bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sea Turtle Navigation and the Detection of Geomagnetic Field Features
Authors: Lohmann Kenneth J. , Lohmann Catherine M. F. 
Published: July 2002

The lives of sea turtles consist of a continuous series of
migrations. As hatchlings, the turtles swim from their natal beaches into
the open
sea, often taking refuge in circular current systems (gyres) that serve
as
moving, open-ocean nursery grounds. The juveniles of many populations
subsequently take up residence in coastal feeding areas that are located
hundreds
or thousands of kilometres from the beaches on which the turtles hatched;

some juveniles also migrate between summer and winter habitats. As adults,

turtles periodically leave their feeding grounds and migrate to breeding
and
nesting regions, after which many return to their own specific feeding
sites.
The itinerant lifestyle characteristic of most sea turtle species is thus
inextricably
linked to an ability to orient and navigate accurately across large expanses
of
seemingly featureless ocean.In some sea turtle populations, migratory performance reaches extremes.
The
total distances certain green turtles (Chelonia mydas) and loggerheads
(Caretta
caretta) traverse over the span of their lifetimes exceed tens of
thousands of
kilometres, several times the diameter of the turtle's home ocean
basin.
Adult migrations between feeding and nesting habitats can require continuous

swimming for periods of several weeks. In addition, the paths of migrating

turtles often lead almost straight across the open ocean and directly to
the
destination, leaving little doubt that turtles can navigate to distant
target
sites with remarkable efficiency.
Maternal investment in northern fur seals (Callorhinus ursinus): interrelationships among mothers' age, size, parturition date, offspring size and sex ratios
Authors: Boltnev Alexander I. , York Anne E. 
Published: July 2002

AbstractThe analysis of life‐history traits suggests that the age and size of female mammals at parturition will affect the birth size and survival of their offspring. We collected data from 252 mother–pup pairs of northern fur seals on Bering Island, Russia, during the 1994 and 1996 breeding seasons to determine the interrelationships among the mothers' age and mass, the sex of the pup, the parturition date, and the length and mass of the pup at birth. Among reproductive females of 19 years, mass increased with age. The mean mass of the oldest class of females (20–23 years) was lighter than the 16–19 year age group but not different from the mean mass of the 7‐ to 15‐year‐old females; a quadratic model of mass on age gave similar results, and indicated a maximum mass at age 19 years. We suggest that this may be an effect of a higher rate of survival among leaner animals. Female pups were lighter than males at birth. There was no evidence that the sex ratio of pups differed from 1:1 over the range of observed mothers' mass and age or parturition dates. Older mothers tended to give birth earlier than younger mothers, and heavier mothers earlier than lighter mothers. The relationship of the size of pups at birth and their mothers' age was adequately described with a quadratic model, which predicted a maximum size for mothers at age 12–13 years. The size of pups at birth and the size of their mothers was described with a logistic model which predicted that the size of pups increased for mothers up to 41 kg, with no further increase for heavier mothers. The total amount of variability in birth size explained by the combined models is < one‐third of the total, which implies that other influences, such as the contribution of the fathers and individual variation, are also important. The relative maternal investment, measured as the ratio of pup mass to mothers' mass, ranged from 20% for younger and smaller females to 10% for older and heavier females. In addition, relative maternal investment was found to be higher than for other pinnipeds.
The influence of fish abundance on the otter (Lutra lutra) populations in Iberian Mediterranean habitats
Authors: Ruiz‐Olmo Jordi , López‐Martín José M. , Palazón Santiago 
Published: July 2002

AbstractRecent studies show that the availability of prey influences the ecology of otters by regulating breeding, carrying capacity and mortality. Mediterranean habitats experience extreme seasonal variation in water flow – a stress period can occur in summer when water flows and levels are low with long periods of drought, while torrential floods usually occur in autumn and spring. Reservoirs can affect this situation by further influencing water flow regimes and acting as a barrier. Our data show the close relationship between the amount of food (fish) available to otters and their use of a stretch of water and the otter density there. The adjustment of the number of individuals (and carrying capacity) in an area can be seen from their mortality, a decrease in their reproductive success, or migration. Our results are consistent with the hypothesis that otters are food‐limited. Torrential rains, summer droughts and dams for water management have repercussions for otter populations in as much as they affect their prey‐species. BarbelsBarbusspp. and, secondarily, nasesChondrostomaspp. are shown to be important to otter ecology and breeding in Mediterranean Iberian rivers. The conservation and management of the otter in these habitats must not ignore the management of food sources. In order not to affect otter populations, the effect of the reservoirs and their dams also must be considered. The release and cessation of floodwater from reservoirs must be progressive and mimic more closely the flow regime of natural rivers.
A novel mobile approach to investigating mating tactics in male grey seals (Halichoerus grypus)
Authors: Lidgard D. C. , Boness D. J. , Bowen W. D. 
Published: July 2002

AbstractStudies of the grey sealHalichoerus grypusmating system, using focal animal sampling constrained by study site location and size, limit the measurement of variation in male mating tactics and success. Using this method, the mating tactics of grey seal males have been classified as either ‘tenured’ or ‘transient’. Preliminary evidence is presented of wider variation in male mating tactics and success using mobile focal‐animal techniques that are not constrained by site, and of the effects of age on behaviour when accounting for body mass. The study was conducted during the breeding seasons of 1997 and 1998 at Sable Island, Nova Scotia. Six young (11–12 years) and five old (20–25 years) males were captured at the beginning of the breeding season, weighed and fitted with a VHF transmitter and time‐depth recorder. Each male was located daily, and a count of late‐lactating females within a 10 m radius recorded as a measure of mating potential. Female guarding and observed copulatory attempts were used as a measure of mating success. Mean initial body mass of young males and old males was similar, 291 ± 13 kg and 298 ± 14 kg, respectively. All males changed location during the study period. Young males changed sites more often and moved shorter distances between sites than old males. Estimated mating success varied from probably no matings to a minimum of seven; there were no differences between young and old males. Maximum duration of stay at a site and the number of late‐lactating females at a site significantly influenced mating success. All the males except for two young males departed on diving excursions during the breeding season and engaged in deep diving behaviour. Diving behaviour did not differ between the age classes. Our results indicate that the current classification of mating tactics in grey seal males is an oversimplification. Preliminary data show that age may account for some of the variation in male behaviour on land and mating success, but not for behaviour at sea.
The implications of grassland and heathland management for the conservation of spider communities: a review
Authors: Bell James R. , Wheater C. Philip , Cullen W. Rod 
Published: July 2002

AbstractBoth intensity and type of habitat management in grasslands and heathlands affect spider communities. With high intensity management, spider communities often lack diversity and are dominated by a fewr‐selected species affiliated with bare ground. Low intensity management produces more complex communities introducing more niches for aerial web spinners and climbing spiders. The preferred management will be site‐dependent and may not be appropriate for all spiders in all situations, particularly for some rare or threatened species. Providing natural cover is recommended when using extreme forms of management or intensive grazing (particularly by sheep). In extreme cases, or where trampling is heavy, the litter layer should be conserved. We advocate research and survey before and after major management implementation. Habitat management for spiders should not be considered alone, but integrated into a holistic plan. Management for spiders may conflict with rare plant conservation and small reserves should examine the viability of providing two contrasting regimes.
Dietary opportunism in side‐striped jackals Canis adustus Sundevall
Authors: Atkinson R. P. D. , Macdonald D. W. , Kamizola R. 
Published: July 2002

AbstractIn our study area in Zimbabwe, half of the fresh‐weight biomass of the diet of side‐striped jackals Canis adustus comprised small and medium‐sized mammals, and a further third consisted of fruit. Three types of mammal (multimammate mice Mastomys spp., bushveldt gerbil Tatera leucogaster and scrub hare Lepus saxatilus) and four species of fruit (mobola plum Parinari curatellifolia, chocolate berry Vitex payos, wild fig Ficus natalensis and waterberry Syzigium guineense) dominated these categories. Captive jackals significantly preferred animal prey items to fruits, and these were also the items that contained the highest levels of apparent available energy and organic matter. Wild jackals, however, did not spend more time in the habitats in which mammals were most abundant, nor did they eat more of them during a period of higher prey population density. We conclude that the feeding of jackals is largely geared by searches for fruit, and that mammals are taken opportunistically when they are encountered.
The omega equation: Q‐G interpretations of simple circulation features
Authors: Pedder Mike A 
Published: July 2002

AbstractQuasi‐geostrophic (Q‐G) theory can be used to infer the vertical circulation associated with a synoptic distribution of pressure and temperature in much the same sense as geostrophic theory is used to infer a three‐dimensional distribution of the horizontal circulation. For the purposes of subjective analysis, a diagnosis of the vertical circulation and implied surface development can be based on identifying the sign and magnitude of a geostrophic forcing function associated with the particular distributions of geopotential and thickness shown on a conventional 500 hPa analysis chart. Examples of idealised circulation features are used to demonstrate both the strengths and the weaknesses of this approach, with reference to an analysis based on three different methods of evaluating the geostrophic forcing. Copyright © 1997 Royal Meteorological Society
Morphological productivity across speech and writing
Authors: Plag Ingo , Dalton-Puffer Christiane , Baayen Harald 
Published: July 2002

Claims about the productivity of a given affix are generally made without differentiating productivity according to type of discourse, although it is commonly assumed that certain kinds of derivational suffixes are more pertinent in certain kinds of texts than in others. Conversely, studies in register variation have paid very little attention to the role derivational morphology may play in register variation.This paper explores the relation between register variation and derivational morphology through a quantitative investigation of the productivity of a number of English derivational suffixes across three types of discourse in the British National Corpus (written language, context-governed spoken language, and everyday conversations). Three main points emerge from the analysis. First, within a single register, different suffixes may differ enormously in their productivity, even if structurally they are constrained to a similar extent. Second, across the three registers under investigation a given suffix may display vast differences in productivity. Third, the register variation of suffixes is not uniform, i.e. there are suffixes that show differences in productivity across registers while other suffixes do not, or do so to a lesser extent. We offer some tentative explanations for these findings and discuss the implications for morphological theory.
The Endoplasmic Reticulum-Associated Maize GL8 Protein Is a Component of the Acyl-Coenzyme A Elongase Involved in the Production of Cuticular Waxes
Authors: Xu Xiaojie , Dietrich Charles R. , Lessire Rene , Nikolau Basil J. , Schnable Patrick S. 
Published: July 2002

Abstract
The gl8 gene is required for the normal accumulation of cuticular waxes on maize (Zea mays) seedling leaves. The predicted GL8 protein exhibits significant sequence similarity to a class of enzymes that catalyze the reduction of a ketone group to a hydroxyl group. Polyclonal antibodies raised against the recombinantEscherichia coli-expressed GL8 protein were used to investigate the function of this protein in planta. Subcellular fractionation experiments indicate that the GL8 protein is associated with the endoplasmic reticulum membranes. Furthermore, polyclonal antibodies raised against the partially purified leek (Allium porrum) microsomal acyl-coenzyme A (CoA) elongase can react with the E. coli-expressed GL8 protein. In addition, anti-GL8 immunoglobulin G inhibited the in vitro elongation of stearoyl-CoA by leek and maize microsomal acyl-CoA elongase. In combination, these findings indicate that the GL8 protein is a component of the acyl-CoA elongase. In addition, the finding that anti-GL8 immunoglobulin G did not significantly inhibit the 3-ketoacyl-CoA synthase, 3-ketoacyl-CoA dehydrase, and (E) 2,3-enoyl-CoA reductase partial reactions of leek or maize acyl-CoA elongase lends further support to our previous hypothesis that the GL8 protein functions as a β-ketoacyl reductase during the elongation of very long-chain fatty acids required for the production of cuticular waxes.
Influence of Iron Status on Cadmium and Zinc Uptake by Different Ecotypes of the Hyperaccumulator Thlaspi caerulescens
Authors: Lombi Enzo , Tearall Kathryn L. , Howarth Jonathan R. , Zhao Fang-Jie , Hawkesford Malcolm J. , McGrath Steve P. 
Published: July 2002

Abstract
We have previously identified an ecotype of the hyperaccumulator Thlaspi caerulescens (Ganges), which is far superior to other ecotypes (including Prayon) in Cd uptake. In this study, we investigated the effect of Fe status on the uptake of Cd and Zn in the Ganges and Prayon ecotypes, and the kinetics of Cd and Zn influx using radioisotopes. Furthermore, the T. caerulescens ZIP (Zn-regulated transporter/Fe-regulated transporter-like protein) genes TcZNT1-G andTcIRT1-G were cloned from the Ganges ecotype and their expression under Fe-sufficient and -deficient conditions was analyzed. Both short- and long-term studies revealed that Cd uptake was significantly enhanced by Fe deficiency only in the Ganges ecotype. The concentration-dependent kinetics of Cd influx showed that theV max of Cd was 3 times greater in Fe-deficient Ganges plants compared with Fe-sufficient plants. In Prayon, Fe deficiency did not induce a significant increase inV max for Cd. Zn uptake was not influenced by the Fe status of the plants in either of the ecotypes. These results are in agreement with the gene expression study. The abundance ofZNT1-G mRNA was similar between the Fe treatments and between the two ecotypes. In contrast, abundance of theTcIRT1-G mRNA was greatly increased only in Ganges root tissue under Fe-deficient conditions. The present results indicate that the stimulatory effect of Fe deficiency on Cd uptake in Ganges may be related to an up-regulation in the expression of genes encoding for Fe2+ uptake, possibly TcIRT1-G.
The Arabidopsis Phospholipase D Family. Characterization of a Calcium-Independent and Phosphatidylcholine-Selective PLDζ1 with Distinct Regulatory Domains
Authors: Qin Chunbo , Wang Xuemin 
Published: July 2002

Abstract
Four types of phospholipase D (PLD), PLDα, β, γ, and δ, have been characterized in Arabidopsis, and they display different requirements for Ca2+, phosphatidylinositol 4,5-bisphosphate (PIP2), substrate vesicle composition, and/or free fatty acids. However, all previously cloned plant PLDs contain a Ca2+-dependent phospholipid-binding C2 domain and require Ca2+ for activity. This study documents a new type of PLD, PLDζ1, which is distinctively different from previously characterized PLDs. It contains at the N terminus a Phox homology domain and a pleckstrin homology domain, but not the C2 domain. A full-length cDNA for Arabidopsis PLDζ1 has been identified and used to express catalytically active PLD in Escherichia coli. PLDζ1 does not require Ca2+ or any other divalent cation for activity. In addition, it selectively hydrolyzes phosphatidylcholine, whereas the other Arabidopsis PLDs use several phospholipids as substrates. PLDζ1 requires PIP2 for activity, but unlike the PIP2-requiring PLDβ or γ, phosphatidylethanolamine is not needed in substrate vesicles. These differences are described, together with a genomic analysis of 12 putative Arabidopsis PLD genes that are grouped into α, β, δ, γ, and ζ based on their gene architectures, sequence similarities, domain structures, and biochemical properties.
A Multiple-Stimuli-Responsive as-1-Related Element of parA Gene Confers Responsiveness to Cadmium but Not to Copper
Authors: Kusaba M. , Takahashi Y. , Nagata T. 
Published: July 2002

Abstract
The expression of parA, an auxin-regulated gene expressed during the culture of tobacco (Nicotiana tabacum L.) mesophyll protoplasts, is induced by cadmium. To identify the cadmium-responsive element, we examined the parA promoter using the GUS reporter gene. Cadmium responsiveness was retained in a 5[prime] deletion of the parA promoter to -78 bp, but it was nullified by further deletion to -49 bp, which implies that the region -49 to -78 bp contained a cadmium-responsive element. This region contains a sequence similar to as-1, an enhancer sequence from the cauliflower mosaic virus 35S RNA promoter that binds the nuclear factor ASF-1. We named the sequence in the parA promoter pas. Gel-shift assays revealed that pas and as-1 compete for the same DNA-binding nuclear protein(s). Since pentamers of either pas and as-1 were able to confer cadmium responsiveness on a minimal promoter but mutant as-1 was not, we propose that pas and as-1 are involved in cadmium-responsive gene expression. Neither pas nor as-1 conferred responsiveness to copper. The specificity of this response, involving the fuction of as-1- related elements including pas, is discussed.
O-Acetylated Oligosaccharides from Pectins of Potato Tuber Cell Walls
Authors: Ishii T. 
Published: July 2002

Abstract
Acetylated trigalacturonides and rhamnogalacturonan I (RG-I)-derived oligosaccharides were isolated from a Driselase digest of potato tuber cell walls by ion-exchange and size-exclusion chromatography. The oligosaccharides were structurally characterized by fast atom bombardment-mass spectroscopy, nuclear magnetic resonance spectroscopy, and glycosyl-linkage composition analysis. One trigalacturonide contained a single acetyl group at O–3 of the reducing galacturonic acid residue. A second trigalacturonide contained two acetyl substituents, which were located on O–3 or O–4 of the nonreducing galacturonic acid residue and O–3 of the reducing galacturonic acid residue. RG-I backbone-derived oligomers had acetyl groups at O–2 of the galacturonic acid residues. Some of these galacturonic acid residues were O-acetylated at both O–2 and O–3 positions. Rhamnosyl residues of RG-I oligomers were not acetylated.
Products of Proline Catabolism Can Induce Osmotically Regulated Genes in Rice1
Authors: Iyer Suresh , Caplan Allan 
Published: July 2002

Abstract
Many plants accumulate high levels of free proline (Pro) in response to osmotic stress. This imino acid is widely believed to function as a protector or stabilizer of enzymes or membrane structures that are sensitive to dehydration or ionically induced damage. The present study provides evidence that the synthesis of Pro may have an additional effect. We found that intermediates in Pro biosynthesis and catabolism such as glutamine and Δ1-pyrroline-5-carboxylic acid (P5C) can increase the expression of several osmotically regulated genes in rice (Oryza sativa L.), including salT anddhn4. One millimolar P5C or its analog, 3,4-dehydroproline, produced a greater effect on gene expression than 1 mm l-Pro or 75 mm NaCl. These chemicals did not induce hsp70,S-adenosylmethionine synthetase, or another osmotically induced gene, Em, to any significant extent. Unlike NaCl, gene induction by P5C did not depend on the normal levels of either de novo protein synthesis or respiration, and did not raise abscisic acid levels significantly. P5C- and 3,4-dehydroproline-treated plants consumed less O2, had reduced NADPH levels, had increased NADH levels, and accumulated many osmolytes associated with osmotically stressed rice. These experiments indicate that osmotically induced increases in the concentrations of one or more intermediates in Pro metabolism could be influencing some of the characteristic responses to osmotic stress.
Heat-Stress Response of Maize Mitochondria1
Authors: Lund Adrian A. , Blum Paul H. , Bhattramakki Dinakar , Elthon Thomas E. 
Published: July 2002

Abstract
We have identified maize (Zea mays L. inbred B73) mitochondrial homologs of the Escherichia coli molecular chaperones DnaK (HSP70) and GroEL (cpn60) using two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblots. During heat stress (42°C for 4 h), levels of HSP70 and cpn60 proteins did not change significantly. In contrast, levels of two 22-kD proteins increased dramatically (HSP22). Monoclonal antibodies were developed to maize HSP70, cpn60, and HSP22. The monoclonal antibodies were characterized with regard to their cross-reactivity to chloroplastic, cytosolic, and mitochondrial fractions, and to different plant species. Expression of mitochondrial HSP22 was evaluated with regard to induction temperature, time required for induction, and time required for degradation upon relief of stress. Maximal HSP22 expression occurred in etiolated seedling mitochondria after 5 h of a +13°C heat stress. Upon relief of heat stress, the HSP22 proteins disappeared with a half-life of about 4 h and were undetectable after 21 h of recovery. Under continuous heat-stress conditions, the level of HSP22 remained high. A cDNA for maize mitochondrial HSP22 was cloned and extended to full length with sequences from an expressed sequence tag database. Sequence analysis indicated that HSP22 is a member of the plant small heat-shock protein superfamily.