bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of male genetic contribution and paternal investment to egg and hatchling size in the cricket, Gryllus firmus
Authors: Weigensberg I. , Carrière Y. , Roff D. A. 
Published: December 2004

AbstractEgg provisions represent the complete energy supply of oviparous organisms from fertilization until hatching, and egg size is generally correlated with initial offspring size and a suite of other early fitness related traits. Since egg size is determined by the mother, little attention has been given to potential sources of paternal effects on either egg size or initial offspring size. This study considers two processes by which the sire can affect the egg size and/or initial body size of his offspring, in the multiply mated cricket, Gryllus firmus. The first is a paternal genetic effect, whereby differences in offspring genotype result in differences in the efficiency of metabolising available resources. The second is a paternal environmental effect, whereby the quality or size of paternal investment varies among male phenotypes and this is correlated with the size of eggs the females subsequently produce. Using a one‐locus two‐allele recessive mutation for pale eye colour as a marker, a mating experiment was designed which enabled the discrimination between eggs fertilized by two males mated simultaneously to a single female. The results of this experiment suggest that sire effects on egg and initial body size occur through both processes. Eggs fertilised by the two males were significantly different at day ten of development, suggesting that the genetic contribution of the sire is affecting embryonic body size. Further, a negative correlation was found between the head size of the pale eyed male and the size of all the eggs that the female laid, suggesting an effect of male size of the amount of nutrients the female receives from her mates. The results of this study suggest that paternal effects may be both more common and more profound than previously thought, and that studies examining early fitness traits that are correlated to egg size or initial body size, in oviparous animals, should consider the possibility and importance of the paternal contribution.
Heritability of sperm competition success in the bulb mite, Rhizoglyphus robini
Authors: Radwan J. 
Published: December 2004

AbstractMultiple mating by females has been proposed to function as a form of mate‐choice, which implies that males should show heritable variation in sperm‐competitive abilities. In this study, repeatability and heritability of sperm competition success was estimated in the bulb mite, Rhizoglyphus robini. Fertilization success of males was estimated in competition with sperm of two other males. Males differed consistently in their sperm competition success, with repeatability estimated at 0.22. The heritability of sperm competition success was estimated using parent‐offspring regression, with the mean fertilization success from two matings used as a measure of each male's competitive ability. There was a significant association between the sperm competition success of fathers and sons. Narrow sense heritability (h2) was 0.284. This result supports the hypotheses proposing the multiple mating is selectively maintained in females by enhancing the reproductive success of their progeny.
The evolution of demographic tactics in lizards: a test of some hypotheses concerning life history evolution
Authors: Clobert J. , Garland T. , Barbault R. 
Published: December 2004

AbstractWe analyze, with an augmented data base, patterns of covariation of the three primary demographic parameters (age at maturity, fecundity, adult survival, all measured in the same unit of time) in lizards. This also constitutes a first attempt to use all three of these parameters for this group of species. We attempt to place these analyses in the framework of recent theories on life history evolution (Ferrière and Clobert, 1992; Charnov, 1993). Life history data were collected from the literature and from our original work, and a composite phylogeny was assembled, based on a variety of published sources. Using a phylogenetically based statistical method (independent contrasts), the allometric (log‐log) relationship of fecundity (and of clutch size) in relation to snout‐vent length was found to differ significantly between the two major clades of extant lizards, Iguania (43 species in our data set) and Scleroglossa (47 species). We therefore emphasize analyses done separately for the two clades. Without removing correlations with body size, the relationships between fecundity and survival, and between fecundity and age at maturity, were also found to differ between clades, which differs from Charnov's (1993) predictions. When correlations with body size were removed statistically, however, the two clades did not differ significantly in these relationships. In a principal components analysis (PCA) of the three demographic variables plus snout‐vent length, the first axis explained the majority (53–57%) of variation in both clades, while the second axis explained 27–31% of the variation and loaded mainly on fecundity. In a PCA of size‐adjusted demographic variables residuals (from log‐log regressions on snout‐vent length), the first axis explained 66–68% of the variation and was clearly interpretable as the classical “slow‐fast” continuum, which has been described in birds and mammals. The PCA of residuals did not provide clear evidence of additional significant patterns of covariation. However, the rate of evolution of mortality (size‐corrected), but not of fecundity or age at maturity, differed significantly between clades. Furthermore, fecundity and age at maturity, both corrected for variation in adult mortality (in addition to body size), were still significantly related, indicating the existence of other patterns of variation in these life history traits. In other words, the ratios between age at maturity and adult mortality, or between fecundity and adult mortality, were not found to be invariant, because the variation not accounted for by these ratios was significantly associated with variation in another variable. This result contradicts the prediction of Charnov (1993), and suggests the existence of other directions of evolution in these life history traits.
Mitochondrial DNA variability in viviparous and ovoviviparous populations of the urodele Salamandra salamandra
Authors: Dopazo H. , Boto L. , Alberch P. 
Published: December 2004

AbstractMitochondrial DNA analysis of 13 populations of S. salamandra along a transect across the North of the Iberian Peninsula showed values of divergence between haplotypes ranging from d = 0.41% to 5.91%. Phenetic and cladistic analysis grouped the isofemale lineages into two main clusters with contrasting phylogeographic patterns. The first group encompasses populations located at each extreme of the Iberian Peninsula. Despite the large geographic distance separating these populations, they exhibit only a minor degree of divergence among haplotypes. In contrast, much higher diversification, in both number of distinct haplotypes, and overall genetic divergence, was observed in the second group of phylogenetically related populations. Surprisingly, this process of radiation and divergence in mtDNA haplotypes occurred in populations in close geographic proximity. All populations sampled in this group are located within a 300 km range, in the central part of our transect across the Northern edge of the Peninsula. Most populations in the central range of our transect exhibit viviparous reproduction — which is derived and highly unusual among urodeles. The genetic distances measured among Asturian (central portion of our transect), viviparous populations are higher than the distances measured between the two main taxonomic clusters. A viviparous population showing an unusual level of mtDNA heterogenetiy is reported and the potential implications of this focus of localized variability are discussed. The dynamics of isofemale lineages among the two reproductive modes was further explored in combination with the previous allozyme data. Several nuclear markers suggest that major mtDNA divergences could be explained by long‐term extrinsic barriers to gene flow. Isofemale lineages indicate a narrow secondary contact zone among populations with different reproductive patterns. The existence of viviparous and ovovivparous populations sharing a common haplotype suggests that reproductive transition in S. salamandra could have arisen in absence of genetic mtDNA differentiation. We finally outline a genetic model system where the acquisition of water independence from a primitively aquatic dependent amphibian life cycle can be analyzed from a microevolutionary perspective.
Similarity, parsimony and conjectures of homology: The chelonian shoulder girdle revisited
Authors: Lee M. S. Y. 
Published: December 2004

AbstractMuch has been written about the definition and recognition of biological homology. Homology is usually defined as similarity inherited from a common ancestor (e.g., papers in Hall, 1994). It is recognised through cladistic analysis: Patterson (1982) and de Pinna (1991) have cogently argued that homology can be equated with synapomorphy (a shared evolutionary novelty uniting a monophyletic group). Such identification involves two stages: first, a possible homology is proposed on the basis of morphological similarity. This similarity might be structural, topological, developmental, or any combination thereof. Next, a cladistic analysis is performed, involving the trait in question and all other informative traits identified. If the trait is congruent with the resultant phylogeny, it is accepted as homologous in all taxa which possess it. If the trait is incongruent with the phylogeny, it is interpreted as homoplasious in certain taxa. This has been termed the test of congruence (Patterson, 1982; de Pinna, 1991).Rieppel (1996) has recently suggested that the test of congruence might be circular, and that as a result certain inferences about the evolution of the chelonian shoulder girdle (Lee, 1996) are poorly substantiated. Here I argue that the test of congruence is not circular, and that the disputed conclusions about the evolution of chelonian shoulder girdle can be defended on the basis of parsimony. More generally, I suggest how considerations of parsimony can and should be used to arbitrate between conflicting conjectures of homology that are both congruent with an accepted phylogeny.
Genetic constraints at the metamorphic boundary: Morphological development in the wood frog, Rana sylvatica
Authors: Phillips P. C. 
Published: December 2004

AbstractOrganisms with complex life‐cycles often experience very different environments in different phases of their life. Genes expressed in more than one phase could potentially create a conflict or constraint on evolutionary change if the pattern of selection on those genes were different in the different phases. The potential importance of this type of constraint across metamorphosis in frogs was assessed by measuring the genetic correlation between several morphological traits in both larval and juvenile Rana sylvatica. Genetic correlations within a stage tended to be moderately high and significant whereas correlations across stages were low and not significant. Errors on the genetic parameters make it impossible to prove that there are no genetic constraints across metamorphosis in this population of frogs, but the results are consistent with the hypothesis that gene expression and developmental regulation are partitioned separately before and after metamorphosis.
Evolution and biogeography of the genus Tarentola (Sauria: Gekkonidae) in the Canary Islands, inferred from mitochondrial DNA sequences
Authors: Nogales M. , López M. , Jiménez‐Asensio J. , Larruga J. M. , Hernández M. , González P. 
Published: December 2004

AbstractSequences from fragments of the 12S ribosomal RNA and cytochrome b mitochondrial genes were used to analyze phylogenetic relationships among geckos of genus Tarentola from the Canary Islands. A surprisingly high level of within island differentiation was found in T. delalandii in Tenerife and T. boettgeri in Gran Canaria. Molecular differentiation between populations of T. angustimentalis on Lanzarote and Fuerteventura, and between Moroccan and Iberian Peninsula T. mauritanica, also indicate that at least two subspecies should be recognized within each of them. Phylogenetic relationships among these species reveals a higher level of differentiation and a more complex colonization pattern than those found for the endemic genus Gallotia. Lack of evidence for the presence of T. boettgeri bischoffi on the island of Madeira does not seem to support the origin of T. delalandii, T. gomerensis and the canarian subspecies of T. boettgeri from this island, whereas molecular data confirms that T. angustimentalis is a sister species of the continental T. mauritanica. Several independent colonization events from the continent and the extinction of some species are probably responsible for the current distribution of Tarentola in the Canary Islands.
Inbreeding depression affects pollen performance in Cucurbita texana
Authors: Jóhannsson M. H. , Gates M. J. , Stephenson A. G. 
Published: December 2004

AbstractMost studies of the effects of inbreeding focus on vegetative vigor and reproductive output through the female (fruit and seed) function. This study not only examines the effects of inbreeding on the female function but it also examines the effects of inbreeding on pollen performance both in vitro and in vivo. This study used Cucurbita texana, a wild gourd, and was performed under field conditions. In vivo performance was assessed by placing equal amounts of pollen from either the inbred or outcrossed plants onto a stigma together with pollen from a tester line. As with other studies, we found that outcrossed plants had greater reproductive output (male flowers and fruits) than plants produced from self pollinations. Unlike most studies of inbreeding depression, which mostly ignore the male function of plants, we also found that the pollen produced by outcrossed plants had faster pollen tube growth in vitro than the pollen produced on selfed plants. Moreover, pollen from selfed plants sired significantly fewer seeds than pollen from outcrossed plants under conditions of pollen competition (i.e. the number of pollen grains deposited onto the stigmas was larger than the number of available ovules). These findings indicate that inbreeding affects the performance of the resulting sporophytic generation and the microgametophytes they produce.
Does time until mating affect progeny sex ratio? A manipulative experiment with the parasitoid wasp Aphelinus asychis
Authors: Fauvergue X. , Hopper K. R. , Antolin M. F. , Kazmer D. J. 
Published: December 2004

AbstractIn haplodiploid organisms, unmated or sperm depleted females are “constrained” to produce only male progeny. If such constrained females reproduce, the population sex ratio will shift toward males and unconstrained females will be selected to produce more females. Assuming that a female's own time spent constrained is an index of the population‐wide level of constrained oviposition, and that constrained and unconstrained females reproduce at the same rate, the proportion of sons that females produce when unconstrained should decrease with increasing time spent constrained. Alternatively, if females cannot measure time spent constrained or if time spent constrained is not an index to the level of constrained oviposition in the population, the proportion of sons among progeny produced when unconstrained should not depend upon time spent constrained and should be female biased to an extent depending upon the average time spent constrained over evolutionary time. To test these predictions, we manipulated the amount of time spent virgin in the parasitoid wasp Aphelinus asychis Walker (Hymenoptera: Aphelinidae) and measured the number of males and females among progeny produced before and after mating. First, we found no interaction between age and age at mating in their effect on fecundity, which suggests that mating does not change fecundity. Second, we found that females mated at 8 days and 15 days produced equal sex ratios after mating but these were slightly more female biased than the sex ratios of females mated at 1 day. This observed “step response” suggests that females may perceive time from emergence to mating as a discrete rather than a continuous variable (i.e., short versus long), or that females do not perceive time per se but assess their age class (i.e., young versus old) at the time of mating.
Models of sexual and asexual coexistence in aphids based on constraints
Authors: Rispe C. , Pierre J.‐S. , Simon J.‐C. , Gouyon P.‐H. 
Published: December 2004

AbstractTwo models are presented to test the hypothesis that in aphids, a particular constraint (the necessity to resist frost) could be the proximal cause for the maintenance of sex. Both models are based on temporal variability in winter survival of asexuals.They show that:

only cyclical parthenogenesis is maintained below a threshold frequency of mild winters, because of the cold‐resistance of sexually‐produced eggs.
above a second threshold, only obligate parthenogenesis is maintained.
in‐between, the first model predicts a mixed evolutionarily stable strategy (ESS). This would reflect well the geographic distribution of the different types of reproduction. The second model, based on the genetic control of the reproduction system in two aphid species, predicts the maintenance of polymorphism with fluctuating proportions of the two life‐cycles. Males produced by obligate parthenogens play an essential role in this equilibrium (no stable polymorphism exists if this male production is set to zero). The value of the lowest possible fitness achieved by overwintering asexuals is critical.
The quantitative genetics of growth in a field cricket
Authors: Simons A. M. , Carrière Y. , Roff D. A. 
Published: December 2004

AbstractBecause of its relationship with both development time and adult size, the rate of growth in determinately growing organisms is an important aspect of their life histories. We reared sixty‐nine families of Gryllus pennsylvanicus derived from a natural population and found significant genetic variation in growth rate as estimated by the slope of linearized growth trajectories. We found no evidence for a genetic tradeoff between rate of growth and survival, nor rate of growth and fecundity. In principle, adult size may be determined both by the rate of growth and the time taken by the nymphs to develop. Our data indicate that variation in adult size is explained by variation in growth rate, not by variation in development time. We conclude with a discussion of the plausible explanations for the presence of genetic variation in growth rate in this natural population.
Human acid sphingomyelinase
Authors: Lansmann Stephanie , Schuette Christina G. , Bartelsen Oliver , Hoernschemeyer Joerg , Linke Thomas , Weisgerber Judith , Sandhoff Konrad 
Published: December 2004

Human acid sphingomyelinase (haSMase, EC 3.1.4.12) catalyzes the lysosomal degradation of sphingomyelin to ceramide and phosphorylcholine. An inherited haSMase deficiency leads to Niemann–Pick disease, a severe sphingolipid storage disorder.The enzyme was purified and cloned over 10 years ago. Since then, only a few structural properties of haSMase have been elucidated. For understanding of its complex functions including its role in certain signaling and apoptosis events, complete structural information about the enzyme is necessary. Here, the identification of the disulfide bond pattern of haSMase is reported for the first time. Functional recombinant enzyme expressed in SF21 cells using the baculovirus expression system was purified and digested by trypsin. MALDI‐MS analysis of the resulting peptides revealed the four disulfide bonds Cys120‐Cys131, Cys385‐Cys431, Cys584‐Cys588 and Cys594‐Cys607. Two additional disulfide bonds (Cys221‐Cys226 and Cys227‐Cys250) which were not directly accessible by tryptic cleavage, were identified by a combination of a method of partial reduction and MALDI‐PSD analysis. In the sphingolipid activator protein (SAP)‐homologous N‐terminal domain of haSMase, one disulfide bond was assigned as Cys120‐Cys131. The existence of two additional disulfide bridges in this region was proved, as was expected for the known disulfide bond pattern of SAP‐type domains. These results support the hypothesis that haSMase possesses an intramolecular SAP‐type activator domain as predicted by sequence comparison [Ponting, C.P. (1994) Protein Sci., 3, 359–361].An additional analysis of haSMase isolated from human placenta shows that the recombinant and the native human protein possess an identical disulfide structure.
H2O2, but not menadione, provokes a decrease in the ATP and an increase in the inosine levels in Saccharomyces cerevisiae
Authors: Osorio Hugo , Carvalho Elisabete , del Valle Mercedes , Günther Sillero María A. , Moradas‐Ferreira Pedro , Sillero Antonio 
Published: December 2004

When Saccharomyces cerevisiae cells, grown in galactose, glucose or mannose, were treated with 1.5 mm hydrogen peroxide (H2O2) for 30 min, an important decrease in the ATP, and a less extensive decrease in the GTP, CTP, UTP and ADP‐ribose levels was estimated. Concomitantly a net increase in the inosine levels was observed. Treatment with 83 mm menadione promoted the appearance of a compound similar to adenosine but no appreciable changes in the nucleotide content of yeast cells, grown either in glucose or galactose.Changes in the specific activities of the enzymes involved in the pathway from ATP to inosine, in yeast extracts from (un)treated cells, could not explain the effect of H2O2 on the levels of ATP and inosine. Application of a mathematical model of differential equations previously developed in this laboratory pointed to a potential inhibition of glycolysis as the main reason for that effect. This theoretical consideration was reinforced both by the lack of an appreciable effect of 1.5 mm (or even higher concentrations) H2O2 on yeast grown in the presence of ethanol or glycerol, and by the observed inhibition of the synthesis of ethanol promoted by H2O2. Normal values for the adenylic charge, ATP and inosine levels were reached at 5, 30 and 120 min, respectively, after removal of H2O2 from the culture medium. The strong decrease in the ATP level upon H2O2 treatment is an important factor to be considered for understanding the response of yeast, and probably other cell types, to oxidative stress.
Structure of the polysaccharide chain of the lipopolysaccharide from Flexibacter maritimus
Authors: Vinogradov Evgeny , MacLean Leann L. , Crump Elizabeth M. , Perry Malcolm B. , Kay William W. 
Published: December 2004

Flexibacter maritimus, a Gram‐negative bacterium, is a fish pathogen responsible for disease in finfish species and a cause of cutaneous erosion disease in sea‐caged salmonids. For the development of serology based diagnostics, protective vaccines, and a study of pathogenesis, the structural analysis of the lipopolysaccharide (LPS) produced by the bacterium has been undertaken. We now report that an acidic O‐specific polysaccharide, obtained by mild acid degradation of the F. maritimus LPS was found to be composed of a disaccharide repeating unit built of 2‐acetamido‐3‐O‐acetyl‐4‐[(S)‐2‐hydroxyglutar‐5‐ylamido]‐2,4,6‐trideoxy‐β‐glucose and 5‐acetamido‐7‐[(S)‐3‐hydroxybutyramido]‐8‐amino‐3,5,7,8,9‐pentadeoxynonulopyranosonic acid (Sug) having the structure: The configuration of the C‐2–C‐7 fragment of the latter monosaccharide (B) was assigned β‐manno; however, the configuration at C‐8 could not be established. NMR data indicate that the two monosaccharides have opposite absolute configurations. The repeating unit includes a linkage via a (S)‐2‐hydroxyglutaric acid residue, reported here for the first time as a component of a bacterial polysaccharide. The LPS was also found to contain a minor amount of a disaccharide β‐Sug‐(2‐3)‐l‐Rha, isolated from the products of the acidic methanolysis of the LPS.