Hatching and larval export of the intertidal crab Neohelice granulata in Mar Chiquita coastal lagoon, Argentina

Synchronization in the events of the reproductive cycle in female Neohelice granulata Dana, 1851 were studied from samples taken weekly and biweekly from September to December 2006 in the Laguna Mar Chiquita. The timing and larval hatching and synchronicity were inferred from numbers of ovigerous females and observing the stages of embryonic development. Synchronization in larval hatching also was observed in females in experiments in dark for a period of 48 hours, at three different salinities (10, 23 and 33 ppm). In addition plankton sampling were performed in order to study larval exportation at the field and its link to the tidal and light/dark cycles. We found that ovigerous females of N. granulata have a marked synchronization in embryonic development which results in that most of berried females are close to hatching within a period of maximum tidal range (days). Within this period, there is a synchronization of hatching at a time scale of hours, governed by environmental conditions. The salinity range used in this study (10-32‰) did not affect hatching synchronicity neither time to hatch. Hatching was synchronized according to endogenous rhythms governed mainly by the tidal cycle and secondarily by the breadth of it. It is also conditioned by the light-dark cycle through an exogenous cycle, so that the hatchings would occur mostly at night high tides.

Short-term urea feeding decreases in vitro hatching of bovine blastocysts

Cows fed high-protein diets may have impaired reproductive performance. Although the pathogenesis has not been completely elucidated, it appears that not only the uterus, but also the follicle and oocyte, are affected by excessive plasma urea nitrogen (PUN) concentrations. Thus, the objective was to determine the effects of short-term urea feeding on the competence of bovine oocytes. Forty crossbred heifers (Bos indicus vs Bos taurus) were allocated to two groups, namely CONTROL (maintenance diet) and UREA (maintenance diet supplemented with 75 g of urea/day), following a cross-over design. Heifers received their respective diets for 6 d (without adaptation). On the sixth day, blood samples were harvested both before and 3 h after feeding, and cumulus oocyte complexes (COCs) were collected by ovum pick-up. Although PUN concentrations were higher in UREA than CONTROL heifers (31.31 mg/dL +/- 1.13 vs 22.12 mg/dL +/- 0.86; mean +/- SEM), neither the number of COCs recovered (8.8 +/- 1.0 vs 9.2 +/- 0.8, UREA vs CONTROL, respectively) nor their quality (based on morphology) differed significantly between groups. Next, oocytes were fertilized and cultured in vitro to assess developmental rates. There was an absence of significant differences between groups for rates of cleavage (Day 3) or blastocyst formation (Days 6, 7 and 9), but the hatched blastocyst rate on Day 11 after fertilization was lower (P < 0.05) in the UREA than the CONTROL groups (64.3 vs 83.5%). Therefore, we inferred that the effects of urea were only manifest later in development. In conclusion, high PUN concentrations decreased oocyte competence in heifers, reinforcing the hypothesis that poor reproductive performance in cows with high PUN was due, at least in part, to a deleterious effect on oocytes. (C) 2011 Elsevier Inc. All rights reserved.

Sex-biased hatching sequences in the cooperatively breeding Noisy Miner

The Noisy Miner Manorina melanocephala (Meliphagidae) is a cooperatively breeding bird species in which sons often remain on their natal home ranges and help one or both of their parents. In a population of Noisy Miners in SE Queensland, Australia, a molecular technique was used to explore adult and offspring sex ratios. and also hatching sequences. Among the adult population, there were 2.31 males for every female, and roughly 99% of helping was performed by males. At hatching and fledging, the population sex ratio was even, with exactly 57 males and 57 females. However, in 17 out of 18 broods the first egg to hatch was male, First-hatched males were significantly larger and heavier than their sisters just prior to fledging. Through their helping behaviour, large healthy sons could clearly enhance the future reproductive success of parents. and benefit the entire group. Sex-biased hatching sequences could potentially provide cooperatively breeding birds with a subtle and precise way of varying investment in the helping sex.

Pre-hatching maternal effects and the tasty chick hypothesis

Question: Are maternal effects (i.e. maternal transfer of immune components to their offspring via the placenta or the egg) specifically directed to the offspring on which ectoparasites predictably aggregate? Organisms: The barn owl (Tyto alba) because late-hatched offspring are the main target of the ectoparasitic fly Carnus hemapterus. Hypothesis: Pre-hatching maternal effects enhance parasite resistance of late- compared with early-hatched nestlings. Search method: To disentangle the effect of natal from rearing ranks on parasite intensity, we exchanged hatchlings between nests to allocate early- and late-hatched hatchlings randomly in the within-brood age hierarchy. Result: After controlling for rearing ranks, cross-fostered late-hatched nestlings were less parasitized but lighter than cross-fostered early-hatched nestlings. Conclusion: Pre-hatching maternal effects increase parasite resistance of late-hatched offspring at a growth cost.

Variation in the hatching response of Ochlerotatus albifasciatus egg batches (Diptera: Culicidae) in temperate Argentina

Egg hatching of winter-collected Ochlerotatus albifasciatus was studied for six months. Batches of eggs were divided into two groups, one of them was stored in the laboratory at 23°C and 12:12 photoperiod, and the other in the field under dead leaves. Every month, from July to December, eggs from the two groups were flooded under both laboratory and field conditions. Unhatched eggs were returned to the original condition and flooded two more times separated by ten-day intervals. Results show that egg diapause is expressed in different intensities, not only on eggs exposed to different conditions but also in those exposed to the same condition, even when they were laid by the same female. Successive inundations yielded incomplete hatches of eggs, and favored the hatching response in the next flooding. Low environmental temperatures before and during the flooding depressed hatching response. This shows that eggs need a warm period before flooding as well as warm temperatures during flooding, to hatch. As drought period was longer hatching response increased, but this was also accompanied by warmer environmental conditions. The experiment performed in laboratory did not show that increment. Field studies showed that a layer of dead leaves protected eggs from extreme temperatures.

Latex constituents from Calotropis procera (R. Br.) display toxicity upon egg hatching and larvae of Aedes aegypti (Linn.)

Calotropis procera R. Br. (Asclepiadaceae) is a well-known medicinal plant with leaves, roots, and bark being exploited by popular medicine to fight many human and animal diseases. This work deals with the fractionation of the crude latex produced by the green parts of the plant and aims to evaluate its toxic effects upon egg hatching and larval development of Aedes aegypti. The whole latex was shown to cause 100% mortality of 3rd instars within 5 min. It was fractionated into water-soluble dialyzable (DF) and non-dialyzable (NDF) rubber-free materials. Both fractions were partially effective to prevent egg hatching and most of individuals growing under experimental conditions died before reaching 2nd instars or stayed in 1st instars. Besides, the fractions were very toxic to 3rd instars causing 100% mortality within 24 h. When both fractions were submitted to heat-treatment the toxic effects were diminished considerably suggesting low thermostability of the toxic compounds. Polyacrylamide gel electrophoresis of both fractions and their newly fractionated peaks obtained through ion exchange chromatography or desalting attested the presence of proteins in both materials. When submitted to protease digestion prior to larvicidal assays NDF lost most of its toxicity but DF was still strongly active. It may be possible that the highly toxic effects of the whole latex from C. procera upon egg hatching and larvae development should be at least in part due to its protein content found in NDF. However the toxicity seems also to involve non protein molecules present in DF.

A new miracidia hatching device for diagnosing schistosomiasis

It is still imperative to develop a parasitological technique highly sensitive for diagnosing schistosomiasis in epidemiological and individual surveys. A simple and cheap hatching device with a collecting container was manufactured and tested under experimental conditions. Twelve Kato-Katz slides were performed as golden standard for comparison. Quantitative results can be carried out by counting miracidia in a plate and parasite load can be calculated (miracidia/gram of feces). Statistically significant values were higher in the hatching test. More sensitive results, with statistical significance, were achieved using 1.5 g of feces (which corresponds to 36 Kato-Katz slides) than by using the Kato-Katz method. Advantages of this technique and its limitations are presented.

Autumnal vs spring hatching in the fairy shrimp Siphonophanes grubii (Dybowski) (Crustacea, Anostraca): diversified bet-hedging strategy ?

Polyphenisms, as opposed to polymorphism, refers to coexistence of several distinct phenotypes having a common genotype. Polyphenism can be selected for in unpredictable environments. Here we document and anlyse a case of siphenism in the north-European fairy shrinp Siphonophanes grubii (Dybowski), in relation to the temporary and unpredictable nature of its habitat. The active part of this species'life cycle usually consists of a single, short-lived, spring cohort. Here we report field observations on autumnal hatching and on a long-lived, overwintering cohort; we show that the winter cohort runs the risk of total failure, due to the pond freezing entirely or drying up during winter. If, however, environmental conditions allow winter survival, animals reach a larger size, reproduce for a longer time, and display higher fecundity, than do animals from the spring cohort. Laboratory experiments support the theory that these differences are purely phenotypic and dependent on temperatur. Using an analytical model adapted from Cohen (1966), we propose that the coexistence of both a winter and a spring cohort in the same ponds can be interpreted as a diversified bet-hedging strategy.

Pathogen-induced hatching and population-specific life-history response to water-borne cues in brown trout (Salmo trutta)

Hatching is an important niche shift, and embryos in a wide range of taxa can either accelerate or delay this life-history switch in order to avoid stage-specific risks. Such behavior can occur in response to stress itself and to chemical cues that allow anticipation of stress. We studied the genetic organization of this phenotypic plasticity and tested whether there are differences among populations and across environments in order to learn more about the evolutionary potential of stress-induced hatching. As a study species, we chose the brown trout (Salmo trutta; Salmonidae). Gametes were collected from five natural populations (within one river network) and used for full-factorial in vitro fertilizations. The resulting embryos were either directly infected with Pseudomonas fluorescens or were exposed to waterborne cues from P. fluorescens-infected conspecifics. We found that direct inoculation with P. fluorescens increased embryonic mortality and induced hatching in all host populations. Exposure to waterborne cues revealed population-specific responses. We found significant additive genetic variation for hatching time, and genetic variation in trait plasticity. In conclusion, hatching is induced in response to infection and can be affected by waterborne cues of infection, but populations and families differ in their reaction to the latter.

Effect of an ectoparasite on lay date, nest-site choice, desertion, and hatching success in the great tit (Parus major)

Ectoparasites are common in most bird species, but experimental evidence of their effects on life-history traits is scarce. We investigated experimentally the effects of the hematophagous hen flea (Ceratophyllus gallinae) on timing of reproduction, nest-site choice, nest desertion, clutch size, and hatching success in the great tit (Parus major). When great tits were offered a choice on their territory between an infested and a parasite-free nest-box, they chose the one without parasites. When there was no choice, the great tits in a territory containing an infested nest-box delayed laying the clutch by 11 days as compared with the birds that were offered a parasite-free nesting opportunity. The finding that there was no difference in phenotypic traits related to dominance between the birds nesting in infested boxes and birds nesting in parasite-free boxes suggests that the delay is not imposed by social dominance. Nest desertion between laying and shortly after hatching was significandy higher in infested nests. There was no difference between infested and parasite-free nests in clutch size, but hatching success and hence brood size at hatching were significantly smaller in infested nests. Nest-box studies of great tits have been seminal in the development of evolutionary, ecological, and behavioral theory, but recently a polemic has arisen in the literature about the validity of the conclusions drawn from nest-box studies where the naturally occurring, detrimental ectoparasites are eliminated by the routine removal of old nests between breeding seasons. Our study suggests that this criticism is valid and that the evaluation of the effects of ectoparasites may improve our understanding of behavioral traits, life-history traits, or population dynamics

Pre-hatching maternal effects inhibit nestling humoral immune response in the tawny owl Strix aluco

Although evidence is accumulating that mothers can transfer antibodies to their offspring, little is known about the consequences of such a transfer to the offspring immune system. Because maternal antibodies are effective only during a short period of time after their transfer to offspring, one hypothesis is that maternal antibodies provides a transitory antigen-specific protection to offspring, thus lessening the need for offspring to mount their own humoral immune response towards these specific antigens. In birds, this scenario predicts that offspring immune response towards a specific antigen is inhibited to a larger extent in hatchlings than in older nestlings. We tested this hypothesis in tawny owls Strix aluco by cross-fostering clutches between nests and then challenging siblings with a vaccine either two times (at 4- and 11-d-old) or only one time at 11-d-old to compare the strength of the humoral response between nestlings born from mothers with naturally high and low levels of antibodies against this vaccine. Because maternal antibodies are expected to be effective only during a short period of time after hatching, we predict that maternal antibodies should inhibit the immune response of nestlings vaccinated from the fourth day after hatching more than in nestlings vaccinated only at a later age. As expected, the inhibitory effect of maternal antibodies was stronger in nestlings vaccinated soon after hatching than in siblings injected at a later age. Therefore, in wild avian populations pre-hatching maternal effects may confer offspring with a transitory immune protection in the first days following hatching.

Effects of hatching asynchrony on sibling negotiation, begging, jostling for position and within-brood food allocation in the barn owl Tyto alba

When siblings differ markedly in their need for food, they may benefit from signalling to each other their willingness to contest the next indivisible food item delivered by the parents. This sib-sib communication system, referred to as 'sibling negotiation', may allow them to adjust optimally to investment in begging. Using barn owl (Two alba) broods. I assessed the role of within-brood age hierarchy on sibling negotiation, and in turn on jostling for position where parents predictably deliver food (i.e. nest-box entrance), begging and within-brood food allocation. More specifically, I examined three predictions derived from a game-theoretical model of sibling negotiation where a senior and a junior sibling compete for food resources (Roulin, 2002a, Johnstone and Roulin, 2003): (1) begging effort invested by the senior sibling should be less sensitive to the junior sibling's negotiation than vice versa; (2) the junior should invest less effort in sibling negotiation than its senior sibling but a similar amount of effort in begging; and (3) within-brood food allocation should be directly related to begging but only indirectly to sibling negotiation. Two-chick broods were created and vocalization in the absence (negotiation signals directed to siblings) and presence (begging signals directed to parents) of parents was recorded. In support of the first prediction, juniors begged at a low cadence after their senior sibling negotiated intensely, probably because negotiation reflects prospective investment in begging and hence willingness to compete. In contrast, the begging of senior siblings was not sensitive to their junior sibling's negotiation. In contrast to the second prediction, juniors negotiated and begged more intensely than their senior sibling apparently because they were hungrier rather than younger. In line with the third prediction, juniors monopolized food delivered by their parents when their senior sibling begged at a low level. The begging cadence of both the junior and senior sibling, the junior's negotiation cadence, the difference in age between the two nest-mates and jostling for position were not associated with the likelihood of monopolizing food. In conclusion, sibling negotiation appears to influence begging behaviour, which, in turn, affects within-brood food allocation. Juniors may negotiate to challenge their senior siblings, and thereby determine whether seniors are less hungry before deciding to beg for food. In contrast, seniors may negotiate to deter juniors from begging.

Estimating the most important criteria for hatching eggs as function of broiler breeders age

This research aimed to compare two female broiler breeder ages during the incubation period regarding management using the Analytic Hierarchy Process method (AHP). This method is characterized by the possibility of analyzing a multicriteria problem and assists a decision making. This study was carried out on a commercial hatchery located in São Paulo, Brazil. Two ages of broiler breeder (42 and 56 weeks) were compared relative to production rate. Production index data were the same in both ages and were submitted to multicriteria decision analysis using the AHP method. The results indicate that broiler breeders of 42 weeks presented better performance than those of 56 week-old. The setter phase (incubation) is more critical than the hatcher. The AHP method was efficient for this analysis and can serve as a methodological basis for future studies to improve the hatchability of broilers eggs.