bluuebunny/crossref_metadata_2025 huggingface dataset:
Biology and conservation of Coptis teeta Wall. – an endemic and endangered medicinal herb of Eastern Himalaya
Authors: PANDIT M. K. , BABU C. R.
Published: July 2002

Medicinal plants are a valuable resource for regional
economic development in the tropics, and the Eastern
Himalaya in particular harbours many such species.
Extensive deforestation and over-exploitation in this
region have brought several species to the brink of
extinction, and Coptis teeta is such an endangered
species; yet scientific information for its conservation
is lacking. Investigations on the distribution range, demography,
ecology, cytology, reproductive biology
and population genetic structure of C. teeta were
carried out; it was found to be endemic to a small area,
to occupy a very narrow habitat and to be highly dispersed
with very small population sizes. Edaphic
factors were found to have played a vital role in
ecological preference, natural distribution and evolutionary
divergence of the species. The species exhibits
a ‘K’ strategy, high male sterility, low reproductive
success and efficiency, inadequate seed dispersal, and
little genetic variability. A combination of these genetic
hurdles and external threats in the form of habitat
disturbance and over-exploitation for commercial
purposes could result in its extinction. The species was
found to have highly specific microsite requirements
that cannot be met in other habitats. It is argued that
in situ conservation measures would be the best strategy
for the continued survival of this species. For
effective management of the species it is recommended
that its habitat be declared a protected
area with the active cooperation of local inhabitants
including the sharing of benefits of conservation.
Expanding multiple antibiotic resistance among clinical
strains of Vibrio cholerae isolated from 1992–7 in Calcutta,
India
Authors: GARG P. , CHAKRABORTY S. , BASU I. , DATTA S. , RAJENDRAN K. , BHATTACHARYA T. , YAMASAKI S. , BHATTACHARYA S. K. , TAKEDA Y. , BALAKRISH NAIR G. , RAMAMURTHY T.
Published: July 2002

Antimicrobial susceptibilities of Vibrio cholerae strains isolated from cholera patients admitted
to the Infectious Diseases Hospital, Calcutta, India for 6 years were analysed to determine the
changing trends; 840 V. cholerae strains isolated in 1992–1997 were included in this study.
Among V. cholerae serogoup O1 and O139, ampicillin resistance increased from 1992 (35 and
70%, respectively) to 1997 (both serogroups 100%). Resistance to furazolidone and
streptomycin was constantly high among V. cholerae O1 strains with gradual increase in
resistance to other drugs such as ciprofloxacin, co-trimoxazole, neomycin and nalidixic acid. V.
cholerae O139 strains exhibited susceptibilities to furazolidone and streptomycin comparable
with those of O1 strains. However, after initial increase in resistance to chloramphenicol and
co-trimoxazole, all the V. cholerae O139 strains became susceptible to these two drugs from
1995 onwards. Both V. cholerae O1 and O139 remained largely susceptible to gentamicin and
tetracycline. V. cholerae non-O1, non-O139 strains, in contrast, exhibited high levels of
resistance to virtually every class of antimicrobial agents tested in this study especially from
1995. Kruskal–Wallis one-way analysis showed that V. cholerae O1 Ogawa serogroup exhibited
significant yearly increase in resistance to nine antibiotics followed by non-O1 non-O139 and
O139 strains to six antibiotics and two antibiotics respectively. Interesting observation
encountered in this study was the dissipation of some of the resistant patterns commonly found
among V. cholerae non-O1 non-O139 or O1 serogroups to the O139 serogroup and vice versa
during the succeeding years.
Novel mating behaviour in Florelliceps stutchburyae gen. nov., sp. nov. (Onychophora: Peripatopsidae) from Australia
Authors: Tait Noel N. , Norman Jennifer M.
Published: July 2002

While mating behaviour in onychophorans has been documented in only a few species, it would appear that male reproductive strategies include both dermal and vaginal insemination. To add to this diversity, the males of many newly described species of Australian onychophorans display elaborate head structures. In some species, these head structures have been shown to carry spermatophores. Here we describe Florelliceps stutchburyae gen. nov., sp. nov., a species possessing a unique head structure. An account of its unusual mating behaviour is provided in which the male's everted head structure was placed against the female's gonopore and held there by the claws of the female's reduced last pair of oncopods. After the individuals separated, the female's genital opening was covered by a spermatophore and histological sections showed that sperm had been released into her reproductive tract. A review of mating behaviour in onychophorans is also included with a discussion of sperm acquisition by the female and its correlation with her reproductive cycle.
Young children who commit crime: Epidemiology, developmental origins,

risk factors, early interventions, and policy implications
Authors: LOEBER ROLF , FARRINGTON DAVID P.
Published: July 2002

An early onset of delinquency prior to age 13 years increases the risk of later serious, violent,

and chronic offending by a factor of 2–3. Also child delinquents, compared to juveniles

who start offending at a later age, tend to have longer delinquent careers. This article summarizes

the report of the Office of Juvenile Justice and Delinquency Prevention's Study Group on

Very Young Offenders, chaired by Rolf Loeber and David P. Farrington. The Study Group,

consisting of 16 scholars and 23 coauthors, worked for 2 years on preparing a report, undertaking

extensive secondary data analyses, and writing chapters in different speciality areas. The report

consists of a state of the art review of the developmental background of child delinquents. The

report also summarizes risk and protective factors in the individual, family, peer group, school,

and neighborhood that affect that development. Lastly, the report renews relevant preventive and

remedial interventions in the juvenile justice system, families, peer groups, schools, and

neighborhoods, and makes a case for improvement in the integration of services for child

delinquents. Policy recommendations are presented to improve methods of dealing with child

delinquents by juvenile justice, child welfare, and mental health agencies.
Academic and
emotional functioning in early adolescence: Longitudinal relations, patterns, and prediction by
experience in middle school
Authors: ROESER ROBERT W. , ECCLES JACQUELYNNE S. , SAMEROFF ARNOLD J.
Published: July 2002

Adopting a motivational perspective
on adolescent development, these two companion studies examined the longitudinal relations
between early adolescents' school motivation (competence beliefs and values),
achievement, emotional functioning (depressive symptoms and anger), and middle school
perceptions using both variable- and person-centered analytic techniques. Data were collected
from 1041 adolescents and their parents at the beginning of seventh and the end of eighth grade
in middle school. Controlling for demographic factors, regression analyses in Study 1 showed
reciprocal relations between school motivation and positive emotional functioning over time.
Furthermore, adolescents' perceptions of the middle school learning environment (support
for competence and autonomy, quality of relationships with teachers) predicted their eighth grade
motivation, achievement, and emotional functioning after accounting for demographic and prior
adjustment measures. Cluster analyses in Study 2 revealed several different patterns of school
functioning and emotional functioning during seventh grade that were stable over 2 years and
that were predictably related to adolescents' reports of their middle school environment.
Discussion focuses on the developmental significance of schooling for multiple adjustment
outcomes during adolescence.
The implications of different developmental patterns of disruptive behavior problems for
school adjustment
Authors: STORMSHAK ELIZABETH A. , BIERMAN KAREN L. ,   THE CONDUCT PROBLEMS PREVENTION RESEARCH GROUP
Published: July 2002

Based upon developmental models of disruptive behavior problems, this study examined the
hypothesis that the nature of a child's externalizing problems at home may be important in
predicting the probability of and nature of school adjustment problems at school entry. Parent
ratings were collected for a sample of 631 behaviorally disruptive children using the Child
Behavior Checklist. Confirmatory factor analyses revealed differentiated ratings of oppositional,
aggressive, and hyperactive/inattentive behaviors at home. Teacher and peer nominations
assessed school adjustment at the end of first grade. As expected from a developmental
perspective, aggressive behaviors indicated more severe dysfunction and were more likely to
generalize to the school setting than were oppositional behaviors. Hyperactive/inattentive
behaviors at home led to more classroom disruption than did aggressive or oppositional
behaviors. Co-occurring patterns of oppositional/aggressive and hyperactive/inattentive
behaviors were more common than were single-problem patterns, and were associated with broad
dysfunction in the social and classroom contexts. The results were interpreted within a
developmental framework, in which oppositional, aggressive, and hyperactive/inattentive
behaviors may reflect distinct (as well as shared) developmental processes that have implications
for the home-to-school generalization of behavior problems and subsequent school
adjustment.
Developmental pathways to antisocial
behavior: The delayed-onset pathway in girls
Authors: SILVERTHORN PERSEPHANIE , FRICK PAUL J.
Published: July 2002

Recent research has suggested that there are two
distinct trajectories for the development of antisocial behavior in boys: a childhood-onset
pathway and an adolescent-onset pathway. After reviewing the limited available research on
antisocial girls, we propose that this influential method of conceptualizing the development of
severe antisocial behavior may not apply to girls without some important modifications.
Antisocial girls appear to show many of the correlates that have been associated with the
childhood-onset pathway in boys, and they tend to show impaired adult adjustment, which is also
similar to boys in the childhood-onset pathway. However, antisocial girls typically show an
adolescent-onset to their antisocial behavior. We have proposed that these girls show a third
developmental pathway which we have labeled the “delayed-onset” pathway. This
model rests on the assumption that many of the putative pathogenic mechanisms that contribute
to the development of antisocial behavior in girls, such as cognitive and neuropsychological
deficits, a dysfunctional family environment, and/or the presence of a callous and
unemotional interpersonal style, may be present in childhood, but they do not lead to severe and
overt antisocial behavior until adolescence. Therefore, we propose that the delayed-onset
pathway for girls is analogous to the childhood-onset pathway in boys and that there is no
analogous pathway in girls to the adolescent-onset pathway in boys. Although this model clearly
needs to be tested in future research, it highlights the need to test the applicability of current
theoretical models for explaining the development of antisocial behavior in girls.
The status and conservation of the Blue-Throated Macaw Ara glaucogularis
Authors: Hesse Alan J. , Duffield Giles E.
Published: July 2002

The conservation status of the Blue-throated Macaw Ara glaucogularis, a Bolivian endemic, is assessed using the most recent information available. The known range of the species is patchily distributed within an 8,600 km2 area of lowland savanna–forest habitat in the Beni department, under private ownership for cattle ranching, which is the main form of land use in the region. Population surveys of the Blue-throated Macaw revealed this species to exist in very low numbers. The immediate threat to the species is illegal trapping for the live bird trade. Effects of cattle grazing and savanna burning may modify habitat characteristics, but there is no direct evidence suggesting that these factors negatively influence the ecological requirements of Ara glaucogularis. The species is highly associated with the Attalea phalerata palm, which it uses for feeding and nesting. Current conservation efforts include: population and distribution surveys and assessment of habitat requirements; environmental awareness targeted at landowners and ranch personnel; collaboration with subnational and central government bodies; and development of strategies to curtail parrot trafficking activities. Recommendations for the long-term conservation of the species include increasing the involvement of landowners to strengthen protection for wild macaws; working with the Bolivian government on strategies to curb macaw trafficking; increasing environmental education activities with local inhabitants; basic research on breeding requirements and limitations of wild Blue-throated Macaws; and investigating the application of private reserves to the Blue-throated Macaw range.
A categorical generalization of Scott domains
Authors: ADÁMEK JIŘÍ
Published: July 2002

Algebraic CPOs naturally generalize to finitely accessible
categories, and Scott domains (i.e.,
consistently complete algebraic CPOs) then correspond to what we call Scott-complete
categories: finitely accessible, consistently (co-)complete categories.
We prove that the
category SCC of all Scott-complete categories and all continuous
functors is cartesian closed
and provides fixed points for a large collection of endofunctors. Thus,
SCC
can serve as a basis for semantics of computer languages.
On the Error-Correcting Capabilities of Cycle Codes of

Graphs
Authors: DECREUSEFOND LAURENT , ZÉMOR GILLES
Published: July 2002

We are interested in a function f(p) that

represents the probability that a random subset of edges of a

Δ-regular graph G contains half the edges of some cycle

of G. f(p) is also the probability that a codeword

is corrupted beyond recognition when words of the cycle code of

G are submitted to the binary symmetric channel. We derive a

precise upper bound on the largest p for which

f(p) can vanish when the number of edges of

G goes to infinity. To this end, we introduce the notion of

fractional percolation on trees, and calculate the related critical

probabilities.
Expression of melatonin receptor transcripts (mel-1a, mel-1b and mel-1c) in Japanese quail oocytes and eggs
Authors: Obłap Ruslan , Olszańska Bożenna
Published: July 2002

Cloning and sequencing of the cDNA for avian melatonin (MEL) receptors have made it possible to investigate the expression of these receptors in different animal tissues and organs by reverse transcription polymerase chain reaction. Our study demonstrates for the first time, the presence of MEL receptor transcripts in maternal RNA from Japanese quail oocytes and in RNA from the early embryos of the laid eggs. Specific primers permitted discrimination between mel-1a, mel-1b and mel-1c receptor sequences, and special techniques used to obtain the biological material made it possible to avoid accidental contamination with cells of somatic origin. Mel-1c transcript was the main one found in the oocytes and was constantly present in the maternal RNA from individual ovulated oocytes, while mel-1a and mel-1b transcripts were only sporadically present. All three MEL receptor transcripts appeared in the RNA from blastoderms of laid eggs, pointing to their de novo synthesis during uterine embryo development. The relative amount of the MEL receptor transcripts was low in relation to that of β-actin, roughly 3 × 10-4 the amount of control β-actin transcript. The presence of MEL receptor transcripts and their de novo synthesis in the 24-h-old bird embryos point to their probable wider distribution and earlier appearance in development than originally thought; the existence of the corresponding functional receptor proteins in such early embryos has not previously been reported.
DNA replication in the 1-cell mouse embryo: stimulatory effect of histone acetylation
Authors: Aoki Fugaku , Schultz Richard M.
Published: July 2002

Temporal and spatial distribution of the sites of DNA replication were examined in 1-cell mouse embryos. Embryos were labelled with bromodeoxyuridine (BrdU) at hourly intervals after fertilisation, and the incorporation of BrdU was examined by laser-scanning confocal microscopy following immunostaining with an anti-BrdU antibody. DNA replication first started uniformly in both the male and female pronuclei in the intranuclear region and then was observed in the peripheral regions of nucleus and nucleolus. These changes, however, occurred asynchronously in that the female pronucleus required a longer time to complete replication in the intranuclear region but not in the peripheral regions. Inhibiting transcription with α-amanitin had no effect on the temporal and spatial patterns of DNA replication. Treatment of the embryos with trapoxin, a specific inhibitor of histone deacetylase, accelerated the completion of replication in the peripheral regions but not in the intranuclear region. These results suggest that DNA replication is temporally and spatially regulated in the 1-cell embryos and that acetylation of histones, but not transcription, is involved in the regulation of DNA replication.
Nicotinamide alters the calcium release pattern and the degradation of MPF activity after fertilisation in ascidian oocytes
Authors: Wilding Martin , Marino Marcella , Dale Daniela
Published: July 2002

Fertilisation in ascidian oocytes triggers a plasma membrane current, the release of intracellular calcium and the degradation of Maturation Promoting Factor (MPF) activity leading to the completion of meiosis and the initiation of embryo development. We have previously shown that the fertilisation current in ascidians is produced through the metabolism of nicotinamide nucleotide (NN) metabolites to ADP ribose. In this study we have used nicotinamide to test whether NN metabolism plays additional roles in fertilisation in ascidians. Nicotinamide treatment blocked calcium-induced calcium release (CICR) and arrested the cell cycle prior to the completion of meiosis I. Nicotinamide further prevented the abolition of MPF activity after fertilisation. Interestingly, nicotinamide treatment caused ascidian oocytes to form interphase-like pronuclei after fertilisation, despite the high MPF activity. The data demonstrate that NN metabolism is involved in calcium signalling through CICR and further suggest that a NN metabolite acts as a messenger connecting MPF activity to the formation of the meiotic apparatus.
Critical perceptions on problem-based learning
Authors: COENRAAD HEMKER H.
Published: July 2002

Problem-based learning (PBL), besides a number of advantages, also has drawbacks. It makes it very difficult for students to identify with a good teacher, and aims, rather, at identification with a peer group. Therefore, it seems more suited for adolescents than for young adults capable of secondary identification. Furthermore, this form of staff–student contact, i.e. the teaching group, does not motivate staff to share knowledge with the students. The knowledge acquired through PBL tends to remain unorganized. It is therefore more suited for disciplines in which a compilation of factual knowledge is important (e.g. medicine) than where a systematic approach is needed (e.g. statistics).
RESCUE AND HARM:
Authors: Kamm F.M.
Published: July 2002

How much must we sacrifice in order to stop strangers from suffering serious losses, and does distance from them alter our obligations? When may we harm some people to help others? How can we best reason about these issues? These are three general questions—the first two are substantive ones, the third a methodological one—that Peter Unger discusses in his book Living High and Letting Die (hereinafter LHLD) and that I discuss in this article.1
Effects of structural similarity and name frequency on picture
naming in Alzheimer's disease
Authors: THOMPSON-SCHILL SHARON L. , GABRIELI JOHN D. E. , FLEISCHMAN DEBRA A.
Published: July 2002

Impairments to either perceptual or word-retrieval
processes have been hypothesized to explain confrontation
naming impairments in patients with Alzheimer's disease
(AD). This study measured the effects of structural similarity,
which affects perceptual processing, and name frequency,
which affects word retrieval, on naming latency and accuracy
in 16 AD patients and 16 age-matched controls. AD patients
named pictures more slowly and made more errors than control
participants. Their naming accuracy was disproportionately
affected by name frequency, but not by structural similarity.
The findings indicate that the processing of structural
properties of objects is unaffected in early-stage AD,
and suggest that word-retrieval impairments underlie the
naming deficit in AD. (JINS, 1999, 5,
659–667.)
Introduction to the Special Issue-Trade and environment: local versus multilateral reforms
Authors: BARRETT SCOTT
Published: July 2002

[We] must ensure that ordinary citizens in all countries actually benefit from tradeÑa trade that...protects the environment.

President William J. Clinton

State of the Union Address, 19 January 1999

The hullabaloo that was the World Trade Organization's millenium
meeting in Seattle has shown us that ordinary people have serious misgivings
about the multilateral trading regime-both the rules and the process.
Future progress in trade liberalization will depend on convincing the
wider public that trade agreements are good for the environment and
good for development (including labour and human rights), not just GDP.
This is more than a public relations challenge. The concerns voiced by the
Seattle protesters-some of them, anyway-raise profound intellectual
questions.
Valuing mangrove resources in Kosrae, Micronesia
Authors: NAYLOR ROSAMOND , DREW MARK
Published: July 2002

Mangrove ecosystems provide a wide range of market and non-market benefits to coastal communities in the developing world, yet they remain undervalued and overexploited in most regions where they are found. This paper analyzes the use and value of mangroves in Kosrae, Micronesia, where the population is largely dependent on the swamps for fuelwood and other ecosystem services, such as erosion control, storm protection, and nutrient flows to shoreline fisheries. The results show that mangroves on the island are worth between $666 thousand and $1 million per year (1996 prices) based on the net value of marketable products alone. In addition, household survey data suggest that the local people are willing to pay between $1 million and $1.26 million per year to protect and use mangrove swamps indefinitely. The results thus indicate that the population places some premium on the existence and indirect ecosystem services of mangroves, over and above the direct use values. Moreover, respondents generally favored—and were willing to pay more for—a tax system designed to manage and preserve the mangroves' direct and indirect services over a permit system focused only the allocation of direct use over time. Valuation analyses using revealed preference and contingent valuation methods lead to additional conclusions regarding the distribution of benefits, with poor households deriving more direct benefits from—but willing to pay less to protect—mangrove ecosystems.
A novel two-component hybrid molecule regulates vascular morphogenesis of the Arabidopsis root
Authors: Mähönen Ari Pekka , Bonke Martin , Kauppinen Leila , Riikonen Marjukka , Benfey Philip N. , Helariutta Ykä
Published: July 2002

The developmental ontogeny of the vascular system (consisting of xylem, phloem and [pro]cambium) is poorly understood despite its central role in plant physiology. We show that in theArabidopsis root meristem, xylem cell lineages are specified early, whereas phloem and procambium are established through a set of asymmetric cell divisions. These divisions require the WOODEN LEG (WOL) gene. The WOL gene encodes a novel two-component signal transducer with an unusual tandem arrangement of two receiver domains. It is expressed specifically in the vasculature from the early stages of embryogenesis on, consistent with a role as a sensor for vascular morphogenesis.
Targeting histone deacetylase complexes via KRAB-zinc finger proteins: the PHD and bromodomains of KAP-1 form a cooperative unit that recruits a novel isoform of the Mi-2α subunit of NuRD
Authors: Schultz David C. , Friedman Josh R. , Rauscher Frank J.
Published: July 2002

Macromolecular complexes containing histone deacetylase and ATPase activities regulate chromatin dynamics and are vitally responsible for transcriptional gene silencing in eukaryotes. The mechanisms that target these assemblies to specific loci are not as well understood. We show that the corepressor KAP-1, via its PHD (planthomeodomain) and bromodomain, links the superfamily of Krüppel associated box (KRAB) zinc finger proteins (ZFP) to the NuRD complex. We demonstrate that the tandem PHD finger and bromodomain of KAP-1, an arrangement often found in cofactor proteins but functionally ill-defined, form a cooperative unit that is required for transcriptional repression. Substitution of highly related PHD fingers or bromodomains failed to restore repression activity, suggesting high specificity in their cooperative function. Moreover, single amino acid substitutions in either the bromodomain or PHD finger, including ones that mimic disease-causing mutations in the hATRX PHD finger, abolish repression. A search for effectors of this repression function yielded a novel isoform of the Mi-2α protein, an integral component of the NuRD complex. Endogenous KAP-1 is associated with Mi-2α and other components of NuRD, and KAP-1-mediated silencing requires association with NuRD and HDAC activity. These data suggest the KRAB-ZFP superfamily of repressors functions to target the histone deacetylase and chromatin remodeling activities of the NuRD complex to specific gene promoters in vivo.
Patterns of Meiotic Recombination on the Long Arm of Human Chromosome 21
Authors: Lynn Audrey , Kashuk Carl , Petersen Michael B. , Bailey Jeffrey A. , Cox David R. , Antonarakis Stylianos E. , Chakravarti Aravinda
Published: July 2002

In this study we quantify the features of meiotic recombination on the long arm of human chromosome 21. We constructed a 67.3-centimorgan (cM) high-resolution, comprehensive, and accurate genetic linkage map of chromosome 21q using 187 highly polymorphic markers covering almost the entire long arm; 46 loci, consisting of mutually recombining marker sets, were ordered with greater than 1000:1 odds and with average interlocus distance of 1.46 cM. These markers were used to accurately identify all exchanges in 186 female and 160 male meioses and to show (1) significant excess of recombination in female versus male meioses, (2) an overall decline in female:male recombination between the centromere and the telomere, (3) greater positive chiasma interference in male than in female meioses, and (4) lack of correlation between exchange frequency and parental age. By comparing the genetic map with the 21q sequence map, we show a general trend of increasing male, but near-constant female, recombination versus physical distance across 21q, explaining the gender-specific recombination effect. The recombination rate varies considerably between genders across 21q but is the greatest (eightfold) in the pericentromeric region, with a rate of approximately 250 kb/cM in females and approximately 2125 kb/cM in males. We used information on the locations of all exchanges to construct an empirical map function that confirms the statistical findings of positive interference. These analyses reveal that occurrence of recombination on 21q is not only gender-specific but also region-specific and that recombination suppression at the centromere is not universal. We also find evidence that male exchange location is highly correlated with gene density.
Efficient Male and Female Germline Transmission of a Human Chromosomal Vector in Mice
Authors: Voet Thierry , Vermeesch Joris , Carens An , Dürr Joachim , Labaere Charlotte , Duhamel Hein , David Guido , Marynen Peter
Published: July 2002

A small accessory chromosome that was mitotically stable in human fibroblasts was transferred into the hprt−hamster cell line CH and developed as a human chromosomal vector (HCV) by the introduction of a selectable marker and the 3′ end of anHPRT minigene preceded by a loxP sequence. This HCV is stably maintained in the hamster cell line. It consists mainly of alphoid sequences of human chromosome 20 and a fragment of human chromosome region 1p22, containing the tissue factor gene F3. The vector has an active centromere, and telomere sequences are lacking. By transfecting a plasmid containing the 5′ end ofHPRT and a Cre-encoding plasmid into the HCV+hamster cell line, the HPRT minigene was reconstituted by Cre-mediated recombination and expressed by the cells. The HCV was then transferred to male mouse R1-ES cells and it did segregate properly. Chimeras were generated containing the HCV as an independent chromosome in a proportion of the cells. Part of the male and female offspring of the chimeras did contain the HCV. The HCV+ F1 animals harbored the extra chromosome in >80% of the cells. The HCV was present as an independent chromosome with an active centromere and the human F3 gene was expressed from the HCV in a human-tissue-specific manner. Both male and female F1 mice did transmit the HCV to F2 offspring as an independent chromosome with properties similar to the original vector. This modified small accessory chromosome, thus, shows the properties of a useful chromosomal vector: It segregates stably as an independent chromosome, sequences can be inserted in a controlled way and are expressed from the vector, and the HCV is transmitted through the male and female germline in mice.
Computational and Experimental Analysis of Microsatellites in Rice (Oryza sativa L.): Frequency, Length Variation, Transposon Associations, and Genetic Marker Potential
Authors: Temnykh Svetlana , DeClerck Genevieve , Lukashova Angelika , Lipovich Leonard , Cartinhour Samuel , McCouch Susan
Published: July 2002

A total of 57.8 Mb of publicly available rice (Oryza sativaL.) DNA sequence was searched to determine the frequency and distribution of different simple sequence repeats (SSRs) in the genome. SSR loci were categorized into two groups based on the length of the repeat motif. Class I, or hypervariable markers, consisted of SSRs ≥20 bp, and Class II, or potentially variable markers, consisted of SSRs ≥12 bp <20 bp. The occurrence of Class I SSRs in end-sequences of EcoRI- and HindIII-digested BAC clones was one SSR per 40 Kb, whereas in continuous genomic sequence (represented by 27 fully sequenced BAC and PAC clones), the frequency was one SSR every 16 kb. Class II SSRs were estimated to occur every 3.7 kb in BAC ends and every 1.9 kb in fully sequenced BAC and PAC clones. GC-rich trinucleotide repeats (TNRs) were most abundant in protein-coding portions of ESTs and in fully sequenced BACs and PACs, whereas AT-rich TNRs showed no such preference, and di- and tetranucleotide repeats were most frequently found in noncoding, intergenic regions of the rice genome. Microsatellites with poly(AT)n repeats represented the most abundant and polymorphic class of SSRs but were frequently associated with the Micropon family of miniature inverted-repeat transposable elements (MITEs) and were difficult to amplify. A set of 200 Class I SSR markers was developed and integrated into the existing microsatellite map of rice, providing immediate links between the genetic, physical, and sequence-based maps. This contribution brings the number of microsatellite markers that have been rigorously evaluated for amplification, map position, and allelic diversity in Oryza spp. to a total of 500.

[Clone sequences for 199 markers (RM1–RM88, RM200–RM345) developed in this lab are available as GenBank accessions AF343840–AF343869 andAF344003–AF344169.]
Phylogenetic Analysis of Ribonuclease H Domains Suggests a Late, Chimeric Origin of LTR Retrotransposable Elements and Retroviruses
Authors: Malik Harmit S. , Eickbush Thomas H.
Published: July 2002

We have conducted a phylogenetic analysis of the Ribonuclease HI (RNH) domains present in Eubacteria, Eukarya, all long-term repeat (LTR)-bearing retrotransposons, and several late-branching clades of non-LTR retrotransposons. Analysis of this simple yet highly conserved enzymatic domain from these disparate sources provides surprising insights into the evolution of eukaryotic retrotransposons. First, it indicates that the lineage of elements leading to vertebrate retroviruses acquired a new RNH domain either from non-LTR retrotransposons or from a eukaryotic host genome. The preexisting retroviral RNH domain degenerated to become the tether (connection) domain of the reverse transcriptase (RT)–RNH complex. Second, it indicates that all LTR retrotransposons arose in eukaryotes well after the origin of the non-LTR retrotransposons. Because of the younger age of the LTR retrotransposons, their complex structure, and the absence of any prokaryotic precursors, we propose that the LTR retrotransposons originated as a fusion between a DNA-mediated transposon and a non-LTR retrotransposon. The resulting two-step mechanism of LTR retrotransposition, in which RNA is reverse transcribed away from the chromosomal target site, rather than directly onto the target site, was probably an adaptation to the uncoupling of transcription and translation in eukaryotic cells.
Imaging High-Resolution Structure of GFP-Expressing Neurons in Neocortex In Vivo
Authors: Chen Brian E. , Lendvai Balazs , Nimchinsky Esther A. , Burbach Barry , Fox Kevin , Svoboda Karel
Published: July 2002

To detect subtle changes in neuronal morphology in response to changes in experience, one must image neurons at high resolution in vivo over time scales of minutes to days. We accomplished this by infecting postmitotic neurons in rat and mouse barrel cortex with a Sindbis virus carrying the gene for enhanced green fluorescent protein. Visualized with 2-photon excitation laser scanning microscopy, infected neurons showed bright fluorescence that was distributed homogeneously throughout the cell, including axonal and dendritic arbors. Single dendritic spines could routinely be resolved and their morphological dynamics visualized. Viral infection and imaging were achieved throughout postnatal development up to early adulthood (P 8–30), although the viral efficiency of infection decreased with age. This relatively noninvasive method for fluorescent labeling and imaging of neurons allows the study of morphological dynamics of neocortical neurons and their circuits in vivo.
Varying Intertrial Interval Reveals Temporally Defined Memory Deficits and Enhancements in NTAN1-Deficient Mice
Authors: Balogh Seth A. , Kwon Yong Tae , Denenberg Victor H.
Published: July 2002

The N-end rule is one ubiquitin-proteolytic pathway that relates the in vivo half-life of a protein to the identity of its N-terminal residue. NTAN1 deamidates N-terminal asparagine to aspartate, which is conjugated to arginine by ATE1. An N-terminal arginine-bearing substrate protein is recognized, ubiquitylated by UBR1/E3α, and subsequently degraded by 26S proteasomes. Previous research showed that NTAN1-deficient mice exhibited impaired long-term memory in the Lashley III maze. Therefore, a series of studies, designed to assess the role of NTAN1 in short- and intermediate-term memory processes, was undertaken. Two hundred sixty mice (126 −/−; 134 +/ +) received Lashley III maze training with intertrial intervals ranging from 2–180 min. Results indicated that inactivation of NTAN1 amidase differentially affects short-, intermediate-, and long-term memory.
Intact Visual Perceptual Discrimination in Humans in the Absence of Perirhinal Cortex
Authors: Stark Craig E.L. , Squire Larry R.
Published: July 2002

While the role of the perirhinal cortex in declarative memory has been well established, it has been unclear whether the perirhinal cortex might serve an additional nonmnemonic role in visual perception. Evidence that the perirhinal cortex might be important for visual perception comes from a recent report that monkeys with perirhinal cortical lesions are impaired on difficult (but not on simple) visual discrimination tasks. We administered these same tasks to nine amnesic patients, including three severely impaired patients with complete damage to perirhinal cortex bilaterally (E.P., G.P., and G.T.). The patients performed all tasks as well as controls. We suggest that the function of perirhinal cortex as well as antero-lateral temporal cortex may differ between humans and monkeys.
Delayed Abscission and Shorter Internodes Correlate with a Reduction in the Ethylene Receptor LeETR1 Transcript in Transgenic Tomato
Authors: Whitelaw Catherine A. , Lyssenko Nicholas N. , Chen Liwei , Zhou Dingbo , Mattoo Autar K. , Tucker Mark L.
Published: July 2002

Stable transformation of tomato (Lycopersicon esculentum cv Ailsa Craig) plants with a construct containing the antisense sequence for the receiver domain and 3′-untranslated portion of the tomato ethylene receptor (LeETR1) under the control of an enhanced cauliflower mosaic virus 35S promoter resulted in some expected and unexpected phenotypes. In addition to reduced LeETR1 transcript levels, the two most consistently observed phenotypes in the transgenic lines were delayed abscission and reduced plant size. Fruit coloration and softening were essentially unaffected, and all the seedlings from first generation seed displayed a normal triple response to ethylene. Two independent lines with a single copy of the transgene and reducedLeETR1 transcript accumulation were selected for detailed phenotypic analysis of second generation (R1) plants. Delayed abscission, shorter internode length, and reduced auxin movement all correlated with the presence of the transgene and the degree of reducedLeETR1 transcript accumulation. No significant differences were noted for fruit coloration or fruit softening on R1 plants and all seedlings from R1 and R2 seed displayed a normal triple response. LeETR2 transcript accumulation was only slightly reduced in the R1 plants compared with azygous plants, andLeETR3 (NR) transcript levels appeared to be unaffected by the transgene. We propose that ethylene signal transduction occurs through parallel paths that partially intersect to regulate shared ethylene responses.
Ethylene Enhances Water Transport in Hypoxic Aspen
Authors: Kamaluddin Mohammed , Zwiazek Janusz J.
Published: July 2002

Water transport was examined in solution culture grown seedlings of aspen (Populus tremuloides) after short-term exposures of roots to exogenous ethylene. Ethylene significantly increased stomatal conductance, root hydraulic conductivity (L  p), and root oxygen uptake in hypoxic seedlings. Aerated roots that were exposed to ethylene also showed enhanced L  p. An ethylene action inhibitor, silver thiosulphate, significantly reversed the enhancement of L  p by ethylene. A short-term exposure of excised roots to ethylene significantly enhanced the root water flow (Q  v), measured by pressurizing the roots at 0.3 MPa. The Q  v values in ethylene-treated roots declined significantly when 50 μm HgCl2was added to the root medium and this decline was reversed by the addition of 20 mm 2-mercaptoethanol. The results suggest that the response of Q  v to ethylene involves mercury-sensitive water channels and that root-absorbed ethylene enhanced water permeation through roots, resulting in an increase in root water transport and stomatal opening in hypoxic seedlings.
Temperature Acclimation of Photosynthesis and Related Changes in Photosystem II Electron Transport in Winter Wheat
Authors: Yamasaki Takenobu , Yamakawa Tomokazu , Yamane Yoshihiro , Koike Hiroyuki , Satoh Kazuhiko , Katoh Sakae
Published: July 2002

Winter wheat (Triticum aestivum L. cv Norin No. 61) was grown at 25°C until the third leaves reached about 10 cm in length and then at 15°C, 25°C, or 35°C until full development of the third leaves (about 1 week at 25°C, but 2–3 weeks at 15°C or 35°C). In the leaves developed at 15°C, 25°C, and 35°C, the optimum temperature for CO2-saturated photosynthesis was 15°C to 20°C, 25°C to 30°C, and 35°C, respectively. The photosystem II (PS II) electron transport, determined either polarographically with isolated thylakoids or by measuring the modulated chlorophyll a fluorescence in leaves, also showed the maximum rate near the temperature at which the leaves had developed. Maximum rates of CO2-saturated photosynthesis and PS II electron transport determined at respective optimum temperatures were the highest in the leaves developed at 25°C and lowest in the leaves developed at 35°C. So were the levels of chlorophyll, photosystem I and PS II, whereas the level of Rubisco decreased with increasing temperature at which the leaves had developed. Kinetic analyses of chlorophyll afluorescence changes and P700 reduction showed that the temperature dependence of electron transport at the plastoquinone and water-oxidation sites was modulated by the temperature at which the leaves had developed. These results indicate that the major factor that contributes to thermal acclimation of photosynthesis in winter wheat is the plastic response of PS II electron transport to environmental temperature.
Molecular Cloning of a Metallothionein-Like Gene from Nicotiana glutinosa L. and Its Induction by Wounding and Tobacco Mosaic Virus Infection
Authors: Choi D. , Kim H. M. , Yun H. K. , Park J. A. , Kim W. T. , Bok S. H.
Published: July 2002

The cloning and characterization of genes expressed in plant disease resistance could be an initial step toward understanding the molecular mechanisms of disease resistance. A metallothionein-like gene that is inducible by tobacco mosaic virus and by wounding was cloned in the process of subtractive cloning of disease resistance-response genes in Nicotiana glutinosa. One 530-bp cDNA clone (KC9–10) containing an open reading frame of 81 amino acids was characterized. Genomic Southern blot hybridization with the cDNA probe revealed that tobacco metallothionein-like genes are present in few or in one copy per diploid genome. Northern blot hybridization detected strong induction of a 0.5-kb mRNA by wounding and tobacco mosaic virus infection, but only mild induction was detected when copper was tested as an inducer. Methyl jasmonate, salicylic acid, and ethylene were also tested as possible inducers of this gene, but they had no effect on its expression. The possible role of this gene in wounded and pathogen-stressed plants is discussed.
Tissue-Specific Activity of Two Manganese Superoxide Dismutase Promoters in Transgenic Tobacco
Authors: Van Camp W. , Herouart D. , Willekens H. , Takahashi H. , Saito K. , Van Montagu M. , Inze D.
Published: July 2002

In eukaryotes, manganese superoxide dismutase is a nuclear-encoded protein that scavenges superoxide radicals in the mitochondrial matrix. We have isolated two manganese superoxide dismutase genes from Nicotiana plumbaginifolia L. and fused the 5[prime] upstream regulatory region of these genes to the β-glucuronidase reporter gene. The two gene fusions displayed a differential tissue specificity in transgenic tobacco (Nicotiana tabacum). Promoter activity of the SodA1 gene fusion was found in the pollen, middle layer, and stomium of anthers, but was usually undetectable in vegetative organs of mature plants. The SodA2 gene fusion was expressed in the leaves, stems, roots, and flowers. SodA2 promoter activity was most prominent in the vascular bundles, stomata, axillary buds, pericycle, stomium, and pollen. Histochemical analysis of succinate dehydrogenase activity suggested that the spatial expression of the two gene fusions is generally correlated with mitochondrial respiratory activity.
Structure-Function Relationship of Monocot Mannose-Binding Lectins
Authors: Barre A. , Van Damme EJM. , Peumans W. J. , Rouge P.
Published: July 2002

The monocot mannose-binding lectins are an extended superfamily of structurally and evolutionarily related proteins, which until now have been isolated from species of the Amaryllidaceae, Alliaceae, Araceae, Orchidaceae, and Liliaceae. To explain the obvious differences in biological activities, the structure-function relationships of the monocot mannose-binding lectins were studied by a combination of glycan-binding studies and molecular modeling using the deduced amino acid sequences of the currently known lectins. Molecular modeling indicated that the number of active mannose-binding sites per monomer varies between three and zero. Since the number of binding sites is fairly well correlated with the binding activity measured by surface plasmon resonance, and is also in good agreement with the results of previous studies of the biological activities of the mannose-binding lectins, molecular modeling is of great value for predicting which lectins are best suited for a particular application.
The Major Intrinsic Protein Family of Arabidopsis Has 23 Members That Form Three Distinct Groups with Functional Aquaporins in Each Group
Authors: Weig A. , Deswarte C. , Chrispeels M. J.
Published: July 2002

Aquaporins, proteins that enhance the permeability of biological membranes to water, are widely distributed in living organisms. They are 26- to 29-kD proteins that belong to the major intrinsic protein (MIP) family of channels. By searching the Arabidopsis thaliana expressed sequence tag database and by using the polymerase chain reaction with oligonucleotides to conserved plant aquaporin domains, we identified 23 expressed Arabidopsis MIP genes. Eight of these had been previously identified as active aquaporins, and two additional ones are now reported to have water-transport activity in Xenopus laevis oocytes. One of these is highly expressed in suspension-cultured cells. On a dendrogram these 23 MIP sequences cluster into three groups: the first group has 11 members and contains the plasma membrane aquaporins, the second group also has 11 members and contains the tonoplast aquaporins, and the third group has only a single member. This MIP protein, provisionally called At-NLM1, is most closely related to the Gm-NOD26 protein that is found in the bacteroid membranes of soybean (Glycine max L.) nodules; At-NLM1 is an active aquaporin when expressed in oocytes. With a semiquantitative slot-blot analysis technique, we determined the expression levels of 22 MIP genes in the various organs. The quantitative polymerase chain reaction was used to determine the effects of various stress treatments on the expression of NLM1.
Mechanosensitive Expression of a Lipoxygenase Gene in Wheat
Authors: Mauch F. , Kmecl A. , Schaffrath U. , Volrath S. , Gorlach J. , Ward E. , Ryals J. , Dudler R.
Published: July 2002

Touch stimulation of wheat (Triticum aestivum L.) seedlings led to a strong and dose-dependent increase in the level of lipoxygenase mRNA transcripts. The touch-induced response occurred within 1 h and was transient. A similar response was observed after wind treatment and wounding. The mechanical strain-regulated lipoxygenase might translate mechanical strain into lipoxygenase pathway-dependent growth responses.