bluuebunny/crossref_metadata_2025 huggingface dataset:
Restriction of placental growth results in greater hypotensive response to α‐adrenergic blockade in fetal sheep during late gestation
Authors: Danielson Li , McMillen I. Caroline , Dyer Jodie L. , Morrison Janna L.
Published: January 2005

Placental insufficiency resulting in restriction of fetal substrate supply and fetal hypoxaemia is a major cause of restricted fetal growth and increased neonatal morbidity. Fetal adaptations to placental restriction (PR) include increases in circulating catecholamines and cortisol and decreased fetal body growth, with relative sparing of brain growth. The mechanisms underlying the redistribution of fetal cardiac output in PR fetuses are not known and the aim of this study was to determine whether maintenance of fetal blood pressure (BP) in the PR fetus is dependent on α‐adrenergic stimulation. PR was induced by removing the majority of uterine caruncles in the ewe before conception. Sterile vascular surgery was performed on seven PR and six control fetuses at 113–120 days' gestation (term = 150 ± 3 days). Fetuses with a mean arterial P < 17 mmHg between 123 and 127 days' gestation were defined as hypoxic. There was a greater fall (P < 0.05) in fetal BP during phentolamine infusion (i.v: 5 mg bolus, 0.2 mg kg−1 min−1 for 2 h) in the hypoxic PR group (−15 ± 2 mmHg) compared with normoxic controls (−5 ± 1 mmHg). The fall in fetal BP during phentolamine infusion was directly related to the level of fetal P. Fetal BP and HR responses to phenylephrine (i.v.: 40 μg kg−1) were not different between PR and control fetuses. The maintenance of BP in the chronically hypoxic fetus is therefore dependent on α‐adrenergic activation, and this fetal adaptation to a suboptimal intrauterine environment pre‐dates the development of significant growth restriction. While this adaptation may play a critical role in the redistribution of fetal cardiac output to ensure the sparing of brain growth, it may have adverse consequences for peripheral vascular function in the neonatal period and in adult life.
Mutation of colocalized residues of the pore helix and transmembrane segments S5 and S6 disrupt deactivation and modify inactivation of KCNQ1 K+ channels
Authors: Seebohm Guiscard , Westenskow Peter , Lang Florian , Sanguinetti Michael C.
Published: January 2005

KCNQ1 (Kv 7.1) α‐subunits and KCNE1 β‐subunits co‐assemble to form channels that conduct the slow delayed rectifier K+ current (IKs) in the heart. Mutations in either subunit cause long QT syndrome (LQTS), an inherited disorder of cardiac repolarization. Here, the functional consequences of the LQTS‐associated missense mutation V310I and several nearby residues were determined. Val310 is located at the base of the pore helix of KCNQ1, two residues below the TIGYG signature sequence that defines the K+ selectivity filter. Channels were heterologously expressed in Xenopus laevis oocytes and currents were recorded using the two‐microelectrode voltage‐clamp technique. V310I KCNQ1 reduced IKs amplitude when co‐expressed with wild‐type KCNQ1 and KCNE1 subunits. Val310 was also mutated to Gly, Ala or Leu to explore the importance of amino acid side chain volume at this position. Like V310I, V310L KCNQ1 channels gated normally. Unexpectedly, V310G and V310A KCNQ1 channels inactivated strongly and did not close normally in response to membrane hyperpolarization. Based on a homology model of the KCNQ1 channel pore, we speculate that the side group of residue 310 can interact with specific residues in the S5 and S6 domains to alter channel gating. When volume of the side chain is small, the stability of the closed state is disrupted and the extent of channel inactivation is enhanced. We mutated putative interacting residues in S5 and S6 and found that mutant Leu273 and Phe340 channels also can disrupt close states and modify inactivation. Together these findings indicate the importance of a putative pore helix−S5−S6 interaction for normal KCNQ1 channel deactivation and confirm its role in KCNQ1 inactivation. Disturbance of these interactions might underly LQTS associated with KCNQ1 mutant channels.
Slow volume transients in amphibian skeletal muscle fibres studied in hypotonic solutions
Authors: Fraser James A. , Rang Catherine E. J. , Usher‐Smith Juliet A. , Huang Christopher L.‐H.
Published: January 2005

The influence of extracellular hypotonicity on the relationship between cell volume (Vc) and resting membrane potential (Em) was investigated in Rana temporaria skeletal muscle. Vc was measured by confocal microscope imaging of fibres through their transverse (xz) planes, and Em was determined using standard microelectrode techniques. Hypotonic solutions first elicited a rapid increase in fibre volume, ΔVR+ that fulfilled expectations of simple osmotic behaviour described in earlier reports. However, this was consistently followed by a slow increase in Vc (ΔVS+) to 10–15% above osmotic predictions. Longer (>1 h) exposures to hypotonic solutions permitted a subsequent slow decrease in Vc (ΔVS−), the eventual magnitude of which exceeded that of the preceding ΔVS+. Restoration of isotonic conditions elicited a prompt recovery in Vc that matched simple osmotic predictions and thus left a net change in Vc. Such alterations in Vc attributable to ΔVS+ then gradually reversed, while those due to ΔVS− persisted. Both ΔVS+ and ΔVS− persisted under conditions of Cl− deprivation. The depolarization of Em that accompanied ΔVR+ was consistent with dilution of intracellular [K+]. Em did not significantly alter during the subsequent ΔVS transients. These empirical features of ΔVS+ and ΔVS− were analysed using the quantitative charge‐difference model of Fraser and Huang, published in 2004. This attributed the ΔVS+ to an electroneutral increase in the effective osmotic activity of normally membrane‐impermeant intracellular anions. In contrast, the ΔVS− could only be explained by an efflux of such anions and was accordingly comparable to organic anion‐dependent regulatory volume decreases reported in other cell types.
Proliferation of Functional Hair Cells in Vivo in the Absence of the Retinoblastoma Protein
Authors: Sage Cyrille , Huang Mingqian , Karimi Kambiz , Gutierrez Gabriel , Vollrath Melissa A. , Zhang Duan-Sun , García-Añoveros Jaime , Hinds Philip W. , Corwin Jeffrey T. , Corey David P. , Chen Zheng-Yi
Published: January 2005

In mammals, hair cell loss causes irreversible hearing and balance impairment because hair cells are terminally differentiated and do not regenerate spontaneously. By profiling gene expression in developing mouse vestibular organs, we identified the retinoblastoma protein (pRb) as a candidate regulator of cell cycle exit in hair cells. Differentiated and functional mouse hair cells with a targeted deletion of
Rb1
undergo mitosis, divide, and cycle, yet continue to become highly differentiated and functional. Moreover, acute loss of
Rb1
in postnatal hair cells caused cell cycle reentry. Manipulation of the pRb pathway may ultimately lead to mammalian hair cell regeneration.
The Selective Cause of an Ancient Adaptation
Authors: Zhu Guoping , Golding G. Brian , Dean Antony M.
Published: January 2005

Phylogenetic analysis reveals that the use of nicotinamide adenine dinucleotide phosphate (NADP) by prokaryotic isocitrate dehydrogenase (IDH) arose around the time eukaryotic mitochondria first appeared, about 3.5 billion years ago. We replaced the wild-type gene that encodes the NADP-dependent IDH of
Escherichia coli
with an engineered gene that possesses the ancestral NAD-dependent phenotype. The engineered enzyme is disfavored during competition for acetate. The selection intensifies in genetic backgrounds where other sources of reduced NADP have been removed. A survey of sequenced prokaryotic genomes reveals that those genomes that encode isocitrate lyase, which is essential for growth on acetate, always have an NADP-dependent IDH. Those with only an NAD-dependent IDH never have isocitrate lyase. Hence, the NADP dependence of prokaryotic IDH is an ancient adaptation to anabolic demand for reduced NADP during growth on acetate.
Secondary Syphilitic Lesions
Authors: Baughn Robert E. , Musher Daniel M.
Published: January 2005

An important theme that emerges from all early historical accounts is that in addition to the decreased virulence ofTreponema pallidum, the incidence of secondary syphilis has decreased drastically over the past three centuries. Even in the early 20th century, most syphilologists were of the opinion that the disease had undergone changes in its manifestations and that they were dealing with an attenuated form of the spirochete. Such opinions were based primarily on the observations that violent cutaneous reactions and fatalities associated with the secondary stage had become extremely rare. The rate of primary and secondary syphilis in the United States increased in 2002 for the second consecutive year. After a decade-long decline that led to an all-time low in 2000, the recent trend is attributable, to a large extent, by a increase in reported syphilis cases among men, particularly homosexual and bisexual men having sex with men. The present review addresses the clinical and diagnostic criteria for the recognition of secondary syphilis, the clinical course and manifestations of the disease if allowed to proceed past the primary stage of disease in untreated individuals, and the treatment for this stage of the disease.
Allergy and Dermatophytes
Authors: Woodfolk Judith A.
Published: January 2005

Tinea pedis (athlete's foot) and onychomycosis (infection of the toenails) caused by the dermatophyte fungusTrichophytonare highly prevalent in adults. SeveralTrichophytonallergens have been identified based on elicitation of immunoglobulin E antibody-mediated immediate-hypersensitivity (IH) responses. Evidence of an etiologic role forTrichophytonin asthma in some subjects with IH and chronic dermatophytosis is provided by bronchial reactivity toTrichophyton. Improvement of asthma after systemic antifungal treatment corroborates this link. A unique feature ofTrichophytonallergens is the ability of the same antigen to elicit delayed-type hypersensitivity (DTH) in individuals who lack IH reactivity. Delayed responses appear to confer protection, while IH responses do not, based on the association with acute versus chronic skin infection. The amino acid sequence identity ofTrichophytonallergens with diverse enzyme families supports a dual role for these proteins in fungal pathogenesis and allergic disease. Characterizing the immunologic properties ofTrichophytonallergens and defining immune mechanisms which drive dichotomous responses are pivotal to understanding the dermatophyte-allergy relationship. Recent studies have identified DTH-associated major T-cell epitopes which could facilitate the development of peptide vaccines. Characterization of additional molecular targets by using new techniques may aid not only in the eradication of infection but also in the resolution of allergic symptoms.
Verticillium disease or "dry bubble" of cultivated mushrooms: theAgaricus bisporuslectin recognizes and binds theVerticillium fungicolacell wall glucogalactomannan
Authors: Bernardo Dolores , Cabo Amelia Pérez , Novaes-Ledieu Monique , Mendoza Concepción García
Published: January 2005

The step of recognition and (or) binding for the development of the disease of the cultivated mushroom Agaricus bisporus by the mycoparasite Verticillium fungicola was studied by several approaches: agglutination of V. fungicola germinated spores by an A. bisporus extract from fruit body cell walls, immunofluorescence microscopy of A. bisporus hyphae from fruit bodies and vegetative mycelia pretreated with purified V. fungicola cell wall glucogalactomannan, and finally, by hemagglutination experiments carried out with an A. bisporus fruit body lectin in the presence and absence of the same glucogalactomannan. Hemagglutinating activity of the purified A. bisporus fruit body lectin was clearly inhibited by the V. fungicola glucogalactomannan, whereas in the A. bisporus vegetative mycelium such lectin was not encountered. All the results obtained make evident the recognition and binding of the A. bisporus fruit body lectin to the V. fungicola cell wall glucogalactomannan, clarifying why the mushrooms, but not the vegetative mycelium, become diseased.Key words: Agaricus bisporus lectin, Verticillium fungicola glucogalactomannan, mycoparasitism.
Lipid nutrition ofSaccharomyces cerevisiaein winemaking
Authors: Belviso Simona , Bardi Laura , Bartolini Alessandra Biondi , Marzona Mario
Published: January 2005

Biosynthesis of cell membrane lipids is a crucial metabolic pathway for the growth and viability of eucaryotic microorganisms. In Saccharomyces cerevisiae, unsaturated fatty acids and ergosterol synthesis needs molecular oxygen. Stuck and sluggish fermentations are related to this aspect of metabolism and constitute a major problem in the wine industry. Anaerobiosis, when lipids are not available in the growth medium, highly stresses cells. They release lipid biosynthesis metabolites and soon cease to multiply. This paper describes an investigation of the nutritional role of exogenous lipids from inactivated yeast cells (IYCs). Fermentations were carried out in a nitrogen-rich synthetic medium similar to grape juice with glucose and fructose as carbon sources, without lipid sources, and in anaerobiosis. The effect of the addition of IYC was assessed. Cell growth, cell lipid composition, glucose and fructose consumption, and acetic acid production were measured during fermentation. Addition of IYC boosted cell growth and sugar consumption, whereas acetic acid production decreased. Biomass yield was influenced by ergosterol availability and increased when IYCs were added. Fatty acid composition of yeast cells was changed by IYC addition.Key words: fermentation, lipids, nutrition, Saccharomyces cerevisiae, wine.
Identification of an unusual VanA element in glycopeptide-resistantEnterococcus faeciumin Brazil following international transfer of a bone marrow transplant patient
Authors: Camargo I L.B.C , Del Peloso P F , Da Costa Leite C F , Goldman G H , Darini A L.C
Published: January 2005

A vancomycin-resistant Enterococcus (VRE) was isolated from a blood culture of a patient in a Brazilian hospital who had a treatment history of a bone marrow transplant in the USA. The organism was identified as Enterococcus faecium, which exhibited an MIC (minimum inhibitory concentration) ≥ 256 µg/mL for vancomycin. This was confirmed by E-test and the vanA gene was detected by PCR. Overlapping PCR revealed a left IR deletion and an additional 1.5 kb fragment between vanSH genes. DdeI digestion of vanRSHAX genes showed the determinant to be a T type variant, and the element was cloned and sequenced. These results revealed an IS1251 downstream of nucleotide 5820 of the VanA element. Insertions like this have not been reported previously in Brazil, but have been detected in the USA. The genotype and association with a patient previously treated in the USA suggest that this VRE was introduced from abroad, probably through inter-hospital strain spread.Key words: vancomycin-resistant enterococci, IS1251, inter-hospital spread.
Human IgA inhibits adherence ofAcanthamoeba polyphagato epithelial cells and contact lenses
Authors: Campos-Rodríguez Rafael , Oliver-Aguillón Gabriela , Vega-Pérez Luz M , Jarillo-Luna Adriana , Hernández-Martínez Dolores , Rojas-Hernández Saúl , Rodríguez-Monroy Marco A , Rivera-Aguilar Víctor , González-Robles Arturo
Published: January 2005

Specific anti-Acanthamoeba IgA antibodies have been detected in the serum and tears of patients and healthy individuals. However, the role of human secretory IgA antibodies in inhibiting the adherence of Acanthamoeba had not been previously investigated. Therefore, the purpose of this study was to purify secretory IgA from human colostrum and analyze its effect on the adherence of Acanthamoeba trophozoites to contact lenses and Madin–Darby canine kidney (MDCK) cells. IgA antibodies to Acanthamoeba polyphaga in colostrum of healthy women as well as in saliva and serum of healthy subjects were analyzed by ELISA and Western blot analysis. In serum, saliva, and colostrum, we detected IgA antibodies that recognized several antigens of A. polyphaga. In addition, colostrum and IgA antibodies purified from it inhibited adherence of A. polyphaga trophozoites to contact lenses and MDCK cells. These results suggest that IgA antibodies may participate in the resistance to the amoebic infection, probably by inhibiting the adherence of the trophozoites to contact lenses and corneal epithelial cells.Key words: Acanthamoeba polyphaga, free-living amoebas, colostrum, IgA.
Microcosm tests of the effects of temperature and microbial species number on the decomposition of Carex aquatilis and Sphagnum fuscum litter from southern boreal peatlands
Authors: Thormann Markus N , Bayley Suzanne E , Currah Randolph S
Published: January 2005

Increased decomposition rates in boreal peatlands with global warming might increase the release of atmospheric greenhouse gases, thereby producing a positive feedback to global warming. How temperature influences microbial decomposers is unclear. We measured in vitro rates of decomposition of senesced sedge leaves and rhizomes (Carex aquatilis), from a fen, and peat moss (Sphagnum fuscum), from a bog, at 14 and 20 °C by the three most frequently isolated fungi and bacteria from these materials. Decomposition rates of the bog litter decreased (5- to 17-fold) with elevated temperatures, and decomposition of the sedge litters was either enhanced (2- to 30-fold) or remained unaffected by elevated temperatures. The increased temperature regime always favoured fungal over bacterial decomposition rates (2- to 3-fold). Different physiological characteristics of these microbes suggest that fungi using polyphenolic polymers as a carbon source cause greater mass losses of these litters. Litter quality exerted a stronger influence on decomposition at elevated temperatures, as litter rich in nutrients decomposed more quickly than litter poorer in nutrients at higher temperatures (8.0%–25.7% for the sedge litters vs. 0.2% for the bryophyte litter). We conclude that not all peatlands may provide a positive feedback to global warming. Cautious extrapolation of our data to the ecosystem level suggests that decomposition rates in fens may increase and those in bogs may decrease under a global warming scenario.Key words: fungi, bacteria, decomposition, temperature, Sphagnum fuscum, Carex aquatilis, peatlands, climate change, microcosms.
Characterization ofPaenibacillus popilliaerRNA operons
Authors: Dingman Douglas W
Published: January 2005

The terminal 39 nucleotides on the 3' end of the 16S rRNA gene, along with the complete DNA sequences of the 5S rRNA, 23S rRNA, tRNAIle, and tRNAAlagenes were determined for Paenibacillus popilliae using strains NRRL B-2309 and Dutky 1. Southern hybridization analysis with a 16S rDNA hybridization probe and restriction-digested genomic DNA demonstrated 8 copies of the 16S rRNA gene in P. popilliae strains KLN 3 and Dutky 1. Additionally, the 23S rRNA gene in P. popilliae strains NRRL B-2309, KLN 3, and Dutky 1 was shown by I-CeuI digestion and pulsed-field gel electrophoresis of genomic DNA to occur as 8 copies. It was concluded that these 3 P. popilliae strains contained 8 rrn operons. The 8 operon copies were preferentially located on approximately one-half of the chromosome and were organized into 3 different patterns of genes, as follows: 16S-23S-5S, 16S-ala-23S-5S, and 16S-5S-ile-ala-23S-5S. This is the first report to identify a 5S rRNA gene between the 16S and 23S rRNA genes of a bacterial rrn operon. Comparative analysis of the nucleotides on the 3' end of the 16S rRNA gene suggests that translation of P. popilliae mRNA may occur in Bacillus subtilis and Escherichia coli.Key words: Paenibacillus, milky disease, rrn operon, rRNA, tRNA.
Genetic characterization of high-level gentamicin-resistant strains of Enterococcus faecalis in Iran
Authors: Feizabadi Mohammad Mehdi , Asadi Sorour , Zohari Maryam , Gharavi Sara , Etemadi Gelavizh
Published: January 2005

The prevalence of resistance to high levels of gentamicin among 182 isolates of Enterococcus faecalis from 2 Iranian hospitals was 42%. Gentamicin resistance was associated with conjugative plasmids (>70 kb) in most strains. Fingerprinting using EcoRI and HindIII showed genetic variation among these plasmids and gave evidence of nosocomial outbreaks and persistence of infection in different wards of the study hospitals, as well as transfer of plasmids between genetically diverse isolates. Using EcoRI, hospital-based specific plasmid fingerprints were detected for the isolates that had previously proved to be unrelated by multilocus enzyme electrophoresis, suggesting the persistence of related plasmids at each hospital, though minor changes in these related plasmids could be detected with HindIII.Key words: Enterococcus faecalis, HLGR, plasmid profiling, plasmid fingerprinting.
Cloning and expression of theClostridium thermocellumL-lactate dehydrogenase gene inEscherichia coliand enzyme characterization
Authors: Özkan Melek , Yllmaz Ebru I , Lynd Lee R , Özcengiz Gülay
Published: January 2005

The structural gene for L-lactate dehydrogenase (LDH) (EC.1.1.1.27) from Clostridium thermocellum 27405 was cloned in Escherichia coli by screening the Lambda Zap II phage library of C. thermocellum genomic DNA. In one positive clone, an open reading frame of 948 base pairs corresponded to C. thermocellum ldh gene encoding for the predicted 315-residue protein. The ldh gene was successfully expressed in E. coli FMJ39 (ldh mutant) under the lac promoter. The recombinant enzyme was partially purified from E. coli cell extracts and its kinetic properties were determined. Clostridium thermocellum LDH was shown to catalyze a highly reversible reaction and to be an allosteric enzyme that is activated by fructose-1,6-diphosphate (FDP). For pyruvate, partially purified LDH had Kmand Vmaxvalues of 7.3 mmol/L and 87 µmol/min, respectively, and in the presence of FDP, a 24-fold decrease in Kmand a 5.7-fold increase in Vmaxwere recorded. The enzyme exhibited no marked catalytic activity for lactate in the absence of FDP, whereas Kmand Vmaxvalues were 59.5 mmol/L and 52 µmol/min, respectively, in its presence. The enzyme did not lose activity when incubated at 65 °C for 5 min.Key words: L-lactate dehydrogenase purification, thermophilic bacteria.
Influence of substrate composition and flow rate on growth ofAzospirillum brasilenseCd in a co-culture with 3 sorghum rhizobacteria
Authors: Lippi Daniela , Paolis Maria Rita De , Mattia Elena Di , Pietrosanti Tito , Cacciari Isabella
Published: January 2005

The ability of Azospirillum brasilense Cd to colonize the niche occupied by 3 bacterial strains previously isolated from sorghum rhizosphere was studied by means of the Biolog system. The isolates were identified by different methods as strains belonging to Pseudomonas putida, Stenotrophomonas maltophilia, and Klebsiella terrigena species. Several C sources, also chosen among the constituents of sorghum root exudates, were used to evaluate the metabolic profiles of Azospirillum and the sorghum rhizobacteria. Azospirillum brasilense Cd exploited the same class of C compounds as the sorghum rhizobacteria and overlapped in their niche requirements. Since structure and functioning of a microbial community are largely affected by the flow rate of nutrient supply, the competitive behavior of A. brasilense Cd was studied in a chemostat mixed culture under C-limited conditions using disodium succinate as C source. Only at high growth rates, i.e., when the C source was highly supplied, A. brasilense Cd appeared to be a good competitor and it became the dominant species, whereas at low growth rates, it was outnumbered by the other species. However, the coexistence of all the strains was always maintained, thus suggesting that interactions other than competition or a potential cross-feeding might occur within the mixed culture.Key words: Azospirillum brasilense, competition, metabolic profile, niche overlap, sorghum rhizobacteria.
Effects of extra food on nestling growth and survival in red-backed voles (Clethrionomys gapperi)
Authors: Kasparian Kristine , Millar John S
Published: January 2005

Nestling mortality is typically high among small mammals, with food often considered an important limiting factor because of the increased energetic costs females incur during lactation. We provided female red-backed voles, Clethrionomys gapperi (Vigors, 1830), with sunflower seeds during lactation to test the hypothesis that food supply influences nestling growth and survival. Food supplementation did not increase nestling survival, but newly emerged young from fed mothers were significantly heavier than those from unfed mothers. High mortality/dispersal of postemergent young, particularly females, was associated with high densities of breeding females. We suggest that any survival advantage incurred from higher nestling growth rates may be mitigated by density-dependent mortality/ dispersal postemergence.
Structuring mechanisms of yellow perch (Perca flavescens) parasite communities: host age, diet, and local factors
Authors: Johnson Michael W , Nelson Patrick A , Dick Terry A
Published: January 2005

Seventeen parasite species were recovered from perch in four small Canadian Shield lakes with different fish species compositions. Parasite species such as Urocleidus adspectus Müller, 1936, Bunodera sacculata Van Cleave and Müller, 1932, and Proteocephalus pearsei La Rue, 1919 are phylogenetically associated with perch and (or) percids; others, such as Crepidostomum cooperi Hopkins, 1931, Spinitectus gracilis Ward and Magath, 1917, and Echinorhyn chus salmonis Müller, 1784, are related to dietary sharing; and larval species such as Apophallus brevis Ransom, 1920 and Raphidascaris acus (Bloch, 1779) are phylogenetically tied to perch but also to bird and fish definitive hosts. Variable patterns of dominance were dependent on trophic level and other host species in the system. As matrix fill increased with host age, the dependence of the parasite component communities on the given infracommunities decreased, confirming that predictable component communities depend on repetitive infracommunities. Shifts in dietary preference with age and (or) size and dietary sharing among host species were important in producing repetitive infracommunities. Host diet and age contributed significantly to the rate of parasite species accumulation. Parasite composition at the infracommunity scale changes with local community structure across the watershed and regardless of lake connectivity. The presence of ecologically derived parasite species is strongly influenced by local factors.
Overwintering in the nest by hatchling map turtles (Graptemys geographica)
Authors: Nagle Roy D , Lutz Clayton L , Pyle Andrew L
Published: January 2005

We monitored 75 natural nests of Graptemys geographica (Lesueur, 1817) in central Pennsylvania to determine the tactics and patterns of hatchling emergence. Following incubation, all hatchlings in 95% of nests delayed emergence from their natal nest cavities throughout autumn and winter until the following spring. Nests were constructed in a variety of substrates ranging from loose sand or coal to hard-packed clay mixed with gravel. Time from egg deposition to natural hatchling emergence averaged 333 days. During winter, hatchlings tolerated subzero temperatures as low as –8 °C, which are lethal to hatchlings of some sympatric species. Emergence occurred from 10 April to 25 May, and most hatchlings were found during morning following rain. There was an interactive effect of minimum daily air temperature and rainfall level 1 day prior to emergence on the number of hatchlings emerging each day. One half of all hatchlings found dead were contained in nests in which autumn emergence had apparently occurred. We speculate that autumn emergence by hatchlings of some turtle species may be an adaptive response to nest conditions likely to provide poor environments for successful overwintering.
Paternity and relatedness of American black bears recolonizing a desert montane island
Authors: Onorato Dave P , Hellgren Eric C , Van Den Bussche Ronald A , Skiles, Jr. J Raymond
Published: January 2005

American black bears (Ursus americanus (Pallas, 1780)) are characterized by female philopatry and male-biased dispersal, with predictable consequences for genetic structure of populations. We studied a recolonizing population of black bears on a desert montane island to test genetic-based predictions of bear social behavior. We assessed genetic paternity and relatedness among bears within Big Bend National Park, Texas, from 1998 to 2001 via maternally and biparentally inherited markers and field observations. Data from seven microsatellite loci permitted us to assign paternity for 7 of 12 cubs, and multiple paternity was revealed in one litter. Levels of relatedness in the Park were comparable to those found in a nearby large population in Coahuila, Mexico. Adult female bears in the Park were more closely related to each other than males were to each other. Microsatellite data were consistent with previous analyses of mtDNA sequences that indicated bears in the Mexico-Texas metapopulation exhibit male-biased dispersal. Demographic and genetic data provided a pedigree for 23 of 31 sampled bears and depicted the matriarchal structure of this recently recolonized population. Although females in this insular population are closely related to each other, as predicted by characteristics of ursine social ecology, incoming dispersal by unrelated males results in periodic supplementation of genetic variation.
Physiological effects of short-term water deprivation in the South American sigmodontine rice ratOligoryzomys nigripesand water ratNectomys squamipeswithin a phylogenetic context
Authors: de França Silveira Ribeiro Martim , da Rocha Pedro Luiz Bernardo , Mendes Lys Angela Favaroni , Perry Steven Franklin , Oliveira Elisabeth Spinelli de
Published: January 2005

Ancestrally, oryzomyine rodents have a sylvan habit, but some species have colonized the semi-arid Brazilian Caatinga. Therefore, the clade provides a suitable model for studying adaptation to such environments within a phylogenetic framework. We investigated physiological responses to short-term water deprivation in two oryzomyine rodents kept in captivity. Oligoryzomys nigripes (Olfers, 1818), a small-bodied rodent, occupies the Caatinga, whereas Nectomys squamipes (Brants, 1827), which is larger and semi-aquatic, lives in moist habitats outside this region. Measurements were also carried out in three additional related species of intermediate body size. Neither O. nigripes nor N. squamipes displays exceptional ability to conserve water, and this condition appears to be plesiomorphic for the clade. The results for O. nigripes, such as the great absolute water intake and the high ratio of water ingested to urine voided, probably derive from allometric specializations correlated with its small body size and greater evaporative water loss. In N. squamipes, low urine osmolality and a reduction of food intake during water deprivation may be related to its semi-aquatic lifestyle. Therefore, the Oryzomyini exemplify Neotropical rodents that can occupy semi-arid environments with no remarkable physiological adaptation for water conservation.
Lek fidelity of male Arctic charr
Authors: Figenschou L , Folstad I , Liljedal S
Published: January 2005

For males, the reproductive advantage of joining a lek varies among leks; consequently, males should join the lek yielding the highest fitness. When males experience low reproductive opportunities at one lek, it may pay to move to another. By observing tagged male Arctic charr (Salvelinus alpinus L., 1758) at three different lek sites within one lake, we examined whether males moved between leks. Some movement was observed, especially between closely located leks, but fish length and spermatocrit, traits indicative of reproductive success, were unrelated to whether or not individuals moved between leks. Little to no movement was observed between more distantly separated leks, even though the costs associated with movements across the relatively short distances between these leks should be low. This suggests that individuals, rather than moving from leks where they have low reproductive success, are relatively stationary. The lek fidelity documented in the present study may be important for production of local genetic differences between Arctic charr leks. Our results suggest that males with low reproductive success may enhance their fitness by means other than dispersal, e.g., by associating with relatives to increase inclusive fitness.
Body temperatures of leatherback turtles (Dermochelys coriacea) in temperate waters off Nova Scotia, Canada
Authors: James Michael C , Mrosovsky N
Published: January 2005

The leatherback sea turtle, Dermochelys coriacea (Vandelli, 1761), has the most extensive range of any reptile, migrating from tropical and subtropical nesting areas to distant foraging habitats, including those in temperate and even boreal waters. This implies flexible thermal functioning. It has been inferred that leatherbacks support active foraging by keeping warm in cold water, rather than becoming lethargic as other marine turtles do. However, data consistent with this view have come from captive turtles in unnatural and stressful conditions. In the present case, foraging leatherbacks were captured at sea off Nova Scotia and their body temperature recorded within 10 min, before such large animals could change their body temperatures appreciably. Mean excess temperature over that of the sea surface (15.0–16.7 °C) averaged 8.2 °C. These results attest to, but underestimate, the capacity of free-swimming leatherbacks to keep warm in northern waters, as data from another turtle that was instrumented to record ocean temperature while diving revealed that leatherbacks foraging in this area at the same time of year may spend 40% of their time diving to waters cooler than the surface.
Phylogenetic relationships and divergence times of the genusTokudaiawithin Murinae (Muridae; Rodentia) inferred from the nucleotide sequences encoding the Cytbgene, RAG 1, and IRBP
Authors: Sato Jun J , Suzuki Hitoshi
Published: January 2005

The phylogenetic relationships of six genera of Murinae (Apodemus, Diplothrix, Micromys, Mus, Rattus, and Tokudaia) were examined using the nucleotide sequences for the mitochondrial cytochrome b (Cytb), as well as the nuclear recombination activating gene 1 (RAG1) and interphotoreceptor retinoid-binding protein (IRBP), with special emphasis on the position of the genus Tokudaia, which is endemic to the Ryukyu Islands. Compared with Cytb at all codon positions, the first and second codon positions of Cytb, RAG1 (1002 base pairs (bp)), and IRBP (1586 bp) sequences were less prone to saturation. Close affinity between the genera Tokudaia and Apodemus was observed in the analyses using the IRBP (1586 bp) and combined nuclear (2588 bp; RAG1 + IRBP) sequences. The divergence time for the Tokudaia–Apodemus clade was estimated at approximately 6.5–8.0 Ma, which is more recent than previously reported, thereby indicating the recent colonization of the Ryukyu Islands by the genus Tokudaia. The other relationships among the main genera were highly ambiguous, owing either to saturation or insufficient phylogenetic information. The radiation of the main genera within a relatively short period of evolutionary time may explain the unresolved topologies, although molecular sources that are less subject to saturation are required to resolve the outstanding issues.
Social structure and mating system of sperm whales off northern Chile
Authors: Coakes Amanda K , Whitehead Hal
Published: January 2005

We studied the social structure and mating system of sperm whales (Physeter macrocephalus L., 1758) off northern Chile over 10 months in 2000, photographically identifying 898 individuals. The mean size of encountered groups of females with immatures was about 23 animals, while the estimated mean size of units (sets of females and immatures with permanent relationships) was 11 animals. About 4% of the population consisted of large mature males, although this varied seasonally. Groups of females and immatures, as well as large males, spent only a matter of days within the study area at a time. There was no evidence for preferred ranges for the males, for males consistently accompanying particular groups, or for males forming coalitions. Males roved between the groups of females and immatures. Both mature males and females or immatures appeared to take the initiative in maintaining or breaking close associations. These results are similar to those from studies off the Galápagos Islands, even though the habitat, nonsocial behaviour, and relative abundance of mature males were quite different in the two areas.
Abundance and mtDNA differentiation of humpback whales (Megaptera novaeangliae) in the Shumagin Islands, Alaska
Authors: Witteveen Briana H , Straley Janice M , von Ziegesar Olga , Steel D , Baker C Scott
Published: January 2005

Despite extensive research on humpback whales (Megaptera novaeangliae (Borowski, 1781)) in parts of the North Pacific, little research has focused on the whales feeding in coastal waters west of Kodiak Island in the Gulf of Alaska. To extend research westward in the North Pacific, small-boat surveys were conducted near the Shumagin Islands during the summers of 1999–2002. Photographs of the natural markings of humpback whales were collected, representing 413 sightings of 171 individual whales. Small samples of skin tissue were collected from 20 individuals, including two mother–calf pairs, for sex identification and comparison of mtDNA haplogroups with previously published results from surveys in other regions of the North Pacific. Individual identification photographs were used in mark–recapture analysis to estimate abundance for the Shumagin Island region. The best estimate was given by a modified Jolly–Seber method: N = 410 (95% CI: 241–683) for 2002. Comparison of photographs with archived photographs from throughout the North Pacific revealed four migratory destinations for 13 of the Shumagin Islands whales: Hawai'i, Japan, offshore Mexico, and coastal Mexico. The frequencies of mtDNA haplogroups differed significantly from those in three other sampled feeding grounds: California, southeastern Alaska, and Prince William Sound. The haplogroup frequencies and migratory destinations of individuals suggested an affinity with the Hawaiian wintering ground but data are insufficient to associate whales off the Shumagin Islands with any surveyed breeding ground.
Similarities in acute phase protein response during hibernation in black bears and major depression in humans: a response to underlying metabolic depression?
Authors: Tsiouris John A , Chauhan Ved P.S , Sheikh Ashfaq M , Chauhan Abha , Malik Mazhar , Vaughan Michael R
Published: January 2005

This study investigated the effects of hibernation with mild hypothermia and the stress of captivity on levels of six acute-phase proteins (APPs) in serial samples of serum from 11 wild and 6 captive black bears (Ursus ameri canus Pallas, 1780) during active and hibernating states. We hypothesize that during hibernation with mild hypothermia, bears would show an APP response similar to that observed in major depression. Enzyme-linked immuno absorbent assay was used to measure alpha2-macroglobulin and C-reactive protein, and a nephelometer to measure alpha1-antitrypsin, hapto globin, ceruloplasmin, and transferrin. Levels of all other proteins except ceruloplasmin were significantly elevated during hibernation in both wild and captive bears at the p < 0.05 to p < 0.001 level. Alpha2-macroglobulin and C-reactive-protein levels were increased in captive versus wild bears in both active and hibernating states at the p < 0.01 to p < 0.0001 level. During hibernation with mild hypothermia, black bears do not show immunosuppression, but show an increased APP response similar to that in patients with major depression. This APP response is explained as an adaptive response to the underlying metabolic depression in both conditions. Metabolic depression in hibernating bears is suggested as a natural model for research to explain the neurobiology of depression.
Laboratory culture ofDreissena polymorphalarvae: spawning success, adult fecundity, and larval mortality patterns
Authors: Stoeckel James A , Padilla Dianna K , Schneider Daniel W , Rehmann Chris R
Published: January 2005

Understanding the entire life history, especially critical periods during the life cycle of a species, is important for understanding population dynamics and is crucial for control of nuisance species. Errors in estimates of growth rates and recruitment in field and modeling studies are likely to occur if one assumes uniform rather than size- or stage-specific mortalities for larval stages. Similarly, effects of brood-stock health on adult fecundity and larval mortality patterns might affect results of laboratory studies investigating larval life history. We maintained zebra mussels, Dreissena polymorpha (Pallas, 1771), in spawning condition in the laboratory for 24 weeks. Healthy larvae were produced for 18 weeks. However, induction of spawning and egg production declined through time. Fecundity increased with size per female, but sperm production did not for males. We found no correlation between clutch size and egg size across a wide range of clutch sizes. Survivorship was greater when larvae were reared at lower densities. Daily larval mortality was strongly size dependent; the average size of dead larvae was similar to the minimum size of live larvae. Highest daily larval mortality occurred during the transition from D stage to umbonal stage, supporting the suggestion of a developmental bottleneck as found in previous field studies.
Spatial structure and land-cover use in a low-density Mediterranean population of Eurasian badgers
Authors: Rosalino Luís Miguel , Macdonald David White , Santos-Reis Margarida
Published: January 2005

Eurasian badgers, Meles meles (L., 1758), have an extensive geographic range throughout which their social organization varies. Their capacity for intraspecific variation can now best be understood by studying them in landscapes that differ from the lush, lowland farmland where their tendency to form large groups has been most intensively investigated. Badgers in cork oak (Quercus suber L.) woodland are thus a priority for study, as this Mediterranean landscape provides an extreme contrast to those studied elsewhere. In this habitat in Portugal, we found 0.36–0.48 badgers/km2, one of the lowest population densities recorded in Western Europe. Here, individuals used seasonally stable home ranges that averaged 4.46 km2and that were occupied by 3–4 adults plus 3–4 cubs of the year. In this landscape, badgers selectively used cork oak woodland with understory and riparian vegetation. As predicted by the resource dispersion hypothesis, home-range size was positively correlated with food-patch dispersion. In southwestern Portugal, badgers depend upon an environmental mosaic such as olive groves and orchards and vegetable gardens for food and cork oak woodlands for shelter and protection.
Modelling roe deer (Capreolus capreolus) in a gradient of forest fragmentation: behavioural plasticity and choice of cover
Authors: Jepsen J U , Topping C J
Published: January 2005

The ability of a species to exhibit behavioural plasticity to environmental conditions has consequences for its success in fragmented landscapes. The roe deer, Capreolus capreolus (L., 1758), is one of the foremost examples of behavioural flexibility among ungulates. This species has increased rapidly in range from its original forest-mosaic habitat into open agricultural plains. Open-land roe deer populations show distinct differences in spatial and social behaviour, including larger group sizes, compared with forest-living roe deer populations. This is traditionally viewed as an antipredator strategy. The presence of strong behavioural plasticity in species response to landscape structure suggests that this should also be a concern in models attempting to describe effects of landscape change on species distribution. To date the implications of behavioural plasticity for modelling species' response to environmental conditions has received little attention. We used an individual-based model of roe deer to evaluate the consequences of behavioural plasticity for predictions made regarding population response to woodland fragmentation. The inclusion of a flexible behavioural strategy, where increased group size could buffer lack of woodland cover, resulted in significantly higher estimates of population size, population persistence, and the ability of the population to cope with fragmentation. This clearly demonstrates that behavioural plasticity in species response to landscape structure may affect our ability to accurately predict the effects of landscape change and should be a concern to modellers.
Role of current and prey odour in the displacement behaviour of the sea starAsterias vulgaris
Authors: Drolet David , Himmelman John H
Published: January 2005

We performed a factorial experiment to investigate the effects of current and prey odours (mussels) on the displacement behaviour of the sea star Asterias vulgaris (Verrill, 1866). This sea star is a common subtidal predator of sessile and slow-moving animals in the western North Atlantic Ocean. In the presence of current and prey odours in a flume, sea stars oriented themselves upstream and 70% succeeded in finding the prey. Also, the degree of orientation toward the prey increased as the sea star approached the prey. In contrast, only 5% of individuals tested in still water found the prey. Thus, for A. vulgaris the presence of macroscale flow is an essential condition for locating distant prey. Sea stars tested in current alone showed rheotactic behaviour, moving diagonally upstream. This behaviour should enhance the probability of encountering prey odour plumes in the field. Sea stars moved faster and straighter in flowing water than in still water. The slow movement of A. vulgaris in still water probably minimizes costs of foraging when there is a low chance of finding prey and the straight diagonal movement in current should ensure that the sea star continuously samples new areas, rather than resampling the same odour-free area.
Stable foraging areas and variable chick diet in Cassin's auklets (Ptychoramphus aleuticus) off southern California
Authors: Adams Josh , Takekawa John Y , Carter Harry R
Published: January 2005

Planktivorous seabirds readily respond to changes in marine ecosystems and have the ability to integrate information regarding variability in abundance, availability, and community composition of key prey resources. We studied the foraging and breeding ecology of the Cassin's auklet, Ptychoramphus aleuticus (Pallas, 1811), off southern California during three breeding seasons (1999–2001), when large intra- and inter-annual variability occurred in local oceanographic conditions during a prolonged La Niña event. Radio-marked parents used consistent core foraging areas within 30 km of their colony, aggregated in shelf waters (<200 m depth), and occasionally foraged in deeper waters. Parents delivered primarily euphausiids, pelagic larval-juvenile fishes, and minor amounts of cephalopods and other crustaceans. Whereas the euphausiid Thysanoessa spinifera Holmes, 1900 was most important during 1999 and 2001, Euphausia pacifica Hansen, 1911 replaced adult T. spinifera in 2000 after an anomalous eastward inflection of the California Current occurred near the auklets' foraging area. Differences in chick diets, however, did not significantly influence fledging success and growth among first chicks, but the proportion of pairs successfully fledging an alpha chick and initiating a second clutch was exceptional in 1999 (63%) and 2000 (75%), and less in 2001 (7%). We suggest that dietary composition was influenced by modified prey availability driven in part by fluctuations in regional upwelling and circulation.