Genetic analysis of the growth rate of Israeli Holstein calves

Weight of male and female Israeli Holstein calves and yearling gain were analyzed on 285 800 records from 105 935 animals from 458 herds recorded between 1994 and 2007. The difference between the sexes increased until around 400 days, at which point the difference between males and females was 110 kg. Yearling gain, defined as 365 × (weight - 35)/age + 35, was greatest for males at approximately 300 days and for females at 225 days. Yearling gain of male and female calves were highly correlated genetically; thus records from both sexes were combined into a joint genetic analysis. Heritability and repeatability were 0.33 and 0.73 in the analysis of both sexes, and similar in the single-sex analyses. Yearling gain is also highly correlated genetically with various measures of mature cow size. Yearling gain was positively correlated with milk, fat, protein production and somatic cell score, but negatively correlated with fertility and cow survival. Yearling gain was also positively correlated with both the sire and maternal grandsire effects on dystocia, but not with calf mortality. The genetic trend for yearling gain was 0.16 kg/year, while phenotypic trends for first and last weighings were both negative.     

安徽滁州雌性丽斑麻蜥繁殖特征

在安徽滁州地区丽斑麻蜥(Eremias argus)年产两窝卵。窝卵数及窝卵重与雌体体长呈正相关,相对窝卵重与雌体体长无关,卵重与窝卵数无关。窝卵数、窝卵重及卵重在窝序间无明显的差异。卵长径与卵短径呈正相关,卵长径与窝卵数呈负相关,而卵短径与窝卵数无关。雌体主要通过增加窝卵数增加繁殖输出。     

Group differences in captive gorillas’ reaction to large crowds

The impact of visitor crowd size on captive animal behaviour can be difficult to interpret in many institutions due to the lack of variation in crowd size over short periods of time. In attempts to compare greater variation in crowd size, animal behaviour is often compared over conditions that create additional confounds, such as day of week or season. Fluctuations in attendance over the holiday season at Disney's Animal Kingdom^® Theme Park provided an opportunity to examine the impact of variation in crowd size on gorilla behaviour without the confounds found in many other studies. Ten western lowland gorillas (Gorilla g. gorilla) in a bachelor group (n = 4) and a family group (n = 6) were observed over a period of 8 weeks in late 2005. Observations were classified into Large Crowd and Small Crowd days and a repeated-measures ANOVA procedure was conducted to determine the effects of crowd size and social group on gorilla behaviour patterns. Few overall differences were found in behaviour during the Large Crowd and Small Crowd conditions. However, similar to previous research, gorillas were less visible during the Large Crowd condition (F_1,8 = 14.15, P = 0.01). There was also an interaction of crowd size and group (F_1,8 = 7.58, P = 0.01), indicating the bachelor group of gorillas was more aggressive during the Large Crowd condition, whereas the family group showed no increase in aggression with large crowds. These results indicate the importance of providing complex enclosures with visual barriers to allow animals to move away from large crowds if they choose. Future research should focus on the individual characteristics of animals and enclosures that may contribute to behavioural differences in visitor–animal interaction research, as well as the proximate cues associated with behaviour change when exposed to large crowds.     

WHAT USE IS AN INFERTILE SPERM? A COMPARATIVE STUDY OF SPERM‐HETEROMORPHIC DROSOPHILA

Sperm size and number are important determinants of male reproductive success. The genus Drosophila exhibits a remarkable diversity of sperm production strategies, including the production of multiple sperm morphs by individual males, a phenomenon called sperm heteromorphism. Sperm-heteromorphic Drosophila species in the obscura group produce large numbers of infertile "parasperm" in addition to fertile eusperm. Parasperm have been hypothesized to perform a number of roles in place of fertilization, predominantly focused on their potential function in postcopulatory sexual selection. However, the evolutionary significance of parasperm remains unknown. Here we measured several male and female morphological, behavioral, and life-history traits in 13 obscura group species to test competing hypotheses of parasperm function using comparative methods. We found that parasperm size was unrelated to female reproductive tract morphology but was negatively related to our two indices of sperm competition, suggesting that postcopulatory sexual selection may indeed have shaped the evolution of parasperm. We also found abundant coevolution between male and female reproductive traits. Some of these relationships have been found in both sperm-monomorphic and sperm-heteromorphic taxa, but others are dissimilar. We discuss the significance of our results to the evolution of reproductive traits and the elusive function of Drosophila parasperm.     

Phylogenetic and geographic variation in host breadth and composition by herbivorous amphipods in the family Ampithoidae

Predicting the host range for herbivores has been a major aim of research into plant-herbivore interactions and an important model system for understanding the evolution of feeding specialization. Among many terrestrial insects, host range is strongly affected by herbivore phylogeny and long historical associations between particular herbivore and plant taxa. For small herbivores in marine environments, it is known that the evolution of host use is sculpted by several ecological factors (e.g., food quality, value as a refuge from predators, and abiotic forces), but the potential for phylogenetic constraints on host use remains largely unexplored. Here, we analyze reports of host use of herbivorous amphipods from the family Ampithoidae (102 amphipod species from 12 genera) to test the hypotheses that host breadth and composition vary among herbivore lineages, and to quantify the extent to which nonpolar secondary metabolites mediate these patterns. The family as a whole, and most individual species, are found on a wide variety of macroalgae and seagrasses. Despite this polyphagous host use, amphipod genera consistently differed in host range and composition. As an example, the genus Peramphithoe rarely use available macrophytes in the order Dictyotales (e.g., Dictyota) and as a consequence, display a more restricted host range than do other genera (e.g., Ampithoe, Cymadusa, or Exampithoe). The strong phylogenetic effect on host use was independent of the uneven distribution of host taxa among geographic regions. Algae that produced nonpolar secondary metabolites were colonized by higher numbers of amphipod species relative to chemically poor genera, consistent with the notion that secondary metabolites do not provide algae an escape from amphipod herbivory. In contrast to patterns described for some groups of phytophagous insects, marine amphipods that use chemically rich algae tended to have broader, not narrower, host ranges. This result suggests that an evolutionary advantage to metabolite tolerance in marine amphipods may be that it increases the availability of appropriate algal hosts (i.e., enlarges the resource base).     

Reproductive conflicts affect labor and immune defense in the queenless ant Diacamma sp. "nilgiri"

In many species of social Hymenoptera, totipotency of workers induces potential conflicts over reproduction. However, actual conflicts remain rare despite the existence of a high reproductive skew. One of the current hypotheses assumes that conflicts are costly and thus selected against. We studied the costs of conflicts in 20 colonies of the queenless ant Diacamma sp. "nilgiri" by testing the effects of conflicts on labor and worker immunocompetence, two parameters closely linked to the indirect fitness of workers. In this species, the dominant female is the only mated worker (gamergate) and monopolizes reproduction. We experimentally induced conflicts by splitting each colony into two groups, a control group containing the gamergate and an orphaned group displaying aggressions until a new dominant worker arises. Immunocompetence was assessed by the clearance of Escherichia coli bacteria that we injected into the ants. Time budget analysis revealed a lower rate of labor and especially brood care in orphaned groups, supporting the existence of a cost of conflicts on labor. Fifteen days after splitting, a lower immunocompetence was also found in orphaned groups, which concerned workers involved and not involved in conflicts. We propose that this immunosuppression induced by conflicts could stem from stress and not directly from aggression.     

Clonal turnover versus clonal decay: a null model for observed patterns of asexual longevity, diversity and distribution

Phylogenetic and phylogeographic studies suggest that a majority of asexual organisms are evolutionarily recent offshoots of extant sexual taxa and that old clonal lineages tend to be isolated from their sexual and younger asexual counterparts. These observations have often been interpreted as support for the long-term disadvantages of asexuality resulting from the mechanisms of clonal decay. Although clonal decay is likely to be an important mechanism that limits the temporal and spatial distribution of asexual lineages, we argue here that contemporary phylogenetic analyses, which are mostly restricted to simple comparisons of "recent" and "ancient" clones, need to be tested against an appropriate null model of neutrality. We use computer simulations to show that many empirical observations of the distribution of asexuality do not in fact reject a null model of the neutral turnover of clones spawned by sexual relatives. In particular, neutral clonal turnover results in qualitatively similar pattern of clonal spatial distribution and age structure, as does a process that includes clonal decay. Although there are important quantitative differences between predictions made by the two models, we show that published empirical data are still inadequate to distinguish between them. Further work on sexual-asexual complexes is therefore required before clonal turnover can be rejected as a parsimonious explanation of the spatial distribution and age structure of asexual lineages.     

Factors that affect the re-attachment of Chondracanthus chamissoi (Rhodophyta, Gigartinales) thalli

Vegetative reproduction of Chondracanthus chamissoi by means of fragmentation and re-attachment of thalli is considered an effective strategy for maintaining natural populations of this species. Here, we evaluate the effects of (1) time of drifting thallus, (2) type of substratum, and (3) photon flux density, on the re-attachment capacity of thallus fragments of C. chamissoi. The results show that re-attachment decreases with the time after detachment, and was higher at the lower photon flux densities tested (10 and 40 μmol photons m⁻²s⁻¹), and on calcareous substratum. Secondary attachment discs are formed along the entire surface of the fragment.     

An actively mixed mini-bioreactor for protein production from suspended animal cells

Biopharmaceutical production would benefit from rapid methods to optimize production of therapeutic proteins by screening host cell line/vector combination, culture media, and operational parameters such as timing of induction. Miniaturized bioreactors are an emerging research area aiming at improving the development speed. In this work, a 3 mm thick mini-bioreactor including two 12 mm wide culture chambers connected by a 5 mm wide channel is described. Active mixing is achieved by pressure shuttling between the two chambers. Gas-liquid phase exchange for oxygen and carbon dioxide is realized by molecular diffusion through 50 microm thick polymethylpentene membranes. With this unique design, a velocity difference between the middle area and the side areas at the interfaces of the culture chambers and the connecting channel is created, which enhances the mixing efficiency. The observed mixing time is on the order of 100 s. The combination of high permeability toward oxygen of polymethylpentene membranes and fluid movement during active pressure shuttling enables higher volumetric oxygen transfer coefficients, 5.7 +/- 0.4-14.8 +/- 0.6 h(-1), to be obtained in the mini-bioreactors than the values found in traditional 50 mL spinner flasks, 2.0-2.5 h(-1). Meanwhile, the calculated volume averaged shear stress, in the range of 10(-2)-10(-1) N/m(2), is within the typical tolerable range of animal cells. To demonstrate the applicability of this mini-bioreactor to culture suspended animal cells, the insect cell, Spodoptera frugiperda, is cultured in mini-bioreactors operated under a K(L)a value of 14.8 +/- 0.6 h(-1) and compared to the same cells cultured in 50 mL spinner flasks operated under a K(L)a value of 2.2 h(-1). Sf-21 cells cultured in the mini-bioreactors present comparable length of lag phases and growth rates to their counterparts cultured in 50 mL spinner flasks, but achieve a higher maximum cell density of 5.3 +/- 0.9 x 10(6) cell/mL than the value of 3.4 +/- 0.4 x 10(6) cell/mL obtained by cells cultured in 50 mL spinner flasks. Sf-21 cells infected with SEAP-baculovirus produce a maximum SEAP concentration of 11.3 +/- 0.7 U/mL when cultured in the mini-bioreactor. In contrast, infected Sf-21 cells cultured in 50 mL spinner flasks produce a maximum SEAP concentration of 7.4 +/- 0.9 U/mL and onset of production is delayed from 18 h in minibioreactor to 40 h in spinner flasks.     

Endocrine regulation of the reproduction in crustaceans: Identification of potential targets for toxicants and environmental contaminants

Progress in ecotoxicological research documents that crustaceans are highly vulnerable to diverse chemicals and toxicants in the environment. In particular, pollutants affecting endocrine homeostasis in crustaceans (i.e., endocrine disruptors) are intensively studied, and serious reproductive disorders have been documented. In this review, current knowledge about the endocrine regulation of the crustacean reproduction is put together with the published ecotoxicological data with an attempt to summarize the potential of xenobiotics to affect crustacean reproduction. Following gaps and trends were identified: (1) Studies are required in the field of neurohormone (serotonin and dopamine) regulation of the reproduction and possible modulations by environmental toxicants such as antidepressant drugs. (2) Molting-related parameters (regulated by ecdysteroid hormones) are closely coordinated with the development and reproduction cycles in crustaceans (cross-links with methyl farnesoate signalling), and their susceptibility to toxicants should be studied. (3) Other biochemical targets for xenobiotics were recently discovered in crustaceans and these should be explored by further ecotoxicological studies (e.g., new information about ecdysteroid receptor molecular biology). (4) Some sex steroid hormones known from vertebrates (testosterone, progesterone) have been reported in crustaceans but knowledge about their targets (crustacean steroid receptors) and signalling is still limited. (5) Determination of the sex in developing juveniles (affecting the sex ratio in population) is a sensitive parameter to various xenobiotics (including endocrine disruptors) but its modulation by general environmental stress and non-specific toxicity should be further studied.