Entire Egg Research Articles

Effects of wheat inclusion and xylanase supplementation of the diet on productive performance, nutrient retention, and endogenous intestinal enzyme activity of laying hens

An experiment was conducted to study the effects of inclusion of a wheat cultivar (high in nonstarch polysaccharides) and xylanase supplementation of the diet on productive performance, pH of the gastrointestinal tract, nutrient retention, and intestinal enzyme activity of Hy-Line W-36 laying hens from 25 to 47 wk of age. The experiment was completely randomized with 8 treatments arranged factorially with 4 levels of wheat (0, 23, 46, and 69%) that corresponded to a dietary arabinoxylan content of 3.0, 3.3, 3.6, and 3.9%, with or without xylanase supplementation. Each treatment was replicated 5 times. For the entire experimental period, egg weight (P < 0.05) and egg mass (P < 0.01) were reduced and the feed conversion ratio was hindered (P < 0.05) with increased levels of wheat in the diet, but ADFI and egg production were not affected. Xylanase supplementation improved egg production (P < 0.05), egg mass (P < 0.01), and the feed conversion ratio (P < 0.01). Diet did not affect egg quality at any age, except for shell thickness at 47 wk that was improved with xylanase supplementation (P < 0.05). Digesta pH of the different organs of the gastrointestinal tract was not affected by wheat inclusion or xylanase supplementation. Ileal viscosity increased (P < 0.001) with wheat inclusion and decreased (P < 0.001) with xylanase supplementation at all ages. Fat digestibility (P < 0.001) decreased with increased levels of wheat but AMEn content of the diets (P < 0.05) and nitrogen retention were not affected. Wheat inclusion increased (P < 0.001) amylase (33 wk), lipase (33 wk), and aminopeptidase (47 wk) activity in the duodenum as well as lipase activity in the jejunum at 47 wk of age. However, xylanase supplementation did not affect the activity of any of the enzymes studied. It is concluded that most of the negative effects of wheat inclusion in the diet were reduced or even disappeared with xylanase supplementation. Wheat with a high nonstarch polysaccharide content (Pishtaz cultivar) can be used at levels of up to 69% in laying-hen diets without negatively affecting bird performance, provided that feeds are supplemented with xylanase.

Embryonic development of a whirligig beetle, Dineutus mellyi, with special reference to external morphology (insecta: Coleoptera, Gyrinidae)

The egg morphology and successive changes of developing embryos of the whirligig beetle, Dineutus mellyi (Adephaga: Gyrinidae) are described from observations based on light and scanning electron microscopy. The egg surface is characterized by minute conical projections covering the entire egg surface, a stalk-like micropylar projection at the anterior pole of the egg, and a longitudinal split line along which the chorion is cleaved during the middle embryonic stages. The germ band or embryo is formed on the ventral egg surface, and develops on the surface throughout the egg period; thus, the egg is a superficial type, as is the case in most coleopteran species. A pair of lateral tracheal gills (LTGs) of the first abdominal segment originates from appendage-like projections arising at the lateral side of pleuropodia, and the LTGs of the second to ninth abdominal segments are arranged in a row with that of the first segment. Therefore, LTGs are structures with serial homology. The paired dorsal tracheal gills (DTGs) of the ninth abdominal segment are formed on the regions just latero-dorsal to the LTGs of this segment. Regarding the pleuropodia as the structures being homologous with thoracic legs, neither the LTGs nor DTGs are homologous with thoracic legs, but originate in the more lateral region corresponding to the future pleura of the thoracic segments. The last (10th) abdominal segment in the larva is formed by the fusion of the embryonic 10th and 11th abdominal segments. Four terminal hooks at the end of the last abdominal segment originate from two pairs of swellings on the posterior end of the embryonic 11th abdominal segment. It is proposed that the terminal hooks possibly correspond to the claws of medially fused cerci of the embryonic 11th abdominal segment.

Optimizing Irradiation Treatment of Shell Eggs Using Simulation

Accurate dose calculation is needed to ensure proper irradiation process control to maintain the freshness of the product. Our objective was to establish the best irradiation treatment for shell eggs taking into account their different components (shell, albumen, yolk). Computer tomography (CT) data were used to generate a 3-D geometry to simulate dose distributions within 1 egg using a radiation transport code (MCNP5). Radiation energies used for simulation were 10 MeV (high-energy) and 1.35 MeV (low-energy) for electron beam, 5 MeV for X-rays, and 1.25 MeV for a gamma-rays source such as Co-60. Low-energy (surface) e-beam simulation indicated that electrons only penetrate up to the thin albumen (0.6 cm). Because of their irregular shape, shell eggs should be irradiated from the side (rather than from top or bottom) for better dose distribution. For high-energy e-beam simulation, the entire egg was irradiated and the best results were obtained when the egg was irradiated from both sides, showing a dose uniformity ratio (D(max)/D(min)) of 1.42. X- or gamma-ray source simulation from one side only, the dose uniformity ratio was 3.38 and 3.12, respectively. For surface-only irradiation, a low-energy e-beam provides a uniform dose distribution. To irradiate the entire egg, 2-sided high-energy e-beam sources are required for an efficient treatment. Unless the product rotates in front of the source, the dose uniformity ratio for X-ray or gamma ray is not adequate for shell egg treatment for pathogen decontamination purposes. Practical Application: Proper control of irradiation treatment of foods such as shell eggs is critical to ensure pathogen inactivation while maintaining product freshness. Simulation allows for accurate calculation of dose distribution within the egg to further establish the best irradiation scheme.

Influence of high environmental temperature on egg production and shell quality: a review

In spite of the large amounts of money invested in research, breeding, and the improvement of commercial egg-type strains, high environmental temperature (HET) has been identified as a major non-genetic constraint limiting expression of their full genetic potential. This environmental stressor has been implicated in adverse marked effects on egg production and eggshell quality of hens. Reports have conclusively indicated that poor performance (i.e. drop in egg production and poor eggshell quality) of layers reared in thermally-stressed environments could be adduced to a complex interplay of low feed intake, malfunctioning of the endocrine system, acid-base imbalance and poor physiological functioning of organs and mechanisms connected with the entire egg production process, via follicular recruitment and growth, ovulation, egg formation, shell formation, egg development, oviposition and oviposition interval.

Validation of a Noninvasive Technique for Estimating Fecundity in the American LobsterHomarus americanus

ABSTRACT We investigated a noninvasive sampling technique that estimates fecundity for ovigerous American lobster based on field measurement and live release. These estimates were compared with fecundity estimates obtained from the widely used traditional invasive technique involving the removal, drying, and weighing of the entire egg mass. The noninvasive technique, which requires the removal of only 10 eggs per female, produced fecundity estimates that were within 4% of those obtained using the traditional invasive method. Applications of this technique may be carried out in an experimental setting where the effects of conservation measures such as v-notching or the establishment of closed areas, aimed at increasing egg production, can be quantified without the use of destructive sampling techniques.

Mutual regulatory interactions of the trunk gap genes during blastoderm patterning in the hemipteran Oncopeltus fasciatus

The early embryo of the milkweed bug, Oncopeltus fasciatus, appears as a single cell layer – the embryonic blastoderm – covering the entire egg. It is at this blastoderm stage that morphological domains are first determined, long before the appearance of overt segmentation. Central to the process of patterning the blastoderm into distinct domains are a group of transcription factors known as gap genes. In Drosophila melanogaster these genes form a network of interactions, and maintain sharp expression boundaries through strong mutual repression. Their restricted expression domains define specific areas along the entire body. We have studied the expression domains of the four trunk gap gene homologues in O. fasciatus and have determined their interactions through dsRNA gene knockdown experiments, followed by expression analyses. While the blastoderm in O. fasciatus includes only the first six segments of the embryo, the expression domains of the gap genes within these segments are broadly similar to those in Drosophila where the blastoderm includes all 15 segments. However, the interactions between the gap genes are surprisingly different from those in Drosophila, and mutual repression between the genes seems to play a much less significant role. This suggests that the well-studied interaction pattern in Drosophila is evolutionarily derived, and has evolved from a less strongly interacting network.

Pattern Recognition and Gestalt Psychology: The Day Nüsslein‐Volhard Shouted “Toll!”

Pattern Recognition and Gestalt Psychology: The Day Nüsslein‐Volhard Shouted “Toll!”

Evolution of an anterior morphogenetic center in long germ insects

Plenary session I: Developmental Biology Symposium: Evolution of developmental regulatory systems Program/Abstract # 25 Evolution of an anterior morphogenetic center in long germ insects Claude Desplan, Ava Brent, Eugenia Olesnicky, Miriam Rosenberg, Claude Desplan Department of Biology, NYU, New York, NY, USA In the derived long-germ mode of insect development, the embryo occupies the entire egg and all segments form simultaneously in a syncytial environment. In Drosophila, this patterning is mediated by a gradient of Bicoid protein but this is a new invention of higher Diptera. We analyzed axis formation in Nasonia, a wasp (Hymenoptera) that has developed long germ independently from higher Diptera. Like bicoid in Drosophila, Nasonia orthodenticle (Nv-otd1) maternal mRNA is localized at the anterior of the eggwhere it generates amorphogenetic gradient. It is also localized at the posterior where it induces the expression of posterior genes much earlier than in short germ insects, where their expression is delayed to the growth zone. mRNA localization in Nasonia also mediates permissive functions achieved by Bicoid in flies: caudal mRNA is posteriorly localized to restrict its function to posterior segments. In Drosophila, this is achieved by translational regulation of caudal mRNA by Bicoid. giant mRNA is localized, anteriorly, where it represses mid-body genes such as Kruppel. This repression thus occurs early in spite of the much slower early Nasonia developmental timing that would not allow zygotic Giant to be expressed early enough to repressKruppel. Therefore, the network ofNasonia developmental genes is made of very similar genes to flies, and these exhibit similar crossinteractions. However, the network has been modified in Nasonia and relies on localized maternal genes to accommodate developmental changes such as the absence of bicoid, the slowermode of development, or the long germ mode of embryogenesis. doi:10.1016/j.ydbio.2009.05.033 Program/Abstract # 26 How many ways to make a chordate: Comparison of the developmental programs of ascidians and vertebrates Daniel Sobral, Andrea Pasini, Patrick Lemaire IBDML, CNRS-Universite de la Mediterranee, Marseille, France Tunicates, including ascidians are the closest living relatives of vertebrates, with whom they share a tadpole-like larval form. At the morphological and embryological level, however, vertebrates share structures and processes that have been lost in ascidians. For example, tail extension in ascidians relies on cell rearrangements and intercalation, rather than on the growth of a tailbud as in vertebrates. More generally, the ascidian stereotyped embryogenesis departs from that of vertebrates, as it is based on invariant cell lineages. We are trying to understand how chordates can form similar tadpole-like larvae in spite of apparently different developmental strategies. We have addressed this question by quantifying the extent of divergence of gene expression profiles between orthologs from Ciona intestinalis and the teleost fishDanio rerio.We found a surprisingly high level of divergence at all stages, including the phylotypic stage. This extent of divergence was similar for developmental regulators and their effectors, but differed between tissues. The muscle program was best conserved in spite of the lack of somites in Ciona. Surprisingly, we found that a complex genetic program similar to that found in vertebrates to regulate the formation of successive somites acts along the ascidian tail, where it has been recruited for A/P epidermal patterning. doi:10.1016/j.ydbio.2009.05.034 Program/Abstract # 27 Diversity of X-chromosome inactivation patterns during early mammalian development Ikuhiro Okamoto, Veronique Duranthon, Dominique Thepot, Nathalie Peynot, Jean Paul Renard, Edith Heard Mammalian Developmental Epigenetics Group, Institut Curie, CNRS UMR3215, INSERM U934, 26 rue d'Ulm, Paris 75005, France Biologie du Developpement et de la Reproduction, INRA 78 352 Jouy en

Conserved properties of a urochordate estrogen receptor-related receptor (ERR) with mammalian ERRalpha

Estrogen receptor-related receptors (ERRs) were the first orphan nuclear receptors identified on the basis of their sequence similarity to the estrogen receptors. Although unique ERRs were found in some marine invertebrates, the molecular functions of these receptors are not well understood. In the present study, we identified three transcript variants of the tunicate Halocynthia roretzi ERR (Hr-ERR), varying in their 3' untranslated regions, and putatively encoding a unique receptor deriving from an ancestor protein common to vertebrate ERRalpha/beta/gamma. Maternal mRNA of Hr-ERR was detected throughout the entire egg cytoplasm and early embryos. Zygotic Hr-ERR was predominantly expressed in the heart, and at lower levels in muscle, stomach, gonad and digestive glands. Electrophoretic mobility shift assay demonstrated that Hr-ERR directly binds to the estrogen-response element (ERE) and ERR-response element (ERRE). Gene reporter assays also showed that Hr-ERR activates transcription through ERE and ERRE. Hr-ERR-mediated transactivation was modulated by various cofactors for mammalian ERRs, such as peroxisome proliferator-activated receptor gamma coactivator 1-alpha and small heterodimer partner. In addition, the ERR antagonists 4-hydroxytamoxifen and diethylstilbestrol inhibited the Hr-ERR-mediated transactivation, whereas Hr-ERR activity on ERE was further induced by genistein, an ERRalpha agonist. Taken together, our results show that Hr-ERR is an unduplicated ERR that however, possesses functional properties common to ERRalpha and not to ERRbeta/gamma.

Hospicidal Behavior of the Cleptoparasitic Bee Coelioxys (Allocoelioxys) coturnix, Including Descriptions of Its Larval Instars (Hymenoptera: Megachilidae)

Abstract In an attempt to determine whether Coelioxys and Radoszkowskiana, both cleptoparasitic members of the Megachilini, had a common cleptoparasitic ancestor, an investigation of the nesting biology and immature stages of C. (Allocoelioxys) coturnix Perez was undertaken in Egypt. The purpose was to compare these aspects of this species with the results of a recent study of R. rufiventris (Spinola) and certain other species of Coelioxys (Rozen and Kamel, 2007). The egg of C. coturnix is deposited on the egg of Megachile minutissima Radoszkowski after the host female departs to collect cell-closure material. On hatching, the first instar, still surrounded by egg chorion, bites the developing host egg and consumes the entire egg content before feeding upon the host provisions. This behavior contrasts with certain other species of Coelioxys, whose eggs are hidden in the host cell while it is being provisioned and third instars normally kill the young host larvae. Because the behavior of C. coturnix closel...

The Drosophila caspases Strica and Dronc function redundantly in programmed cell death during oogenesis

Programmed cell death (PCD) in the Drosophila ovary occurs either during mid-oogenesis, resulting in degeneration of the entire egg chamber or during late oogenesis, to facilitate the development of the oocyte. PCD during oogenesis is regulated by mechanisms different from those that control cell death in other Drosophila tissues. We have analyzed the role of caspases in PCD of the female germline by examining caspase mutants and overexpressing caspase inhibitors. Imprecise P-element excision was used to generate mutants of the initiator caspase strica. While null mutants of strica or another initiator caspase, dronc, display no ovary phenotype, we find that strica exhibits redundancy with dronc, during both mid- and late oogenesis. Ovaries of double mutants contain defective mid-stage egg chambers similar to those reported previously in dcp-1 mutants, and mature egg chambers with persisting nurse cell nuclei. In addition, the effector caspases drice and dcp-1 also display redundant functions during late oogenesis, resulting in persisting nurse cell nuclei. These findings indicate that caspases are required for nurse cell death during mid-oogenesis, and participate in developmental nurse cell death during late oogenesis. This reveals a novel pathway of cell death in the ovary that utilizes strica, dronc, dcp-1 and drice, and importantly illustrates strong redundancy among the caspases.

Changes in numbers of large ovarian follicles, plasma luteinizing hormone and estradiol-17β concentrations and egg production figures in farmed ostriches throughout the year

In this study we described and analysed changes in the numbers of large ovarian follicles (diameter 6.1–9.0 cm) and in the plasma concentrations of luteinizing hormone (LH) and estradiol-17β (E 2β) in relation to individual egg production figures of farmed ostriches ( Struthio camelus spp.) throughout one year. Ultrasound scanning and blood sampling for plasma hormone analysis were performed in 9 hens on a monthly basis during the breeding season and in two periods of the non-breeding season. Our data demonstrated that: (1) large follicles were detected and LH concentrations were elevated already 1 month before first ovipositions of the egg production season took place; (2) E 2β concentrations increased as soon as the egg production season started; (3) numbers of large follicles, LH and E 2β concentrations were elevated during the entire egg production season; and that (4) numbers of large follicles, LH and E 2β concentrations decreased simultaneous with or following the last ovipositions of the egg production season. By comparing these parameters during the egg production season with their pre-and post-seasonal values, significant differences were found in the numbers of large follicles and E 2β concentrations between the pre-seasonal, seasonal and post-seasonal period; while LH concentrations were significantly different between the seasonal and post-seasonal period. In conclusion, our data demonstrate that changes in numbers of large follicles and in concentrations of LH and E 2β closely parallel individual egg production figures and provide some new cues that egg production in ostriches is confined to a marked reproductive season. Moreover, our data provide indications that mechanism, initiating, maintaining and terminating the egg production season in farmed breeding ostriches are quite similar to those already known for other seasonal breeding bird species.

Measuring egg size using digital photography: testing Hoyt's method using Florida Scrub-Jay eggs

Egg volumes are most often estimated using a mathematical model that incorporates length and width measurements and a species-specific shape variable. Although adequate in many respects, this technique does not account for intraspecific variation in egg shape. We developed a computer-automated technique that uses calibrated digital photographs to render precise measurements of several egg-size parameters including length, width, volume, and surface area. The system extracts egg outlines from photographs, and divides each egg into latitudinal slices that are subsequently regarded as simple geometric shapes (cylinders or cone frustra) with volumes and surface areas that can be summed to generate size parameters for the entire egg. We tested this technique using 491 eggs from Florida Scrub-Jay (Aphelocoma coerulescens) nests and compared the resulting egg volumes with volumes calculated using the preeminent method of estimating volume from linear measurements. Our method was highly accurate, and differences between the volumes from our method and the alternative method were strongly associated with variation in egg shape. Advantages of our technique include decreased handling of eggs and increased accuracy. Software resources and additional information regarding the technique are available at http://www.archbold-station.org/abs/data/birddata/Bridge-JFO-eggsize.htm. SINOPSIS. Medidas de huevos utilizando fotograf´ ia digital: poniendo a pruebas el m´ etodo

Dogfish egg case structural studies by ATR FT-IR and FT-Raman spectroscopy

The dogfish egg case is a composite structure that combines mechanical tensile strength, toughness and elasticity with high permeability to small molecules and ions. Presumably, it provides both a protective and a filtering role for the egg/embryo contained within it. In this work, we performed structural studies of the Galeus melastomus egg case at two different stages of the hardening process, utilizing ATR FT-IR and FT-Raman spectroscopy. Based on these data we deduce that: (a) The G. melastomus egg case, in close analogy to that of the related species Scyliorhinus cunicula, is a complex, composite structure which consists mainly of an analogue of collagen IV. This network forming protein appears to have common secondary structural characteristics in the entire egg case. (b) The outermost layer of the non-sclerotized egg case is especially rich in tyrosine, while the innermost layer is rich in polysaccharides, presumably glycosaminoglycans, and lipids. These differences are diminished upon hardening. (c) Disulfide bonds do not appear to play a significant role in cross-linking. However, cross-links involving tyrosine residues appear to sclerotize the egg case. It is proposed that the intensity of the Raman band at ca. 1615 cm −1, which is due to ring stretching vibrations of Tyr, might be a useful indicator of the sclerotization status of a certain proteinaceous tissue, when tyrosines are involved in sclerotization mechanisms.

Fertilization triggers localized activation of Src-family protein kinases in the zebrafish egg

Fertilization triggers activation of Src-family kinases in eggs of various species including marine invertebrates and lower vertebrates. While immunofluorescence studies have localized Src-family kinases to the plasma membrane or cortical cytoplasm, no information is available regarding the extent to which these kinases are activated in different regions of the zygote. The objective of the present study was to detect the subcellular distribution of activated Src-family kinases in the fertilized zebrafish egg. An antibody specific for the active, non-phosphorylated form of Src-family PTKs was used to detect these activated kinases by immunofluorescence. The results demonstrate that Fyn, and possibly other Src family members are activated by dephosphorylation of the C-terminal tyrosine at fertilization. The activated Src-family kinases are asymmetrically distributed around the egg cortex with an area of higher kinase activity localized adjacent to the micropyle near the presumptive animal pole. Fertilization initially caused elevation of kinase activity in the cytoplasm underlying the micropyle, but this quickly spread to involve the entire zygote cortex. Later, during egg activation, formation of the blastodisc involved concentration of active Src-family kinase in the blastodisc cortex. As cytokinesis began, activated Src-family kinases were no longer limited to the cortex, but became more evenly distributed in the clear apical cytoplasm of the blastomeres. The results demonstrate that the cortex of the zebrafish egg is functionally differentiated and that fertilization triggers localized activation of Src-family kinases at the point of sperm entry, which subsequently progresses through the entire egg cortex.

Phylogenetic diversity of epibiotic bacteria in the accessory nidamental glands of squids (Cephalopoda: Loliginidae and Idiosepiidae)

Bacterial communities were identified from the accessory nidamental glands (ANGs) of European and Western Pacific squids of the families Loliginidae and Idiosepiidae, as also in the egg capsules, embryo and yolk of two loliginid squid species, and in the entire egg of one idiosepiid squid species. The results of phylogenetic analyses of 16S RNA gene (rDNA) confirmed that several phylotypes of α-proteobacteria, γ-proteobacteria and Cytophaga–Flavobacteria–Bacteroides phylum were present as potential symbiotic associations within the ANGs. Several identified clones were related to reference strains, while others had no known close relatives. Gram positive strains were rare in loliginid squids. Several bacterial groups may play important roles in the function of the ANGs, such as production of the toxic compounds involved in egg protection and carotenoid pigments. Within the eggs, no bacteria were associated with embryo or yolk of Loligo vulgaris and Sepioteuthis lessoniana, but α- and γ-proteobacteria were present in the egg capsules. Most bacterial strains detected in the egg capsules were the same as those found in the ANGs. The cephalopods of temperate regions (European cuttlefishes and the squid L. vulgaris) appear to be associated with one Agrobacterium strain (Agro2) while tropical-subtropical strains (Asian and Australian loliginids) are associated with Silicibacter-related strains, suggesting a biogeographic clustering for the Agrobacterium-like strains.

A Pair of Shelled Eggs Inside A Female Dinosaur

An oviraptosaurian specimen (Dinosauria, Theropoda) from an Upper Cretaceous formation in China retains a pair of shelled eggs in the pelvis, providing direct evidence that oviraptorosaurian dinosaurs laid paired elongatoolithid eggs. The presence of the paired eggs suggests that theropod dinosaurs had two functional oviducts (like crocodiles) but that each oviduct produced only one egg at a time and that an entire egg clutch was laid through multiple ovipositions (like birds). The orientations of the eggs inside the skeleton and in clutches indicate that the mother came to the center of the nest to lay eggs.

Phylogenetics of Eggshell Morphogenesis in Antheraea (Lepidoptera: Saturniidae): Unique Origin and Repeated Reduction of the Aeropyle Crown

Integrated phylogenetic and developmental analyses should enhance our understanding of morphological evolution and thereby improve systematists' ability to utilize morphological characters, but case studies are few. The eggshell (chorion) of Lepidoptera (Insecta) has proven especially tractable experimentally for such analyses because its morphogenesis proceeds by extracellular assembly of proteins. This study focuses on a morphological novelty, the aeropyle crown, that arises at the end of choriogenesis in the wild silkmoth genus Antheraea. Aeropyle crowns are cylindrical projections, ending in prominent prongs, that surround the openings of breathing tubes (aeropyle channels) traversing the chorion. They occur over the entire egg surface in some species, are localized to a circumferential band in many others, and in some are missing entirely, thus exhibiting variation typical of discrete characters analyzed in morphological phylogenetics. Seeking an integrated developmental-phylogenetic view, we first survey aeropyle crown variation broadly across Antheraea and related genera. We then map these observations onto a robust phylogeny, based on three nuclear genes, to test the adequacy of character codings for aeropyle crown variation and to estimate the frequency and direction of change in those characters. Thirdly, we draw on previous studies of choriogenesis, supplemented by new data on gene expression, to hypothesize developmental-genetic bases for the inferred chorion character transformations. Aeropyle crowns are inferred to arise just once, in the ancestor of Antheraea, but to undergo four or more subsequent reductions without regain, a pattern consistent with Dollo's Law. Spatial distribution shows an analogous trend, though less clear-cut, toward reduction of coverage by aeropyle crowns. These trends suggest either that there is little or no natural selection on the details of the aeropyle crown structure or that evolution toward functional optima is ongoing, although no direct evidence exists for either. Genetic, biochemical, and microscopy studies point to at least two developmental changes underlying the origin of the aeropyle crown, namely, reinitiation of deposition of chorionic lamellae after the end of normal choriogenesis (i.e., heterochrony), and sharply increased production of underlying "filler" proteins that push the nascent final lamellae upward to form the crown (i.e., heteroposy). Identification of a unique putative cis-regulatory element shared by unrelated genes involved in aeropyle crown formation suggests a possible simple mechanism for repeated evolutionary reduction and spatial restriction of aeropyle crowns.

Sand Seals in Coho Salmon Redds: Do They Improve Egg Survival?

AbstractWe investigated whether sand seals form in the upper egg pocket of salmonid redds and improve egg survival in a sediment‐impacted coastal stream in northern California. Sand seals can potentially reduce infiltration of detrimental finer sand and silt into the lower egg pocket. We predicted sand seals would form when the redds were exposed to streamflows high enough to entrain coarse sand and form seals. Using artificial redds of coho salmon Oncorhynchus kisutch, we conducted sediment analyses of the upper and lower egg pockets and found that protective sand seals formed in redds when discharge was two or more times the flow that entrains the median particle size of the streambed. When the coarse sand in the upper egg pocket was incorporated into a two‐stage model that predicted survival to hatching and emergence, it greatly improved predictions in years with higher flows in both natural and artificial redds. However, the sand seals provided little protection when suspended sediment flux was high from logging or road construction. We built the model used for these predictions with data from artificial redds and applied it to natural redds during 6 years of different flow regimes. Predictor variables included cumulative flow above the entrainment flow, peak discharge, coarse sand in the upper egg pocket, fine sediment in riffle gravel, coarse sand in the upper and entire egg pocket, suspended sediment flux, and presence of predaceous worms. The model explained 67% of the variance in egg survival to emergence in coho salmon natural redds. We suggest that managers consider the complex interactions of streamflow, sediment transport, formation of sand seals, and fine‐sediment infiltration when estimating salmonid reproductive success in sediment‐impacted streams.

Identification and isolation of boar sperm specific antigens with potential role in sperm–egg interaction

Investigations on specific and functionally active sperm antigens would bring about the elucidation of the mechanisms of gamete interaction and help the search to new approaches for prognosis and regulation of fertility. Previously, we have produced a polyclonal rabbit anti-boar spermatozoa antibody (RABSA) that might affect the fertilizing capacity of boar spermatozoa. The sperm specificity of RABSA was demonstrated by double immunodiffusion, immunoelectrophoresis and ELISA against boar spermatozoa, as well as against saline extracts of boar reproductive and somatic organs. Using indirect immunofluorescence (IIF) test, here we provide evidence that RABSA stained the acrosomes of ejaculated and capacitated boar and human spermatozoa, the fluorescence being intensified on the equatorial region after the acrosome reaction. The RABSA cognate antigen/s is a subject of interest because of their specific localization in sperm structures, which is shown to be a binding and/or fusion competence region. Using ion-exchange (Heparin–Sepharose) chromatography, we eluted an antigen with molecular mass 60 kDa (Ag60) in SDS–PAGE from NP40 extracts of capacitated boar spermatozoa. In Western blot, RABSA recognized specifically this antigen. The Ag60 did not affect the sperm–ligand activity of zona pellucida in a porcine sperm–zona binding assay. IIF experiments showed that zona-free porcine oocytes preincubated with Ag60 and RABSA presented fluorescent labeling over the entire egg surface. The biological and IIF experiments provide evidence supporting the involvement of Ag60 in functional steps required for sperm–egg binding and/or fusion, but not sperm–zona pellucida binding.