microsoft Academic Search

We report that a player's behavioral response to a preceding athletic event in competitive squash is consistent when competing against the same opponent (p > .25) but inconsistent when competing against different opponents (p < .25). Some evidence of systematic behavior within the inconsistent responses was identified, from which a consequent strategy was analyzed and tested using a stochastic (Markov)

Tim McGarry; Ian M. Franks

1995-01-01

113

Specific incremental test in elite squash players  

PubMed Central

Objectives: To compare cardiorespiratory responses between incremental treadmill (non-specific) and field (sport specific) tests in elite squash players. Methods: Seven elite players (ranked 1 to 25 in their national federation including the World number 1) randomly performed an incremental treadmill test (TT) and a squash specific graded test (ST) to exhaustion. The ST consisted of repeated displacements replicating the game of squash, at increasing speed on the court. In both tests, ventilatory variables and heart rate were determined at the ventilatory threshold, respiratory compensation point, and maximal loads (max). Results: Heart rate and percentage maximal oxygen uptake (V·O2MAX) at the ventilatory threshold and respiratory compensation point were not different between the ST and TT, whereas V·O2MAX was higher in the ST than in the TT (63.6 (3.0) v 54.9 (2.5) ml/kg/min; p<0.001). Time to exhaustion was not different between the ST and TT (1056 (180) v 962 (71) seconds) but correlated with the ranking of the players only in the ST (r = –0.96, p<0.001). Conclusions: V·O2MAX values derived from laboratory testing were not relevant for accurately estimating fitness in elite squash players. So the ST may be used as an additional test for determination of training intensity. Improved training advice for prescribing aerobic exercise or perfecting stroke technique may result from these results.

Girard, O; Sciberras, P; Habrard, M; Hot, P; Chevalier, R; Millet, G

2005-01-01

114

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

115

Alteration of neuromuscular function in squash.  

PubMed

The alteration in neuromuscular function of knee extensor muscles was characterised after a squash match in 10 trained players. Maximal voluntary contraction (MVC) and surface EMG activity of vastus lateralis (VL) and vastus medialis (VM) muscles were measured before and immediately after a 1-h squash match. M-wave and twitch contractile properties were analysed following single stimuli. MVC declined (280.5+/-46.8 vs. 233.6+/-35.4 Nm, -16%; P<0.001) after the exercise and this was accompanied by an impairment of central activation, as attested by decline in voluntary activation (76.7+/-10.4 vs. 71.3+/-9.6%, -7%; P<0.05) and raw EMG activity of the two vastii (-17%; P<0.05), whereas RMS/M decrease was lesser (VL: -5%; NS and VM: -12%; P=0.10). In the fatigued state, no significant changes in M-wave amplitude (VL: -9%; VM: -5%) or duration were observed. Following exercise, the single twitch was characterised by lower peak torque (-20%; P<0.001) as well as shorter half-relaxation time (-13%; P<0.001) and reduced maximal rate of twitch tension development (-23%; P<0.001) and relaxation (-17%; P<0.05). A 1-h squash match play caused peripheral fatigue by impairing excitation-contraction coupling, whereas sarcolemmal excitability seems well preserved. Our results also emphasise the role of central activation failure as a possible mechanism contributing to the torque loss observed in knee extensors. Physical conditioners should consider these effects when defining their training programs for squash players. PMID:19231287

Girard, Olivier; Micallef, Jean-Paul; Noual, Julien; Millet, Grégoire P

2010-01-01

116

Genetic diversity assessment of summer squash landraces using molecular markers.  

PubMed

Plant identification, classification, and genotyping within a germplasm collection are essential elements for establishing a breeding program that enhances the probability of plants with desirable characteristics in the market place. In this study, random amplified polymorphic DNA (RAPD) was used as a molecular tool to assess the diversity and relationship among 20 summer squash (Curcubita pepo L.) landraces traditionally used to treat hypertension and prostate hyperplasia. A total of 10 RAPD primers produced 65 reproducible bands of which 46 (70.77 %) were polymorphic, indicating a large number of genotypes within the summer squash lines. Cluster analysis divided the summer squash germplasm into two groups, one including one landrace and a second containing 19 landraces that could be divided into five sub-groups. Results of this study indicate the potential of RAPD markers for the identification and assessment of genetic variations among squash landraces and provide a number of choices for developing a successful breeding program to improve summer squash. PMID:23666102

Mady, Emad A; Helaly, Alaa Al-Din; Abu El-Hamd, Abdel Naem; Abdou, Arafa; Shanan, Shamel A; Craker, Lyle E

2013-07-01

117

Eigenfunctions of the curl operator in spherical coordinates  

Microsoft Academic Search

The eigenfunctions of the curl operator are obtained by separation of variables in spherical coordinates, making use of the spin-weighted spherical harmonics. It is shown that the eigenfunctions of the curl operator with vanishing divergence can be written in terms of a single scalar potential that satisfies the Helmholtz equation. It is also shown that these eigenfunctions give a complete

G. F. Torres del Castillo

1994-01-01

118

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

Code of Federal Regulations, 2010 CFR

...2010-01-01 false Watermelon, squash, cucumber, and oriental melon from the Republic...319.56-36 Watermelon, squash, cucumber, and oriental melon from the Republic... ), squash (Cucurbita maxima ), cucumber (Cucumis sativus ), and...

2010-01-01

119

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

Code of Federal Regulations, 2010 CFR

...2009-01-01 false Watermelon, squash, cucumber, and oriental melon from the Republic...319.56-36 Watermelon, squash, cucumber, and oriental melon from the Republic... ), squash (Cucurbita maxima ), cucumber (Cucumis sativus ), and...

2009-01-01

120

Heart Rate Response and Lactic Acid Concentration in Squash Players.  

ERIC Educational Resources Information Center

It was concluded that playing squash is an activity that results in heart rate responses of sufficient intensity to elicit aerobic training effects without producing high lactic acid concentration in the blood. (MM)

Beaudin, Paula; And Others

1978-01-01

121

Direct discretization of planar div-curl problems  

NASA Technical Reports Server (NTRS)

A control volume method is proposed for planar div-curl systems. The method is independent of potential and least squares formulations, and works directly with the div-curl system. The novelty of the technique lies in its use of a single local vector field component and two control volumes rather than the other way around. A discrete vector field theory comes quite naturally from this idea and is developed. Error estimates are proved for the method, and other ramifications investigated.

Nicolaides, R. A.

1989-01-01

122

Enhanced photoresponse in curled graphene ribbons  

NASA Astrophysics Data System (ADS)

Graphene has become one of the most promising materials for future optoelectronics due to its ultrahigh charge-carrier mobility, high light transmission, and universal absorbance in the near-infrared and visible spectral ranges. However, a zero band gap and ultrafast recombination of the photoexcited electron-hole pairs limit graphene's potential in photovoltaic generation. Recent studies have shown that hot carriers can enhance photovoltaic generation in graphene p-n junctions through the photothermoelectric effect (PTE). It is, therefore, desirable to synthesize graphene nanostructures with an intrinsic PTE-induced photocurrent response. Here we report a simple method to synthesize quasi-one dimensional (quasi-1D) curled graphene ribbons (CGRs) that generate a photocurrent response with two orders of magnitude enhancement. Scanning photocurrent and photoluminescence measurements reveal that the photocurrent response is primarily attributed to the PTE and that the infrared emission may arise from thermal radiation. These results offer a new way to fabricate graphene-based optoelectronics with an enhanced photoresponse.Graphene has become one of the most promising materials for future optoelectronics due to its ultrahigh charge-carrier mobility, high light transmission, and universal absorbance in the near-infrared and visible spectral ranges. However, a zero band gap and ultrafast recombination of the photoexcited electron-hole pairs limit graphene's potential in photovoltaic generation. Recent studies have shown that hot carriers can enhance photovoltaic generation in graphene p-n junctions through the photothermoelectric effect (PTE). It is, therefore, desirable to synthesize graphene nanostructures with an intrinsic PTE-induced photocurrent response. Here we report a simple method to synthesize quasi-one dimensional (quasi-1D) curled graphene ribbons (CGRs) that generate a photocurrent response with two orders of magnitude enhancement. Scanning photocurrent and photoluminescence measurements reveal that the photocurrent response is primarily attributed to the PTE and that the infrared emission may arise from thermal radiation. These results offer a new way to fabricate graphene-based optoelectronics with an enhanced photoresponse. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr03988a

Jarrahi, Zeynab; Cao, Yunhao; Hong, Tu; Puzyrev, Yevgeniy S.; Wang, Bin; Lin, Junhao; Huffstutter, Alex H.; Pantelides, Sokrates T.; Xu, Ya-Qiong

2013-11-01

123

Enhanced photoresponse in curled graphene ribbons.  

PubMed

Graphene has become one of the most promising materials for future optoelectronics due to its ultrahigh charge-carrier mobility, high light transmission, and universal absorbance in the near-infrared and visible spectral ranges. However, a zero band gap and ultrafast recombination of the photoexcited electron-hole pairs limit graphene's potential in photovoltaic generation. Recent studies have shown that hot carriers can enhance photovoltaic generation in graphene p-n junctions through the photothermoelectric effect (PTE). It is, therefore, desirable to synthesize graphene nanostructures with an intrinsic PTE-induced photocurrent response. Here we report a simple method to synthesize quasi-one dimensional (quasi-1D) curled graphene ribbons (CGRs) that generate a photocurrent response with two orders of magnitude enhancement. Scanning photocurrent and photoluminescence measurements reveal that the photocurrent response is primarily attributed to the PTE and that the infrared emission may arise from thermal radiation. These results offer a new way to fabricate graphene-based optoelectronics with an enhanced photoresponse. PMID:24131998

Jarrahi, Zeynab; Cao, Yunhao; Hong, Tu; Puzyrev, Yevgeniy S; Wang, Bin; Lin, Junhao; Huffstutter, Alex H; Pantelides, Sokrates T; Xu, Ya-Qiong

2013-12-21

124

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

125

[Entomophilic pollination of squash, Cucurbita moschata (Cucurbitaceae)].  

PubMed

The objectives of this work were to determine the squash entomofauna in the region of Viçosa, Minas Gerais state, to study their behavior on flowers and their importance for pollination, verifying the role of each pollinator. The most common species were Trigona spinipes (Fabricius), Trigona hyalinata (Lepeletier), Apis mellifera (L.) and Melipona quadrifasciata (Lepeletier). The visitation behavior of A. mellifera, M. quadrifasciata, and Bombus morio (Swederus) were similar. They visited flowers for nectar collection, positioning themselves vertically between the corolla and the sexual structures of the flowers, with the back directed toward the floral axis, which permitted the removal of pollen from the anthers of flowers with stamens and its deposition on the stigma of flowers with pistils, being considered therefore effective pollinators. Trigona spinipes and T. hyalinata foraged in groups, preventing other species from landing on the flowers which they occupied. Due to their small body size and only infrequent contact with the sexual structures of the flowers, these species are considered occasional pollinators. The number of fruits produced differed between freely visited flowers, those prevented from receiving visits and those visited only a single time by M. quadrifasciata, B. morio, A. mellifera, T. hyalinata or T. spinipes. Flowers prevented from receiving visits or visited only once by T. spinipes did not produce fruits. The remaining pollination systems led to fruitification, with open pollination or a single visit from either M. quadrifasciata or B. morio leading to most fruit production. PMID:20498949

Serra, Bruna D V; Campos, Lucio A de O

2010-01-01

126

Squashing models for optical measurements in quantum communication.  

PubMed

Measurements with photodetectors are naturally described in the infinite dimensional Fock space of one or several modes. For some measurements, a model has been postulated which describes the full measurement as a composition of a mapping (squashing) of the signal into a small dimensional Hilbert space followed by a specified target measurement. We present a formalism to investigate whether a given measurement pair of full and target measurements can be connected by a squashing model. We show that a measurement used in the Bennett-Brassard 1984 (BB84) protocol does allow a squashing description, although the corresponding six-state protocol measurement does not. As a result, security proofs for the BB84 protocol can be based on the assumption that the eavesdropper forwards at most one photon, while the same does not hold for the six-state protocol. PMID:18851610

Beaudry, Normand J; Moroder, Tobias; Lütkenhaus, Norbert

2008-08-29

127

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

128

Expression of ascorbic acid oxidase in zucchini squash (Cucurbita pepo L. )  

SciTech Connect

The expression of ascorbic acid oxidase was studied in zuchini 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 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 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, the authors have proposed several hypotheses to explain how dehydroascorbic acid might cause cell wall loosening.

Lin, Liangshiou; Varner, J.E. (Washington Univ., St. Louis, MO (United States))

1991-05-01

129

Performance of Virus Resistant Transgenic Yellow Summer Squash in Alabama  

Microsoft Academic Search

Production of summer squash in Alabama and the southeastern United States is generally limited to spring and early summer due to the abundance of aphid transmitted viruses during the late summer and fall. Cucumber mosaic virus (CMV), Watermelon mosaic virus (WMV), Zucchini yellow mosaic virus (ZYMV), and Papaya ring spot virus (PRSV) are the most common viruses affecting Cucurbits in

Edward J. Sikora; John F. Murphy; Jason Burkett

2006-01-01

130

Effect of the shoulder position on the biceps brachii EMG in different dumbbell curls  

Microsoft Academic Search

Incline Dumbbell Curl (IDC) and Dumbbell Preacher Curl (DPC) are two variations of the standard Dumbbell Biceps Curl (DBC), generally applied to optimize biceps brachii contribution for elbow flexion by fixing shoulder at a specific angle. The aim of this study is to identify changes in the neuromuscular activity of biceps brachii long head for IDC, DPC and DBC exercises,

Liliam F. Oliveira; Thiago T. Matt; Daniel S. Alves; Marco A. C. Garcia

2009-01-01

131

Material Object as Document: A "Hair-Curling" Classroom Exercise.  

ERIC Educational Resources Information Center

Discusses a research seminar for senior history majors that uses three documents: a written text, a photograph, and a material object. Focuses on how the object, a 19th-century curling iron, is used to elucidate discussion not only of the object, but hypotheses about individuals and society, and about historical research. (DSK)

Terry, James S.

1998-01-01

132

Covolume solutions of three dimensional div-curl equations  

NASA Technical Reports Server (NTRS)

Delaunay-Voronoi mesh systems provide a generalization of the classical rectangular staggered meshes to unstructured meshes. It is shown how such 'covolume' discretizations may be applied to div-curl systems in three dimensions. Error estimates are proved and confirmed by a numerical illustration.

Nicolaides, R. A.; Wu, X.

1995-01-01

133

A New Curl-Up Test of Abdominal Endurance.  

ERIC Educational Resources Information Center

This study evaluates a new method of administering a trunk-curl test of abdominal muscular endurance and establishes a series of norms for college students and adults. The test utilizes a piece of cardboard that is cut out so that it can be held at the level of the navel of the testee and perpendicular to the floor. The test is administered with…

Noble, Larry

134

A putative role for the tomato genes DUMPY and CURL-3 in brassinosteroid biosynthesis and response.  

PubMed

The dumpy (dpy) mutant of tomato (Lycopersicon esculentum Mill.) exhibits short stature, reduced axillary branching, and altered leaf morphology. Application of brassinolide and castasterone rescued the dpy phenotype, as did C-23-hydroxylated, 6-deoxo intermediates of brassinolide biosynthesis. The brassinolide precursors campesterol, campestanol, and 6-deoxocathasterone failed to rescue, suggesting that dpy may be affected in the conversion of 6-deoxocathasterone to 6-deoxoteasterone, similar to the Arabidopsis constitutive photomorphogenesis and dwarfism (cpd) mutant. Measurements of endogenous brassinosteroid levels by gas chromatography-mass spectrometry were consistent with this hypothesis. To examine brassinosteroid-regulated gene expression in dpy, we performed cDNA subtractive hybridization and isolated a novel xyloglucan endotransglycosylase that is regulated by brassinosteroid treatment. The curl-3 (cu-3) mutant (Lycopersicon pimpinellifolium ¿Jusl. Mill.) shows extreme dwarfism, altered leaf morphology, de-etiolation, and reduced fertility, all strikingly similar to the Arabidopsis mutant brassinosteroid insensitive 1 (bri1). Primary root elongation of wild-type L. pimpinellifolium seedlings was strongly inhibited by brassinosteroid application, while cu-3 mutant roots were able to elongate at the same brassinosteroid concentration. Moreover, cu-3 mutants retained sensitivity to indole-3-acetic acid, cytokinins, gibberellin, and abscisic acid while showing hypersensitivity to 2, 4-dichlorophenoxyacetic acid in the root elongation assay. The cu-3 root response to hormones, coupled with its bri1-like phenotype, suggests that cu-3 may also be brassinosteroid insensitive. PMID:10631252

Koka, C V; Cerny, R E; Gardner, R G; Noguchi, T; Fujioka, S; Takatsuto, S; Yoshida, S; Clouse, S D

2000-01-01

135

Evolution of perturbations of squashed Kaluza-Klein black holes: Escape from instability  

SciTech Connect

The squashed Kaluza-Klien (KK) black holes differ from the Schwarzschild black holes with asymptotic flatness or the black strings even at energies for which the KK modes are not excited yet, so that squashed KK black holes open a window in higher dimensions. Another important feature is that the squashed KK black holes are apparently stable and, thereby, let us avoid the Gregory-Laflamme instability. In the present paper, the evolution of scalar and gravitational perturbations in time and frequency domains is considered for these squashed KK black holes. The scalar field perturbations are analyzed for general rotating squashed KK black holes. Gravitational perturbations for the so-called zero mode are shown to be decayed for nonrotating black holes, in concordance with the stability of the squashed KK black holes. The correlation of quasinormal frequencies with the size of extra dimension is discussed.

Ishihara, Hideki; Kimura, Masashi; Konoplya, Roman A.; Murata, Keiju; Soda, Jiro; Zhidenko, Alexander [Department of Mathematics and Physics, Graduate School of Science, Osaka City University, Osaka 558-8585 (Japan); Department of Physics, Kyoto University, Kyoto 606-8501 (Japan); Department of Physics, Kyoto University, Kyoto 606-8501 (Japan) Kavli Institute for Theoretical Physics, Zhong Guan Cun East Street 55, Beijing 100080 (China); Instituto de Fisica, Universidade de Sao Paulo, Caixa Postal 66318, 05315-970, Sao Paulo-SP (Brazil)

2008-04-15

136

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

137

Perturbative partition function for a squashed S5  

NASA Astrophysics Data System (ADS)

We compute the index of 6d {N}=(1,0) theories on S^5× {R} containing vector and hypermultiplets. We only consider the perturbative sector without instantons. By compactifying {R} to S^1 with a twisted boundary condition and taking the small radius limit, we derive the perturbative partition function on a squashed S^5. The 1-loop partition function is represented in a simple form with the triple sine function.

Imamura, Yosuke

2013-07-01

138

Leaf Shape  

NSDL National Science Digital Library

This illustrated guide is designed to help students recognize and learn the different types of leaf shapes. The single Web page, which can be easily printed for use at field sites, shows five leaf shapes.

139

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.

140

Curling and rolling dynamics of naturally curved ribbons.  

PubMed

When a straight rod is bent and suddenly released on one end, a burst of dispersive flexural waves propagates down the material as predicted by linear beam theories. However, we show that for ribbons with a longitudinal natural radius of curvature a0, geometrical constraints lead to strain localization which controls the dynamics. This localized region of deformation selects a specific curling deformation front which travels down the ribbon when initially flattened and released. Performing experiments on different ribbons, in air and in water, we show that initially, on length scales on the order of a0, the curling front moves as a power law of time with an exponent ranging from 0.5 to 2 for increasing values of the ribbons' width. At longer time scales, the material wraps itself at a constant speed Vr into a roll of radius R ? a0. The relationship between Vr and R is calculated by a balance between kinetic, elastic and gravitational energy and both internal and external powers dissipated. When gravity and drag are negligible, we observe that a0/R reaches a limiting value of 0.48 that we predict by solving the Elastica on the curled ribbon considering the centrifugal forces due to rotation. The solution we propose represents a solitary traveling curvature wave which is reminiscent to propagating instabilities in mechanics. PMID:24695463

Arriagada, Octavio Albarrán; Massiera, Gladys; Abkarian, Manouk

2014-05-01

141

75 FR 29309 - Notice of Decision to Issue Permits for the Importation of Fresh Male Summer Squash Flowers From...  

Federal Register 2010, 2011, 2012, 2013

...Permits for the Importation of Fresh Male Summer Squash Flowers From Israel Into the Continental...continental United States of fresh male summer squash flowers from Israel. Based on...weeds via the importation of fresh male summer squash flowers from Israel....

2010-05-25

142

75 FR 6346 - Notice of Availability of a Pest Risk Analysis for the Importation of Fresh Male Summer Squash...  

Federal Register 2010, 2011, 2012, 2013

...Analysis for the Importation of Fresh Male Summer Squash Flowers From Israel Into the Continental...associated with the importation of fresh male summer squash flowers from Israel into the continental...to allow the importation of fresh male summer squash flowers, Cucurbita pepo L....

2010-02-09

143

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

144

Neural Networks Letter Neural networks with a continuous squashing function in the output are universal approximators  

Microsoft Academic Search

In 1989 Hornik as well as Funahashi established that multilayer feedforward networks without the squashing function in the output layer are universal approximators. This result has been often used improperly because it has been applied to multilayer feedforward networks with the squashing function in the output layer. In this paper, we will prove that also this kind of neural networks

J. L. Castro; C. J. Mantas; J. M. Benitez

145

78 FR 25620 - Importation of Female Squash Flowers From Israel Into the Continental United States  

Federal Register 2010, 2011, 2012, 2013

...fly trapping and monitoring, packing the flowers, and a phytosanitary...the process of growing and packing female squash flowers for export...PES and one trap outside the entrance of each PES. The traps would...that, while being used for packing female squash flowers...

2013-05-02

146

Curl-meter of Electrical Fields In The Ground.  

NASA Astrophysics Data System (ADS)

A special instrument U curl-meter was designed and manufactured in the Institute of Physics of the Earth of RAS for measuring of variable electric fields during alternation of stressedly-deformed state in rock mass. The instrument consist the four-electrode unit and a circuit of analogue signal processing for separation of E U circulations or according to the StokesSs theorem, Curl E in absence of indirect sources. Four electrodes are laied out in rocks on angles of square and they are affixed by ring-type circuit to uninverting inputs of precision operational amplifiers. First input is connected to electrode N1, the second one is connected to N2 and so on. The independent inputs are grounded to a arbitrary point (the fifth electrode is SzeroT). The transmission factors of the circuit are set by resistors accurate to within 0.25 %. First and third, and also second and fourth outputs of the amplifiers are connected to the grad EX and grad EY calculation circuit (deduction circuits). So, if the vector components have different signs of both two EX values and two values EY, the gradient calculation circuit generates signal extremums. If in this case the signs inside pairs are identical , that means that the signal not- ring-type and it is absent on output (difference of the equal values with equal signs). The signals from outputs of the gradient calculations act into adding device for calculation of Curl E (circulation). Curl-meter differs by high security from clutters and from cues on any of inputs rather of "zero point" (ground) reacting only on a ring-type current, thus it is essential (on the order) the noise level and drift of operational amplifiers is moderated. Curl-meter works in a complex of measuring devices on Obninsk seismological polygon for study of behavior of superlow frequency of tectonic genesis electromagnetic emission. Through four inputs (electrode spacing 7x7 2, resistance between welding rods 0.8 - 1.1 kOm), manufactured from fine- dyspersated of a graphitic dust with connecting on the basis of paraffine confidently registers signals by 0.2 microvolts amplitude in a frequency range 0.05 - 20 Hz on a background of considerable clutters of an industrial genesis. Technique in operation in geophysical observations the three-electrode installations were not applied in these studies because of a low industrial noise immunity and low sensitivity (5 microvolts). 1 This work was carried out by finance support RFFR Grant N 01-05-64153 2

Krylov, S. M.; Maibuk, Z.-Ju. Ja.; Nikiforova, N. N.

147

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

148

Curricular Resource Library (cURL): Earth and Environmental Sciences  

NSDL National Science Digital Library

The cURL Earth and Environmental Sciences collection provides access to educational materials emphasizing the origin, evolution, and current state of the Earth. The collection is targeted toward undergraduate students and offers access to information about solid-earth geological processes, surficial processes, geochemistry, ecology, and aquatic sciences. By studying the approximately 4.5 billion-year history of our planet, including development of our atmosphere, water bodies, mountains, and natural resources, one learns more about the current functioning of the planet and possible environmental implications of human interferences with the natural system.

2004-08-20

149

Effect of the shoulder position on the biceps brachii emg in different dumbbell curls.  

PubMed

Incline Dumbbell Curl (IDC) and Dumbbell Preacher Curl (DPC) are two variations of the standard Dumbbell Biceps Curl (DBC), generally applied to optimize biceps brachii contribution for elbow flexion by fixing shoulder at a specific angle. The aim of this study is to identify changes in the neuromuscular activity of biceps brachii long head for IDC, DPC and DBC exercises, by taking into account the changes in load moment arm and muscle length elicited by each dumbbell curl protocol. A single cycle (concentric-eccentric) of DBC, IDC and DPC, was applied to 22 subjects using a submaximal load of 40% estimated from an isometric MVC test. The neuromuscular activity of biceps brachii long head was compared by further partitioning each contraction into three phases, according to individual elbow joint range of motion. Although all protocols elicited a considerable level of activation of the biceps brachii muscle (at least 50% of maximum RMS), the contribution of this muscle for elbow flexion/extension varied among exercises. The submaximal elbow flexion (concentric) elicited neuro muscular activity up to 95% of the maximum RMS value during the final phase of IDC and DBC and 80% for DPC at the beginning of the movement. All exercises showed significant less muscle activity for the elbow extension (eccentric). The Incline Dumbbell Curl and the classical Dumbbell Biceps Curl resulted in similar patterns of biceps brachii activation for the whole range of motion, whereas Dumbbell Preacher Curl elicited high muscle activation only for a short range of elbow joint angle. Key pointsThe Incline Dumbbell Curl and the Dumbbell Biceps Curl resulted in a considerable neuromuscular effort throughout the whole elbow range of motion.The Incline Dumbbell Curl and the Dumbbell Biceps Curl may be preferable for the improvement of biceps brachii force in training programs. PMID:24150552

Oliveira, Liliam F; Matta, Thiago T; Alves, Daniel S; Garcia, Marco A C; Vieira, Taian M M

2009-01-01

150

Effect of the shoulder position on the biceps brachii emg in different dumbbell curls  

PubMed Central

Incline Dumbbell Curl (IDC) and Dumbbell Preacher Curl (DPC) are two variations of the standard Dumbbell Biceps Curl (DBC), generally applied to optimize biceps brachii contribution for elbow flexion by fixing shoulder at a specific angle. The aim of this study is to identify changes in the neuromuscular activity of biceps brachii long head for IDC, DPC and DBC exercises, by taking into account the changes in load moment arm and muscle length elicited by each dumbbell curl protocol. A single cycle (concentric-eccentric) of DBC, IDC and DPC, was applied to 22 subjects using a submaximal load of 40% estimated from an isometric MVC test. The neuromuscular activity of biceps brachii long head was compared by further partitioning each contraction into three phases, according to individual elbow joint range of motion. Although all protocols elicited a considerable level of activation of the biceps brachii muscle (at least 50% of maximum RMS), the contribution of this muscle for elbow flexion/extension varied among exercises. The submaximal elbow flexion (concentric) elicited neuro muscular activity up to 95% of the maximum RMS value during the final phase of IDC and DBC and 80% for DPC at the beginning of the movement. All exercises showed significant less muscle activity for the elbow extension (eccentric). The Incline Dumbbell Curl and the classical Dumbbell Biceps Curl resulted in similar patterns of biceps brachii activation for the whole range of motion, whereas Dumbbell Preacher Curl elicited high muscle activation only for a short range of elbow joint angle. Key pointsThe Incline Dumbbell Curl and the Dumbbell Biceps Curl resulted in a considerable neuromuscular effort throughout the whole elbow range of motion.The Incline Dumbbell Curl and the Dumbbell Biceps Curl may be preferable for the improvement of biceps brachii force in training programs.

Oliveira, Liliam F.; Matta, Thiago T.; Alves, Daniel S.; Garcia, Marco A.C.; Vieira, Taian M.M.

2009-01-01

151

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

152

Strong gravitational lensing in a rotating Kaluza-Klein black hole with squashed horizons  

NASA Astrophysics Data System (ADS)

We have investigated the strong gravitational lensing in a rotating squashed Kaluza-Klein (KK) black hole spacetime. Our result show that the strong gravitational lensings in the rotating squashed KK black hole spacetime have some distinct behaviors from those in the backgrounds of the four-dimensional Kerr black hole and of the squashed KK Gödel black hole. In the rotating squashed KK black hole spacetime, the marginally circular photon radius ? ps , the coefficient , , the deflection angle ?( ?) in the ? direction and the corresponding observational variables are independent of whether the photon goes with or against the rotation of the background, which is different with those in the usual four-dimensional Kerr black hole spacetime. Moreover, we also find that with the increase of the scale of extra dimension ?0, the marginally circular photon radius ? ps and the angular position of the relativistic images ? ? first decreases and then increases in the rotating squashed KK black hole for fixed rotation parameter b, but in the squashed KK Gödel black hole they increase for the smaller global rotation parameter j and decrease for the larger one. In the extremely squashed case ? 0 = 0, the coefficient a in the rotating squashed KK black hole increases monotonously with the rotation parameter, but in the squashed KK Gödel black hole it is a constant and independent of the global rotation of the Gödel Universe. These information could help us to understand further the effects of the rotation parameter and the scale of extra dimension on the strong gravitational lensing in the black hole spacetimes.

Ji, Liyong; Chen, Songbai; Jing, Jiliang

2014-03-01

153

Leaf Activities.  

ERIC Educational Resources Information Center

Leaf activities can provide a means of using basic concepts of outdoor education to learn in elementary level subject areas. Equipment needed includes leaves, a clipboard with paper, and a pencil. A bag of leaves may be brought into the classroom if weather conditions or time do not permit going outdoors. Each student should pick a leaf, examine…

Mingie, Walter

154

A quick enzyme squash technique for detailed studies on female meiosis in Solanum.  

PubMed

A simple enzyme squash technique that enables detailed studies of meiosis in potato ovules has been developed. Fixation of ovules in iron-propionic-ethanol followed by enzymatic maceration and squashing in acetocarmine yielded numerous well preserved megasporocytes with nicely spread chromosomes. Resolution was sufficient, allowing detailed analysis of chromosome pairing and chiasma formation and readily permitting distinction between normal and desynaptic mutant plants. Whereas the use of previously developed ovule squash techniques has been restricted to cytogenetic analyses of plant species with relatively large megasporocytes and large chromosomes, the present technique is potentially more useful for analyses of species with small megasporocytes and small chromosomes. PMID:3303456

Jongedijk, E

1987-05-01

155

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

156

An analytical model considering the fringing fields for calculating the pull-in voltage of micro curled cantilever beams  

Microsoft Academic Search

This paper derives a high precision analytical solution to determine the pull-in voltages of a micro curled beam subjected to electrostatic loads. The analytical model considers the fringing fields between the micro curled beam and the ground plane as well as the initial curling induced by the stress gradient. Furthermore, the electromechanical coupling effects are also involved in the present

Yuh-Chung Hu; Chung-Sheng Wei

2007-01-01

157

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.

158

Curled actuated shapes of ionic polymer metal composites strips  

NASA Astrophysics Data System (ADS)

The curled actuated shapes of ionic polymer metal composites (IPMCs) are described within a nonlinear physics-based model of IPMC actuators. A key characteristic of the model is the refined, even if black box based, modeling of the relative permittivity of the IPMCs which strongly influences the actuation performances of the IPMC, when voltages higher than 1 V are involved. A varying-along-the-thickness relative permittivity is proposed to take into account the highly heterogeneous layers resulting from electrode deposition, where a charge redistribution occurs. Moreover, the presence of the metal electrodes has been considered as hampering the IPMCs' bending deformations, so reducing the actuation performances of the IPMC. A series of numerical tests have been planned and discussed to show the characteristics of the model; in particular, the model is shown to be strong enough to catch the not monotonic behavior of IPMCs, when back relaxation is manifested.

Nardinocchi, Paola; Pezzulla, Matteo

2013-06-01

159

Entanglement verification with realistic measurement devices via squashing operations  

SciTech Connect

Many protocols and experiments in quantum information science are described in terms of simple measurements on qubits. However in a real implementation the exact description is more difficult and more complicated observables are used. The question arises whether a claim of entanglement in the simplified description still holds, if the difference between the realistic and simplified models is taken into account. We show that a positive entanglement statement remains valid if a certain positive linear map connecting the two descriptions--a so-called squashing operation--exists; then lower bounds on the amount of entanglement are also possible. We apply our results to polarization measurements of photons using only threshold detectors, and derive procedures under which multiphoton events can be neglected.

Moroder, Tobias; Luetkenhaus, Norbert [Quantum Information Theory Group, Institute of Theoretical Physics I, University Erlangen-Nuremberg, Staudtstrasse 7/B2, D-91058 Erlangen (Germany); Max Planck Institute for the Science of Light, Guenther-Scharowsky-Strasse 1/24, D-91058 Erlangen (Germany); Institute for Quantum Computing and Department of Physics and Astronomy, University of Waterloo, 200 University Avenue West, N2L 3G1 Waterloo, Ontario (Canada); Guehne, Otfried [Institut fuer Quantenoptik und Quanteninformation, Oesterreichische Akademie der Wissenschaften, Technikerstrasse 21A, A-6020 Innsbruck (Austria); Institut fuer Theoretische Physik, Universitaet Innsbruck, Technikerstrasse 25, A-6020 Innsbruck (Austria); Beaudry, Normand; Piani, Marco [Institute for Quantum Computing and Department of Physics and Astronomy, University of Waterloo, 200 University Avenue West, N2L 3G1 Waterloo, Ontario (Canada)

2010-05-15

160

Leaf Development  

PubMed Central

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.

2013-01-01

161

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

2013-01-01

162

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

163

Leaf Type  

NSDL National Science Digital Library

This illustrated guide to leaf types is designed to help students understand the differences between compound and simple leaves. This single Web page can be easily printed for use at field sites. Along with an explanation of both types, the guide includes a short description of related terms.

164

Purification and serological analyses of tospoviral nucleocapsid proteins expressed by Zucchini yellow mosaic virus vector in squash.  

PubMed

A plant viral vector engineered from an in vivo infectious clone of Zucchini yellow mosaic virus (ZYMV) was used to express the nucleocapsid proteins (NPs) of tospoviruses in planta. The open reading frames (ORFs) of NPs of different serogroups of tospoviruses, including Tomato spotted wilt virus, Impatiens necrotic spot virus, Watermelon silver mottle virus, Peanut bud necrosis virus, and Watermelon bud necrosis virus (WBNV), were in frame inserted in between the P1 and HC-Pro genes of the ZYMV vector. Six histidine residues and an NIa protease cleavage site were added at the C-terminal region of the inserts to facilitate purification and process of free form of the expressed NPs, respectively. Approximately 1.2-2.5 mg/NPs 100 g tissues were purified from leaf extracts of zucchini squash. The expressed WBNV NP was used as an immunogen for the production of highly specific polyclonal antisera and monoclonal antibodies. The procedure provides a convenient and fast way for production of large quantities of pure NPs of tospoviruses in planta. The system also has a potential for production of any proteins of interest in cucurbits. PMID:15992936

Chen, Tsung-Chi; Hsu, Hei-Ti; Jain, Rekesh K; Huang, Ching-Wen; Lin, Chen-Hsuan; Liu, Fang-Lin; Yeh, Shyi-Dong

2005-11-01

165

Pinch-off of axisymmetric squashed underwater bubbles  

NASA Astrophysics Data System (ADS)

Up until now, theoretical and computational studies of bubble pinch-off have assumed for simplification that the neck near break-up is nearly cylindrical, and that the surrounding water flows inwards radially. In this regime, azimuthal perturbations, however small initially, give rise to vibrations that dominate the collapse. Here we use a boundary integral simulation to investigate the surface evolution starting from initial states in the opposite limit, where the neck shape is composed of two cones with large opening angle. We also compare simulation results near the minimum against predictions from a leading-order expansion that is valid for strongly squashed neck shapes, in contrast to previous slender-neck expansions. We derive the instantaneous condition that the exterior flow must satisfy in order for the shape to evolve without changing the opening angle. The simulation shows that this condition is unstable. The small component of vertical flow present initially grows in magnitude and always acts to make the neck more slender. Thus all initial states evolve towards a dynamics that supports memory-encoding vibrations.

Herbst, Daniel C.; Zhang, Wendy W.

2010-11-01

166

[KI-67 PAP stain for histologic grading of brain tumors by squash preparations].  

PubMed

Using Ki-67 monoclonal antibody to the nuclear antigen of proliferating cells, the squash preparations of 141 brain tumors and the 36 frozen sections from corresponding tumor tissues were stained with peroxidase-antiperoxidase method. The staining indices in squash preparations correlated well to those in the corresponding frozen sections. There were good correlations between the percentage of stained cells and the histologic grade in agreement with known biologic behavior. In order of decreasing malignancy, the averages of Ki-67 staining indices were 26.7% for metastatic carcinomas, 12.6% for glioblastomas, and less than 2.8% for benign mesodermal tumor groups. Ki-67 staining with squash preparations could be applied to small tissues obtained by transsphenoidal surgery and stereotactic surgery as valuable adjuncts to intraoperative histologic diagnosis and the estimation of histologic malignancy. PMID:2470401

Shibata, T; Ostertag, C B; Volk, B

1989-01-01

167

Squashing model for detectors and applications to quantum-key-distribution protocols  

NASA Astrophysics Data System (ADS)

We develop a framework that allows a description of measurements in Hilbert spaces that is smaller than their natural representation. This description, which we call a "squashing model," consists of a squashing map that maps the input states of the measurement from the original Hilbert space to the smaller one, followed by a targeted prescribed measurement on the smaller Hilbert space. This framework has applications in quantum key distribution, but also in other cryptographic tasks, as it greatly simplifies the theoretical analysis under adversarial conditions.

Gittsovich, O.; Beaudry, N. J.; Narasimhachar, V.; Alvarez, R. Romero; Moroder, T.; Lütkenhaus, N.

2014-01-01

168

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

169

Daily physical activity in ankylosing spondylitis: validity and reliability of the IPAQ and SQUASH and the relation with clinical assessments  

PubMed Central

Introduction The aim of this study was to investigate the construct validity and test-retest reliability of the International Physical Activity Questionnaire (IPAQ; long form) and the Short QUestionnaire to Assess Health-enhancing physical activity (SQUASH) and to investigate the relation between daily physical activity and clinical assessments in patients with ankylosing spondylitis (AS). Methods For validity, the self-report questionnaires IPAQ and SQUASH were compared with daily physical activity assessed with the ActiGraph accelerometer during 7 consecutive days in 63 AS outpatients. For reliability, the IPAQ and SQUASH were administered twice approximately 1 week apart in 52 AS outpatients. In all 115 patients, clinical assessments were performed at the outpatient clinic. Results IPAQ and SQUASH total scores correlated significantly with accelerometer outcome: ? = 0.38 and r = 0.35, respectively. Intraclass correlation coefficients between first and second assessments of the IPAQ and SQUASH were 0.83 and 0.89, respectively. Bland-Altman analyses showed no systemic bias, but in particular for the IPAQ the 95% limits of agreement were wide. Daily physical activity assessed by accelerometer, IPAQ, and SQUASH correlated significantly with disease activity, physical activity, and quality of life. A relation with spinal mobility was found only for the accelerometer and SQUASH. The direction of these correlations indicates that higher daily physical activity is related to lower disease activity and better physical function, spinal mobility and quality of life. Conclusions Both physical activity questionnaires showed modest construct validity. The SQUASH showed good test-retest reliability, superior to the IPAQ. These results indicate that the SQUASH is more suitable than the IPAQ to assess daily physical activity in AS population studies. However, it is desirable to add questions on AS-specific physical activity. Further studies are needed to investigate the causality of the relation between daily physical activity and clinical assessments.

2013-01-01

170

SERINE PROTEINASE INHIBITOR FAMILY IN SQUASH SEEDS: MUTATIONAL VARIABILITY MECHANISM AND CORRELATION  

Microsoft Academic Search

Proteinase inhibitors from squash seeds were analyzed for mutational variability. The non-homologous positions were subjected to an analysis of the interrelation between occurring residues and the mechanism of variability, using the algorithm of genetic semihomology (1). The study also concerned mutational correlation at particular positions and their contact with each other. It was observed that: • the number of residues

JACEK LELUK

171

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

172

Changes in starch and soluble sugar concentrations in winter squash mesocarp during storage at different temperatures  

Microsoft Academic Search

The effects of storage at 5, 10 or 15°C for 6 months on the concentrations of starch and soluble sugar in winter squash (Cucurbita maxima Duch.) cultivar ‘TC2A’ fruits were examined. Starch contents were significantly lower at 15°C than at the other temperatures, although concentrations decreased throughout the storage period at all temperatures. Total soluble sugar contents increased during the

Daisuke Kami; Takato Muro; Keita Sugiyama

2011-01-01

173

Adventitious regeneration in vitro occurs across a wide spectrum of squash ( Cucurbita pepo ) genotypes  

Microsoft Academic Search

Cucurbita pepo L. (squash, pumpkin) is a highly polymorphic vegetable species of major importance. Our study characterized a spectrum of C. pepo germplasm for the ability to regenerate in vitro by direct organogenesis from cotyledon explants. Cultivars tested included both cultivated subspecies, texana and pepo, and nearly all of their respective cultivar-groups. Direct shoot regeneration occurred in all accessions, and

Krishnan Kathiravan; G. Vengedesan; Sima Singer; Benjamin Steinitz; Harry S. Paris; Victor Gaba

2006-01-01

174

Squash Vein Yellowing Virus, Causal Agent of Watermelon Vine Decline in Florida1  

Microsoft Academic Search

INTRODUCTION: Plants from the cucurbit family (Cucurbitaceae) are grown throughout the world for their edible fruits. The family includes watermelons (Citrullus lanatus), cantaloupes (Cucumis melo), cucumbers (C. sativus), pumpkins (Cucurbita pepo) and numerous varieties of summer and winter squash (C. pepo, C. moschata and C. maxima). It also includes those grown as ornamental vines (Luffa spp.) and a few common

Carlye Baker; Susan Webb; Scott Adkins

175

The in vitro Neurotoxic and Myotoxic Effects of the Venom from the Suta Genus (Curl Snakes) of Elapid Snakes  

Microsoft Academic Search

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

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

2007-01-01

176

Chopping of Near- and Mid-Infrared Radiation Using a Curled Electrostatic MEMS Actuator  

SciTech Connect

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. 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 microns on a side.

Dausch, David; Goodwin, Scott; Exarhos, Gregory J.; Andresen, B. F. and Fulop, G. F.

2003-04-01

177

Assessing Soybean Leaf Area and Leaf Biomass by Spectral Measurements.  

National Technical Information Service (NTIS)

Red and photographic infrared spectral radiances were correlated with soybean total leaf area index, green leaf area index, chlorotic leaf area index, green leaf biomass, chlorotic leaf biomass, and total biomass. The most significant correlations were fo...

B. N. Holben C. J. Fan C. J. Tucker

1979-01-01

178

Incidence and behavior of Salmonella and Escherichia coli on whole and sliced zucchini squash (Cucurbitapepo) fruit.  

PubMed

The incidence of coliform bacteria (CB), thermotolerant coliforms (TC), Escherichia coli, and Salmonella was determined for zucchini squash fruit. In addition, the behavior of four serotypes of Salmonella and a cocktail of three E. coli strains on whole and sliced zucchini squash at 25+/-2 degrees C and 3 to 5 degrees C was tested. Squash fruit was collected in the markets of Pachuca city, Hidalgo State, Mexico. CB, TC, E. coli, and Salmonella were detected in 100, 70, 62, and 10% of the produce, respectively. The concentration ranged from 3.8 to 7.4 log CFU per sample for CB, and >3 to 1,100 most probable number per sample for TC and E. coli. On whole fruit stored at 25+/-2 degrees C or 3 to 5 degrees C, no growth was observed for any of the tested microorganisms or cocktails thereof. After 15 days at 25+/-2 degrees C, the tested Salmonella serotypes had decreased from an initial inoculum level of 7 log CFU to <1 log, and at 3 to 5 degrees C they decreased to approximately 2 log. Survival of E. coli was significantly greater than for the Salmonella strains at the same times and temperatures; after 15 days, at 25+/-2 degrees C E. coli cocktail strains had decreased to 3.4 log CFU per fruit and at 3 to 5 degrees C they decreased to 3.6 log CFU per fruit. Both the Salmonella serotypes and E. coli strains grew when inoculated onto sliced squash: after 24 h at 25+/-2 degrees C, both bacteria had grown to approximately 6.5 log CFU per slice. At 3 to 5 degrees C, the bacterial growth was inhibited. The squash may be an important factor contributing to the endemicity of Salmonella in Mexico. PMID:20819351

Castro-Rosas, Javier; Santos López, Eva María; Gómez-Aldapa, Carlos Alberto; González Ramírez, Cesar Abelardo; Villagomez-Ibarra, José Roberto; Gordillo-Martínez, Alberto José; López, Angélica Villarruel; del Refugio Torres-Vitela, M

2010-08-01

179

Dynamic characteristics of the output light from a vibrating hole assisted fiber curl cord and its application to intrusion location  

NASA Astrophysics Data System (ADS)

When a hole assisted fiber (HAF) curl cord expands and contracts, the polarization direction of the light emitted from it rotates. A curl cord is divided into several sections by fixing it at several points. When the curl cord is flipped at a point within one of these sections, then vibration is observed with the characteristic frequency to the flipped section. The vibration period of a HAF curl cord can be detected by monitoring the light power emitted from the curl cord after passing through a polarizer. We confirmed theoretically and experimentally that the vibration period of the polarization change is proportional to the length of the section including the flipped point, which can be applied to intrusion location.

Tateda, Mitsuhiro; Mizushima, Akihiro

2014-05-01

180

Confirmation of bean leaf beetle, Cerotoma trifurcata, feeding on cucurbits  

PubMed Central

The objective of these studies was to assess the degree to which bean leaf beetle, Cerotoma trifurcata (Forster), will feed on cucurbits. In 2003, we documented an infestation of C. trifurcata in a commercial pumpkin field near Rosemount, MN, USA. To evaluate C. trifurcata feeding on cucurbits, we conducted laboratory no-choice and choice test feeding studies. In the laboratory, C. trifurcata fed most heavily on cotyledon-stage cucumber plants, followed by pumpkin and squash. With soybean plants present, C. trifurcata still fed on cucumber plants. However, C. trifurcata appeared to prefer soybeans until the quality of the soybean plants was diminished through feeding damage. This is the first known report of C. trifurcata feeding on cucurbits. The pest potential of C. trifurcata in cucurbit cropping systems should be further evaluated.

Koch, R.L.; Burkness, E.C.; Hutchison, W.D.

2004-01-01

181

Physiological correlates of multiple-sprint ability and performance in international-standard squash players.  

PubMed

From measures on a battery of fitness tests in elite-standard squash players on different tiers of a national performance program, we examined the relationships among test scores and player rank, and fitness factors important for squash-specific multiple-sprint ability. Thirty-one (20 men, 11 women) squash players from the England Squash performance program participated: n = 12 senior; n = 7 transition; n = 12 talented athlete scholarship scheme (TASS) players. In 1 test session and in a fixed order, the players completed a battery of tests to assess countermovement jump height, reactive strength, change-of-direction speed, and multiple-sprint ability on squash-specific tests and endurance fitness. Two-way analysis of variance compared senior, transition, and TASS players by sex on all measures except jump height where only senior and transition players were compared. Effect size (ES) was calculated for all comparisons. Pearson's correlation examined relationships among test scores and multiple-sprint ability. Spearman's ? investigated relationships among test scores and players' rank in men and women separately. Regardless of sex, seniors outperformed TASS players on all except the endurance test (p < 0.05, ES at least 1.1). Seniors had better multiple-sprint ability than did transition players (p < 0.01, ES = 1.2). Transition outperformed TASS players on the reactive-strength test (p < 0.05, ES = 1.0). Men outperformed women in all tests at all performance program tiers (p < 0.05, ES at least 0.5). In men, rank was related to multiple-sprint ability, fastest-multiple-sprint-test repetition, and change-of-direction speed (? = 0.78, 0.86, 0.59, respectively). In women, rank was related to fastest multiple-sprint-test repetition (? = 0.65). In men and women, multiple-sprint ability was related to change-of-direction speed (r = 0.9 and 0.84) and fastest-multiple-sprint-test repetition (r = 0.96 for both) and to reactive strength in men (r = -0.71). The results confirm that high-intensity variable-direction exercise capabilities are important for success in elite squash. PMID:22240546

Wilkinson, Michael; Cooke, Matthew; Murray, Stafford; Thompson, Kevin G; St Clair Gibson, Alan; Winter, Edward M

2012-02-01

182

A deformation of quantum affine algebra in squashed Wess-Zumino-Novikov-Witten models  

NASA Astrophysics Data System (ADS)

We proceed to study infinite-dimensional symmetries in two-dimensional squashed Wess-Zumino-Novikov-Witten models at the classical level. The target space is given by squashed S3 and the isometry is SU(2)L × U(1)R. It is known that SU(2)L is enhanced to a couple of Yangians. We reveal here that an infinite-dimensional extension of U(1)R is a deformation of quantum affine algebra, where a new deformation parameter is provided with the coefficient of the Wess-Zumino term. Then we consider the relation between the deformed quantum affine algebra and the pair of Yangians from the viewpoint of the left-right duality of monodromy matrices. The integrable structure is also discussed by computing the r/s-matrices that satisfy the extended classical Yang-Baxter equation. Finally, two degenerate limits are discussed.

Kawaguchi, Io; Yoshida, Kentaroh

2014-06-01

183

The gravity dual of supersymmetric gauge theories on a 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 U(1)×U(1)-invariant squashed three-sphere, with a non-trivial background gauge field. This is described by a supersymmetric solution of four-dimensional N=2 gauged supergravity with a non-trivial instanton for the graviphoton field. The particular gauge theory in turn determines the lift to a solution of eleven-dimensional supergravity. We compute the partition function for a class of Chern-Simons quiver gauge theories on both sides of the duality, in the large N limit, finding precise agreement for the functional dependence on the squashing parameter. This constitutes an exact check of the gauge/gravity correspondence in a non-conformally invariant setting.

Martelli, Dario; Passias, Achilleas; Sparks, James

2012-11-01

184

Responses of squash to salinity, waterlogging, and subsequent drainage: II. Root and shoot growth  

Microsoft Academic Search

The responses of root and shoot growth to concurrent salinity and waterlogging, and subsequent drainage of summer squash (Cucurbita pepo) were studied in a greenhouse experiment. Plants were well watered or flooded with full?strength Hoagland solution containing 100 mol\\/m sodium chloride (NaCl) or no NaCl for 14 d. Waterlogged plants were then transferred to drained conditions for 7 d of

Bingru Huang; D. Scott NeSmith; David C. Bridges; Jerry W. Johnson

1995-01-01

185

Improved postharvest quality in patagonian squash ( Cucurbita moschata) coated with radiation depolymerized chitosan  

Microsoft Academic Search

Different molecular weight chitosans were evaluated on the decay of coated Anquito squashes (Cucurbita moschata) as well as the maintenance of the fruit quality along five storage months. The original chitosan (Mw=391kDa, 83% DD), was depolymerized by gamma radiation. Apart from chain scission, other chemical changes were not detected by FTIR or UV–vis analyses. The molecular weight characterization of chitosans

Maria Alicia Pugliese; Maria Teresa Goitia; Mariana Yossen; Norma Cifone; Enrique Agulló; Noemi Andreucetti

2011-01-01

186

The effects of carbohydrate loading 48 hours before a simulated squash match.  

PubMed

The aim of this study was to ascertain whether a high carbohydrate diet in the days before movement patterns simulating a squash match would increase carbohydrate oxidation during the match, and alter physical performance. Nine New Zealand level squash players were recruited to complete a simulated squash match on two occasions: 1) following a 48-hr high carbohydrate (11.1g·kg-1); and 2) following a calorie-matched low carbohydrate (2.1 g·kg-1) diet. The interventions were assigned in a randomized, single-blind, cross-over design. The match simulation was designed to mimic a five-game match lasting approximately 1 hr. Performance was measured as time to complete each game. Expired respiratory gases and heart rate were continuously collected throughout the trial using a portable gas analysis system. Capillary blood glucose and lactate samples were obtained during a 90 s rest period between each game. Rating of perceived exertion was also recorded after each set. Respiratory exchange ratio was significantly higher during exercise following the high CHO diet (0.80 vs. 0.76) p < .001) and this was associated with significantly faster time to complete the games (2340 ± 189 s vs. 2416 ± 128 s, p = .036). Blood glucose and lactate concentrations were also significantly higher in the high carbohydrate condition (p = .038 and p = .021 respectively). These results suggest that ingestion of a diet high in carbohydrate (>10 g/kg body weight) preceding simulated competitive squash produces increased rates of carbohydrate oxidation and maintains higher blood glucose concentrations. These metabolic effects were associated with improved physical performance. PMID:24092769

Raman, Aaron; Macdermid, Paul W; Mündel, Toby; Mann, Michael; Stannard, Stephen R

2014-04-01

187

A new method for assessing squash tactics using 15 court areas for ball locations.  

PubMed

Tactics in squash have typically been assessed using the frequency of different shot types played at different locations on the court either without reference to other relevant information or on the basis of the preceding shot. This paper presents a new squash specific method for categorizing court locations in which the ball was played, a novel techniques for assessing the reliability of this method and presents typical shots responses in these new areas controlled for preceding shot as well as the time between shots and the handedness of the players. Twelve games were viewed using the SAGIT/Squash software and 2907 shots viewed a second time from a video image taken from behind the court with an overall agreement of 88.90% for the court location data and 99.52% for shot type. 3192 shots from 9 matches from the 2003 World Team Championships were analyzed in SAGIT/Squash. In the court areas analyzed between 2 and 7 shot responses were predominant suggesting tactical patterns were evident. This was supported by differences evident between shot responses played from the two back corners where the backhand side was characterized by a predominance of straight drives whereas straight and crosscourt drives were played on the forehand side. These results tended to confirm that tactics i.e., consistent shot types, are played although these are only apparent when factors that determine shot selection are accounted for. This paper has controlled for some of these factors but others need to be considered e.g., if individual player profiles are to be ascertained. PMID:24548850

Vu?kovi?, Goran; James, Nic; Hughes, Mike; Murray, Stafford; Milanovi?, Zoran; Perš, Janez; Sporiš, Goran

2014-04-01

188

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

Microsoft Academic Search

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,\\u000a for example, in that they have (2 + 1)-dimensional holographic duals, and the fermionic content and their interactions with\\u000a charged scalars are an important aspect of their applications.

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

2011-01-01

189

ANALYSIS OF TRITIUM INCORPORATION INTO INDIVIDUAL CELLS BY AUTORADIOGRAPHY OF SQUASH PREPARATIONS  

PubMed Central

The relation between tritium content of individual cells and grain count obtained in autoradiographs of squashed cells was investigated. The tissues used were root meristems of Tradescantia paludosa and intestinal epithelium of the mouse. The relation between grain count and tritium content is affected by self-absorption which depends on the thickness of the labeled cell. Therefore, squashed preparations were sectioned to determine the uniformity of thickness of nuclei. In a preparation of mouse cells, thicknesses were 1.18 ± 0.35 µ, and in a preparation of Tradescantia cells, 2.97 ± 0.35 µ. The effects of similar and larger variations in thickness upon grain count were studied in material squashed with different pressures; no marked correlation was found. The lack of correlation is explained by the geometric relation between labeled nuclei and the emulsion. By counting grains and directly measuring tritium content in a glass proportional counting tube in the same preparation, the yield of grains per disintegration was measured in Tradescantia cells and found to be 1 grain for 10.9 disintegrations with AR 10 autoradiographic film and 1 grain for 19.3 disintegrations for NTB nuclear track liquid emulsion. Latent image fading may pose a problem with long exposures; the conditions of its occurrence are as yet not well known.

Wimber, Donald E.; Quastler, Henry; Stein, Otto L.; Wimber, Doris R.

1960-01-01

190

Buttercup squash provides a marketable alternative to blue hubbard as a trap crop for control of striped cucumber beetles (Coleoptera: Chrysomelidae).  

PubMed

Winter squash is a vital agricultural commodity worldwide. In the Northeastern United States, the primary insect pest is the striped cucumber beetle, Acalymma vittatum F. Using a Blue Hubbard squash (Cucurbita maxima Duchesne) perimeter trap crop system can reduce insecticide use by >90% in butternut squash (C. moschata Poir), the primary winter squash grown in this region. Despite the savings in insecticide costs, growers may be reluctant to give up field space for a perimeter crop of Blue Hubbard squash, which comprises only 5% of the winter squash market in New England as compared with 19% for buttercup squash. Finding a more marketable trap crop would lower the barrier for adoption of this system. We tested eight varieties of three species of cucurbits for attractiveness to beetles relative to Blue Hubbard and butternut squash, and chose buttercup squash as the most promising replacement. We compared the effect of a buttercup border, Blue Hubbard border, or control (no border) on beetle numbers, herbivory, insecticide use, pollination, and pollen limitation in the main crop. We found that buttercup squash performed equally well as Blue Hubbard as a trap crop, with 97% reduction in total insecticide use compared with control fields. Honey bees (Apis mellifera L.) and squash bees (Peponapis pruinosa Say) were the predominant pollinators, and border treatments did not affect visitation. Hand pollination did not increase reproduction or yield, indicating that natural pollination was sufficient for full yield. This study confirms the effectiveness of perimeter trap crop systems and offers growers a more marketable trap crop for managing cucumber beetle damage. PMID:22182562

Cavanagh, Andrew F; Adler, Lynn S; Hazzard, Ruth V

2010-12-01

191

A virus and its vector, pepper yellow leaf curl virus and Bemisia tabaci , two new invaders of Indonesia  

Microsoft Academic Search

Bemisia tabaci is a species of sap-sucking insect belonging to the Aleyrodidae and are commonly known as whiteflies. The species is made\\u000a up of a complex of distinct genetic groups which have a strong geographic pattern to their genetic structure. Two members\\u000a of this complex known as the B and Q biotypes have proven to be particularly invasive, spreading with

Paul J. De Barro; Sri Hendrastuti Hidayat; Don Frohlich; Siti Subandiyah; Shigenori Ueda

2008-01-01

192

Regulation of Compound Leaf Development by PHANTASTICA in Medicago truncatula1[C][W][OPEN  

PubMed Central

Plant leaves, simple or compound, initiate as peg-like structures from the peripheral zone of the shoot apical meristem, which requires class I KNOTTED-LIKE HOMEOBOXI (KNOXI) transcription factors to maintain its activity. The MYB domain protein encoded by the ASYMMETRIC LEAVES1/ROUGH SHEATH2/PHANTASTICA (ARP) gene, together with other factors, excludes KNOXI gene expression from incipient leaf primordia to initiate leaves and specify leaf adaxial identity. However, the regulatory relationship between ARP and KNOXI is more complex in compound-leafed species. Here, we investigated the role of ARP and KNOXI genes in compound leaf development in Medicago truncatula. We show that the M. truncatula phantastica mutant exhibited severe compound leaf defects, including curling and deep serration of leaf margins, shortened petioles, increased rachises, petioles acquiring motor organ characteristics, and ectopic development of petiolules. On the other hand, the M. truncatula brevipedicellus mutant did not exhibit visible compound leaf defects. Our analyses show that the altered petiole development requires ectopic expression of ELONGATED PETIOLULE1, which encodes a lateral organ boundary domain protein, and that the distal margin serration requires the auxin efflux protein M. truncatula PIN-FORMED10 in the M. truncatula phantastica mutant.

Ge, Liangfa; Peng, Jianling; Berbel, Ana; Madueno, Francisco; Chen, Rujin

2014-01-01

193

Molecular characterization of Haynaldia villosa chromatin in wheat lines carrying resistance to wheat curl mite colonization  

Microsoft Academic Search

Wheat-Haynaldia villosa (L.) Schur, hybrid lines were tested as potential sources of resistance to colonization by the wheat curl mite, the vector of wheat streak mosaic virus. Two lines, Add 6V-1 and Sub 6V-1, were found to be mite-resistant. Fluorescence in situ hybridization using total genomic DNA, from H. villosa in the presence of unlabelled wheat DNA, confirmed that Add

Q. Chen; R. L. Conner; A. Laroche

1996-01-01

194

The effects of wind-stress curl on the Japan\\/East Sea circulation  

Microsoft Academic Search

The wind-driven ocean circulation of the Japan\\/East Sea (JES) is studied using a primitive-equation two-layer model forced by monthly mean climatological wind of ECMWF. The modeled circulation in the upper layer is characterized by a large basin-wide cyclonic circulation generated by the positive wind-stress curl occupying most of the JES in winter and four small gyres inside of the large

Jong-Hwan Yoon; Kazuko Abe; Tomoko Ogata; Yoichi Wakamatsu

2005-01-01

195

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

196

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

2012-07-18

197

A Triphasic Orthotropic Laminate Model for Cartilage Curling Behavior: Fixed Charge Density vs. Mechanical Properties Inhomogeneity  

PubMed Central

Osmotic pressure and associated residual stresses play important roles in cartilage development and biomechanical function. The curling behavior of articular cartilage was believed to be the combination of results from the osmotic pressure derived from fixed negative charges on proteoglycans and the structural and compositional and material property inhomogeneities within the tissue. In the present study, the in vitro swelling and curling behaviors of thin strips of cartilage were analyzed with a new structural model using the triphasic mixture theory with a collagen-proteoglycan solid matrix composed of a three-layered laminate with each layer possessing a distinct set of orthotropic properties. A conewise linear elastic matrix was also incorporated to account for the well-known tension-compression nonlinearity of the tissue. This model can account, for the first time, for the swelling-induced curvatures found in published experimental results on excised cartilage samples. The results suggest that for a charged hydrated soft tissue, such as articular cartilage, the balance of proteoglycan swelling and the collagen restraining within the solid matrix is the origin of the in situ residual stress, and that the layered collagen ultrastructure, e.g., relatively dense and with high stiffness at the articular surface, play the dominate role in determining curling behaviors of such tissues.

Wan, Leo Q.; Guo, X. Edward; Mow, Van C.

2010-01-01

198

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

PubMed Central

Recent single-molecule experiments have observed that formation of a plectonemically super-coiled 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, Sebastien

2013-01-01

199

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

PubMed

This study investigated thin layer drying of squash seeds under semi fluidized and fluidized bed conditions with initial moisture content about 83.99% (d.b.). An experimental fluidized bed dryer was also used in this study. Air temperature levels of 50, 60, 70 and 80 °C were applied in drying samples. To estimate the drying kinetic of squash seed, seven mathematical models were used to fit the experimental data of thin layer drying. Among the applied models, Two-term model has the best performance to estimate the thin layer drying behavior of the squash seeds. Fick's second law in diffusion was used to determine the effective moisture diffusivity of squash seeds. The range of calculated values of effective moisture diffusivity for drying experiments were between 0.160?×?10(-9) and 0.551?×?10(-10) m(2)/s. Moisture diffusivity values decreased as the input air temperature decreased. Activation energy values were found to be between 31.94 and 34.49 kJ/mol for 50 °C to 80 °C, respectively. The specific energy consumption for squash seeds was calculated at the boundary of 0.783?×?10(6) and 2.303?×?10(6) kJ/kg. Increasing in drying air temperature in different bed conditions led to decrease in specific energy value. Results showed that applying the semi fluidized bed condition is more effective for convective drying of squash seeds. The aforesaid drying characteristics are useful to select the best operational point of fluidized bed dryer and to precise design of system. PMID:24425968

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

2013-08-01

200

Abdominal and hip flexor muscle activity during 2 minutes of sit-ups and curl-ups.  

PubMed

Previous studies have compared muscle activity between different types of sit-ups and curl-ups. However, few have examined the exercises used by the armed forces or investigated the influence of exercise duration on muscle activation. The aim of this study was to compare abdominal and hip flexor muscle activity between the style of sit-up used by the British Army and 4 variations of a curl-up, at the start, middle, and end of a 2-minute exercise period. Surface electromyograms (EMGs) were recorded from the upper and lower rectus abdominis, external oblique, transversus abdominis and internal oblique, and the rectus femoris (RF) of 23 British Army personnel. Isometric maximal voluntary contractions were used to normalize integrated EMGs to allow them to be compared between exercises. Curl-ups with arms crossed and feet restrained produced the highest integrated EMG in all the abdominal muscles (p < 0.05). Feet-restrained sit-ups and curl-ups also resulted in significantly higher activity in the RF than in nonrestrained versions of the curl-up (p < 0.001). The significant increase observed in muscle activity between the start and the end of the exercises (p < 0.001) was deemed to be in response to a reduction in force producing capacity of existing motor units. The RF experienced the greatest increase during exercises that activated the muscle the most, that is, sit-ups and curl-ups with feet restrained (p < 0.001). Previous research has indicated that such exercises produce high shear and compressive forces in the lower back, which can be injurious. Thus, if an organization wishes to assess the endurance of abdominal muscles, rather than hip flexors, then curl-ups without restraint of the feet should be performed instead of exercises in which the feet are restrained. PMID:23207881

Burden, Adrian M; Redmond, Colin G

2013-08-01

201

Generalized Squashing Factors for Covariant Description of Magnetic Connectivity in the Solar Atmosphere  

NASA Astrophysics Data System (ADS)

The study of magnetic connectivity in the solar corona reveals a need to generalize the field line mapping technique to arbitrary geometry of the boundaries and systems of coordinates. Indeed, the global description of the connectivity in the corona requires the use of the photospheric and solar wind boundaries. Both are closed surfaces and therefore do not admit a global regular system of coordinates. At least two overlapping regular systems of coordinates (charts) for each of the boundary are necessary in this case to avoid a spherical-pole-like singularity in the coordinates of the footpoints. This implies that the basic characteristic of magnetic connectivity -- squashing degree or factor Q of elemental flux tubes (Titov et al. 2002) -- must be rewritten in covariant form. Such a covariant expression of Q is derived in this work. The derived expression is very flexible and highly efficient for describing the global magnetic connectivity in the solar corona. In addition, a general expression for a new characteristic Q_\\perp which defines a squashing of the flux tubes in the directions perpendicular to the field lines is determined. This new quantity makes it possible, first, to filter out the quasi-separatrix layers whose large values of Q are caused by a projection effect at the field lines nearly touching the photosphere. And, secondly, it allows us to identify those flux tubes whose squashing in a perpendicular direction is overridden by the projection effect. Thus, the value Q_\\perp provides a much more precise description of the volumetric properties of the magnetic field structure. The difference between Q and Q_\\perp is illustrated by comparing their distributions for the Titov-Demoulin (1999) model of a twisted magnetic configuration. This research is supported by NASA and the Center for Integrated Space Weather Modeling (an NSF Science and Technology Center).

Titov, V. S.

2006-12-01

202

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.

203

The effects of wind-stress curl on the Japan/East Sea circulation  

NASA Astrophysics Data System (ADS)

The wind-driven ocean circulation of the Japan/East Sea (JES) is studied using a primitive-equation two-layer model forced by monthly mean climatological wind of ECMWF. The modeled circulation in the upper layer is characterized by a large basin-wide cyclonic circulation generated by the positive wind-stress curl occupying most of the JES in winter and four small gyres inside of the large circulation. One of the four small gyres is cyclonic and located along the Primorskii coast. Two other small gyres located off Vladivostok form a dipole with a cylonic gyre to the east and anti-cyclonic gyre to the west. The remaining small gyre is cyclonic and located around the East Korean Bay (EKB). The gyre dipole off Vladivostok is generated by the dipole of wind-stress curl off Vladivostok. The cyclonic gyre of the dipole does not change its strength so much seasonally and plays an important role in separating the low-salinity coastal water from the coast and advecting it eastward along the Subpolar Front as subsurface low-salinity core, which spreads into the subsurface of the Tsushima Warm Current Region as the Japan/East Sea Intermediate Water. The anti-cyclonic gyre west of the cyclonic gyre of the dipole off Vladivostok generated in winter decreases much in amplitude or disappears until summer depending on parameters, interfacial friction, vertical stability, and topographic constraint. The coastal current reversal from southwestward to northeastward along the North Korean coast suggested by the ARGOS buoy deployed in summer in 1994 during the CREAMS cruise appears to be closely related with the development of this anti-cyclonic gyre. The cyclonic gyre in the EKB is generated by a dipole of wind-stress curl off the EKB and might be important for the separation of the East Korean Warm Current. The cyclonic gyre along the Primorskii coast is generated by the positive wind-stress curl northwest of Hokkaido and persists to exist throughout a year with a volume transport more than 1.0 Sv, and may explain the track of the ARGOS buoy deployed in summer in 1994 during the CREAMS cruise. It is concluded that the wind-driven surface circulation account for an important part of the circulation of the Northern JES since the modeled surface circulation seems to capture many characteristic features of the circulation in the northern JES, and the amount of volume transport of modeled circulations and gyres is comparable to the inflow transport at the Tsushima Straits.

Yoon, Jong-Hwan; Abe, Kazuko; Ogata, Tomoko; Wakamatsu, Yoichi

2005-06-01

204

Aluminum-Induced Rapid Root Inhibition and Changes in Cell-Wall Components of Squash Seedlings.  

PubMed Central

Growth of squash (Cucurbita maxima Duch.) roots was significantly inhibited by 1 mM AlCl3 as early as 1 h after the treatment. The growth inhibition was confined to the elongating zone (1-6 mm from the root tip). Chemical analysis of cell-wall polysaccharides from roots revealed that aluminum increased pectin, hemi-cellulose, and cellulose contents after 3 h of treatment. The effect of aluminum on pectin content was found in the elongating zone including the root tip, whereas change in cellulose content was confined to only nonelongating zones. Hemicellulose content increased in all of the regions along the root axis. The increase in the pectin fraction was due to the increases in uronic acids, galactose, and arabinose constituents, whereas hemicellulose content changed due to increases in glucose, xylose, galactose, and arabinose. The results clearly indicate that aluminum rapidly reduced squash root growth by inhibiting cell elongation and altering metabolism of cell-wall polysaccharides in the nonelongating zone as well as in the elongating zone.

Van, H. L.; Kuraishi, S.; Sakurai, N.

1994-01-01

205

Improved postharvest quality in patagonian squash ( Cucurbita moschata) coated with radiation depolymerized chitosan  

NASA Astrophysics Data System (ADS)

Different molecular weight chitosans were evaluated on the decay of coated Anquito squashes ( Cucurbita moschata) as well as the maintenance of the fruit quality along five storage months. The original chitosan (Mw=391 kDa, 83% DD), was depolymerized by gamma radiation. Apart from chain scission, other chemical changes were not detected by FTIR or UV-vis analyses. The molecular weight characterization of chitosans was done by size exclusion chromatography with dual light scattering and concentration detection (SEC-MALLS-RI). The coating effectiveness was evaluated on the following parameters: fungal decay incidence, weight loss, firmness, total reducing sugar, soluble solid, flesh color, carotene content, pH and titratable acidity. No sign of fungal decay was observed in squashes coated with 122 and 56 kDa chitosans, which were also the most effective treatments in reducing the weight loss. The chitosan with Mw=122 kDa was also the best treatment considering firmness, internal aspect, sugar and carotene content. Then, radiation degraded chitosan was better in C. moschata preservation than the original chitosan.

Pugliese, Maria Alicia; Goitia, Maria Teresa; Yossen, Mariana; Cifone, Norma; Agulló, Enrique; Andreucetti, Noemi

2011-12-01

206

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

207

Leaf Sequencing Method and System.  

National Technical Information Service (NTIS)

A method of delivering radiation treatment using multi-leaf collimation includes the step of providing a radiation fluence map which includes an intensity profile. The fluence map is converted into a preliminary leaf sequence, wherein the preliminary leaf...

J. Palta J. G. Li S. Kamath S. Ranka S. Sahni

2003-01-01

208

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

209

Photoreceptor for Curling Behavior in Peranema trichophorum and Evolution of Eukaryotic Rhodopsins  

PubMed Central

When it is gliding, the unicellular euglenoid Peranema trichophorum uses activation of the photoreceptor rhodopsin to control the probability of its curling behavior. From the curled state, the cell takes off in a new direction. In a similar manner, archaea such as Halobacterium use light activation of bacterio- and sensory rhodopsins to control the probability of reversal of the rotation direction of flagella. Each reversal causes the cell to change its direction. In neither case does the cell track light, as known for the rhodopsin-dependent eukaryotic phototaxis of fungi, green algae, cryptomonads, dinoflagellates, and animal larvae. Rhodopsin was identified in Peranema by its native action spectrum (peak at 2.43 eV or 510 nm) and by the shifted spectrum (peak at 3.73 eV or 332 nm) upon replacement of the native chromophore with the retinal analog n-hexenal. The in vivo physiological activity of n-hexenal incorporated to become a chromophore also demonstrates that charge redistribution of a short asymmetric chromophore is sufficient for receptor activation and that the following isomerization step is probably not required when the rest of the native chromophore is missing. This property seems universal among the Euglenozoa, Plant, and Fungus kingdom rhodopsins. The rhodopsins of animals have yet to be studied in this respect. The photoresponse appears to be mediated by Ca2+ influx.

Saranak, Jureepan; Foster, Kenneth W.

2005-01-01

210

Impact of wind stress curl on the primary production in the Humboldt Upwelling System  

NASA Astrophysics Data System (ADS)

Upwelling systems are primarily controlled by alongshore wind stress and nearshore wind stress curl. A regional model is used to determine in what extent the primary production in the Peru Current System can be driven by the spatio-temporal structure of wind forcings. Atmospheric forcings that differ in spatial resolution and in the length of the time period considered are found to produce significantly different mean surface chlorophyll distribution and subsurface circulation in key subregions. We show that strongly negative nearshore wind stress curl can control the spatial structure of the alongshore poleward undercurrent which brings nutrient-rich waters to be upwelled, hence generating a productive zone similar to satellite observations. The biological response to local wind stress variability at intraseasonal to interannual timescales is also investigated. A burst in the wind can induce a vertical displacement of the nutricline and modify nutrient input into the euphotic zone, as well as a deepening of the mixed-layer depth and increase dilution and light limitation. These two mechanisms, leading to opposite impact on the coastal productivity are investigated and quantified.

Albert, Aurélie; Echevin, Vincent; Lévy, Marina

2010-05-01

211

Sphingolipid Long-Chain Base Synthesis in Plants (Characterization of Serine Palmitoyltransferase Activity in Squash Fruit Microsomes).  

PubMed Central

The activity of serine palmitoyltransferase (palmitoyl-coenzyme A [CoA]:L-serine [Ser]-C-palmitoyltransferase [decarboxylating], EC 2.3.1.50), the enzyme catalyzing the first step in the synthesis of the long-chain base required for sphingolipid assembly, has been characterized in a plant system. Enzyme activity in a microsomal membrane fraction from summer squash fruit (Cucurbita pepo L. cv Early Prolific Straightneck) was assayed by monitoring the incorporation of L-[3H]Ser into the chloroform-soluble product, 3-ketosphinganine. Addition of NADPH to the assay system resulted in the conversion of 3-ketosphinganine to sphinganine. The apparent Km for Ser was approximately 1.8 mM. The enzyme exhibited a strong preference for palmitoyl-CoA, with optimal activity at a substrate concentration of 200 [mu]M. Pyridoxal 5[prime]-phosphate was required as a coenzyme. The pH optimum was 7.6, and the temperature optimum was 36 to 40[deg]C. Enzyme activity was greatest in the microsomal fraction obtained by differential centrifugation and was localized to the endoplasmic reticulum using marker enzymes. Two known mechanism-based inhibitors of the mammalian enzyme, L-cycloserine and [beta]-chloro-L-alanine, were effective inhibitors of enzyme activity in squash microsomes. Changes in enzyme activity with size (age) of squash fruit were observed. The results from this study suggest that the properties and catalytic mechanism of Ser palmitoyltransferase from squash are similar to those of the animal, fungal, and bacterial enzyme in most respects. The specific activity of the enzyme in squash microsomes ranged from 0.57 to 0.84 nmol min-1 mg-1 of protein, values 2- to 20-fold higher than those previously reported for preparations from animal tissues.

Lynch, D. V.; Fairfield, S. R.

1993-01-01

212

Nucleostemin-like 1 is required for embryogenesis and leaf development in Arabidopsis.  

PubMed

Arabidopsis NSN1 encodes a nucleolar GTP-binding protein and is required for flower development. Defective flowers were formed in heterozygous nsn1/+ plants. Homozygous nsn1 plants were dwarf and exhibited severe defects in reproduction. Arrests in embryo development in nsn1 could occur at any stage of embryogenesis. Cotyledon initiation and development during embryogenesis were distorted in nsn1 plants. At the seedling stage, cotyledons and leaves of nsn1 formed upward curls. The curled leaves developed meristem-like outgrowths or hyperplasia tissues in the adaxial epidermis. Long and enlarged pavement cells, characteristic of the abaxial epidermis of wild type plants, were found in the adaxial epidermis in nsn1 leaves, suggesting a disoriented leaf polarity in the mutant. The important role of NSN1 in embryo development and leaf differentiation was consistent with the high level expression of the NSN1 gene in the developing embryos and the primordia of cotyledons and leaves. The CLAVATA 3 (CLV3) gene, a stem cell marker in the Arabidopsis shoot apical meristem (SAM), was expressed in expanded regions surrounding the SAM of nsn1 plants, and induced ectopically in the meristem-like outgrowths in cotyledons and leaves. The nsn1 mutation up-regulated the expression levels of several genes implicated in the meristem identity and the abaxial cell fate, and repressed the expression of other genes related to the specification of cotyledon boundary and abaxial identity. These results demonstrate that NSN1 represents a novel GTPase required for embryogenesis, leaf development and leaf polarity establishment in Arabidopsis. PMID:22058024

Wang, Xiaomin; Xie, Bo; Zhu, Maosheng; Zhang, Zhongming; Hong, Zonglie

2012-01-01

213

DISPOSICIÓN SAGITAL DEL RAQUIS LUMBAR Y TORÁCICO EN EL EJERCICIO DE CURL DE BÍCEPS CON BARRA EN BIPEDESTACIÓN Sagittal disposition of the lumbar and thoracic spine in the standing barbell Curl  

Microsoft Academic Search

Sagittal spinal curvatures of thoracic and lumbar spine were evaluated in 40 male recreational weight lifters voluntaries of private gyms (mean age: 24.6 ± 5.6 years) while relaxed stan- ding and during the standing bilateral curl bar exercise. The tho- racic kyphosis was measured at the end of sixth repetition, whi- le lumbar lordosis was measured at the end of

Pedro Ángel López Miñarro; Juan Luis Yuste Lucas; Pedro Luis Rodríguez García; Pedro A. López-Miñarro

214

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

215

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

216

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

217

Cooperation in Vira1 Movement: The Geminivirus BL1 Movement Protein Interacts with BR1 and Redirects It from the Nucleus to the'Cell Periphery  

Microsoft Academic Search

For plant viruses to systemically infect a host requires the active participation of viral-encoded movement proteins. It has been suggested that BL1 and BR1, the two movement proteins encoded by the bipartite geminivirus squash leaf curl virus (SqLCV), act cooperatively to facilitate movement of the viral single-stranded DNA genome from its site of replication in the nucleus to the cell

Anton A. Sanderfoot; Sondra G. Lazarowitz

1995-01-01

218

Generalized Squashing Factors for Covariant Description of Magnetic Connectivity in the Solar Corona  

NASA Technical Reports Server (NTRS)

The study of magnetic connectivity in the solar corona reveals a need to generalize the field line mapping technique to arbitrary geometry of the boundaries and systems of coordinates. Indeed, the global description of the connectivity in the corona requires the use of the photospheric and solar wind boundaries. Both are closed surfaces and therefore do not admit a global regular system of coordinates. At least two overlapping regular systems of coordinates for each of the boundaries are necessary in this case to avoid spherical-pole-like singularities in the coordinates of the footpoints. This implies that the basic characteristic of magnetic connectivity-the squashing degree or factor Q of elemental flux tubes, according to Titov and coworkers-must be rewritten in covariant form. Such a covariant expression of Q is derived in this work. The derived expression is very flexible and highly efficient for describing the global magnetic connectivity in the solar corona. In addition, a general expression for a new characteristic Q1, which defines a squashing of the flux tubes in the directions perpendicular to the field lines, is determined. This new quantity makes it possible to filter out the quasi-separatrix layers whose large values of Q are caused by a projection effect at the field lines nearly touching the photosphere. Thus, the value Q1 provides a much more precise description of the volumetric properties of the magnetic field structure. The difference between Q and Q1 is illustrated by comparing their distributions for two configurations, one of which is the Titov-Demoulin model of a twisted magnetic field.

Titov, V. S.

2007-01-01

219

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

220

Unclosed HIV-1 Capsids Suggest a Curled Sheet Model of Assembly  

PubMed Central

The RNA genome of retroviruses is encased within a protein capsid. To gather insight into the assembly and function of this capsid, we used electron cryotomography to image human immunodeficiency virus (HIV) and equine infectious anemia virus (EIAV) particles. While the majority of viral cores appeared closed, a variety of unclosed structures including rolled sheets, extra flaps, and cores with holes in the tip were also seen. Simulations of nonequilibrium growth of elastic sheets recapitulated each of these aberrations and further predicted the occasional presence of seams, for which tentative evidence was also found within the cryotomograms. To test the integrity of viral capsids in vivo, we observed that ?25% of cytoplasmic HIV complexes captured by TRIM5? had holes large enough to allow internal green fluorescent protein (GFP) molecules to escape. Together, these findings suggest that HIV assembly at least sometimes involves the union in space of two edges of a curling sheet and results in a substantial number of unclosed forms.

Yu, Zhiheng; Dobro, Megan J.; Woodward, Cora L.; Levandovsky, Artem; Danielson, Cindy M.; Sandrin, Virginie; Shi, Jiong; Aiken, Christopher; Zandi, Roya; Hope, Thomas J.; Jensen, Grant J.

2012-01-01

221

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

222

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

223

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

224

Deer predation on leaf miners via leaf abscission.  

PubMed

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. PMID:18004533

Yamazaki, Kazuo; Sugiura, Shinji

2008-03-01

225

Transmission of cucumber leaf spot virus by Olpidium radicale.  

PubMed

The ability of zoospores of four cultures of Olpidium radicale and one of O. brassicae to transmit viruses acquired in vitro from dilute virus solutions was compared. Transmission was demonstrated by infectivity and serological assays of the roots of cucumber seedlings 6 days after inoculation. A bulk culture of O. radicale, from cucumber plant roots collected near Nantes, France, a single-sporangial culture derived from it, and a single-sporangial culture from melon plant roots collected near Woodland, California, U.S.A., transmitted cucumber leaf spot virus (CLSV) and the cucumber fruit streak strain of CLSV (CLSV-FS). A bulk culture of O. radicale from melon plant roots collected at Montfavet, France, did not transmit CLSV or CLSV-FS. All four cultures transmitted cucumber necrosis and melon necrotic spot viruses, used as positive controls, but they did not transmit cucumber soil-borne, squash necrosis, petunia asteroid mosaic or tobacco necrosis viruses. In each of the trials a single-sporangial culture of O. brassicae from lettuce plant grown in California transmitted only tobacco necrosis virus. PMID:1765774

Campbell, R N; Lecoq, H; Wipf-Scheibel, C; Sim, S T

1991-12-01

226

Sphingolipid Long-Chain Base Synthesis in Plants' Characterization of Serine Palmitoyltransferase Activity in Squash Fruit Microsomes  

Microsoft Academic Search

lhe activity of serine palmitoyltransferase (palmitoyl-coenzyme A (CoA):i-serine (Ser)-C-palmitoyltransferase (decarboxylating), EC 2.3.1.50), the enzyme catalyzing the first step in the synthesis of the long-chain base required for sphingolipid assembly, has been characterized in a plant system. Enzyme activity in a micro- soma1 membrane fraction from summer squash fruit (Cucurbita pepo 1. cv Early Prolific Straightneck) was assayed by monitoring the

Daniel V. Lynch; Scott R. Fairfield

227

Effect of ambient storage on the quality characteristics of aerobically packaged fish curls incorporated with different flours.  

PubMed

The present study was conducted to evaluate the effect of ambient storage on the quality attributes of aerobically packaged fish curls incorporated with optimum levels of different flours. The curls were developed by extrusion technology using fish meat (Catla catla). The fish curls containing optimum levels of different flours viz. 20 percent corn flour, 10 percent black gram flour and 10 percent peanut flour were compared with the control snacks containing 30 percent rice flour and assessed for storage quality and shelf life at ambient temperature. The curls were aerobically packaged in LDPE (low density polyethylene) pouches and evaluated for various physicochemical, microbiological and sensory parameters. Mean values of pH of all the curls showed significantly (p?curls incorporated with optimum level of different flours were acceptable up to 21 days of ambient storage within the LDPE pouches. PMID:24624316

Raja, Waseem Hussain; Kumar, Sunil; Bhat, Zuhaib Fayaz; Kumar, Pavan

2014-01-01

228

Extracting the Young's Modulus and Stress Gradient of Thin Films from the Pull-in Voltage of a Micro Curled Cantilever Beam  

Microsoft Academic Search

This paper presents a high-precision algorithm for extracting the Young's modulus and stress gradient of thin films from the pull-in voltage measurement of a micro curled cantilever beam made of thin film materials. The algorithm considers the important issues including the fringing fields, the electromechanical coupling, and the stress-induced initial curling of the micro structures. The deviation of the extracted

Yuh-Chung Hu; Chung-Sheng Wei; Chun-Ching Hsiao; D. T. W. Li

2007-01-01

229

Numerical study on the curling and warping of hardened rigid pavement slabs  

NASA Astrophysics Data System (ADS)

In-service hardened concrete pavement suffers from environmental loadings caused by curling and warping of the slab. Traditionally, these loadings are computed on the basis of treating the slab as an elastic material, and of evaluating separately the curling and warping components. This dissertation simulates temperature distribution and moisture distribution through the slabs by use of a developed numerical model that couples the heat transfer and moisture transport. The computation of environmental loadings treats the slab as an elastic-viscous material, which considers the relaxation behavior and Pickett effect of the concrete. The heat transfer model considers the impacts of solar radiation, wind speed, air temperature, pavement slab albedo, etc. on the pavement temperature distribution. This dissertation assesses the difference between documented models that aim to predict pavement temperature, highlighting their pros and cons. The moisture transport model is unique for the documented models; it mimics the wetting and drying events occurring at the slab surface. These events are estimated by a proposed statistical algorithm, which is verified by field rainfall data. Analysis of the predicted results examines on the roles of the local air RH (relative humidity), wind speed, rainy pattern in the moisture distribution through the slab. The findings reveal that seasonal air RH plays a decisive role on the slab's moisture distribution; but wind speed and its daily variation, daily RH variation, and seasonal rainfall pattern plays only a secondary role. This dissertation sheds light on the computation of environmental loadings that in-service pavement slabs suffer from. Analysis of the computed stresses centers on the stress relaxation near the surface, stress evolution after the curing ends, and the impact of construction season on the stress's magnitude. An unexpected finding is that the total environmental loadings at the cyclically-stable state divert from the thermal stresses. At such a state, the total stress at the daytime is roughly equal to the thermal stress; whereas the total stress during the nighttime is far greater than the thermal stress. An explanation for this phenomenon is that during the night hours, the decline of the slab's near-surface temperature leads to a drop of the near-surface RH. This RH drop results in contraction therein and develops additional tensile stresses. The dissertation thus argues that estimating the environmental loadings by solely computing the thermally-induced stresses may reach delusive results. It recommends that the total environmental loadings of in-service slabs should be estimated by a sophisticated model coupling both moisture component and temperature component.

Qin, Yinghong

230

Stem and Leaf Plot  

NSDL National Science Digital Library

This site, created by Michelle Lacey of Yale University, gives a definition and an example of stem and leaf plots. The author helps to explain how these graphs are used, and in what fields and/or disciplines. Even though brief, this is still a valuable reference item for anyone interested in statistics.

Lacey, Michelle

2009-11-23

231

Maple Leaf Outdoor Centre.  

ERIC Educational Resources Information Center

Maple Leaf Outdoor Centre (Ontario) has added year-round outdoor education facilities and programs to help support its summer camp for disadvantaged children. Schools, youth centers, religious groups, and athletic teams conduct their own programs, collaborate with staff, or use staff-developed programs emphasizing adventure education and personal…

Maguire, Molly; Gunton, Ric

2000-01-01

232

Molecular characterization of Haynaldia villosa chromatin in wheat lines carrying resistance to wheat curl mite colonization.  

PubMed

Wheat-Haynaldia villosa (L.) Schur, hybrid lines were tested as potential sources of resistance to colonization by the wheat curl mite, the vector of wheat streak mosaic virus. Two lines, Add 6V-1 and Sub 6V-1, were found to be mite-resistant. Fluorescence in situ hybridization using total genomic DNA, from H. villosa in the presence of unlabelled wheat DNA, confirmed that Add 6V-1 is a disomic wheat-H. villosa chromosome addition line. Sub 6V-1 turned out to be a homoeologous wheat-H. villosa chromosome translocation line rather than a substitution. The translocation in Sub 6V-1 occurred between a wheat chromosome and a chromosome from H. villosa through Robertsonian fusion of misdivided centromeres. Only the short arm of the group 6 chromosome of H. villosa was involved in the genetic control of mite resistance, a conclusion based on the genomic in situ hybridization signal and specific DNA fragments obtained by polymerase chain reaction. PMID:24162394

Chen, Q; Conner, R L; Laroche, A

1996-10-01

233

Movement of soil-applied imidacloprid and thiamethoxam into nectar and pollen of squash (Cucurbita pepo).  

PubMed

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. PMID:22761727

Stoner, Kimberly A; Eitzer, Brian D

2012-01-01

234

Inhibition of human beta-factor XIIa by squash family serine proteinase inhibitors.  

PubMed

Many inhibitors of trypsin and human beta-factor XIIa have been isolated from squash and related seeds and sequenced (Wieczorek et al., Biochem. Biophys. Res. Comm. (1985) 126, 646-652). The association equilibrium constants (Ka) of several of these inhibitors have now been determined with human beta-factor XIIa using a modification of the method of Green and Work (Park et al., Fed. Proc. Fed. Am. Soc. Exp. Biol. (1984) 43, 1962). The Ka's range from 7.8 x 10(4) M-1 to 3.3 x 10(8) M-1. Two isoinhibitors from Cucurbita maxima seeds, CMTI-I and CMTI-III, differ in only a single glutamate to lysine change in the P'4 position. This results in a factor of 62 increase in the Ka of the lysine inhibitor, CMTI-III (Ka = 3.3 x 10(8) M-1). To our knowledge, this is the largest effect ever seen for a residue substitution at the P'4 position of a serine proteinase inhibitor. The result is even more surprising because beta-factor XIIa's natural substrate, Factor XI, contains Gly in the P'4 position. PMID:2306254

Wynn, R; Laskowski, M

1990-02-14

235

Partitioning Yield Loss on Yellow Squash into Nematode and Insect Components  

PubMed Central

The effect of a contplex of several insect and nematode pests on yield of yellow squash (Cucurbita pepo L.) was examined in two field tests in southern Florida. Applications of permethrin for insect control and oxamyl primarily for nematode control plus some insect control were made alone and in combination to achieve differential reduction of various insect and nematode components contributing to yield loss. The effect of these components on yield was further analyzed by multiple regression. Yield losses in weight of small fruit to nematode and insect pests together were estimated at 23.4% and 30.4% in each of the two tests, respectively. In the first test, this loss was attributed to the melonworm, Diaphania hyalinata, while in the second test, it was attributed to D. hyalinata and the nematodes Quinisulcius acutus and particularly Rotylenchulus reniforrnis. D. hyalinata accounted for further losses of 9.0% and 10.3%, respectively, from direct damage to the fruit. Despite the presence of low levels of Diabrotica balteata, Liriomyza sativae, and Myzus persicae, yields were little affected by these pests. Prediction of yield loss by multiple regression analysis was more accurate when both insect and nematode populations were present in the plots than when nematodes alone were present.

McSorley, R.; Waddill, V. H.

1982-01-01

236

Smooth, Squashed And Rotating: Not The Stellar Halo We Used To Know  

NASA Astrophysics Data System (ADS)

The phase-space structure of the stellar halo is intimately linked to the formation history of the Galaxy. In this talk I will discuss the rotation properties and spatial structure of the stellar halo as traced by Blue Horizontal Branch (BHB) stars. Using SDSS spectroscopic data I find an apparent dichotomy between relatively metal-rich and metal-poor stars. I argue that a retrograde signal in the metal-poor stars is due to an underestimate of the Local Standard or Rest while the kinematic signature of the metal-rich stars may be linked to a (massive) accretion event. In addition, I introduce a new method to discern BHB stars from Blue Straggler stars using a colour dependent membership probability, thus circumventing the need for spectroscopic data. This new method is applied to a sample of A-type stars selected from the latest SDSS DR8 photometric catalog. I find that the (inner) stellar halo is 'squashed, broken but smooth' and discuss the implications of this result. Finally, I compare these observational results to state-of-the-art cosmological simulations.

Deason, Alis J.; Belokurov, V.; Evans, N. W.

2012-01-01

237

Partitioning yield loss on yellow squash into nematode and insect components.  

PubMed

The effect of a contplex of several insect and nematode pests on yield of yellow squash (Cucurbita pepo L.) was examined in two field tests in southern Florida. Applications of permethrin for insect control and oxamyl primarily for nematode control plus some insect control were made alone and in combination to achieve differential reduction of various insect and nematode components contributing to yield loss. The effect of these components on yield was further analyzed by multiple regression. Yield losses in weight of small fruit to nematode and insect pests together were estimated at 23.4% and 30.4% in each of the two tests, respectively. In the first test, this loss was attributed to the melonworm, Diaphania hyalinata, while in the second test, it was attributed to D. hyalinata and the nematodes Quinisulcius acutus and particularly Rotylenchulus reniforrnis. D. hyalinata accounted for further losses of 9.0% and 10.3%, respectively, from direct damage to the fruit. Despite the presence of low levels of Diabrotica balteata, Liriomyza sativae, and Myzus persicae, yields were little affected by these pests. Prediction of yield loss by multiple regression analysis was more accurate when both insect and nematode populations were present in the plots than when nematodes alone were present. PMID:19295683

McSorley, R; Waddill, V H

1982-01-01

238

Curl flux, coherence, and population landscape of molecular systems: Nonequilibrium quantum steady state, energy (charge) transport, and thermodynamics.  

PubMed

We established a theoretical framework in terms of the curl flux, population landscape, and coherence for non-equilibrium quantum systems at steady state, through exploring the energy and charge transport in molecular processes. The curl quantum flux plays the key role in determining transport properties and the system reaches equilibrium when flux vanishes. The novel curl quantum flux reflects the degree of non-equilibriumness and the time-irreversibility. We found an analytical expression for the quantum flux and its relationship to the environmental pumping (non-equilibriumness quantified by the voltage away from the equilibrium) and the quantum tunneling. Furthermore, we investigated another quantum signature, the coherence, quantitatively measured by the non-zero off diagonal element of the density matrix. Populations of states give the probabilities of individual states and therefore quantify the population landscape. Both curl flux and coherence depend on steady state population landscape. Besides the environment-assistance which can give dramatic enhancement of coherence and quantum flux with high voltage at a fixed tunneling strength, the quantum flux is promoted by the coherence in the regime of small tunneling while reduced by the coherence in the regime of large tunneling, due to the non-monotonic relationship between the coherence and tunneling. This is in contrast to the previously found linear relationship. For the systems coupled to bosonic (photonic and phononic) reservoirs the flux is significantly promoted at large voltage while for fermionic (electronic) reservoirs the flux reaches a saturation after a significant enhancement at large voltage due to the Pauli exclusion principle. In view of the system as a quantum heat engine, we studied the non-equilibrium thermodynamics and established the analytical connections of curl quantum flux to the transport quantities such as energy (charge) transfer efficiency, chemical reaction efficiency, energy dissipation, heat and electric currents observed in the experiments. We observed a perfect transfer efficiency in chemical reactions at high voltage (chemical potential difference). Our theoretical predicted behavior of the electric current with respect to the voltage is in good agreements with the recent experiments on electron transfer in single molecules. PMID:24985680

Zhang, Z D; Wang, J

2014-06-28

239

Barley leaf stripe disease.  

PubMed

Leaf stripe is one of the most important diseases of barley in Iran especially in Gorgan, Mazandran and near Tehran (Varamin). Most obvious symptoms of the disease are described. Long pale or yellow stripes become darker as the fungus sporulates on the leaf surface. Infected plants usually are stunted and produce sterile spikes, rarely a few seeds are produced. Infected spikes and late-forming tillers may produce fertile spikes. The fungus is seed brone and survives in the outer layers of infected seed. To study the seed-borne disease, we have used the different methods (ISTA). Coleoptiles of seedlings are infected by the fungus under cool, moist conditions, a soil temperature below 15 degrees C is necessary for seed infection. The fungus penetrates through coleoptiles and grows systemically within the plant, produces toxin and kills cells and discolors leaf tissue between veins, thus causing striped lesions. When conditions are wet or humid, spores are produced on the surface of leaves at above the time spikes of healthy plant. Morphological characteristics of the vegetative and reproductive structures of the fungus show that it is Drechslera graminea (Rabenh) Shoemaker. PMID:12701433

Zad, J; Aghakhani, M; Etebarian, R; Okhovat, M

2002-01-01

240

Amino-acid sequence of two trypsin isoinhibitors, ITD I and ITD III from squash seeds (Cucurbita maxima).  

PubMed

The amino-acid sequences of two trypsin isoinhibitors, ITD I and ITD III, from squash seeds (Cucurbita maxima) were determined. Both isoinhibitors contain 29 amino-acid residues, including 6 half cystine residues. They differ only by one amino acid. Lysine in position 9 of ITD III is substituted by glutamic acid in ITD I. Arginine in position 5 is present at the reactive site of both isoinhibitors. The previously published sequence of ITD III has been shown to be incorrect. PMID:6840699

Wilusz, T; Wieczorek, M; Polanowski, A; Denton, A; Cook, J; Laskowski, M

1983-01-01

241

Wheat curl mite, Aceria tosichella, and transmitted viruses: an expanding pest complex affecting cereal crops.  

PubMed

The wheat curl mite (WCM), Aceria tosichella, and the plant viruses it transmits represent an invasive mite-virus complex that has affected cereal crops worldwide. The main damage caused by WCM comes from its ability to transmit and spread multiple damaging viruses to cereal crops, with Wheat streak mosaic virus (WSMV) and Wheat mosaic virus (WMoV) being the most important. Although WCM and transmitted viruses have been of concern to cereal growers and researchers for at least six decades, they continue to represent a challenge. In older affected areas, for example in North America, this mite-virus complex still has significant economic impact. In Australia and South America, where this problem has only emerged in the last decade, it represents a new threat to winter cereal production. The difficulties encountered in making progress towards managing WCM and its transmitted viruses stem from the complexity of the pathosystem. The most effective methods for minimizing losses from WCM transmitted viruses in cereal crops have previously focused on cultural and plant resistance methods. This paper brings together information on biological and ecological aspects of WCM, including its taxonomic status, occurrence, host plant range, damage symptoms and economic impact. Information about the main viruses transmitted by WCM is also included and the epidemiological relationships involved in this vectored complex of viruses are also addressed. Management strategies that have been directed at this mite-virus complex are presented, including plant resistance, its history, difficulties and advances. Current research perspectives to address this invasive mite-virus complex and minimize cereal crop losses worldwide are also discussed. PMID:23179064

Navia, Denise; de Mendonça, Renata Santos; Skoracka, Anna; Szyd?o, Wiktoria; Knihinicki, Danuta; Hein, Gary L; da Silva Pereira, Paulo Roberto Valle; Truol, Graciela; Lau, Douglas

2013-02-01

242

Giardia Cyst Wall Protein 1 Is a Lectin That Binds to Curled Fibrils of the GalNAc Homopolymer  

PubMed Central

The infectious and diagnostic stage of Giardia lamblia (also known as G. intestinalis or G. duodenalis) is the cyst. The Giardia cyst wall contains fibrils of a unique ?-1,3-linked N-acetylgalactosamine (GalNAc) homopolymer and at least three cyst wall proteins (CWPs) composed of Leu-rich repeats (CWPLRR) and a C-terminal conserved Cys-rich region (CWPCRR). Our goals were to dissect the structure of the cyst wall and determine how it is disrupted during excystation. The intact Giardia cyst wall is thin (?400 nm), easily fractured by sonication, and impermeable to small molecules. Curled fibrils of the GalNAc homopolymer are restricted to a narrow plane and are coated with linear arrays of oval-shaped protein complex. In contrast, cyst walls of Giardia treated with hot alkali to deproteinate fibrils of the GalNAc homopolymer are thick (?1.2 µm), resistant to sonication, and permeable. The deproteinated GalNAc homopolymer, which forms a loose lattice of curled fibrils, is bound by native CWP1 and CWP2, as well as by maltose-binding protein (MBP)-fusions containing the full-length CWP1 or CWP1LRR. In contrast, neither MBP alone nor MBP fused to CWP1CRR bind to the GalNAc homopolymer. Recombinant CWP1 binds to the GalNAc homopolymer within secretory vesicles of Giardia encysting in vitro. Fibrils of the GalNAc homopolymer are exposed during excystation or by treatment of heat-killed cysts with chymotrypsin, while deproteinated fibrils of the GalNAc homopolymer are degraded by extracts of Giardia cysts but not trophozoites. These results show the Leu-rich repeat domain of CWP1 is a lectin that binds to curled fibrils of the GalNAc homopolymer. During excystation, host and Giardia proteases appear to degrade bound CWPs, exposing fibrils of the GalNAc homopolymer that are digested by a stage-specific glycohydrolase.

Chatterjee, Aparajita; Carpentieri, Andrea; Ratner, Daniel M.; Bullitt, Esther; Costello, Catherine E.; Robbins, Phillips W.; Samuelson, John

2010-01-01

243

Vector wind, horizontal divergence, wind stress and wind stress curl from SEASAT-SASS at one degree resolution  

NASA Technical Reports Server (NTRS)

Conventional data obtained in 1983 are contrasted with SEASAT-A scatterometer and scanning multichannel microwave radiometer (SMMR) data to show how observations at a single station can be extended to an area of about 150,000 square km by means of remotely sensed data obtained in nine minutes. Superobservations at a one degree resolution for the vector winds were estimated along with their standard deviations. From these superobservations, the horizontal divergence, vector wind stress, and the curl of the wind stress can be found. Weather forecasting theory is discussed and meteorological charts of the North Pacific Ocean are presented. Synoptic meteorology as a technique is examined.

Pierson, W. J., Jr.; Sylvester, W. B.; Salfi, R. E.

1984-01-01

244

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

245

Molecular characterization of a new begomovirus that infects Euphorbia heterophylla and Solanum lycopersicum in Venezuela.  

PubMed

We report the complete nucleotide sequence of a begomovirus isolate infecting Euphorbia heterophylla and tomato (Solanum lycopersicum) in central Venezuela. Based on the current taxonomic criteria for the genus Begomovirus, the isolate was shown to represent a novel species, tentatively named Euphorbia mosaic Venezuela virus (EuMVV). Its DNA-A is most closely related to those of Euphorbia-infecting begomoviruses from the Caribbean and Central America. The DNA B component forms a phylogenetic cluster with Euphorbia and Sida-infecting begomoviruses from the squash leaf curl virus (SLCV) cluster. EuMVV is transmissible to S. lycopersicum and Capsicum annuum by biolistics of infectious cloned DNA-A and DNA-B components and induces characteristic leaf downward curling and yellowing in S. lycopersicum and and yellowing and leaf distortion in Capsicum annuum. PMID:22052541

Zambrano, Karla; Fernández-Rodríguez, Thaly; Marys, Edgloris

2012-02-01

246

Trapping of Tomato yellow leaf curl virus (TYLCV) and other plant viruses with a GroEL homologue from the whitefly Bemisia tabaci  

Microsoft Academic Search

Summary. To avoid destruction in the haemolymph of their vector, many plant circulative viruses interact with GroEL homologues produced by insect endosymbiotic bacteria. We have exploited this phenomenon to devise tools allowing trapping of plant viruses by either GroEL purified from the whitefly Bemisia tabaci or by whitefly GroEL over-expressed in E. coli. PCR tubes or 96-well plates coated with

F. Akad; N. Dotan; H. Czosnek

2004-01-01

247

A review of the mechanisms and components that determine the transmission efficiency of Tomato yellow leaf curl virus (Geminiviridae; Begomovirus) by its whitefly vector.  

PubMed

Begomoviruses are a group of icosahedral single stranded DNA viruses exclusively transmitted by the sweet potato whitefly Bemisia tabaci in a persistent, circulative manner. In this mode of transmission, begomoviruses are acquired by their insect vector as intact virions from the plant phloem, move along the food canal, foregut and esophagus and reach the midgut where they are absorbed into the hemolymph via the filter chamber. The filter chamber is the site where most of the ingested food is filtered, and the first site where the majority of begomoviruses appear to be translocated into the hemolymph via unknown proteins or receptors. Transport from the filter chamber to the hemolymph is aided by a Heat Shock Protein 70. Virus particles not translocated across the filter chamber circulate in the midgut loop but it is not known whether absorption into the hemolymph occurs along this loop. Localization studies have confirmed that begomoviruses are not associated with the hindgut and absorption of virions in this organ is unlikely. In the hemolymph, virions have been shown to interact with a GroEL chaperone produced by the whitefly's endosymbiontic bacteria for ensuring their safe journey to the salivary glands. Virions penetrate the primary salivary glands via unknown proteins or receptors and are transported and secreted outside the whitefly to the plant with salivary secretions. Several recent studies have demonstrated the implications of insect and endosymbiont proteins such as the heat shock protein 70 and the bacterial GroEL protein, in the transmission of begomoviruses by B. tabaci. Additional studies attempting to identify other proteins that aid or interact with begomoviruses along their circulation pathway in the whitefly are reviewed in this paper. PMID:24508344

Ghanim, Murad

2014-06-24

248

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

249

?C1, the pathogenicity factor of TYLCCNV, interacts with AS1 to alter leaf development and suppress selective jasmonic acid responses  

PubMed Central

Viruses induce pathogenic symptoms on plants but the molecular basis is poorly understood. Here, we show that transgenic Arabidopsis expressing the pathogenesis protein ?C1 of Tomato yellow leaf curl China virus (TYLCCNV), a geminivirus, can phenocopy to a large extent disease symptoms of virus-infected tobacco plants in having upward curled leaves, radialized leaves with outgrowth tissues from abaxial surfaces, and sterile flowers. These morphological changes are paralleled by a reduction in miR165/166 levels and an increase in PHB and PHV transcript levels. Two factors, ASYMMETRIC LEAVES 1 (AS1) and ASYMMETRIC LEAVES 2 (AS2), are known to regulate leaf development as AS1/AS2 complex. Strikingly, ?C1 plants phenocopy plants overexpressing AS2 at the morphological and molecular level and ?C1 is able to partially complement as2 mutation. ?C1 binds directly to AS1, elicits morphological and gene expression changes dependent on AS1 but not AS2, and attenuates expression of selective jasmonic acid (JA)-responsive gene. Our results show that ?C1 forms a complex with AS1 to execute its pathogenic functions and to suppress a subset of JA responses.

Yang, Jun-Yi; Iwasaki, Mayumi; Machida, Chiyoko; Machida, Yasunori; Zhou, Xueping; Chua, Nam-Hai

2008-01-01

250

Remote Sensing of Leaf Water Content in the Near Infrared.  

National Technical Information Service (NTIS)

A stochastic leaf radiation model was used to predict leaf spectral reflectance as a function of leaf water content for a dicot leaf. Simulated spectral reflectances, corresponding to different leaf water contents or equivalent water thicknesses, were ana...

C. J. Tucker

1979-01-01

251

The Gürün Curl, SE Turkey: a potential link from crustal tectonics to mantle dynamics in the Arabia-Eurasia collision-escape zone  

NASA Astrophysics Data System (ADS)

The Anatolian plate is an active orogen in which spatial and temporal transitions between subduction, collision, and escape dynamics can be evaluated. Within the scope of the Continental Dynamics - Central Anatolian Tectonics project (CD-CAT), integrated efforts are combined to explore connections between surface and deep mantle as Anatolia transitioned from subduction to escape. In this study, we investigate a portion of this system that is situated between the Central Anatolian Fault Zone in the NW and East Anatolian Fault Zone in the SE. In this area, Paleozoic-Mesozoic platform carbonates, ophiolitic rocks and their Cenozoic volcano-sedimentary cover form a ~50 km wide belt oriented NE-SW in the west and curving toward the east and then toward the south in the east. The core of this structure comprises the Binbo?a metamorphic massif and the Göksun ophiolite, and the outer rim is delimited by the Kangal and Malatya basins which are filled with Neogene sediments and volcanics. We call this large structure the 'Gürün Curl' for its curved shape; it is ~200 km long and ~250 km wide. The origin of the Gürün Curl and its potential connection with deep processes are investigated using a multi-disciplinary approach. The main questions we would like to address are the following: what exactly defines this observed curvature? Were the belts originally curved, or were they deformed into the Curl? Was it affected by topographic, crustal and/or lithospheric processes? When and how did it form? Four main fault-zones dissect the Gürün curl: three sub-parallel NNE-SSW oriented left lateral faults (from west to east, the Sariz, Gürün, and Malatya faults) and the ~E-W oriented right lateral Sürgü fault in the south. The kinematics and evolution of these faults are investigated in connection with the development and deformation of Miocene basins throughout the curl (e.g. Gürün, Darende, Elbistan basins) as well as the spatial, temporal, and geochemical evolution of mafic volcanic activity (Miocene to Pliocene alkaline and subalkaline basaltic flows present in and to the north and west of the area). Within a large network of seismic stations deployed this year for the CD-CAT project, ten of them are positioned within the Curl and will provide the opportunity to image it at depth. In the first stage of our investigation, we are testing whether this large-scale curvature could represent an originally linear feature that rotated during collision processes (orocline). To test this hypothesis, we have sampled Eocene and Miocene sedimentary rocks at three locations within the curl (west, center and east) for paleomagnetism to track the possible rotation history of the region since the Eocene.

Lefebvre, C.; Umhoefer, P. J.; Kaymakci, N.; Meijers, M. J.; Teyssier, C. P.; Whitney, D. L.; Reid, M. R.; Gencalioglu Kuscu, G.; Cosca, M. A.; Brocard, G. Y.; Rojay, B.

2013-12-01

252

Leaf trait relationships in Australian plant species  

Microsoft Academic Search

Leaf trait data were compiled for 258 Australian plant species from several habitat types dominated by woody perennials. Specific leaf area (SLA), photosynthetic capacity, dark respiration rate and leaf nitrogen (N) and phosphorus (P) concentrations were positively correlated with one another and negatively correlated with average leaf lifespan. These trait relationships were consistent with previous results from global datasets. Together,

Ian J. Wright; Philip K. Groom; Byron B. Lamont; Pieter Poot; Peter B. Reich; E-Detlef Schulze; Erik J. Veneklaas; Mark Westoby; Penrith South

2004-01-01

253

7 CFR 29.3033 - Leaf.  

Code of Federal Regulations, 2010 CFR

...2009-01-01 2009-01-01 false Leaf. 29.3033 Section 29.3033 Agriculture Regulations of the Department of Agriculture...Tobacco (u.s. Type 31 and Foreign Type 93) § 29.3033 Leaf. Whole, unstemmed leaf. Leaf, when...

2009-01-01

254

7 CFR 29.3033 - Leaf.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Leaf. 29.3033 Section 29.3033 Agriculture Regulations of the Department of Agriculture...Tobacco (u.s. Type 31 and Foreign Type 93) § 29.3033 Leaf. Whole, unstemmed leaf. Leaf, when...

2010-01-01

255

The molecular genetic analysis of leaf senescence  

Microsoft Academic Search

The cloning of genes induced during leaf senescence and the study of their modes of regulation conducted in the past two years have revealed some of the molecular mechanisms underlying leaf senescence. The identification of genetic mutants that control leaf senescence in Arabidopsis thaliana opened up new possibilities for genetically analyzing leaf senescence in a model system. Encouraging experimental data

Hong Gil Nam

1997-01-01

256

Changes in leaf hydraulic conductance correlate with leaf vein embolism in Cercis siliquastrum L  

Microsoft Academic Search

The impact of xylem cavitation and embolism on leaf ( K leaf) and stem ( K stem) hydraulic conductance was measured in current-year shoots of Cercis siliquastrum L. (Judas tree) using the vacuum chamber technique. K stem decreased at leaf water potentials (? L) lower than -1.0 MPa, while K leaf started to decrease only at ? L L K leaf

Andrea Nardini; Sebastiano Salleo; Fabio Raimondo

2003-01-01

257

The effects of different sit- and curl-up positions on activation of abdominal and hip flexor musculature.  

PubMed

The purpose of this study was to evaluate abdominal muscle activation with variations in trunk flexion (sit or curl up) positions, including the protocol currently used by the Canadian Society of Exercise Physiology (CSEP) Health and Fitness Program. Electromyographic (EMG) data were collected during isometric contractions from the upper rectus abdominis (URA), lower rectus abdominis (LRA), external obliques (EO), lower abdominal stabilizers (LAS), rectus femoris (RF), and the biceps femoris (BF) in 14 subjects. Sit-up positions were varied and randomized through 3 variables: the distance the hand traveled along the floor (5, 10, or 15 cm), bent knee or extended knee, and fixed or non-fixed feet. In regard to the distance the hand traveled along the floor, the 10 cm position produced the highest activation of the LRA (p = 0.02), the 5 cm distance produced the lowest RF activation (p = 0.001), and the 15 cm distance produced the lowest activation of the URA (p = 0.001). There was no significant difference between bent-knee and extended-leg sit-up positions; however, there was a trend (p = 0.1) showing that the bent-knee sit-up position produced higher levels of LAS activation and lower levels of RF activation. Foot fixation resulted in significantly lower activation levels of all abdominal sites and higher levels for the RF (p < 0.0001). The technique used for the CSEP Health and Fitness program partial curl- or sit-up test produced the highest or equal activation levels for all abdominal muscle sites. PMID:18923563

Parfrey, Kevin C; Docherty, David; Workman, R Chad; Behm, David G

2008-10-01

258

Relationships of leaf dark respiration to leaf nitrogen, specific leaf area and leaf life-span: a test across biomes and functional groups  

Microsoft Academic Search

Based on prior evidence of coordinated multiple leaf trait scaling, we hypothesized that variation among species in leaf\\u000a dark respiration rate (R\\u000a d) should scale with variation in traits such as leaf nitrogen (N), leaf life-span, specific leaf area (SLA), and net photosynthetic\\u000a capacity (A\\u000a max). However, it is not known whether such scaling, if it exists, is similar among

Peter B. Reich; Michael B. Walters; David S. Ellsworth; James M. Vose; John C. Volin; Charles GreshamWilliam; William D. Bowman

1998-01-01

259

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

260

Life in the Leaf Litter  

NSDL National Science Digital Library

Produced by the Center for Biodiversity and Conservation, Life in the Leaf Litter is a guide to the diversity of soil organisms and the crucial role that invertebrates play in woodland ecosystems. The booklet was based, in part, on a leaf litter survey conducted by the CBC's Metro Program and the Museum's Division of Invertebrate Zoology in Central Park's woodlands, which led to the discovery of a new genus and species of centipede, Nannarrup hoffmani. The booklet may be downloaded as a pdf or ordered free of charge.

261

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

262

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

263

Unified framework for an a posteriori error analysis of non-standard finite element approximations of H(curl)-elliptic problems  

Microsoft Academic Search

Recently, a unified framework for a residual-based a posteriori error analysis of standard conforming finite element methods as well as non-standard techniques such as nonconforming and mixed methods has been developed. This paper provides such a framework for an a posteriori error control of nonconforming finite element discretizations of H(curl)-elliptic problems as they arise from low-frequency electromagnetics. These nonconforming approximations

C. Carstensen; R. Hoppe

2009-01-01

264

CURL 10: development and field-test of a 10 kV\\/10 MVA resistive current limiter based on bulk MCP-BSCCO 2212  

Microsoft Academic Search

Within the German project CURL 10 a full scale three-phase resistive current limiter was developed and successfully tested up to the nominal voltage and power (10 kV, 10 MVA). This is up today the largest HTS current limiter world wide. The device is based on bifilar coils of MCP-BSCCO 2212 bulk material and operates at T=66 K. Per phase 30

Joachim Bock; Frank Breuer; Heribert Walter; Steffen Elschner; Martin Kleimaier; Ronald Kreutz; Mathias Noe

2005-01-01

265

System technology and test of CURL 10, a 10 kV, 10 MVA resistive high-Tc superconducting fault current limiter  

Microsoft Academic Search

A full scale three-phase resistive high-Tc superconducting fault current limiter (SCFCL) designed for 10 kV, 10 MVA, has been developed, manufactured, and tested within a publicly funded German project called CURL 10. The device is based on 90 bifilar coils of MCP BSCCO-2212 bulk material. The operating temperature of 66 K is achieved by cooling of liquid nitrogen using two

Ronald Kreutz; Joachim Bock; Frank Breuer; Klaus-Peter Juengst; Martin Kleimaier; Hans-Udo Klein; Detlef Krischel; Mathias Noe; Ralph Steingass; Karl-Heinz Weck

2005-01-01

266

7 CFR 30.2 - Leaf tobacco.  

Code of Federal Regulations, 2010 CFR

...30.2 Leaf tobacco. Tobacco in the forms in which...manufacturing processes. Leaf tobacco does not include any manufactured or semimanufactured tobacco, stems which have been removed from leaves, cuttings, clippings,...

2009-01-01

267

7 CFR 30.2 - Leaf tobacco.  

Code of Federal Regulations, 2010 CFR

...30.2 Leaf tobacco. Tobacco in the forms in which...manufacturing processes. Leaf tobacco does not include any manufactured or semimanufactured tobacco, stems which have been removed from leaves, cuttings, clippings,...

2010-01-01

268

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

269

Endoplasmic reticulum-targeted GFP reveals ER remodeling in Mesorhizobium-treated Lotus japonicus root hairs during root hair curling and infection thread formation.  

PubMed

The endoplasmic reticulum (ER) of the model legume Lotus japonicus was visualized using green fluorescent protein (GFP) fused with the KDEL sequence to investigate the changes in the root hair cortical ER in the presence or absence of Mesorhizobium loti using live fluorescence imaging. Uninoculated root hairs displayed dynamic forms of ER, ranging from a highly condensed form to an open reticulum. In the presence of M. loti, a highly dynamic condensed form of the ER linked with the nucleus was found in deformed, curled, and infected root hairs, similar to that in uninoculated and inoculated growing zone I and II root hairs. An open reticulum was primarily found in mature inoculated zone III root hairs, similar to that found in inactive deformed/curled root hairs and infected root hairs with aborted infection threads. Co-imaging of GFP-labeled ER with light transmission demonstrated a correlation between the mobility of the ER and other organelles and the directionality of the cytoplasmic streaming in root hairs in the early stages of infection thread formation and growth. ER remodeling in root hair cells is discussed in terms of possible biological significance during root hair growth, deformation/curling, and infection in the Mesorhizobium-L. japonicus symbiosis. PMID:24337802

Perrine-Walker, F M; Kouchi, H; Ridge, R W

2014-07-01

270

Investigation of seasonal variability of the wind stress curl over the North Atlantic Ocean by means of empirical orthogonal function analysis  

NASA Technical Reports Server (NTRS)

The seasonal variability of the wind stress curl over the North Atlantic is investigated by means of empirical orthogonal function (EOF) analysis. The curl field is calculated from 1 year of First Global GARP Experiment wind data. It was found that 44 percent of the variability is contained in four significant eigenvectors. Their spatial patterns are characterized by basin-sized oscillations with larger amplitude to the north of 40 deg N. Their associated time series coefficients have the highest amplitude during the winter and show a tendency toward a white frequency spectrum which nevertheless exhibits noticeable peaks or gaps at certain frequencies. Physically, the first EOF is seen as the seasonal fluctuations of the mean wind stress curl pattern. Five other eigenvectors are also found to be above the noise level, but they account for only a smaller percentage of variability (19 percent). They are characterized by smaller spatial scales than the basin size. Their time series coefficients show a whiter frequency spectrum.

Barnier, B.

1986-01-01

271

LEAF: A Microcomputer Program for Constructing the Tukey Stem and Leaf Graph.  

ERIC Educational Resources Information Center

This paper presents a BASIC microcomputer program that constructs the Tukey (1977) stem and leaf graph. Options within the LEAF program include a modified stem and leaf where the stem is split and a parallel stem and leaf graph where two separate sets of data are displayed from a common stem. (Author)

Pascale, Pietro J.; Smith, Joseph

1986-01-01

272

Use of visible and near-infrared spectroscopy for predicting antioxidant compounds in summer squash (Cucurbita pepo ssp pepo).  

PubMed

The food industry and plant breeding programmes require fast, clean and low-cost screening techniques for nutritional compounds determination in food matrices. This is the first report on the study of the potential of near-infrared spectroscopy (NIRS) for the prediction of antioxidant compounds in summer squash tissues collected since 2009-2012. Modified partial least-squares (MPLS) regression was used to correlate spectral information and the different antioxidant compounds in the samples. The coefficients of determination in the external validation (r(2)ev) obtained were for ascorbic acid (0.77 and 0.86), chlorophyll a (0.79 and 0.66), chlorophyll b (0.86 and 0.79) and total phenolic compounds (0.65 and 0.68) in exocarp and mesocarp tissues, respectively, supporting that NIRS is able to predict in a rapid way these components for screening purposes. Major wavelengths influencing the calibration equations showed that chromophores as well as fibre components of the fruits highly participated in developing the NIR equations. PMID:24996338

Blanco-Díaz, María Teresa; Del Río-Celestino, Mercedes; Martínez-Valdivieso, Damián; Font, Rafael

2014-12-01

273

Permeability and Channel-Mediated Transport of Boric Acid across Membrane Vesicles Isolated from Squash Roots1  

PubMed Central

Boron is an essential micronutrient for plant growth and the boron content of plants differs greatly, but the mechanism(s) of its uptake into cells is not known. Boron is present in the soil solution as boric acid and it is in this form that it enters the roots. We determined the boron permeability coefficient of purified plasma membrane vesicles obtained from squash (Cucurbita pepo) roots and found it to be 3 × 10?7 ±1.4 × 10?8 cm s?1, six times higher than the permeability of microsomal vesicles. Boric acid permeation of the plasma membrane vesicles was partially inhibited (30%–39%) by mercuric chloride and phloretin, a non-specific channel blocker. The inhibition by mercuric chloride was readily reversible by 2-mercaptoethanol. The energy of activation for boron transport into the plasma membrane vesicles was 10.2 kcal mol?1. Together these data indicate that boron enters plant cells in part by passive diffusion through the lipid bilayer of the plasma membrane and in part through proteinaceous channels. Expression of the major intrinsic protein (MIP) PIP1 in Xenopus laevis oocytes resulted in a 30% increase in the boron permeability of the oocytes. Other MIPs tested (PIP3, MLM1, and GlpF) did not have this effect. We postulate that certain MIPs, like those that have recently been shown to transport small neutral solutes, may also be the channels through which boron enters plant cells.

Dordas, Christos; Chrispeels, Maarten J.; Brown, Patrick H.

2000-01-01

274

Modeling Leaf Production and Senescence in Wheat  

Microsoft Academic Search

4 Abstract: A major component in a crop growth model is leaf area development, which has a major influence on photosynthesis and transpiration. The knowledge about the leaf area development of wheat especially in high temperature environments is incomplete. The aim of this study was to quantify leaf production and senescence of 15 spring wheat cultivars. Field experiments were conducted

J. Pourreza; A. Soltani; A. Naderi; A. Aynehband

2009-01-01

275

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

276

Hormonal regulation of leaf senescence in Lilium.  

PubMed

In addition to floral senescence and longevity, the control of leaf senescence is a major factor determining the quality of several cut flowers, including Lilium, in the commercial market. To better understand the physiological process underlying leaf senescence in this species, we evaluated: (i) endogenous variation in the levels of phytohormones during leaf senescence, (ii) the effects of leaf darkening in senescence and associated changes in phytohormones, and (iii) the effects of spray applications of abscisic acid (ABA) and pyrabactin on leaf senescence. Results showed that while gibberellin 4 (GA(4)) and salicylic acid (SA) contents decreased, that of ABA increased during the progression of leaf senescence. However, dark-induced senescence increased ABA levels, but did not affect GA(4) and SA levels, which appeared to correlate more with changes in air temperature and/or photoperiod than with the induction of leaf senescence. Furthermore, spray applications of pyrabactin delayed the progression of leaf senescence in cut flowers. Thus, we conclude that (i) ABA plays a major role in the regulation of leaf senescence in Lilium, (ii) darkness promotes leaf senescence and increases ABA levels, and (iii) exogenous applications of pyrabactin inhibit leaf senescence in Lilium, therefore suggesting that it acts as an antagonist of ABA in senescing leaves of cut lily flowers. PMID:22854182

Arrom, Laia; Munné-Bosch, Sergi

2012-10-15

277

Leaf traits and leaf life spans of two xeric-adapted palmettos.  

PubMed

Plants of nutrient-poor, arid environments often have leaf traits that include small size, sclerophylly, long life span, low nutrient concentration, and low photosynthetic rate. Hence, the success of two large-leaved palmettos in peninsular Florida's seasonally xeric, nutrient-impoverished uplands seems anomalous, given that their leaves are orders of magnitude larger than the leaves of sympatric species. An examination of a 16-yr data set of leaf traits and leaf life spans across four vegetative associations differing in available light showed that Serenoa repens and Sabal etonia had low rates of leaf production coupled with long leaf life spans reaching 3.5 yr in heavily shaded plants. The adaptation of these palmettos to xeric, nutrient-poor habitats has generated dwarf statures, diminished leaf sizes and numbers, increased leaf life spans, and reduced rates of leaf production relative to other palms and congeners of more mesic sites. Leaf and petiole size, plant leaf canopy area, and leaf life span increased in both palmettos with decreasing available light, helping to compensate for reduced photosynthetic rates under shaded conditions and for the high leaf construction costs of the large, thick palmetto leaves. Large leaf size in these palmettos, likely due to phylogenetic conservatism, is compensated by other leaf traits (e.g., heavily cutinized epidermises, thick laminas) that increase survival in seasonally xeric, nutrient-impoverished environments. PMID:21636496

Abrahamson, Warren G

2007-08-01

278

Salinity effects on leaf anatomy  

Microsoft Academic Search

Increasing salinity led to substantially higher ratios of mesophyll surface area to leaf area (A\\/sup mes\\/\\/A) for Phaseolus vulgaris and Gossypium hirsutum and a smaller increase for Atriplex patula, a salt-tolerant species. The increase in internal surface for COâ absorption did not lead to higher COâ uptake rates, since the COâ resistance expressed on the basis of mesophyll cell wall

D. J. Longstreth; P. S. Nobel

1979-01-01

279

Combining ability of summer-squash lines with different degrees of parthenocarpy and PRSV-W resistance  

PubMed Central

The aim was to assess heterosis in a set of 16 summer-squash hybrids, and evaluate the combining capacity of the respective parental lines, which differed as to the degree of parthenocarpy and resistance to PRSV-W (Papaya Ringspot Virus-Watermelon strain). The hybrids were obtained using a partial diallel cross design (4 × 4). The lines of parental group I were 1 = ABX-037G-77-03-05-01-01-bulk, 2 = ABX-037G-77-03-05-03-10-bulk, 3 = ABX-037G-77-03-05-01-04-bulk and 4 = ABX-037G-77-03-05-05-01-bulk, and of group II, 1? = ABX-037G-77-03-05-04-08-bulk, 2? = ABX-037G-77-03-05-02-11-bulk, 3? = Clarice and 4? = Caserta. The 16 hybrids and eight parental lines were evaluated for PRSV-W resistance, parthenocarpic expression and yield in randomized complete-block designs, with three replications. Parthenocarpy and the resistance to PRSV-W were rated by means of a scale from 1 to 5, where 1 = non-parthenocarpic or high resistance to PRSV-W, and 5 = parthenocarpic or high susceptibility to PRSV-W. Both additive and non-additive gene effects were important in the expression of parthenocarpy and resistance to PRSV-W. Whereas estimates of heterosis in parthenocarpy usually tended towards a higher degree, resistance to PRSV-W was towards higher susceptibility. At least one F1 hybrid was identified with a satisfactory degree of parthenocarpy, resistance to PRSV-W and high fruit-yield.

Nogueira, Douglas Willian; Maluf, Wilson Roberto; dos Reis Figueira, Antonia; Maciel, Gabriel Mascarenhas; Gomes, Luiz Antonio Augusto; Benavente, Cesar Augusto Ticona

2011-01-01

280

Influence of cover crop and intercrop systems on Bemisia argentifolli (Hemiptera: Aleyrodidae) infestation and associated squash silverleaf disorder in zucchini.  

PubMed

Field experiments were conducted to evaluate the effects of cover cropping and intercropping on population densities of silverleaf whitefly, Bemisia argentifolli Bellow and Perring, and the incidence of squash silverleaf disorder (SSL) in zucchini, Cucurbita pepo L., in Oahu, HI. Two cover crops, buckwheat (BW), Fagopyrum esculentum Moench, and white clover (WC), Trifolium repens L., or sunn hemp (SH), Crotolaria juncea L., and an intercropped vegetable, okra, Abelmonchus esculentus L., were evaluated during the 2003, 2005, and 2006 growing seasons, respectively. Population densities of whiteflies and SSL severity varied during the three field experiments. In 2003, the severity of SSL and percentage of leaves displaying symptoms were significantly lower on zucchini plants in WC than BW plots throughout the crops' growth cycle. Additionally, the percentage of leaves per plant displaying SSL symptoms was significantly greater in bare-ground (BG) compared with the pooled BW and WC treatments on each inspection date. In 2005, zucchini intercropped with okra had lower numbers of adult whiteflies and resulted in significantly lower severity of SSL than pooled BW and WC treatments. During 2006, zucchini grown with SH had significantly lower numbers of all whitefly stages (i.e., egg, immature, and adult) and less SSL severity symptoms than BW. Despite these differences in whitefly numbers and SSL severity, marketable yields were not significantly lower in BW compared with WC or SH treatment plots during the study. The mechanisms underlying these results and the feasibility of using cover crops and intercrops to manage B. argentifolli and SSL are discussed. PMID:19389294

Manandhar, Roshan; Hooks, Cerruti R R; Wright, Mark G

2009-04-01

281

Combining ability of summer-squash lines with different degrees of parthenocarpy and PRSV-W resistance.  

PubMed

The aim was to assess heterosis in a set of 16 summer-squash hybrids, and evaluate the combining capacity of the respective parental lines, which differed as to the degree of parthenocarpy and resistance to PRSV-W (Papaya Ringspot Virus-Watermelon strain). The hybrids were obtained using a partial diallel cross design (4 × 4). The lines of parental group I were 1 = ABX-037G-77-03-05-01-01-bulk, 2 = ABX-037G-77-03-05-03-10-bulk, 3 = ABX-037G-77-03-05-01-04-bulk and 4 = ABX-037G-77-03-05-05-01-bulk, and of group II, 1' = ABX-037G-77-03-05-04-08-bulk, 2' = ABX-037G-77-03-05-02-11-bulk, 3' = Clarice and 4' = Caserta. The 16 hybrids and eight parental lines were evaluated for PRSV-W resistance, parthenocarpic expression and yield in randomized complete-block designs, with three replications. Parthenocarpy and the resistance to PRSV-W were rated by means of a scale from 1 to 5, where 1 = non-parthenocarpic or high resistance to PRSV-W, and 5 = parthenocarpic or high susceptibility to PRSV-W. Both additive and non-additive gene effects were important in the expression of parthenocarpy and resistance to PRSV-W. Whereas estimates of heterosis in parthenocarpy usually tended towards a higher degree, resistance to PRSV-W was towards higher susceptibility. At least one F(1) hybrid was identified with a satisfactory degree of parthenocarpy, resistance to PRSV-W and high fruit-yield. PMID:22215966

Nogueira, Douglas Willian; Maluf, Wilson Roberto; Dos Reis Figueira, Antonia; Maciel, Gabriel Mascarenhas; Gomes, Luiz Antonio Augusto; Benavente, Cesar Augusto Ticona

2011-10-01

282

A Putative Role for the Tomato Genes DUMPY and CURL3 in Brassinosteroid Biosynthesis and Response1  

Microsoft Academic Search

The dumpy (dpy) mutant of tomato (Lycopersicon esculentum Mill.) exhibits short stature, reduced axillary branching, and altered leaf morphology. Application of brassinolide and castasterone res- cued the dpy phenotype, as did C-23-hydroxylated, 6-deoxo inter- mediates of brassinolide biosynthesis. The brassinolide precursors campesterol, campestanol, and 6-deoxocathasterone failed to res- cue, suggesting that dpy may be affected in the conversion of 6-deoxocathasterone

Chala V. Koka; R. Eric Cerny; Randy G. Gardner; Takahiro Noguchi; Shozo Fujioka; Suguru Takatsuto; Shigeo Yoshida; Steven D. Clouse

2000-01-01

283

Complete nucleotide sequences of a distinct bipartite begomovirus, bitter gourd yellow vein virus, infecting Momordica charantia.  

PubMed

Momordica charantia (Cucurbitaceae), a vegetable crop commonly cultivated throughout Pakistan, and begomoviruses, a serious threat to crop plants, are natives of tropical and subtropical regions of the world. Leaf samples of M. charantia with yellow vein symptoms typical of begomovirus infections and samples from apparently healthy plants were collected from areas around Lahore in 2004. Full-length clones of a bipartite begomovirus were isolated from symptomatic samples. The complete nucleotide sequences of the components of one isolate were determined, and these showed the arrangement of genes typical of Old World begomoviruses. The complete nucleotides sequence of DNA A showed the highest nucleotide sequence identity (86.9%) to an isolate of Tomato leaf curl New Delhi virus (ToLCNDV), confirming it to belong to a distinct species of begomovirus, for which the name Bitter gourd yellow vein virus (BGYVV) is proposed. Sequence comparisons showed that BGYVV likely emerged as a result of inter-specific recombination between ToLCNDV and tomato leaf curl Bangladesh virus (ToLCBDV). The complete nucleotide sequence of DNA B showed 97.2% nucleotide sequence identity to that of an Indian strain of Squash leaf curl China virus. PMID:20924621

Tahir, Muhammad; Haider, Muhammad Saleem; Briddon, Rob W

2010-11-01

284

Ontogenetic changes in leaf phenology of two co-occurring Mediterranean oaks differing in leaf life span  

Microsoft Academic Search

Large differences in leaf physiology and morphology between ontogenetic stages of a single woody species have often been observed.\\u000a Far less attention, however, has been devoted to studying the ontogenetic changes observed in leaf phenology patterns, despite\\u000a the relevance of leaf phenology in determining the leaf carbon balance and leaf and plant mortality. Leaf emergence patterns\\u000a and leaf longevity were

Sonia Mediavilla; Alfonso Escudero

2009-01-01

285

Leaf wetness within a lily canopy  

NASA Astrophysics Data System (ADS)

A wetness duration experiment was carried out within a lily field situated adjacent to coastal dunes in the Netherlands. A within-canopy model was applied to simulate leaf wetness in three layers, with equal leaf area indices, within the canopy. This simulation model is an extension of an existing model. It appeared that in most cases leaf wetness started in the uppermost layer followed by the middle and bottom layer, respectively. The same occurred during the early morning drying process. Just after sunrise the upper layer started to dry, followed by the middle and bottom layer, respectively. The longest leaf wetness duration occurred in the bottom layer. The calculated leaf wetness durations were within 10 minutes of the results obtained using a leaf wetness sensor.

Jacobs, Adrie F. G.; Heusinkveld, Bert G.; Klok, Elisabeth J.

2005-09-01

286

Insect leaf mines from the Eocene Anglesea locality, Victoria, Australia  

Microsoft Academic Search

The first Tertiary leaf mines described from Australia are six mines from the Anglesea locality in Victoria. They are referable to five leaf mining taxa. Two of the mines are associated with a Lauraceae leaf. A third leaf mine is preserved in a ‘mummified’ leaf with affinities to Elaeocarpaceae. The remaining two mines are on leaves that are too poorly

A. C. Rozefelds

1988-01-01

287

7 CFR 28.467 - Leaf Grade 7.  

Code of Federal Regulations, 2010 CFR

... 2009-01-01 2009-01-01 false Leaf Grade 7. 28.467 Section 28.467 Agriculture...Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.467 Leaf Grade 7. Leaf Grade 7 is leaf which...

2009-01-01

288

Classification and quantification of leaf curvature  

PubMed Central

Various mutants of Arabidopsis thaliana deficient in polarity, cell division, and auxin response are characterized by certain types of leaf curvature. However, comparison of curvature for clarification of gene function can be difficult without a quantitative measurement of curvature. Here, a novel method for classification and quantification of leaf curvature is reported. Twenty-two mutant alleles from Arabidopsis mutants and transgenic lines deficient in leaf flatness were selected. The mutants were classified according to the direction, axis, position, and extent of leaf curvature. Based on a global measure of whole leaves and a local measure of four regions in the leaves, the curvature index (CI) was proposed to quantify the leaf curvature. The CI values accounted for the direction, axis, position, and extent of leaf curvature in all of the Arabidopsis mutants grown in growth chambers. Comparison of CI values between mutants reveals the spatial and temporal variations of leaf curvature, indicating the strength of the mutant alleles and the activities of the corresponding genes. Using the curvature indices, the extent of curvature in a complicated genetic background becomes quantitative and comparable, thus providing a useful tool for defining the genetic components of leaf development and to breed new varieties with leaf curvature desirable for the efficient capture of sunlight for photosynthesis and high yields.

Liu, Zhongyuan; Jia, Liguo; Mao, Yanfei; He, Yuke

2010-01-01

289

Salinity Effects on Leaf Anatomy  

PubMed Central

Increasing salinity led to substantially higher ratios of mesophyll surface area to leaf area (Ames/A) for Phaseolus vulgaris and Gossypium hirsutum and a smaller increase for Atriplex patula, a salt-tolerant species. The increase in internal surface for CO2 absorption did not lead to higher CO2 uptake rates, since the CO2 resistance expressed on the basis of mesophyll cell wall area (rcell) increased even more with salinity. The differences among species in the sensitivity of photosynthesis to salinity in part reflect the different Ames/A and rcell responses.

Longstreth, David J.; Nobel, Park S.

1979-01-01

290

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

291

Chloroplast Response to Low Leaf Water Potentials  

PubMed Central

Cyclic and noncyclic photophosphorylation and electron transport by photosystem 1, photosystem 2, and from water to methyl viologen (“whole chain”) were studied in chloroplasts isolated from sunflower (Helianthus annus L. var Russian Mammoth) leaves that had been desiccated to varying degrees. Electron transport showed considerable inhibition at leaf water potentials of ?9 bars when the chloroplasts were exposed to an uncoupler in vitro, and it continued to decline in activity as leaf water potentials decreased. Electron transport by photosystem 2 and coupled electron transport by photosystem 1 and the whole chain were unaffected at leaf water potentials of ?10 to ?11 bars but became progressively inhibited between leaf water potentials of ?11 and ?17 bars. A low, stable activity remained at leaf water potentials below ?17 bars. In contrast, both types of photophosphorylation were unaffected by leaf water potentials of ?10 to ?11 bars, but then ultimately became zero at leaf water potentials of ?17 bars. Although the chloroplasts isolated from the desiccated leaves were coupled at leaf water potentials of ?11 to ?12 bars, they became progressively uncoupled as leaf water potentials decreased to ?17 bars. Abscisic acid and ribonuclease had no effect on chloroplast photophosphorylation. The results are generally consistent with the idea that chloroplast activity begins to decrease at the same leaf water potentials that cause stomatal closure in sunflower leaves and that chloroplast electron transport begins to limit photosynthesis at leaf water potentials below about ?11 bars. However, it suggests that, during severe desiccation, the limitation may shift from electron transport to photophosphorylation.

Keck, R. W.; Boyer, J. S.

1974-01-01

292

"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

293

7 CFR 29.2437 - Heavy Leaf (B Group).  

Code of Federal Regulations, 2010 CFR

...Dark-brown Heavy Leaf. Heavy, mature, close, lean in oil, inelastic, weak...Dark-brown Heavy Leaf. Heavy, mature, close, lean in oil, inelastic, weak...Leaf. Medium to heavy body, mature, close, lean in oil, inelastic,...

2010-01-01

294

7 CFR 29.2437 - Heavy Leaf (B Group).  

Code of Federal Regulations, 2010 CFR

...Dark-brown Heavy Leaf. Heavy, mature, close, lean in oil, inelastic, weak...Dark-brown Heavy Leaf. Heavy, mature, close, lean in oil, inelastic, weak...Leaf. Medium to heavy body, mature, close, lean in oil, inelastic,...

2009-01-01

295

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

296

Leaf Morphology Affects Horseradish Regeneration In Vitro  

Microsoft Academic Search

The morphology of horseradish (Armoracia rusticana P. Gaertn., B. Mey & Scherb.) leaves varies through the growing season. The leaves range from laminate (complete) in the summer to pinnate (fern-leaf) toward the end of the growing season in the fall, with intermediate types appearing regularly. The causes of these changes are not understood. To determine whether leaf morphology affects their

A. M. Shehata; R. M. Skirvin; M. A. Norton

2008-01-01

297

Leaf peroxidase isozyme polymorphism of wild apple  

Microsoft Academic Search

The main aims of the study were to reveal the isozyme resemblances in the leaf peroxidase of wild apple and to define the traits related to the identification of Malus sylvestris Mill. The results of the study are based on leaf isozyme analysis of seven progenies selected according to the specific features of mother trees at their natural sites from

R. Petrokas; V. Stanys

2008-01-01

298

Leaf litter decomposition in three Adirondack lakes  

SciTech Connect

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, carbon, nitrogen, and bacterial populations. The rate of decomposition of litter depended on the leaf species tested as well as on the lake water in which they were incubated. Of the five leaf species tested, red maple decomposed much faster and red spruce more slowly, i.e., red maple > sugar maple > beech > leather leaf > red spruce. Further, the data indicated that the rate of decomposition of the leaves differed among the lakes in the order Woods (pH approx. 5) < Sagamore (pH approx. 6) < Panther (pH approx. 7), and that the microbial colonization of some leaf species was affected. Accumulations of leaf litter in acid lakes due to reduction in microbial decomposition may affect nutrient recycling in lake ecosystems. 8 references, 4 tables.

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

1983-04-01

299

Leaf and Air Temperature under Hawaii Conditions  

Microsoft Academic Search

During the daylight hours pineapple leaf tem ­ per ature was consistently higher than the air temperature measured in an instrument shelter at the same elevation as the plants. The values usually ranged from 1.5° to 3.5° C. above the air temperature but occasionally a leaf exp osed to direct sunlight had a temperature as mu ch as 7.6 °

T. L. NOFFSINGER

300

Carrot red leaf virus in Israel  

Microsoft Academic Search

Carrot (Daucus carota) plants in commercial fields in Israel quite often evince symptoms of leaf reddening (mainly of older leaves), leaf yellowing, and sometimes plant stunting. These symptoms were observed mainly on plants near the edges of the fields and they were attributed to trace element deficiencies, herbicide drifts and low temperature injuries. Incidence of symptomcarrying plants varied in different

S. Marco

1993-01-01

301

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

302

Leaf epifauna of the seagrass Thalassia testudinum  

Microsoft Academic Search

The abundance, composition and trophic relationships of metazoan leaf epifauna of the marine angiosperm Thalassia testudinum König were studied in Barbados, West Indies. Approximately 90 species from 11 phyla consisted chiefly of nematodes, harpacticoid copepods, crustacean nauplii, ostracods, and turbellarians. Epiflora- and detritus-feeders dominated the epifauna. Increasing leaf epiphytism was accompanied by faunal changes, most notably increased nematode, harpacticoid and

J. B. Lewis; C. E. Hollingworth

1982-01-01

303

Leaf Histology--Two Modern Methods.  

ERIC Educational Resources Information Center

Two methods for examining leaf structure are presented; both methods involve use of "superglue." The first method uses the glue to form a thin, permanent, direct replica of a leaf surface on a microscope slide. The second method uses the glue to examine the three-dimensional structure of spongy mesophyll. (JN)

Freeman, H. E.

1984-01-01

304

The red edge of plant leaf reflectance  

Microsoft Academic Search

The red edge is the sharp change in leaf reflectance between 680 and 750 nm and has been measured on leaves of a variety of species by first derivative reflectance spectrophotometry. A parameter ?re was defined as the wavelength of maximum slope and found to be dependent on chlorophyll concentration (p<0.001), with additional effects of species, developmental stage, leaf layering

D. N. H. Horler; M. Dockray; J. Barber

1983-01-01

305

Physiological, anatomical and leaf hydraulic effects on leaf water ?18O enrichment in different plant species  

NASA Astrophysics Data System (ADS)

Stable oxygen isotope ratios (?18O) of plant and source waters are valuable tools in the analysis of water and carbon fluxes at leaf, plant, and ecosystem scales. Recent improvements in mechanistic models have significantly advanced the understanding of isotopic leaf water enrichment, which is an important source of ?18O variability in plants and ecosystems. However, the marked variability in leaf water ?18O values that have been reported for different plant species hampers efforts to interpret and then apply data on leaf water ?18O values for studies conducted at the ecosystem scale. To improve the understanding and application of ?18O values in leaf water, we tested the interplay of physiological, morphological, anatomical and leaf hydraulic properties as drivers of leaf water ?18O values across 17 Eucalyptus species growing in a common garden. We observed large differences in leaf water ?18O across the 17 species. These differences were only partly driven by physiological and leaf morphological differences across species. A sensitivity analysis using state-of-the-art leaf water enrichment models showed that the parameter - effective path length - (L) is of critical importance for the variability of leaf water ?18O across different species. The data show that L can be related to a suite of leaf properties that include physiology, anatomy and hydraulics. Consequently, consideration of leaf properties will significantly improve the interpretation of ?18O values in leaf water across different plant species and will therefore help in the application of ?18O values in carbon and water cycle assessments at both the plant and the ecosystem scale.

Kahmen, A.; Arndt, S. K.; Dawson, T. E.

2007-12-01

306

Two WUSCHEL-related homeobox genes, narrow leaf2 and narrow leaf3, control leaf width in rice.  

PubMed

Leaf shape is one of the key determinants of plant architecture. Leaf shape also affects the amount of sunlight captured and influences photosynthetic efficiency; thus, it is an important agronomic trait in crop plants. Understanding the molecular mechanisms governing leaf shape is a central issue of plant developmental biology and agrobiotechnology. Here, we characterized the narrow-leaf phenotype of FL90, a linkage tester line of rice (Oryza sativa). Light and scanning electron microscopic analyses of FL90 leaves revealed defects in the development of marginal regions and a reduction in the number of longitudinal veins. The narrow-leaf phenotype of FL90 shows a two-factor recessive inheritance and is caused by the loss of function of two WUSCHEL-related homeobox genes, NAL2 and NAL3 (NAL2/3), which are duplicate genes orthologous to maize NS1 and NS2 and to Arabidopsis PRS. The overexpression of NAL2/3 in transgenic rice plants results in wider leaves containing increased numbers of veins, suggesting that NAL2/3 expression regulates leaf width. Thus, NAL2/3 can be used to modulate leaf shape and improve agronomic yield in crop plants. PMID:23420902

Ishiwata, Aiko; Ozawa, Misa; Nagasaki, Hiroshi; Kato, Makio; Noda, Yusaku; Yamaguchi, Takahiro; Nosaka, Misuzu; Shimizu-Sato, Sae; Nagasaki, Akie; Maekawa, Masahiko; Hirano, Hiro-Yuki; Sato, Yutaka

2013-05-01

307

Are leaf physiological traits related to leaf water isotopic enrichment in restinga woody species?  

PubMed

During plant-transpiration, water molecules having the lighter stable isotopes of oxygen and hydrogen evaporate and diffuse at a faster rate through the stomata than molecules having the heavier isotopes, which cause isotopic enrichment of leaf water. Although previous models have assumed that leaf water is well-mixed and isotopically uniform, non-uniform stomatal closure, promoting different enrichments between cells, and different pools of water within leaves, due to morpho-physiological traits, might lead to inaccuracies in isotopic models predicting leaf water enrichment. We evaluate the role of leaf morpho-physiological traits on leaf water isotopic enrichment in woody species occurring in a coastal vegetation of Brazil known as restinga. Hydrogen and oxygen stable isotope values of soil, plant stem and leaf water and leaf traits were measured in six species from restinga vegetation during a drought and a wet period. Leaf water isotopic enrichment relative to stem water was more homogeneous among species during the drought in contrast to the wet period suggesting convergent responses to deal to temporal heterogeneity in water availability. Average leaf water isotopic enrichment relative to stem water during the drought period was highly correlated with relative apoplastic water content. We discuss this observation in the context of current models of leaf water isotopic enrichment as a function of the Péclet effect. We suggest that future studies should include relative apoplastic water content in isotopic models. PMID:24068091

Rosado, Bruno H P; De Mattos, Eduardo A; Sternberg, Leonel Da S L

2013-09-01

308

Leaf wetness distribution within a potato crop  

NASA Astrophysics Data System (ADS)

The Netherlands has a mild maritime climate and therefore the major interest in leaf wetness is associated with foliar plant diseases. During moist micrometeorological conditions (i.e. dew, fog, rain), foliar fungal diseases may develop quickly and thereby destroy a crop quickly. Potato crop monocultures covering several hectares are especially vulnerable to such diseases. Therefore understanding and predicting leaf wetness in potato crops is crucial in crop disease control strategies. A field experiment was carried out in a large homogeneous potato crop in the Netherlands during the growing season of 2008. Two innovative sensor networks were installed as a 3 by 3 grid at 3 heights covering an area of about 2 hectares within two larger potato crops. One crop was located on a sandy soil and one crop on a sandy peat soil. In most cases leaf wetting starts in the top layer and then progresses downward. Leaf drying takes place in the same order after sunrise. A canopy dew simulation model was applied to simulate spatial leaf wetness distribution. The dew model is based on an energy balance model. The model can be run using information on the above-canopy wind speed, air temperature, humidity, net radiation and within canopy air temperature, humidity and soil moisture content and temperature conditions. Rainfall was accounted for by applying an interception model. The results of the dew model agreed well with the leaf wetness sensors if all local conditions were considered. The measurements show that the spatial correlation of leaf wetness decreases downward.

Heusinkveld, B. G.

2010-07-01

309

An Apparent Anomaly in Peanut Leaf Conductance  

PubMed Central

Conductance to gaseous transfer is normally considered to be greater from the abaxial than from the adaxial side of a leaf. Measurements of the conductance to water vapor of peanut leaves (Arachis hypogaea L.) under well watered and stress conditions in a controlled environment, however, indicated a 2-fold higher conductance from the adaxial side of the leaf than from the abaxial. Studies of conductance as light level was varied showed an increase in conductance from either surface with increasing light level, but conductance was always greater from the adaxial surface at any given light level. In contrast, measurements of soybean (Glycine max [L.] Merr.) and snapbean (Phaseolus vulgaris L.) leaf conductance showed an approximate 2-fold greater conductance from the abaxial surface than from the adaxial. Approximately the same number of stomata were present on both peanut leaf surfaces and stomatal size was similar. Electron microscopic examination of peanut leaves did not reveal any major structural differences between stomata on the two surfaces that would account for the differences in conductance. Light microscope studies of leaf sections revealed an extensive network of bundle sheaths with achloraplastic bundle sheath extensions; the lower epidermis was lined with a single layer of large achloraplastic parenchyma cells. Measurements of net photosynthesis made on upper and lower leaf surfaces collectively and individually indicated that two-thirds of the peanut leaf's total net photosynthesis can be attributed to diffusion of CO2 through the adaxial leaf surface. Possibly the high photosynthetic efficiency of peanut cultivars as compared with certain other C3 species is associated with the greater conductance of CO2 through their upper leaf surfaces. Images

Pallas, James E.

1980-01-01

310

Low genetic diversity of Squash vein yellowing virus in wild and cultivated cucurbits in the U.S. suggests a recent introduction.  

PubMed

Squash vein yellowing virus (SqVYV) isolates were collected from cultivated and weedy cucurbits representing major hosts and locations in the U.S. and analyzed to better understand the diversity and population structure. No differences in symptoms were observed in field-collected isolate source plants or subsequently inoculated greenhouse plants, and the complete genome of an SqVYV isolate from a wild cucurbit host (smellmelon, Cucumis melo var. dudaim) was highly similar (99.4% nucleotide identity, 99.3% amino acid identity) to the previously published type isolate from squash. Although analysis of the coat protein (CP) and two serine proteases (P1a and P1b) sequences for 41 isolates showed little diversity across seven years of sampling, it revealed two distinct groups of SqVYV isolates with low intra-group diversity. Our analyses also suggested that recombination had occurred between SqVYV isolates, similar to other ipomoviruses. Selection pressures on the genome regions analyzed were negative indicating purifying selection was occurring. The magnitude of negative selection in SqVYV was consistent with what has been reported for other ipomoviruses, and was greatest for the CP and least for the P1b. The observed genetic diversity was similar to that reported for Cucumber vein yellowing virus but less than that reported for Sweet potato mild mottle virus, Cassava brown streak virus and Ugandan cassava brown streak virus. Collectively, these results indicate that the current U.S. population of SqVYV has undergone a recent genetic bottleneck and was introduced from elsewhere. PMID:22142477

Webster, Craig G; Adkins, Scott

2012-02-01

311

Diurnal Changes in Maize Leaf Photosynthesis 1  

PubMed Central

Maize (Zea mays L. cv. Pioneer 3184) leaf elongation rate was measured diurnally and was related to diurnal changes in the activities of sucrose metabolizing enzymes and carbohydrate content in the elongating portion of the leaf. The rate of leaf elongation was greatest at midday (1300 hours) and was coincident with the maximum assimilate export rate from the distal portion of the leaf. Leaf elongation during the light period accounted for 70% of the total observed increase in leaf length per 24 hour period. Pronounced diurnal fluctuations were observed in the activities of acid and neutral invertase and sucrose phosphate synthase. Maximum activities of sucrose phosphate synthase and acid invertase were observed at 0900 hours, after which activity declined rapidly. The activity of sucrose phosphate synthase was substantially lower than that observed in maize leaf source tissue. Neutral invertase activity was greatest at midday (1200 hours) and was correlated positively with diurnal changes in leaf elongation rate. There was no significant change in the activity of sucrose synthase over the light/dark cycle. Sucrose accumulation rate increased during a period when leaf elongation rate was maximal and beginning to decline. Maximum sucrose concentration was observed at 1500 hours, when the activities of sucrose metabolizing enzymes were low. At no time was there a significant accumulation of hexose sugars. The rate of starch accumulation increased after the maximum sucrose concentration was observed, continuing until the end of the light period. There was no delay in the onset of starch mobilization at the beginning of the dark period, and essentially all of the starch was depleted by the end of the night. Mobilization of starch in the elongating tissue at night could account for a significant proportion of the calculated increase in the tissue dry weight due to growth. Collectively, the results suggested that leaf growth may be controlled by the activities of certain sucrose metabolizing enzymes and may be coordinated with assimilate export from the distal, source portion of the leaf. Results are discussed with reference to diurnal photoassimilation and export in the distal, source portion of the leaf.

Kalt-Torres, Willy; Huber, Steven C.

1987-01-01

312

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

313

Fossil leaf economics quantified: calibration, Eocene case study, and implications  

Microsoft Academic Search

Leaf mass per area (MA) is a central ecological trait that is intercorrelated with leaf life span, photosynthetic rate, nutrient concentration, and palatability to herbivores. These coordinated variables form a globally convergent leaf economics spectrum, which represents a general continuum running from rapid resource acquisition to maximized resource retention. Leaf economics are little studied in ancient ecosystems because they cannot

Dana L. Royer; Lawren Sack; Peter Wilf; Christopher H. Lusk; Gregory J. Jordan; Ülo Niinemets; Ian J. Wright; Mark Westoby; Bárbara Cariglino; Phyllis D. Coley; Asher D. Cutter; Kirk R. Johnson; Conrad C. Labandeira; Angela T. Moles; Matthew B. Palmer; Fernando Valladares

2007-01-01

314

7 CFR 28.516 - Leaf Grade No. 6.  

Code of Federal Regulations, 2010 CFR

... 2009-01-01 2009-01-01 false Leaf Grade No. 6. 28.516 Section 28.516...Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.516 Leaf Grade No. 6. Leaf grade No. 6 shall...

2009-01-01

315

7 CFR 28.471 - Below Leaf Grade Cotton.  

Code of Federal Regulations, 2010 CFR

...2009-01-01 2009-01-01 false Below Leaf Grade Cotton. 28.471 Section 28.471...TESTING, AND STANDARDS Standards Below Leaf Grade Cotton § 28.471 Below Leaf Grade Cotton. Below leaf grade cotton is...

2009-01-01

316

7 CFR 28.471 - Below Leaf Grade Cotton.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Below Leaf Grade Cotton. 28.471 Section 28.471...TESTING, AND STANDARDS Standards Below Leaf Grade Cotton § 28.471 Below Leaf Grade Cotton. Below leaf grade cotton is...

2010-01-01

317

7 CFR 28.514 - Leaf Grade No. 4.  

Code of Federal Regulations, 2010 CFR

... 2010-01-01 2010-01-01 false Leaf Grade No. 4. 28.514 Section 28.514...Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.514 Leaf Grade No. 4. Leaf grade No. 4 shall...

2010-01-01

318

7 CFR 28.516 - Leaf Grade No. 6.  

Code of Federal Regulations, 2010 CFR

... 2010-01-01 2010-01-01 false Leaf Grade No. 6. 28.516 Section 28.516...Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.516 Leaf Grade No. 6. Leaf grade No. 6 shall...

2010-01-01

319

7 CFR 28.515 - Leaf Grade No. 5.  

Code of Federal Regulations, 2010 CFR

... 2009-01-01 2009-01-01 false Leaf Grade No. 5. 28.515 Section 28.515...Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.515 Leaf Grade No. 5. Leaf grade No. 5 shall...

2009-01-01

320

NARROW LEAF 7 controls leaf shape mediated by auxin in rice  

Microsoft Academic Search

Elucidation of the genetic basis of the control of leaf shape could be of use in the manipulation of crop traits, leading\\u000a to more stable and increased crop production. To improve our understanding of the process controlling leaf shape, we identified\\u000a a mutant gene in rice that causes a significant decrease in the width of the leaf blade, termed narrow

Kenji Fujino; Yasuyuki Matsuda; Kenjirou Ozawa; Takeshi Nishimura; Tomokazu Koshiba; Marco W. Fraaije; Hiroshi Sekiguchi

2008-01-01

321

Short communication Leaf optical properties and photosynthetic leaf absorptances in several Australian seagrasses  

Microsoft Academic Search

Thisstudyinvestigated within-and among-species variability intheleafoptical properties ofeightlarge-bodiedseagrasses,Posidoniaaustralis, Posidonia sinuosa, Posidonia coriacea, Posidonia angustifolia, Amphibolis antarctica, Amphibolis griffithii, Zostera tasmanica, and Zostera capricorni and the small-bodied Halophila ovalis from the east and west coasts of Australia. Leaf spectral transmittance (TL(l)), reflectance (RL(l)), and non-photosynthetic absorptance (AL(NP)) were measured in order to calculate leaf spectral absorptance (AL(l)) and photosynthetic leaf absorptance (AL(PAR)).

Michael J. Durako

322

Reflectance model of a plant leaf  

NASA Technical Reports Server (NTRS)

A light ray, incident at 5 deg to the normal, is geometrically plotted through the drawing of the cross section of a soybean leaf using Fresnel's Equations and Snell's Law. The optical mediums of the leaf considered for ray tracing are: air, cell sap, chloroplast, and cell wall. The above ray is also drawn through the same leaf cross section considering cell wall and air as the only optical mediums. The values of the reflection and transmission found from ray tracing agree closely with the experimental results obtained using a Beckman DK-2A Spectroreflectometer. Similarly a light ray, incident at about 60 deg to the normal, is drawn through the palisade cells of a soybean leaf to illustrate the pathway of light, incident at an oblique angle, through the palisade cells.

Kumar, R.; Silva, L.

1973-01-01

323

The red edge of plant leaf reflectance  

NASA Technical Reports Server (NTRS)

A detailed study of the red edge spectral feature of green vegetation based on laboratory reflectance spectrophotometry is presented. A parameter lambda is defined as the wavelength is defined as the wavelength of maximum slope and found to be dependent on chlorophyll concentration. Species, development stage, leaf layering, and leaf water content of vegetation also influences lambda. The maximum slope parameter is found to be independent of simulated ground area coverage. The results are interpreted in terms of Beer's Law and Kubelka-Munk theory. The chlorophyll concentration dependence of lambda seems to be explained in terms of a pure absorption effect, and it is suggested that the existence of two lambda components arises from leaf scattering properties. The results indicate that red edge measurements will be valuable for assessment of vegetative chlorophyll status and leaf area index independently of ground cover variations, and will be particularly suitable for early stress detection.

Horler, D. N. H.; Dockray, M.; Barber, J.

1983-01-01

324

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

325

Spectroscopic Measurement of Leaf Water Status  

NASA Technical Reports Server (NTRS)

A leaf drying experiment was carried out in the laboratory in which simultaneous spectral reflectance in the 350-2450 nm region, and leaf weights, were measured at 10 second intervals over a 40 minute period. As the leaf water weight dropped from approximately 60 to 38%. a nearly-linear rise in reflectance at all wavelengths beyond 1000 nm was observed. A principal components analysis of the time series of spectra in the 2000-2500 nm wavelength region showed that over 99% of the variance in the spectra, that were individually scaled to have a sum equal to that of the mean spectrum and subsequently mean corrected, was in the first component. This result shows that it is feasible to determine leaf water content remotely with an imaging spectrometer independent of the surface irradiance effects caused by topography.

Goetz, Alexander F. H.; Boardman, Joseph W.

1995-01-01

326

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

327

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

328

Error Compensation in Leaf Power Problems  

Microsoft Academic Search

The k-Leaf Power recognition problem is a particular case of graph power problems: For a given graph it asks whether there exists an un- rooted tree—the k-leaf root—with leaves one-to-one labeled by the graph vertices and where the leaves have distance at most k iff their correspond- ing vertices in the graph are connected by an edge. Here we study

Michael Dom; Jiong Guo; Falk Hüffner; Rolf Niedermeier

2006-01-01

329

Nutrient influences on leaf photosynthesis  

SciTech Connect

The net rate of CO/sub 2/ uptake for leaves of Gossypium hirsutum L. was reduced when the plants were grown at low concentrations of NO/sub 3//sup -/, PO/sub 4//sup 2 -/, or K/sup +/. The water vapor conductance was relatively constant for all nutrient levels, indicating little effect on stomatal response. Although leaves under nutrient stress tended to be lower in chlorophyll and thinner, the ratio of mesophyll surface area to leaf area did not change appreciably. Thus, the reduction in CO/sub 2/ uptake rate at low nutrient levels was due to a decrease in the CO/sub 2/ conductance expressed per unit mesophyll cell wall area (g/sub CO/sup cell//sub 2/). The use of g/sub CO//sup cell//sub 2/ and nutrient levels expressed per unit of mesophyll cell wall provides a new means of assessing nutrient effects on CO/sub 2/ uptake of leaves. 14 figures, 1 table.

Longstreth, D.J.; Nobel, P.S.

1980-01-01

330

Critique of stepwise multiple linear regression for the extraction of leaf biochemistry information from leaf reflectance data  

Microsoft Academic Search

This study examined the use of stepwise multiple linear regression to quantify leaf carbon, nitrogen, lignin, cellulose, dry weight, and water compositions from leaf level reflectance (R). Two fresh leaf and one dry leaf datasets containing a broad range of native and cultivated plant species were examined using unconstrained stepwise multiple linear regression and constrained regression with wavelengths reported from

Y. L. Grossman; S. L. Ustin; S. Jacquemoud; E. W. Sanderson; G. Schmuck; J. Verdebout

1996-01-01

331

Leaf morphology shift linked to climate change.  

PubMed

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. PMID:22764114

Guerin, Greg R; Wen, Haixia; Lowe, Andrew J

2012-10-23

332

Root Hypoxia Reduces Leaf Growth 1  

PubMed Central

This study examined the potential role of restricted phloem export, or import of substances from the roots in the leaf growth response to root hypoxia. In addition, the effects of root hypoxia on abscisic acid (ABA) and zeatin riboside (ZR) levels were measured and their effects on in vitro growth determined. Imposition of root hypoxia in the dark when transpirational water flux was minimal delayed the reduction in leaf growth until the following light period. Restriction of phloem transport by stem girdling did not eliminate the hypoxia-induced reduction in leaf growth. In vitro growth of leaf discs was inhibited in the presence of xylem sap collected from hypoxic roots, and also by millimolar ABA. Disc growth was promoted by sap from aerated roots and by 0.1 micromolar ZR. The flux of both ABA and ZR was reduced in xylem sap from hypoxic roots. Leaf ABA transiently increased twofold after 24 hours of hypoxia exposure but there were no changes in leaf cytokinin levels. Images Figure 3 Figure 4

Smit, Barbara A.; Neuman, Dawn S.; Stachowiak, Matthew L.

1990-01-01

333

EFFECT OF LEAF ANATOMY ON HYPOSTOMATOUS LEAF GAS EXCHANGE: A THEORETICAL STUDY WITH THE 2DLEAF MODEL  

Microsoft Academic Search

PACHEPSKY L. B. and ACOCK B. Effect of leaf anatomy on hypostomatous leaf gas exchange: A theoretical study with the 2DLEAF model. BIOTRONICS 27, 1-14, 1998. The two-dimensional model of leaf gas exchange, 2DLEAF, which accounts for leaf intercellular structure, was used to study the effect of leaf anatomy on the photosynthesis and transpiration rates of hypostomatous Cg plants. The

L. B. P ACHEPSKYI; B. ACOCK

334

Black leaf streak and viral leaf streak: New banana diseases in East Africa  

Microsoft Academic Search

Black leaf streak, caused by Mycosphaerella fijiensis a virulent pathogen of bananas and plantains, is recorded from Zanzibar. This is the first record of this important pathogen from East Africa. Viral leaf streak of bananas is also identified from Zanzibar. The presence of panama disease and high infestations of root nematode are also noted.

A. J. Dabek; J. M. Waller

1990-01-01

335

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

336

Nitrogen Effects on Leaf Anatomy within the Intercalary Meristems of Tall Fescue Leaf Blades  

Microsoft Academic Search

Longitudinal elongation contributes most to leaf area expansion of grasses and its rate is known to be strongly affected by N. Our objective was to determine the effect of two N regimes (N0and N+) on the gradient of leaf tissue formation in meristems of two contrasting tall fescue (Festuca arundinacea Schreb.) genotypes. Proportions of epidermal, mesophyll and vascular tissue as

Ingo F. Rademacher; C. Jerry Nelson

2001-01-01

337

Leaf lifespan as a determinant of leaf structure and function among 23 amazonian tree species  

Microsoft Academic Search

The relationships between resource availability, plant succession, and species' life history traits are often considered key to understanding variation among species and communities. Leaf lifespan is one trait important in this regard. We observed that leaf lifespan varies 30-fold among 23 species from natural and disturbed communities within a 1-km radius in the northern Amazon basin, near San Carlos de

P. B. Reich; C. Uhl; M. B. Walters; D. S. Ellsworth

1991-01-01

338

Measurement of leaf relative water content by infrared reflectance  

NASA Technical Reports Server (NTRS)

From basic considerations and Beer's law, a leaf water content index incorporating reflectances of wavelengths from 0.76 to 0.90 microns and from 1.55 to 1.75 microns was developed that relates leaf reflectance to leaf relative water content. For the leaf succulent, Agave deserti, the leaf water content index was not significantly different from the relative water content for either individual leaves or an entire plant. Also, the relative water contents of intact plants of Encelia farinosa and Hilaria rigida in the field were estimated by the leaf water content index; variations in the proportion of living to dead leaf area could cause large errors in the estimate of relative water content. Thus, the leaf water content index may be able to estimate average relative water content of canopies when TM4 and TM5 are measured at a known relative water content and fraction of dead leaf material.

Hunt, E. Raymond, Jr.; Rock, Barrett N.; Nobel, Park S.

1987-01-01

339

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

340

BOREAS TE-9 NSA Leaf Chlorophyll Density  

NASA Technical Reports Server (NTRS)

The BOREAS TE-9 team collected several data sets related to chemical and photosynthetic properties of leaves in boreal forest tree species. These data were collected to help provide an explanation of potential seasonal and spatial changes of leaf pigment properties in boreal forest species at the NSA. At different dates (FFC-Winter, FFC-Thaw, IFC-1, IFC-2, and IMC-3), foliage samples were collected from the upper third of the canopy for five NSA sites (YJP, OJP, OBS, UBS, and OA) near Thompson, Manitoba. Subsamples of 100 needles for black spruce, 20 needles for jack pine, and single leaf for trembling aspen were cut into pieces and immersed in a 20-mL DMF aliquot in a Nalgene test tube. The extracted foliage materials were then oven-dried at 68 C for 48 hours and weighed. Extracted leaf dry weight was converted to a total leaf area basis to express the chlorophyll content in mg/sq cm of total leaf area. The data are provided in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

Hall, Forrest G. (Editor); Curd, Shelaine (Editor); Margolis, Hank; Sy, Mikailou

2000-01-01

341

Chloroplast Response to Low Leaf Water Potentials  

PubMed Central

Quantum yields were measured for CO2 fixation by sunflower (Helianthus annuus L.) leaves having various water potentials and for dichlorophenolindophenol photoreduction by chloroplasts isolated from similar leaves having various water potentials. In red radiation, the quantum yield for CO2 was 0.076 for an attached sunflower leaf at a water potential of ?3 to ?4 bars but was 0.020 for the same leaf at ?15.3 bars. After recovery to a water potential of ?5 bars, the quantum yield rose to 0.060. Soybean (Glycine max L. [Merr.]) leaves behaved similarly. Chloroplasts from a sunflower leaf with a water potential of ?3.6 bars had a quantum yield for 4 equivalents of 0.079, but when tissue from the same leaf had a water potential of ?14.8 bars, the quantum yield of the chloroplasts decreased to 0.028. The decrease could not be attributed to differences in rates of respiration by the leaves or the chlorophyll content or absorption spectrum of the leaves and chloroplasts. The data are the first to demonstrate an effect of low leaf water potential on the quantum yield and they indicate that changes occurred close to the primary photochemical events of photosynthesis. The similarity in response of the leaves and chloroplasts indicates that certain changes in photosynthesis at low water potentials are attributable to the chloroplasts rather than the stomata.

Mohanty, Prasanna; Boyer, John S.

1976-01-01

342

Pentacyclic triterpenoids from olive fruit and leaf.  

PubMed

This work establishes a new procedure for the extraction and analysis of pentacyclic triterpenes, with which fruits and leaves from three Spanish olive cultivars ("Picual", "Hojiblanca", and "Arbequina") has been studied. The leaf contains important amounts of oleanolic acid (3.0-3.5% DW), followed by significant concentrations of maslinic acid and minor levels of ursolic acid, erythrodiol, and uvaol. The abundance and profile of triterpenoids change during the leaf ontogeny. In the fruit, triterpenes are exclusively located in the epicarp at concentrations 30-fold lower than that in the leaf. Maslinic acid is the main triterpenoid, only accompanied of oleanolic acid. Along the ripening the levels of these triterpenes decreased. All the analyzed leaves and fruits come from the same agricultural estate, with identical climate and culturing conditions. For this reason, the found differences could majorly be attributable to the genetic factors of the olive cultivars. PMID:20712364

Guinda, Angeles; Rada, Mirela; Delgado, Teresa; Gutiérrez-Adánez, Pilar; Castellano, José María

2010-09-01

343

Relationship between Leaf Water and Leaf Waxes in Growing Pine Needles  

NASA Astrophysics Data System (ADS)

There has been an increasing interest in reconstruction of paleoclimate and paleo-environment using hydrogen isotopic ratios of plant lipids extracted from sediments. It has been shown that ?D of plant lipids is related to the ?D of leaf water, which in turn is related to the ?D of precipitation and relative humidity. However, the ?D of leaf water changes significantly through the life of a leaf, it is not clear how the leaf water dynamics affects the bulk isotopic composition of lipids that are synthesized throughout the life of the leaf. This work is a detailed study of the relationship between ?D values in leaf water and in leaf wax n-acids for two species of pine needles, red pine ( Pinus resinosa) and white pine ( Pinus strobus). In an earlier investigation we found that the ?D of leaf water in pine needles increased as they were elongated through the needle-growing season. The leaf water of red pine needles has higher ?D values than that of white pine needles at each comparable stage of growth. In addition, for a given needle, the leaf water ?D also increased from the base to the tip of the needle. To examine the variation of lipid ?D in relation to that of leaf water ?D, we collected 4 sets of needles during their elongation period, obtained the bulk leaf water, then sectioned them into smaller segments along the length, and measured ?D values of n-acids with 24 to 32 carbons. We test how the measured D/H ratios of leaf waxes vary with time, between two species, and with the position in the needle (relative distance from the tip, 0-1). A multiple regression analysis shows the following results. 1) The ?D values of all types of n-acids are significantly correlated with the position of the sample; ?D is lower near the base and higher near the tip. This result is consistent with the along-needle isotopic distribution of leaf water. 2) Leaf waxes of red pine needles are significantly more enriched in D than white pine needles, also consistent with leaf water ?D variation between the two species. 3) Regardless of temporal increases of leaf water ?D, the ?D of 4 out of 5 wax n-acids shows a decreasing trend with time, although only two (C-24, 32) are statistically significant. This may reflect use of stored hydrogen (from stored carbohydrates) at earlier stages of growth. 4) The significance of the overall regression of ?D against time, species and relative position increases from low carbon to high carbon number lipids (for C-24, 26, 28, 30, and 32, r2=0.34, 0.31, 0.56, 0.61, and 0.83), suggesting that longer wax n-acids are more influenced by local leaf water.

Majumdar, S.; Feng, X.; Hou, J.; Faiia, A. M.; Huang, Y.

2007-12-01

344

High efficient of females of B-type Bemisia tabaci as males in transmitting the whitefly-borne tomato yellow leaf curl virus to tomato plant with Q-PCR method confirmation.  

PubMed

It has been previously reported that TYLCV can be transmitted from viruliferous males to non-viruliferous females and from viruliferous females to non-viruliferous males, but not between insects of the same sex; female whiteflies transmit TYLCV-Is with higher efficiency than males through symptoms recognition and viral DNA identification in tomato test plants (one insect per plant, with 48 h AAP and 48 h IAP). However, it remains unclear whether non-infected female and male could obtain same virus from TYLCV-infected tomato plants, and whether TYLCV-infected female and male could transmit same virus to non-viruliferous tomato plants. To address this issue, quantitative real-time PCR were applied to detect TYLCV content in adults or tomato plant. The acquisition and transmission experiments showed that both female and male can acquire and transmit the virus and no acquisition capability difference was observed between newly emerged female and male, however, female demonstrated superior transmission capability than male. Moreover, gene expressions profilings of GroEL and Hamiltonella in non-viruliferous and viruliferous female was all higher than that in male. These results further indicated that sex is an important factor affecting TYLCV transmission efficiency in B. tabaci. PMID:23336021

Xie, Wen; Xu, Yan-Xia; Jiao, Xiao-Guo; Zhang, You-Jun

2012-11-01

345

High efficient of females of B-type Bemisia tabaci as males in transmitting the whitefly-borne tomato yellow leaf curl virus to tomato plant with Q-PCR method confirmation  

PubMed Central

It has been previously reported that TYLCV can be transmitted from viruliferous males to non-viruliferous females and from viruliferous females to non-viruliferous males, but not between insects of the same sex; female whiteflies transmit TYLCV-Is with higher efficiency than males through symptoms recognition and viral DNA identification in tomato test plants (one insect per plant, with 48 h AAP and 48 h IAP). However, it remains unclear whether non-infected female and male could obtain same virus from TYLCV-infected tomato plants, and whether TYLCV-infected female and male could transmit same virus to non-viruliferous tomato plants. To address this issue, quantitative real-time PCR were applied to detect TYLCV content in adults or tomato plant. The acquisition and transmission experiments showed that both female and male can acquire and transmit the virus and no acquisition capability difference was observed between newly emerged female and male, however, female demonstrated superior transmission capability than male. Moreover, gene expressions profilings of GroEL and Hamiltonella in non-viruliferous and viruliferous female was all higher than that in male. These results further indicated that sex is an important factor affecting TYLCV transmission efficiency in B. tabaci.

Xie, Wen; Xu, Yan-xia; Jiao, Xiao-guo; Zhang, You-jun

2012-01-01

346

Expressing a whitefly GroEL protein in Nicotiana benthamiana plants confers tolerance to tomato yellow leaf curl virus and cucumber mosaic virus, but not to grapevine virus A or tobacco mosaic virus  

Microsoft Academic Search

Transgenesis offers many ways to obtain virus-resistant plants. However, in most cases resistance is against a single virus\\u000a or viral strain. We have taken a novel approach based on the ability of a whitefly endosymbiotic GroEL to bind viruses belonging\\u000a to several genera, in vivo and in vitro. We have expressed the GroEL gene in Nicotiana benthamiana plants, postulating that upon virus

Dagan Edelbaum; Rena Gorovits; Sonoko Sasaki; Masato Ikegami; Henryk Czosnek

2009-01-01

347

A divergent isolate of tomato yellow leaf curl virus from Oman with an associated DNA beta satellite: an evolutionary link between Asian and the Middle Eastern virus-satellite complexes.  

PubMed

Tomato is cultivated in the coastal region of Al-Batinah, in the Sultanate of Oman, during the winter season, to meet the high demand for fresh produce in the domestic market. In order to identify the causal agent of a widespread disease associated with infestations of the whitefly Bemisia tabaci (Genn.) leaves were collected from tomato plants showing symptoms characteristic of the disease in Al-Batinah during 2004 and 2005. Total nucleic acids were isolated from the tomato leaves and used as the template for Phi29 DNA polymerase amplification of begomoviral circular DNA. Putative full unit length begomoviral DNA multimers were digested with Nco I and cloned into the plasmid vector pGEM7Zf+. The complete nucleotide (nt) sequence was determined as 2,765 bases, indicative of a monopartite begomoviral genome. A comparison of the genome sequence for the seven field isolates examined, indicated that they shared 99% nt identity. The virus from Oman was most closely related to TYLCV-IR at 91% nt identity, a monopartite begomoviral species described previously from Iran. Based on the guidelines of the ICTV the Oman isolate has been designated TYLCV-Om and is considered an isolate of TYLCV-IR. A satellite DNA (satDNA beta), was amplified by polymerase chain reaction using degenerate primers and cloned, and the DNA sequence was determined. Analysis of the complete nt sequence of 1,371 bases indicated that the satDNA shared 88.5% similarity with its closest relatives, which are DNA beta molecules from tomato in Pakistan. This is the first report of a satDNA beta associated with the TYLCV species. The TYLCV-Om and associated satDNA, thus represent a begomovirus-complex at the Asian-Middle East crossroads that quiet uniquely share geographical and genetic hallmarks of both. PMID:17932737

Khan, Akhtar Jamal; Idris, Ali M; Al-Saady, Nadiya Abubaker; Al-Mahruki, Madleen Said; Al-Subhi, Ali Masoud; Brown, J K

2008-02-01

348

Perfect is best: low leaf fluctuating asymmetry reduces herbivory by leaf miners.  

PubMed

Fluctuating asymmetry (FA) represents small, random variation from symmetry and can be used as an indicator of plant susceptibility to herbivory. We investigated the effects of FA of two oak species, Quercus laevis and Q. geminata, and the responses of three herbivore guilds: leaf miners, gallers, and chewers. To examine differences in FA and herbivory between individuals, 40 leaves from each tree were collected, and FA indices were calculated. To examine differences in FA and herbivory within-individuals, we sampled pairs of mined and unmined leaves for asymmetry measurements. Differences in growth of leaf miners between leaf types were determined by tracing 50 mines of each species on symmetric leaves and asymmetric leaves. Asymmetric leaves contained significantly lower concentrations of tannins and higher concentrations of nitrogen than symmetric leaves for both plant species. Both frequency of asymmetric leaves on plants and levels of asymmetry positively influenced the abundance of Brachys, Stilbosis and other leaf miners, but no significant relationship between asymmetry and herbivory was observed for Acrocercops. Brachys and Stilbosis mines were smaller on asymmetric leaves, but differences in mine survivorship between symmetric and asymmetric leaves were observed only for Stilbosis mines. This study indicated that leaf miners might use leaf FA as a cue to plant quality, although differential survivorship among leaf types was not observed for all species studied. Reasons for the different results between guilds are discussed. PMID:15378348

Cornelissen, Tatiana; Stiling, Peter

2005-01-01

349

Leaf anatomy of three herbaceous bamboo species.  

PubMed

Fully developed leaves of Cryptochloa capillata (Swallen) Soderstrom, Raddia brasilienses Bertol and Pharus lappulaceus Aublet (Poaceae: Bambusoideae) were collected at Restinga de Jacarepiá, Environment Proctection Area of Massambaba, county of Rio de Janeiro, State of Rio de Janeiro, Brazil, and studied by optical microscope. Leaf anatomy is described in order to contribute to the Poaceae family study. Anatomic features observed in the three studied species such as: midrib with complex vascular system, mesophyll consisting of tabular lobed chlorophyllous elements and fusoid cells, vascular bundles with double sheath, epidermis made up of long cells, short cells, micro-hairs, prickles and silica bodies correspond to the "bambusoid type" of leaf anatomy. PMID:12659043

Vieira, R C; Gomes, D M S; Sarahyba, L S; Arruda, R C O

2002-11-01

350

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.

BEGIN:VCARD VERSION:2.1 FN:Steve Case N:Case;Steve ORG:University of Kansas REV:2005-04-13 END:VCARD

1994-07-30

351

Stem and leaf morphoanatomy of Maytenus ilicifolia.  

PubMed

Maytenus ilicifolia is a woody medicinal plant, employed mainly for its antiulcerogenic properties. The stem and leaf morphoanatomy has been studied, aiming to supply knowledge for the pharmacognostic and taxonomic species identification. The vegetative material was fixed, freehand sectioned and stained according to usual microtechniques. The stem organization, in secondary growth, shows periderm beneath the remaining epidermis, conspicuous sclerenchymatic ring in the cortex and cambium forming phloem outside and xylem inside. The leaf is simple, alternate and lanceolate and has sparsely spiny teeth along the margin. Epidermal cells containing calcium oxalate crystals, thick cuticle that forms cuticular flanges, dorsiventral mesophyll and amphicrival bundle in the midrib and petiole are observed. PMID:15664461

Duarte, M R; Debur, M C

2005-01-01

352

Mueller matrix of a dicot leaf  

NASA Astrophysics Data System (ADS)

A better understanding of the information contained in the spectral, polarized bidirectional reflectance and transmittance of leaves may lead to improved techniques for identifying plant species in remotely sensed imagery as well as better estimates of plant moisture and nutritional status. Here we report an investigation of the optical polarizing properties of several leaves of one species, Cannabis sativa, represented by a 3x3 Mueller matrix measured over the wavelength region 400-2,400 nm. Our results support the hypothesis that the leaf surface alters the polarization of incident light - polarizing off nadir, unpolarized incident light, for example - while the leaf volume tends to depolarized incident polarized light.

Vanderbilt, Vern C.; Daughtry, Craig S. T.

2012-05-01

353

Two-dimensional leaf orientation distributions  

NASA Technical Reports Server (NTRS)

Combined inclination/azimuth leaf angle distributions are important for accurate models of vegetation canopy reflectance. It is shown that appropriate mathematical representations can be constructed from beta distributions under most circumstances. This is illustrated by analyzing observational data on soybean leaves and balsam fir needles. There are some problems when the data is imprecise and when correlations between inclination and azimuth angle are induced by heliotropism. Otherwise, the two-dimensional beta-type distribution appears to be a versatile tool for describing complete inclination/azimuth leaf angle distributions.

Strebel, D. E.; Goel, N. S.; Ranson, K. J.

1985-01-01

354

Is leaf dry matter content a better predictor of soil fertility than specific leaf area?  

PubMed Central

Background and Aims Specific leaf area (SLA), a key element of the ‘worldwide leaf economics spectrum’, is the preferred ‘soft’ plant trait for assessing soil fertility. SLA is a function of leaf dry matter content (LDMC) and leaf thickness (LT). The first, LDMC, defines leaf construction costs and can be used instead of SLA. However, LT identifies shade at its lowest extreme and succulence at its highest, and is not related to soil fertility. Why then is SLA more frequently used as a predictor of soil fertility than LDMC? Methods SLA, LDMC and LT were measured and leaf density (LD) estimated for almost 2000 species, and the capacity of LD to predict LDMC was examined, as was the relative contribution of LDMC and LT to the expression of SLA. Subsequently, the relationships between SLA, LDMC and LT with respect to soil fertility and shade were described. Key Results Although LD is strongly related to LDMC, and LDMC and LT each contribute equally to the expression of SLA, the exact relationships differ between ecological groupings. LDMC predicts leaf nitrogen content and soil fertility but, because LT primarily varies with light intensity, SLA increases in response to both increased shade and increased fertility. Conclusions Gradients of soil fertility are frequently also gradients of biomass accumulation with reduced irradiance lower in the canopy. Therefore, SLA, which includes both fertility and shade components, may often discriminate better between communities or treatments than LDMC. However, LDMC should always be the preferred trait for assessing gradients of soil fertility uncoupled from shade. Nevertheless, because leaves multitask, individual leaf traits do not necessarily exhibit exact functional equivalence between species. In consequence, rather than using a single stand-alone predictor, multivariate analyses using several leaf traits is recommended.

Hodgson, J. G.; Montserrat-Marti, G.; Charles, M.; Jones, G.; Wilson, P.; Shipley, B.; Sharafi, M.; Cerabolini, B. E. L.; Cornelissen, J. H. C.; Band, S. R.; Bogard, A.; Castro-Diez, P.; Guerrero-Campo, J.; Palmer, C.; Perez-Rontome, M. C.; Carter, G.; Hynd, A.; Romo-Diez, A.; de Torres Espuny, L.; Royo Pla, F.

2011-01-01

355

Cytokinin Regulates Compound Leaf Development in Tomato[C][W  

PubMed Central

Leaf shape diversity relies on transient morphogenetic activity in leaf margins. However, how this morphogenetic capacity is maintained is still poorly understood. Here, we uncover a role for the hormone cytokinin (CK) in the regulation of morphogenetic activity of compound leaves in tomato (Solanum lycopersicum). Manipulation of CK levels led to alterations in leaf complexity and revealed a unique potential for prolonged growth and morphogenesis in tomato leaves. We further demonstrate that the effect of CK on leaf complexity depends on proper localization of auxin signaling. Genetic analysis showed that reduction of CK levels suppresses the effect of Knotted1 like homeobox (KNOXI) proteins on leaf shape and that CK can substitute for KNOXI activity at the leaf margin, suggesting that CK mediates the activity of KNOXI proteins in the regulation of leaf shape. These results imply that CK regulates flexible leaf patterning by dynamic interaction with additional hormones and transcription factors.

Shani, Eilon; Ben-Gera, Hadas; Shleizer-Burko, Sharona; Burko, Yogev; Weiss, David; Ori, Naomi

2010-01-01

356

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...

357

The Role of Mangrove Ecosystems: Mangrove Leaf Area Indices.  

National Technical Information Service (NTIS)

Leaf area index (LAI) on total leaf surface per unit ground area is one parameter which may be used to estimate the photosynthetic capacity of individual plants or entire ecosystems. Techniques used for determining LAI in south Florida mangrove ecosystems...

D. J. Pool

1973-01-01

358

Pharmacognostic evaluation of Cayratia trifolia (Linn.) leaf  

PubMed Central

Objective To present a detailed pharmacognostic study of the leaf of Cayratia trifolia (C. trifolia) Linn. (Vitaceae), an important plant in the Indian system of medicine. Methods The macroscopy, microscopy, physiochemical analysis, preliminary testing, fluorescence analysis of powder of the plant and other WHO recommended methods for standardization were investigated. Results Leaves are trifoliolated with petioles (2–3 cm) long. Leaflets are ovate to oblong-ovate, (2–8 cm) long, (1.5–5 cm) wide, pointed at the tip. The leaf surface shows the anisocytic type stomata covered with guard cells followed by epidermis layer. Leaf surface contents including veins, vein islet and vein termination were also determined. Transverse section of leaf shows the epidermis layer followed by cuticle layer and vascular bandles (xylem and phloem). The mesophyll is differentiated into palisade and spongy parenchyma. Abundant covering trichomes emerge from the upper epidermis. Trichomes are uniseriate and multicellular. Strips of collenchyma are present below and upper layer of epidermis. Conclusions It can be concluded that the pharmacognostic profile of the C. trifolia is helpful in developing standards for quality, purity and sample identification.

Kumar, Dinesh; Gupta, Jyoti; Kumar, Sunil; Arya, Renu; Kumar, Tarun; Gupta, Ankit

2012-01-01

359

Anatomy of non-uniform leaf photosynthesis  

Microsoft Academic Search

Since 1986, non-uniform photosynthesis over the leaf area that may be attributed to patchy stomatal closure, has been an important issue in stress physiology of photosynthesis. In this review, I first outline the gaseous environment within the intercellular spaces, because this is the most fundamental background of this problem. Then, recent studies approaching non-uniform photosynthesis are reviwed. After examining techniques

Ichiro Terashima

1992-01-01

360

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

361

Environmental Correlates of Leaf Stomata Density  

NSDL National Science Digital Library

In this Experiment, students make impressions of leaf stomata (using clear nail polish) and test a hypothesis of their choice about how leaf stomata density might vary under different environmental conditions. Leaf stomata are the principal means of gas exchange in vascular plants. Stomata are small pores, typically on the undersides of leaves, that are opened or closed under the control of a pair of banana-shaped cells called guard cells. When open, stomata allow CO2 to enter the leaf for synthesis of glucose, and also allow for water, H2O, and free oxygen, O2, to escape. In addition to opening and closing the stomata (stomata behavior), plants may exert control over their gas exchange rates by varying stomata density in new leaves when they are produced (such as in the spring or summer). The more stomata per unit area (stomata density) the more CO2 can be taken up, and the more water can be released. Thus, higher stomata density can greatly amplify the potential for behavioral control over water loss rate and CO2 uptake.

Vatnick, Itzick

2010-02-16

362

Plant leaf imaging technique for agronomy  

Microsoft Academic Search

Recent physiological studies on nutrition and growth have shown that leaf area is a reliable index of growth factor determining carbohydrate metabolism, yield and quality of crops. Software was developed using image processing toolbox of MATLAB, for calculating parameters of multiple leaves like area, length, width etc. Sample of 50 leaves of various shapes and sizes were used in measurements

V. D. Shivling; Ajay Singla; C. Ghanshyam; Pawan Kapur; Savita Gupta

2011-01-01

363

Turbine rotor-stator leaf seal and related method  

DOEpatents

A seal assembly for installation between rotating and stationary components of a machine includes a first plurality of leaf spring segments secured to the stationary component in a circumferential array surrounding the rotating component, the leaf spring segments each having a radial mounting portion and a substantially axial sealing portion, the plurality of leaf spring segments shingled in a circumferential direction.

Herron, William Lee (Cincinnati, OH); Butkiewicz, Jeffrey John (Simpsonville, SC)

2003-01-01

364

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

365

Systematic vegetative anatomy and ensiform leaf development in Xyris (Xyridaceae)  

Microsoft Academic Search

Ensiform leaf development in monocotyledons follows a broadly similar sequence in a wide range of relatively unrelated taxa, indicating a plastic developmental pattern, possibly associated with stressed environmental conditions, sinceXyrisspecies tend to grow in relatively damp but nutrient-poor environments. The bifacial leaf sheath surrounds the apex and the subadjacent primordium. A conical unifacial leaf tip «Vorläuferspitze» is established at an

M. J. SAJO; P. J. RUDALL

1999-01-01

366

7 CFR 30.31 - Classification of leaf tobacco.  

Code of Federal Regulations, 2010 CFR

...2009-01-01 false Classification of leaf tobacco. 30.31 Section 30.31...STOCKS AND STANDARDS Classification of Leaf Tobacco Covering Classes, Types and Groups of Grades § 30.31 Classification of leaf tobacco. For the purpose of this...

2009-01-01

367

Field estimation of leaf nitrogen by light transmittance  

Microsoft Academic Search

A highly significant negative correlation was found between percentage transmittance of photosynthetically active radiation (%TPAR) through a varied sample of walnut leaves and their extractable chlorophyll content (expressed on a leaf?area basis). The %TPAR was negatively correlated with leaf nitrogen (N) expressed on a leaf?area basis. When leaves were sampled from throughout the canopy of a walnut tree, no correlation

A. Erez; S. A. Weinbaum

1985-01-01

368

Superdiffusive Bounds on Self-repellent Brownian Polymers and Diffusion in the Curl of the Gaussian Free Field in d=2  

NASA Astrophysics Data System (ADS)

We consider two models of random diffusion in random environment in two dimensions. The first example is the self-repelling Brownian polymer, this describes a diffusion pushed by the negative gradient of its own occupation time measure (local time). The second example is a diffusion in a fixed random environment given by the curl of massless Gaussian free field. In both cases we show that the process is superdiffusive: the variance grows faster than linearly with time. We give lower and upper bounds of the order of tloglog t, respectively, tlog t. We also present computations for an anisotropic version of the self-repelling Brownian polymer where we give lower and upper bounds of t(log t)1/2, respectively, tlog t. The bounds are given in the sense of Laplace transforms, the proofs rely on the resolvent method. The true order of the variance for these processes is expected to be t(log t)1/2 for the isotropic and t(log t)2/3 for the non-isotropic case. In the appendix we present a non-rigorous derivation of these scaling exponents.

Tóth, Bálint; Valkó, Benedek

2012-04-01

369

Synthesis of single and multi unit-wall MgB{sub 2} nanotubes by arc plasma in inert liquid via self-curling mechanism  

SciTech Connect

Magnesium diboride (MgB{sub 2}) is known as a promising superconductor due to its high transmission temperature. Similarly to single-wall carbon nanotube, unique characteristics would be seen if a nanotube structure of MgB{sub 2} having a unit-wall of Mg and B atomic bilayer is prepared. However, such MgB{sub 2} nanotubes have not ever been synthesized. In this article, formation mechanism of unit-wall MgB{sub 2} nanotube is elucidated by molecular mechanics calculation. From the viewpoint of energetic stability, the unit-wall will be curled up to form nanotube structure when MgB{sub 2} crystal is disassembled to an isolated unit-wall layer. An experiment using arc plasma in inert liquid was utilized to produce unit-wall MgB{sub 2} nanotubes. As a result, a single and multiunit-wall MgB{sub 2} nanotube was successfully synthesized. In this reaction field, the arc plasma may play a role to produce isolated MgB{sub 2} unit-wall fragment, and the cold cathode surface can contribute to preserve MgB{sub 2} nanotube structure.

Sano, Noriaki; Tamon, Hajime [Department of Chemical Engineering, Kyoto University, Kyoto 615-8510 (Japan); Kawanami, Osamu [Department of Mechanical and System Engineering, University of Hyogo, 2167 Shoha, Himeji 671-2280 (Japan)

2011-02-01

370

Relating Leaf Nitrogen, Leaf Photosynthesis and Canopy CO2 Exchange in a Temperate Winter Barley Field  

NASA Astrophysics Data System (ADS)

Net exchange of CO2 between the atmosphere and the soil-vegetation interface (NEE) is controlled by a wide range of biochemical and biophysical processes where leaf photosynthesis is often the most important. In mechanistically and physically based photosynthesis models (e.g. Farquhar et al. 1980) leaf nutrient status is a limiting factor for the photosynthetic capacity since it is implicitly incorporated through the parameters of maximum rate of carboxylation of CO2 (Vcmax) and the maximum rate of electron transport (Jmax). These are closely related to leaf nitrogen concentration (Na) and leaf chlorophyll content (Cab) and often show a characteristic seasonal dynamic. When simulating CO2 exchange, model outputs are sensitive to leaf photosynthetic capacity, which is labour consuming to verify through field measurements. A less time consuming method is to measure leaf "greenness" (SPAD), which is closely related to chlorophyll content and thus photosynthetic capacity. In the present study field measurements of leaf photosynthesis (LI-6400, LICOR Inc.), leaf reflectance (SPAD-502, Minolta), and LAI (LAI-2000, LICOR Inc.) were conducted on agricultural fields in Western Denmark during one growing season. The leaf photosynthesis measurements provided the basis for estimating photosynthetic capacity. SPAD measurements and LAI was measured with a higher spatial and temporal resolution. SPAD readings were calibrated against Cab and Na analyzed on leaf material in the laboratory and later correlated to photosynthetic capacity. These data were used to parameterize a coupled photosynthesis and stomatal model that was run for the growing season 2012 to estimate NEE. As a part of the hydrological observatory HOBE (hobe.dk), fluxes of greenhouse gasses are continuously measured by eddy covariance systems at three field sites in the Skjern River Catchment, Western Denmark, providing the basis for estimating the exchange of energy, water vapour, and CO2 on canopy scale. One of the sites is situated at the field under investigation in the present study. Here we compare modeled NEE with the measured CO2 fluxes. The presented approach is shown to provide an efficient field sampling method for model parameterization with high temporal and spatial resolution and a physiological basis for scaling fluxes from leaf level to canopy scale. We further evaluate the potential for applying the model approach in connection with upscaling by means of satellite data.

Jensen, R.; Boegh, E.; Herbst, M.; Friborg, T.

2012-12-01

371

Impact of epidermal leaf mining by the aspen leaf miner (Phyllocnistis populiella) on the growth, physiology, and leaf longevity of quaking aspen.  

PubMed

The aspen leaf miner, Phyllocnistis populiella, feeds on the contents of epidermal cells on both top (adaxial) and bottom (abaxial) surfaces of quaking aspen leaves, leaving the photosynthetic tissue of the mesophyll intact. This type of feeding is taxonomically restricted to a small subset of leaf mining insects but can cause widespread plant damage during outbreaks. We studied the effect of epidermal mining on aspen growth and physiology during an outbreak of P. populiella in the boreal forest of interior Alaska. Experimental reduction of leaf miner density across two sites and 3 years significantly increased annual aspen growth rates relative to naturally mined controls. Leaf mining damage was negatively related to leaf longevity. Leaves with heavy mining damage abscised 4 weeks earlier, on average, than leaves with minimal mining damage. Mining damage to the top and bottom surfaces of leaves had different effects on physiology. Mining on the top surface of the leaf had no significant effect on photosynthesis or conductance and was unrelated to leaf stable C isotope ratio (delta(13)C). Mining damage to the bottom leaf surface, where stomata are located, had significant negative effects on net photosynthesis and water vapor conductance. Percent bottom mining was positively related to leaf delta(13)C. Taken together, the data suggest that the primary mechanism for the reduction of photosynthesis by epidermal leaf mining by P. populiella is the failure of stomata to open normally on bottom-mined leaves. PMID:18523809

Wagner, Diane; DeFoliart, Linda; Doak, Patricia; Schneiderheinze, Jenny

2008-08-01

372

Measurements of leaf orientation, light distribution and sunlit leaf area in a boreal aspen forest  

Microsoft Academic Search

A new instrument called a Multiband Vegetation Imager (MVI) (Kucharik et al., 1997), which uses a 16-bit charge-coupled device (CCD) camera and filter exchange mechanism to capture 2-band (visible and near-infrared) image pairs of plant canopies, has been used to measure the light distribution over sunlit leaves and indirectly infer leaf area index (LAI), sunlit LAI and leaf angle distribution

Christopher J Kucharik; John M. Norman; Stith T. Gower

1998-01-01

373

Nitrogen EÄects on Leaf Anatomy within the Intercalary Meristems of Tall Fescue Leaf Blades  

Microsoft Academic Search

Longitudinal elongation contributes most to leaf area expansion of grasses and its rate is known to be strongly aÄected by N. Our objective was to determine the eÄect of two N regimes (N0 and Ná) on the gradient of leaf tissue formation in meristems of two contrasting tall fescue (Festuca arundinacea Schreb.) genotypes. Proportions of epidermal, mesophyll and vascular tissue

INGO F. RADEMACHER; C. JERRY NELSON

2001-01-01

374

Seasonal variation in Daucus carota leaf-surface and leaf-tissue chemical profiles  

Microsoft Academic Search

The purpose of this work was to document seasonal changes in leaf-surface and whole-leaf chemistry of Daucus carota cohorts that differed in life-cycle phenology (winter annual, annual, or biennial), with particular focus on compounds that serve as contact oviposition stimulants for Papilio polyxenes, the black swallowtail butterfly. Cohorts of carrot plants exhibiting different life-cycle phenologies were established, and plants from

Janie S Brooks; Paul Feeny

2004-01-01

375

Leaf optical properties and photosynthetic leaf absorptances in several Australian seagrasses  

Microsoft Academic Search

This study investigated within- and among-species variability in the leaf optical properties of eight large-bodied seagrasses, Posidonia australis, Posidonia sinuosa, Posidonia coriacea, Posidonia angustifolia, Amphibolis antarctica, Amphibolis griffithii, Zostera tasmanica, and Zostera capricorni and the small-bodied Halophila ovalis from the east and west coasts of Australia.Leaf spectral transmittance [TL(?)], reflectance [RL(?)], and non-photosynthetic absorptance [AL(NP)] were measured in order to

Michael J. Durako

2007-01-01

376

Final report on the safety assessment of AloeAndongensis Extract, Aloe Andongensis Leaf Juice,aloe Arborescens Leaf Extract, Aloe Arborescens Leaf Juice, Aloe Arborescens Leaf Protoplasts, Aloe Barbadensis Flower Extract, Aloe Barbadensis Leaf, Aloe Barbadensis Leaf Extract, Aloe Barbadensis Leaf Juice,aloe Barbadensis Leaf Polysaccharides, Aloe Barbadensis Leaf Water, Aloe Ferox Leaf Extract, Aloe Ferox Leaf Juice, and Aloe Ferox Leaf Juice Extract.  

PubMed

Plant materials derived from the Aloe plant are used as cosmetic ingredients, including Aloe Andongensis Extract, Aloe Andongensis Leaf Juice, Aloe Arborescens Leaf Extract, Aloe Arborescens Leaf Juice, Aloe Arborescens Leaf Protoplasts, Aloe Barbadensis Flower Extract, Aloe Barbadensis Leaf, Aloe Barbadensis Leaf Extract, Aloe Barbadensis Leaf Juice, Aloe Barbadensis Leaf Polysaccharides, Aloe Barbadensis Leaf Water, Aloe Ferox Leaf Extract, Aloe Ferox Leaf Juice, and Aloe Ferox Leaf Juice Extract. These ingredients function primarily as skin-conditioning agents and are included in cosmetics only at low concentrations. The Aloe leaf consists of the pericyclic cells, found just below the plant's skin, and the inner central area of the leaf, i.e., the gel, which is used for cosmetic products. The pericyclic cells produce a bitter, yellow latex containing a number of anthraquinones, phototoxic compounds that are also gastrointestinal irritants responsible for cathartic effects. The gel contains polysaccharides, which can be acetylated, partially acetylated, or not acetylated. An industry established limit for anthraquinones in aloe-derived material for nonmedicinal use is 50 ppm or lower. Aloe-derived ingredients are used in a wide variety of cosmetic product types at concentrations of raw material that are 0.1% or less, although can be as high as 20%. The concentration of Aloe in the raw material also may vary from 100% to a low of 0.0005%. Oral administration of various anthraquinone components results in a rise in their blood concentrations, wide systemic distribution, accumulation in the liver and kidneys, and excretion in urine and feces; polysaccharide components are distributed systemically and metabolized into smaller molecules. aloe-derived material has fungicidal, antimicrobial, and antiviral activities, and has been effective in wound healing and infection treatment in animals. Aloe barbadensis (also known as Aloe vera)-derived ingredients were not toxic in acute oral studies using mice and rats. In parenteral studies, the LD(50) using mice was > 200 mg/kg, rats was > 50 mg/kg, and using dogs was > 50 mg/kg. In intravenous studies the LD(50) using mice was > 80 mg/kg, rats was > 15 mg/kg, and dogs was > 10 mg/kg. The 14-day no observed effect level (NOEL) for the Aloe polysaccharide, acemannan, in the diet of Sprague-Dawley rats, was 50,000 ppm or 4.1 to 4.6 g/kg day(-1). In a 3-month study using mice, Aloe vera (extracted in ethanol) given orally in drinking water at 100 mg/kg produced reproductive toxicity, inflammation, and mortality above that seen in control animals. Aloe vera extracted in methanol and given to mice at 100 mg/kg in drinking water for 3 months caused significant sperm damage compared to controls. Aloe barbadensis extracted with water and given to pregnant Charles Foster albino rats on gestational days (GDs) 0 through 9 was an abortifacient and produced skeletal abnormalities. Both negative and positive results were found in bacterial and mammalian cell genotoxicity assays using Aloe barbadensis-derived material, Aloe Ferox-derived material, and various anthraquinones derived from Aloe. Aloin (an anthraquinone) did not produce tumors when included in the feed of mice for 20 weeks, nor did aloin increase the incidence of colorectal tumors induced with 1,2-dimethylhydrazine. Aloe-emodin (an anthraquinone) given to mice in which tumor cells had been injected inhibited growth of malignant tumors. Other animal data also suggest that components of Aloe inhibit tumor growth and improve survival. Various in vitro assays also demonstrated anticarcinogenic activity of aloe-emodin. Diarrhea was the only adverse effect of note with the use of Aloe-derived ingredients to treat asthma, ischemic heart disease, diabetes, ulcers, skin disease, and cancer. Case reports include acute eczema, contact urticaria, and dermatitis in individuals who applied Aloe-derived ingredients topically. The Cosmetic Ingredient Review Expert Panel concluded that anthraquinone levels in the several Aloe Barbaden

2007-01-01

377

Plant size effects on the relationships among specific leaf area, leaf nutrient content, and photosynthetic capacity in tropical woody species  

Microsoft Academic Search

To test whether leaf trait relationships vary with plant size, specific leaf area (SLA), area- and mass-based leaf nutrient contents (Narea and Nmass, Parea and Pmass), and area- and mass-based leaf photosynthetic capacities (Aarea and Amass) of 127 small individuals (woody plants shorter than 2 m) and 47 large trees (taller than 10 m) were measured in a tropical montane rain forest,

Fude Liu; Wenjie Yang; Zhongsheng Wang; Zhen Xu; Hong Liu; Ming Zhang; Yuhong Liu; Shuqing An; Shucun Sun

2010-01-01

378

The assessment of leaf water content using leaf reflectance ratios in the visible, near?, and short?wave?infrared  

Microsoft Academic Search

The common features of spectral reflectance from vegetation foliage upon leaf dehydration are decreasing water absorption troughs in the near?infrared (NIR) and short?wave?infrared (SWIR). We studied which leaf water index in the NIR and SWIR is most suitable for the assessment of leaf water content and the detection of leaf dehydration from the laboratory standpoint. We also examined the influence

A. Hoehn; L. S. Stodieck; D. M. Klaus; W. W. Adams III; W. J. Emery

2008-01-01

379

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

380

Leaf abscission phenology of a scrub oak: consequences for growth and survivorship of a leaf mining beetle  

Microsoft Academic Search

Brachys tessellatus is a leaf-mining beetle that attacks Quercus laevis (turkey oak), a deciduous scrub oak in the fall line Sandhills of the southeastern United States. This oak species varies substantially in leaf abscission phenology. In the fall of 1994 we examined leaf abscission patterns at three sites in central South Carolina and found that leaves containing active miners abscised

Kim J. Waddell; Charles W. Fox; Kenneth D. White; Timothy A. Mousseau

2001-01-01

381

Physiological, anatomical and leaf hydraulic effects on leaf water delta18O enrichment in different plant species  

Microsoft Academic Search

Stable oxygen isotope ratios (delta18O) of plant and source waters are valuable tools in the analysis of water and carbon fluxes at leaf, plant, and ecosystem scales. Recent improvements in mechanistic models have significantly advanced the understanding of isotopic leaf water enrichment, which is an important source of delta18O variability in plants and ecosystems. However, the marked variability in leaf

A. Kahmen; S. K. Arndt; T. E. Dawson

2007-01-01

382

Using Stream Leaf Packs to Explore Community Assembly  

NSDL National Science Digital Library

In this TIEE experiment, students will explore functional and taxonomic diversity in a stream ecosystem, learn about food web relationships, and learn about the ways in which abiotic and biotic factors determine what organisms are present in a community. Students will make and install artificial leaf packs in a stream, wait for the leaf packs to be colonized by stream organisms, measure abiotic variables that could influence leaf pack colonization, retrieve the leaf packs and classify the organisms they find in both taxonomic and functional ways, and participate in a class discussion of how the leaf pack community is situated within a larger ecosystem.

Hartley, Laurel

2011-08-29

383

The mechanical transmission of euonymus mosaic virus, maple leaf perforation by leaf extract or leaf nucleic acid to herbaceous plants  

Microsoft Academic Search

Conditions for the mechanical transmission of some woody viruses to herbaceous hosts were studied. Viruses from naturally-infected\\u000a spindle tree (Euonymus europaea) and maple (Acer pseudoplatanus) leaves were mechanically transmitted by the homogenate prepared by using charcoal and celite to beans (Phaseolus vulqaris cv. Kocovska and Perlicka). The transmission of Euonymus mosaic virus and maple leaf perforation by nucleic acids prepared

ValÉria ŠUbÍKovÁ

1973-01-01

384

Use of NAP gene to manipulate leaf senescence in plants  

DOEpatents

The present invention discloses transgenic plants having an altered level of NAP protein compared to that of a non-transgenic plant, where the transgenic plants display an altered leaf senescence phenotype relative to a non-transgenic plant, as well as mutant plants comprising an inactivated NAP gene, where mutant plants display a delayed leaf senescence phenotype compared to that of a non-mutant plant. The present invention also discloses methods for delaying leaf senescence in a plant, as well as methods of making a mutant plant having a decreased level of NAP protein compared to that of a non-mutant plant, where the mutant plant displays a delayed leaf senescence phenotype relative to a non-mutant plant. Methods for causing precocious leaf senescence or promoting leaf senescence in a plant are also disclosed. Also disclosed are methods of identifying a candidate plant suitable for breeding that displays a delayed leaf senescence and/or enhanced yield phenotype.

Gan, Susheng; Guo, Yongfeng

2013-04-16

385

Variations in the polarized leaf reflectance of Sorghum bicolor  

NASA Technical Reports Server (NTRS)

The polarized reflectance factor, Rq, of sorghum (Sorghum bicolor, L.) leaves from field-grown plants was measured in situ in the summers of 1983 and 1984. In 1983, three leaves of two randomly selected plants were measured at 2-week intervals. The value of Rq varied, depending on leaf and day of measurement. Measured values of Rq for the adaxial leaf surface ranged from 16 to 53; for the abaxial leaf surface the values ranged from 28 to 69. In 1984, measurements consisted of repeated observations made on the same leaf at biweekly intervals. The values of Rq from the adaxial leaf surface ranged from 26 to 38. Values of Rq from the abaxial leaf surface increased throughout the season, from 16 to 45. Differences in Rq were attributed to changes in surface details of the leaf.

Grant, Lois; Daughtry, C. S. T.; Vanderbilt, V. C.

1987-01-01

386

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

387

Leaf-wax n-alkanes record the plant-water environment at leaf flush.  

PubMed

Leaf-wax n-alkanes (2)H/(1)H ratios are widely used as a proxy in climate reconstruction. Although the broad nature of the relationship between n-alkanes ?(2)H 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 ?(2)H value and monitored the ?(2)H values of leaf-wax n-alkanes and of stem, leaf, stream, and atmospheric waters throughout the entire growing season. Here we found the ?(2)H 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 ?(2)H 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 ?(2)H values during the time of wax synthesis. We observed that the isotope ratios of this precipitation generally were (2)H-enriched compared with mean annual precipitation. This model provides a mechanistic basis of the often-observed (2)H-enrichment from the expected fractionation values in studies of broadleaf angiosperm leaf-wax ?(2)H. In addition, these findings may have implications for the spatial and temporal uses of n-alkane ?(2)H 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. PMID:23359675

Tipple, Brett J; Berke, Melissa A; Doman, Christine E; Khachaturyan, Susanna; Ehleringer, James R

2013-02-12

388

BOREAS TE-5 Leaf Gas Exchange Data  

NASA Technical Reports Server (NTRS)

The BOREAS TE-5 team collected measurements in the NSA and SSA on gas exchange, gas composition, and tree growth. The leaf photosynthetic gas exchange data were collected in the BOREAS NSA and the SSA from 06-Jun- 1994 to 13-Sep- 1994 using a LI-COR 6200 portable photosynthesis system. The data were collected to compare the photosynthetic capacity, stomata] conductance, and leaf intercellular CO, concentrations among the major tree species at the BOREAS sites. The data are average values from diurnal measurements on the upper canopy foliage (sun leaves). The data are available in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Activity Archive Center (DAAC).

Hall, Forrest G. (Editor); Curd, Shelaine (Editor); Ehleriinger, Jim; Brooks, J. Renee; Flanagan, Larry

2000-01-01

389

BOREAS TE-5 Leaf Carbon Isotope Data  

NASA Technical Reports Server (NTRS)

The BOREAS TE-5 team collected measurements in the NSA and SSA on gas exchange, gas composition, and tree growth. This documentation describes leaf carbon isotope data that were collected in 1993 and 1994 at the NSA and SSA OJP sites, the SSA OBS site, and the NSA UBS site. In addition, leaf carbon isotope data were collected in 1994 only at the NSA and SSA OA sites. These data was collected to provide seasonal integrated physiological information for 10 to 15 common species at these 6 BOREAS sites. The data are stored in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

Hall, Forrest G. (Editor); Curd, Shelaine (Editor); Ehleriinger, Jim; Brooks, J. Renee; Flanagan, Larry

2000-01-01

390

Preventing leaf identity theft with hormones.  

PubMed

Genetic analysis of plant development has begun to demonstrate the importance of hormone synthesis and transport in regulating morphogenesis. In the case of leaf development, for example, auxin pooling determines where a primordium will emerge and leads to the activation of transcription factors, which determine leaf identities by modulating abscisic acid (ABA) and gibberellic acid (GA) concentrations. Signal transduction studies suggest that negative regulation of transcription factors through protein turnover is commonly used as a mechanism of hormone action. Together, these findings suggest that auxin might degrade a repressor that allows the activation of genes that modulate ABA/GA ratios in emerging leaves. With our increased understanding of the molecular basis of hormone signaling, it is becoming possible to overlay important regulators onto signaling modules that determine morphological outputs. PMID:16054431

Lumba, Shelley; McCourt, Peter

2005-10-01

391

Molecular and functional characterization of CpACS27A gene reveals its involvement in monoecy instability and other associated traits in squash (Cucurbita pepo L.).  

PubMed

A number of Cucurbita pepo genotypes showing instable monoecy or partial andromonoecy, i.e. an incomplete conversion of female into bisexual flowers, have been detected. Given that in melon and cucumber andromonoecy is the result of reduction of ethylene production in female floral buds, caused by mutations in the ethylene biosynthesis genes CmACS7 and CsACS2; we have cloned and characterized two related C. pepo genes, CpACS27A and CpACS27B. The molecular structure of CpACS27A and its specific expression in the carpels of female flowers during earlier stages of flower development suggests that this gene is the Cucurbita ortholog of CmACS7 and CsACS2. CpACS27B is likely to be a paralogous pseudogene since it has not been found to be expressed in any of the analyzed tissues. CpACS27A was sequenced in Bolognese (Bog) and Vegetable Spaghetti (Veg), two monoecious inbred lines whose F2 was segregating for partial andromonoecy. The Bog allele of CpACS27A carried a missense mutation that resulted in a substitution of the conserved serine residue in position 176 by an alanine. Segregation analysis indicated that this mutant variant is necessary but not sufficient to confer the andromonoecious phenotype in squash. In concordance with its involvement in stamen arrest, a reduction in CpACS27A expression has been found in bisexual flower buds at earlier stages of development. This reduction in CpACS27A expression was concomitant with a downregulation of other ethylene biosynthesis and signaling genes during earlier and later stages of ovary development. The role of CpACS27A is discussed regarding the regulation of ethylene biosynthesis and signaling genes in the control of andromonoecy-associated traits, such as the delayed maturation of corolla and stigma as well as the parthenocarpic development of the fruit. PMID:24595516

Martínez, Cecilia; Manzano, Susana; Megías, Zoraida; Barrera, Alejandro; Boualem, Adnane; Garrido, Dolores; Bendahmane, Abdelhafid; Jamilena, Manuel

2014-06-01

392

Parasitic wasps orient to green leaf volatiles  

Microsoft Academic Search

Summary Undamaged plants emit low levels of green leaf volatiles (GLVs), while caterpillar-damaged and artificially damaged plants emit relatively higher levels of certain GLVs. Female braconid parasitoids,Microplitis croceipes, oriented to both damaged plants and to individual GLVs in no-choice tests in a wind tunnel, but seldom oriented to undamaged plants. Female ichneumonid parasitoids,Netelia heroica, also oriented to individual GLVs in

Douglas W. Whitman; Fred J. Eller

1990-01-01

393

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.

394

Ancient pinnate leaf mimesis among lacewings.  

PubMed

Insects have evolved diverse methods of predator avoidance, many of which implicate complex adaptations of their wings (e.g., Phylliidae, Nymphalidae, Notodontidae). Among these, angiosperm leaf mimicry is one of the most dramatic, although the historical origins of such modifications are unclear owing to a dearth of paleontological records. Here, we report evidence of pinnate leaf mimesis in two lacewings (Neuroptera): Bellinympha filicifolia Y. Wang, Ren, Liu & Engel gen. et sp. nov. and Bellinympha dancei Y. Wang, Ren, Shih & Engel, sp. nov., from the Middle Jurassic, representing a 165-million-year-old specialization between insects and contemporaneous gymnosperms of the Cycadales or Bennettitales. Furthermore, such lacewings demonstrate a preangiosperm origin for leaf mimesis, revealing a lost evolutionary scenario of interactions between insects and gymnosperms. The current fossil record suggests that this enigmatic lineage became extinct during the Early Cretaceous, apparently closely correlated with the decline of Cycadales and Bennettitales at that time, and perhaps owing to the changing floral environment resulted from the rise of flowering plants. PMID:20805491

Wang, Yongjie; Liu, Zhiqi; Wang, Xin; Shih, Chungkun; Zhao, Yunyun; Engel, Michael S; Ren, Dong

2010-09-14

395

Stomatal Closure during Leaf Dehydration, Correlation with Other Leaf Physiological Traits1  

PubMed Central

The question as to what triggers stomatal closure during leaf desiccation remains controversial. This paper examines characteristics of the vascular and photosynthetic functions of the leaf to determine which responds most similarly to stomata during desiccation. Leaf hydraulic conductance (Kleaf) was measured from the relaxation kinetics of leaf water potential (?l), and a novel application of this technique allowed the response of Kleaf to ?l to be determined. These “vulnerability curves” show that Kleaf is highly sensitive to ?l and that the response of stomatal conductance to ?l is closely correlated with the response of Kleaf to ?l. The turgor loss point of leaves was also correlated with Kleaf and stomatal closure, whereas the decline in PSII quantum yield during leaf drying occurred at a lower ?l than stomatal closure. These results indicate that stomatal closure is primarily coordinated with Kleaf. However, the close proximity of ?l at initial stomatal closure and initial loss of Kleaf suggest that partial loss of Kleaf might occur regularly, presumably necessitating repair of embolisms.

Brodribb, Tim J.; Holbrook, N. Michele

2003-01-01

396

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

397

Watermelon chlorotic stunt virus (WmCSV): a serious disease threatening watermelon production in Jordan.  

PubMed

The incidence of watermelon chlorotic stunt disease and the molecular characterization of the Jordanian isolate of Watermelon chlorotic stunt virus (WmCSV-[JO]) are described in this study. Symptomatic leaf samples obtained from watermelon (Citrullus lanatus Thunb.), melon (Cucumis melo L.), squash (Cucurbita pepo), cucumber (Cucumis sativus L.), and bottle gourd (Lagenaria siceraria) plants were tested for WmCSV-[JO] infection by PCR. The virus could be detected in 8 melon and 87 watermelon samples obtained from Ghor Assafi (southern part of Jordan Valley). Three samples collected from Mafraq (eastern part of Jordan) were found mixed infected with WmCSV-[JO] and Squash leaf curl virus. The full-length DNA-A and DNA-B genomes of WmCSV-[JO] were amplified, and sequences were deposited in the GenBank under accession numbers EU561237 and EU561236, respectively. Sequence analysis reveals that WmCSV-[JO] is closely related to other virus isolates from Israel (WmCSV-[IL]), Yemen (WmCSV-[YE]), Iran (WmCSV-[IR]), Lebanon (WmCSV-[LB]), and Sudan (WmCSV-[SD]). DNA-A of WmCSV-[JO] showed highest nucleotide identity (99.42%) with WmCSV-[IL], while DNA-B had highest nucleotide identity (95.52%) with WmCSV-[YE]. Data of this study demonstrate that digestion of DNA-B genome of WmCSV isolates with ApaI enzyme can discriminate between these isolates at the molecular level. Infectious clones of WmCSV-[JO] were constructed and agroinoculated to Nicotiana benthamiana plants. Inoculated plants developed mild disease symptoms 4 weeks post inoculation, while watermelon plants biolistically inoculated with WmCSV-[JO] developed characteristic mottling, yellowing and severe leaf curling symptoms 3 weeks post inoculation. PMID:21399920

Al-Musa, A; Anfoka, G; Al-Abdulat, A; Misbeh, S; Haj Ahmed, F; Otri, I

2011-08-01

398

The origin of the diversity of leaf venation pattern.  

PubMed

The leaf venation pattern of plants shows remarkable diversity and species-specificity. However, the mechanism underlying the pattern formation and pattern diversity remains unclear. We developed a mathematical model that is based on the positive feedback regulation between plant hormone auxin and its efflux carrier. This system can generate auxin flow pathways by self-organization from an almost homogeneous state. This result explains a well-known experimental phenomenon referred as to "polar auxin transport." The model can produce diverse leaf venation patterns with spatial regularity under similar conditions to those of leaf development, that is, in the presence of leaf expansion and auxin sink. Final venation patterns are strikingly affected by leaf shape and leaf expansion. These results indicate that the positive feedback regulation between auxin and its efflux carrier is a central dynamic in leaf venation pattern formation. The diversity of leaf venation patterns in plant species is probably due to the differences of leaf shape and leaf expansion pattern. PMID:16894601

Fujita, Hironori; Mochizuki, Atsushi

2006-10-01

399

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

400

Using Leaf Samples to Establish a Library of Tropical Leaf Fingerprints  

NASA Astrophysics Data System (ADS)

Variation in leaf chemistry is directly expressed in spectroscopic patterns of tropical canopies. The goal of the Spectranomics project is to explore this variation in the hopes of developing a method to measure tropical forest diversity remotely from airborne or space-bound spectroscopy in the future. We analyzed tomato leaves for various chemical compositions to better understand the Spectranomics approach to quantifying chemical data of tropical species. We also compared our data to standard data in each analysis. Our results allow us to give the tomato leaves a chemical signature in which we are able to use to compare to other leaf samples. Using this process, we are able to create a library of leaf signatures and document the variety of tree species in tropical forests around the world.

Ngo, P.; Nguyen, R.; Anderson, C.; Weiss, P.

2010-12-01

401

Coordination between leaf and stem traits related to leaf carbon gain and hydraulics across 32 drought-tolerant angiosperms.  

PubMed

We examined 15 traits in leaves and stems related to leaf C economy and water use for 32 co-existing angiosperms at ridge sites with shallow soil in the Bonin Islands. Across species, stem density was positively correlated to leaf mass per area (LMA), leaf lifespan (LLS), and total phenolics and condensed tannins per unit leaf N (N-based), and negatively correlated to leaf osmotic potential and saturated water content in leaves. LMA and LLS were negatively correlated to photosynthetic parameters, such as area-, mass-, and N-based assimilation rates. Although stem density and leaf osmotic potential were not associated with photosynthetic parameters, they were associated with some parameters of the leaf C economy, such as LMA and LLS. In the principal component (PCA) analysis, the first three axes accounted for 74.4% of total variation. Axis 1, which explained 41.8% of the total variation, was well associated with parameters for leaf C and N economy. Similarly, axis 2, which explained 22.3% of the total variation, was associated with parameters for water use. Axis 3, which explained 10.3% of the total variation, was associated with chemical defense within leaves. Axes 1 and 2 separated functional types relatively well, i.e., creeping trees, ruderal trees, other woody plants, C(3) shrubs and forbs, palms, and CAM plants, indicating that plant functional types were characterized by similar attributes of traits related to leaf C and N economy and water use. In addition, when the plot was extended by two unrelated traits, leaf mass-based assimilation rates and stem density, it also separated these functional types. These data indicate that differences in the functional types with contrasting plant strategies can be attributed to functional integration among leaf C economy, hydraulics, and leaf longevity, and that both leaf mass-based assimilation rates and stem density are key factors reflecting the different functions of plant species. PMID:18297313

Ishida, Atsushi; Nakano, Takashi; Yazaki, Kenichi; Matsuki, Sawako; Koike, Nobuya; Lauenstein, Diego L; Shimizu, Michiru; Yamashita, Naoko

2008-05-01

402

Endophytic fungi reduce leaf-cutting ant damage to seedlings  

PubMed Central

Our study examines how the mutualism between Atta colombica leaf-cutting ants and their cultivated fungus is influenced by the presence of diverse foliar endophytic fungi (endophytes) at high densities in tropical leaf tissues. We conducted laboratory choice trials in which ant colonies chose between Cordia alliodora seedlings with high (Ehigh) or low (Elow) densities of endophytes. The Ehigh seedlings contained 5.5 times higher endophyte content and a greater diversity of fungal morphospecies than the Elow treatment, and endophyte content was not correlated with leaf toughness or thickness. Leaf-cutting ants cut over 2.5 times the leaf area from Elow relative to Ehigh seedlings and had a tendency to recruit more ants to Elow plants. Our findings suggest that leaf-cutting ants may incur costs from cutting and processing leaves with high endophyte loads, which could impact Neotropical forests by causing variable damage rates within plant communities.

Bittleston, L. S.; Brockmann, F.; Wcislo, W.; Van Bael, S. A.

2011-01-01

403

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

2013-12-01

404

Opinion: prospects for improving photosynthesis by altering leaf anatomy.  

PubMed

Engineering higher photosynthetic efficiency for greater crop yields has gained significant attention among plant biologists and breeders. To achieve this goal, manipulation of metabolic targets and canopy architectural features has been heavily emphasized. Given the substantial variations in leaf anatomical features among and within plant species, there is large potential to engineer leaf anatomy for improved photosynthetic efficiency. Here we review how different leaf anatomical features influence internal light distribution, delivery of CO(2) to Rubisco and water relations, and accordingly recommend features to engineer for increased leaf photosynthesis under different environments. More research is needed on (a) elucidating the genetic mechanisms controlling leaf anatomy, and (b) the development of a three dimensional biochemical and biophysical model of leaf photosynthesis, which can help pinpoint anatomical features required to gain a higher photosynthesis. PMID:23116676

Tholen, Danny; Boom, Carolina; Zhu, Xin-Guang

2012-12-01

405

Control of wheat leaf growth under saline conditions  

Microsoft Academic Search

\\u000a Water relations parameters in individual cells and the biophysical parameters controlling leaf growth were studied in context\\u000a of salt stress. Various levels of NaCI, ranging from 25 to 250mo1 m-3, were used to salinize the medium. The parameters were measured in growing zone of the first emerged leaf of wheat seedlings\\u000a (cv. Flanders, a British variety). In case of leaf

Hamayun Arif; A. Deri Tomos

406

Quality of paper boards from arecanut leaf sheath  

Microsoft Academic Search

A study was carried on utilizing arecanut leaf sheath for making paper boards. Paper boards were made with various combinations of arecanut leaf sheath with waste paper, 1:1, 1:2, 1:3, 3:1, 2:1, control (100% areca leaf sheath) and the qualities of these paper boards were tested as per the Bureau of Indian Standards (IS: 1060 (part-I)-1966). The paper boards made

R Raghupathy; R Viswanathan

2002-01-01

407

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

408

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

409

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

410

Predicting tropical plant physiology from leaf and canopy spectroscopy  

Microsoft Academic Search

A broad regional understanding of tropical forest leaf photosynthesis has long been a goal for tropical forest ecologists,\\u000a but it has remained elusive due to difficult canopy access and high species diversity. Here we develop an empirical model\\u000a to predict sunlit, light-saturated, tropical leaf photosynthesis using leaf and simulated canopy spectra. To develop this\\u000a model, we used partial least squares

Christopher E. Doughty; Gregory P. Asner; Roberta E. Martin

2011-01-01

411

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

412

Clumped distribution of oak leaf miners between and within plants  

Microsoft Academic Search

Leaf miners typically show non-random distributions both between and within plants. We tested the hypothesis that leaf miners on two oak species were clumped on individual host trees and individual branches and addressed whether clumping was influenced by aspects of plant quality and how clumping and\\/or interactions with other oak herbivores affected leaf-miner survivorship. Null models were used to test

Tatiana Cornelissen; Peter Stiling

2008-01-01

413

Plant Transpiration and its Sensitivity to Increasing Carbon Dioxide Concentration at Leaf, Canopy and Regional Scales  

Microsoft Academic Search

This thesis assembles simulation models for plant transpiration and uses these models to investigate the sensitivity of transpiration rates to the elevation of atmospheric CO_2 concentration at leaf, canopy and regional scales. The leaf transpiration model assembly (LTMA) simulates stomatal conductance, leaf net photosynthesis, leaf boundary layer conductance, mass and energy transfer, leaf energy balance. The stomatal conductance model and

Xiwu Zhan

1995-01-01

414

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

415

Antibacterial activity of various leaf extracts of Merremia emarginata  

PubMed Central

Objective To investigate the antibacterial activity and phytochemical screening of the aqueous, methanol and petroleum ether leaf extracts of Merremia emarginata (M. emarginata). Methods The antibacterial activity of leaf extracts of M. emarginata were evaluated by agar well diffusion method against four selected bacterial species. Results The presence of tannins, flavonoids, amino acids, starch, glycosides and carbohydrates in the different leaf extracts was established. The methanol extract was more effective against Bacillus cereus and Escherichia coli, whereas aqueous extract was more effective against Staphylococcus aureus and Pseudomonas aeruginosa. Conclusions : The results in the present study suggest that M. emarginata leaf can be used in treating diseases caused by the tested organisms.

Elumalai, EK; Ramachandran, M; Thirumalai, T; Vinothkumar, P

2011-01-01

416

Further Studies of the Heat Transfer from a Leaf  

PubMed Central

The resistance to the diffusion of heat and water vapor external to a leaf, can be derived from measurement of the rate of change of the leaf temperature, after a sudden alteration of the intensity of irradiation. The theory of the method has been developed to accommodate the case of a leaf that is freely transpiring, exchanging longwave radiation with the environment and with different internal resistances on the 2 sides of the leaf. It has been successfully applied to measurements on wet blotting paper in the laboratory.

Linacre, E. T.

1967-01-01

417

INTERSPECFIC VARIATION IN SO2 FLUX - LEAF SURFACE 'VERSUS' INTERNAL FLUX, AND COMPONENTS OF LEAF CONDUCTANCE  

EPA Science Inventory

The object of the study was to clarify the relationships among stomatal, residual, and epidermal conductances in determining the flux of SO2 air pollution to leaves. Variations in leaf SO2 and H2O vapor fluxes were determined using four plant species: Pisum sativum L. (garden pea...

418

Leaf anatomy during leaf development of photoautotrophically in vitro -grown tobacco plants as affected by growth irradiance  

Microsoft Academic Search

Tobacco (Nicotiana tabacum L.) plants were cultured in vitro photoautotrophically at three levels of irradiance (PAR 400–700 nm): low (LI, 60 µmol m?2 s?1), middle (MI, 180 µmol m?2 s?1) and high (HI, 270 µmol m?2 s?1). Anatomy of the fourth leaf from bottom was followed during leaf development. In HI and MI plants, leaf area expansion started\\u000a earlier as

B. Radochová; I. Tichá

2009-01-01

419

On the temporal variation of leaf magnetic parameters: Seasonal accumulation of leaf-deposited and leaf-encapsulated particles of a roadside tree crown.  

PubMed

Understanding the accumulation behaviour of atmospheric particles inside tree leaves is of great importance for the interpretation of biomagnetic monitoring results. In this study, we evaluated the temporal variation of the saturation isothermal remanent magnetisation (SIRM) of leaves of a roadside urban Platanus × acerifolia Willd. tree in Antwerp, Belgium. We hereby examined the seasonal development of the total leaf SIRM signal as well as the leaf-encapsulated fraction of the deposited dust, by washing the leaves before biomagnetic analysis. On average 38% of the leaf SIRM signal was exhibited by the leaf-encapsulated particles. Significant correlations were found between the SIRM and the cumulative daily average atmospheric PM10 and PM2.5 measurements. Moreover, a steady increase of the SIRM throughout the in-leaf season was observed endorsing the applicability of biomagnetic monitoring as a proxy for the time-integrated PM exposure of urban tree leaves. Strongest correlations were obtained for the SIRM of the leaf-encapsulated particles which confirms the dynamic nature of the leaf surface-accumulated particles. PMID:25000572

Hofman, Jelle; Wuyts, Karen; Van Wittenberghe, Shari; Samson, Roeland

2014-09-15

420

Spectroscopic determination of leaf nutritional, morpholgical, and metabolic traits  

NASA Astrophysics Data System (ADS)

Terrestrial ecosystems, particularly forests, play an important role in the global carbon and water cycles. Remote sensing observations are invaluable to the study of vegetation patterning, ecosystem functioning, and dynamics. This research examined the relationships between leaf optical properties and important leaf structural, biochemical, and metabolic traits that describe the photosynthetic capacity, recalcitrance, and nutrient dynamics of plant canopies. This was done utilizing leaf-level reflectance spectroscopy in conjunction with traditional chemometric statistical techniques designed to handle high-dimensionality data, specifically partial least-squares regression (PLSR). A suite of leaf biochemical and morphological traits were estimated with high accuracy and precision using measurements of dried and ground leaf material with a portable spectroradiometer in conjunction with PLSR modeling. An important result from this study was that a single model could be developed to accurately estimate the variation in leaf traits, including nitrogen and carbon content, lignin, fiber and cellulose, isotopic nitrogen-15, and leaf mass per area, across species, growth environments, throughout the vertical profile of a canopy, and with leaf lifespan. A residual analysis of the model prediction errors showed no significant biases observed by tree species, canopy position, or leaf age. Fresh-leaf reflectance spectroscopy was used to identify the linkages between leaf photosynthetic metabolism and leaf optical properties within controlled and natural environments, and across diverse plant species. Two key parameters controlling photosynthetic rates - the maximum rates of RuBisCO carboxylation (Vcmax) and RuBP regeneration ( Jmax) --- were directly estimated using leaf spectra and concurrent gas-exchange measurements. The models for each variable captured the pronounced temperature sensitivity of plants, and integrated the significant variability in metabolism across species that is related to differences in leaf structure and biochemistry. The PLSR models displayed high accuracy in predictions using independent validation data. Models identified key spectral regions related to leaf biochemistry, including foliar nitrogen and pigments, as well as wavelengths related to the regulation of photosynthesis, dissipation of excess energy and chlorophyll fluorescence. In sum, this research provides a novel empirical basis for estimating parameters critical to the measurement of photosynthetic activity in plants.

Serbin, Shawn P.

421

Proteomic profiling of Tectona grandis L. leaf.  

PubMed

Tectona grandis L. (teak) is one of the premier hardwood timbers in the world, ranking at present in the top five tropical hardwood species in terms of worldwide plantation area. Characterization of the proteins present in teak leaves will provide a basis for the development of new tools aimed at assisting tree selection, the monitoring of plant propagation, and the certification of clonal and phenotypic identities. In this paper, we describe the extraction, separation, and identification of leaf proteins from T. grandis using a TCA/acetone protocol, 2DE, and MALDI-TOF. After TCA/acetone protein extraction of leaves, 998 well-resolved spots were detected in Coomassie-stained gels within the 10-114 kDa relative molecular mass (Mr) range at a pH ranging from 3 to 11. A total of 120 spots were digested and subjected to MS. Of these, 100 nonredundant protein species were successfully identified. Functional classification of the identified proteins revealed that proteins involved in photosynthesis, protein translation, and energy production were the most abundant. This work is the first high-throughput attempt to study the T. grandis leaf proteome and represents a stepping stone for further differential expression proteomic studies related to growth, development, biomass production, and culture-associated physiological responses. PMID:22522810

Quiala, Elisa; Cañal, María Jesús; Rodríguez, Roberto; Yagüe, Norma; Chávez, Maité; Barbón, Raúl; Valledor, Luis

2012-04-01

422

Leaf metallome preserved over 50 million years.  

PubMed

Large-scale Synchrotron Rapid Scanning X-ray Fluorescence (SRS-XRF) elemental mapping and X-ray absorption spectroscopy are applied here to fossil leaf material from the 50 Mya Green River Formation (USA) in order to improve our understanding of the chemistry of fossilized plant remains. SRS-XRF of fossilized animals has previously shown that bioaccumulated trace metals and sulfur compounds may be preserved in their original distributions and these elements can also act as biomarkers for specific biosynthetic pathways. Similar spatially resolved chemical data for fossilized plants is sparsely represented in the literature despite the multitude of other chemical studies performed. Here, synchrotron data from multiple specimens consistently show that fossil leaves possess chemical inventories consisting of organometallic and organosulfur compounds that: (1) map discretely within the fossils, (2) resolve fine scale biological structures, and (3) are distinct from embedding sedimentary matrices. Additionally, the chemical distributions in fossil leaves are directly comparable to those of extant leaves. This evidence strongly suggests that a significant fraction of the chemical inventory of the examined fossil leaf material is derived from the living organisms and that original bioaccumulated elements have been preserved in situ for 50 million years. Chemical information of this kind has so far been unknown for fossilized plants and could for the first time allow the metallome of extinct flora to be studied. PMID:24804302

Edwards, N P; Manning, P L; Bergmann, U; Larson, P L; van Dongen, B E; Sellers, W I; Webb, S M; Sokaras, D; Alonso-Mori, R; Ignatyev, K; Barden, H E; van Veelen, A; Anné, J; Egerton, V M; Wogelius, R A

2014-04-01

423

Leaf metallome preserved over 50 million years.  

PubMed

Large-scale Synchrotron Rapid Scanning X-ray Fluorescence (SRS-XRF) elemental mapping and X-ray absorption spectroscopy are applied here to fossil leaf material from the ?50 Mya Green River Formation (USA) in order to improve our understanding of the chemistry of fossilized plant remains. SRS-XRF of fossilized animals has previously shown that bioaccumulated trace metals and sulfur compounds may be preserved in their original distributions and these elements can also act as biomarkers for specific biosynthetic pathways. Similar spatially resolved chemical data for fossilized plants is sparsely represented in the literature despite the multitude of other chemical studies performed. Here, synchrotron data from multiple specimens consistently show that fossil leaves possess chemical inventories consisting of organometallic and organosulfur compounds that: (1) map discretely within the fossils, (2) resolve fine scale biological structures, and (3) are distinct from embedding sedimentary matrices. Additionally, the chemical distributions in fossil leaves are directly comparable to those of extant leaves. This evidence strongly suggests that a significant fraction of the chemical inventory of the examined fossil leaf material is derived from the living organisms and that original bioaccumulated elements have been preserved in situ for 50 million years. Chemical information of this kind has so far been unknown for fossilized plants and could for the first time allow the metallome of extinct flora to be studied. PMID:24668317

Edwards, N P; Manning, P L; Bergmann, U; Larson, P L; van Dongen, B E; Sellers, W I; Webb, S M; Sokaras, D; Alonso-Mori, R; Ignatyev, K; Barden, H E; van Veelen, A; Anné, J; Egerton, V M; Wogelius, R A

2014-04-26

424

77 FR 62499 - Leaf River Energy Center LLC; Notice of Application  

Federal Register 2010, 2011, 2012, 2013

...Regulatory Commission [Docket No. CP12-526-000] Leaf River Energy Center LLC; Notice of Application Take notice that on September 24, 2012, Leaf River Energy Center LLC (Leaf River), 53 Riverside Avenue, Westport,...

2012-10-15

425

Non-Curling Polyhydroxyalkanoate Sutures.  

National Technical Information Service (NTIS)

Absorbable polyester fibers, braids, and surgical meshes with improved handling properties have been developed. These devices are preferably derived from biocompatible copolymers or homopolymers of 4-hydroxybutyrate. These devices provide a wider range of...

S. Rizk

2005-01-01

426

Modeling chickpea growth and development: Leaf production and senescence  

Microsoft Academic Search

Quantitative information regarding leaf area development in chickpea (Cicer arietinum L.) is scarce. Data from four field experiments with a range of treatments including genotype, sowing date and plant density across four location-season combinations were analyzed to quantify main effects of temperature, photoperiod and plant population density on plant leaf area in chickpea. All experiments were conducted under well-watered conditions.

A. Soltani; M. J. Robertson; Y. Mohammad-Nejad; A. Rahemi-Karizaki

2006-01-01

427