bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ascidian sperm penetration and the translocation of a cell surface glycosidase
Authors: Lambert Charles C. 
Published: June 2005

AbstractSperm bind to vitelline coat (VC) glycosides of ascidian eggs by means of a sperm surface glycosidase (Hoshi et al.: Zool Sci 2:65, 1985). In the genus Ascidia, N‐acetylglucosamine (NAG) is the VC ligand. After initial binding by the tip of the head, sperm pass through the VC and perivitelline space leaving the single mitochondrion outside. This process can also be followed in vitro on a coverslip. Analysis of recorded video images shows that the sperm moves away from the anchored mitochondrion. Our model for sperm penetration suggests that mitochondrial translocation is responsible for driving the sperm into the egg. In the work presented here, we have demonstrated that ascidian sperm have N‐acetyl‐β‐D‐glucosaminidase (NAGase) activity with an acidic pH optimum. This enzyme, which can be removed from the sperm with Triton X‐100, binds to concanavalin A, demonstrating that it is glycosylated. Histochemical methods disclose that the enzyme is originally located at the tip of the head but subsequently remains with the surface overlying the mitochondrion during translocation. Fluorescent Con A was used as a second label for localization of the enzyme on the cell surface during translocation. Colocalization of both probes of the enzyme support a crucial facet of our model; the sperm surface VC binding site remains over the mitochondrion during translocation. This would couple mitochondrial translocation with sperm penetration and drive the sperm into the egg.
Seasonality of serum testosterone levels and sperm density in Tursiops truncatus
Authors: Schroeder J. Pete , Keller Karl V. 
Published: June 2005

AbstractWe trained a mature male bottlenose dolphin, Tursiops truncatus, to provide semen samples on command. After completion of the 10‐week training period, semen was collected twice weekly and blood was sampled twice monthly for a period of 28 months. Total sperm per ejaculate ranged from near 0 to 54.6 × 109 (n = 1332). Sperm densities from each session ranged from no sperm to 1,587 × 106/ml (n = 241). Testosterone levels ranged from 1.1 to 54.4 ng/ml (n = 79). Seasonal variations were observed in total sperm per ejaculate, sperm density per ml of ejaculate, and in serum testosterone levels. Peak sperm densities were detected during September and October of three consecutive breeding seasons. Serum testosterone levels peaked in June, decreased during July and August, and were lowest in September and October, the period of greatest sperm density. Peak sperm production and density were coincident with the peak period of breeding activity but at a time when serum testosterone levels were lowest.
Chloride‐type cells in the skin of the metamorphosing bonefish (Albula sp.) leptocephalus
Authors: Pfeiler Edward , Lindley Virginia 
Published: June 2005

AbstractThe skin of metamorphosing bonefish (Albula sp.) larvae (leptocephali) was examined using both scanning (SEM) and transmission electron microscopy (TEM). SEM revealed that surface epithelial cells of larvae that were just entering the metamorphic phase possessed numerous ridges and that epithelial pores occurred randomly at cell junctions. The pores were very similar to those seen in gill tissue of adult marine teleost fishes where they have been shown to represent the apical crypts of chloride cells. TEM confirmed the presence of chloride‐type cells in the epidermis of early metamorphosing larvae that contained both numerous mitochondria and an extensive system of tubules that appeared to be derived from the plasma membrane. SEM of intermediate and advanced metamorphosing larvae showed that the ridged epithelial cells tended to be more disorganized and were possibly degenerating but that epithelial pores were still evident. TEM of the skin of early metamorphosing larvae also showed a loosely organized internal structure in some of the epithelial cells. The ultrastructure of the skin is discussed in terms of the morphological and physiological changes that take place during metamorphosis.
Effects of salts in promoting the adhesion of amphibian gastrula cells
Authors: Komazaki Shinji 
Published: June 2005

AbstractPresumptive ectodermal and endodermal cells were isolated from the gastrula of the newt Cynops pyrrhogaster, and the effects of salts on embryonic cell adhesion were examined. When the concentrations of NaCl, KCl, MgSO4 and Ca (NO3)2 in the culture medium were increased individually, they all effectively promoted ectodermal cell adhesion. MgSO4 and Ca(NO3)2 promoted endodermal cell adhesion, but NaCl and KCl did not. The culture medium containing increased NaCl (90 mM) nonspecifically promoted ectodermal cell adhesion to the four substrata studied—polystyrene dish, glass, collagen, and fibronectin. The effects of drugs that influence the membrane permeability of Na+ and Ca2+ and the replacement of Na+, Cl−, and Ca2+ with other ions were studied. The results show that the flow of Na+ and Ca2+ into the cytoplasm promotes ectodermal cell adhesion but exerts no influence on endodermal cell adhesion.
Pattern of hemipenis use in the male lizard Anolis sagrei after unilateral castration
Authors: Tokarz Richard R. 
Published: June 2005

AbstractThis study investigated whether sensory feedback from the testis and sperm duct determines the pattern of hemipenis use in male A. sagrei. Males were unilaterally castrated and observed in copulations that began 2 wk after surgery. Independent of whether the left or right testis had been removed, unilaterally castrated males showed no significant difference in the frequency of use of either the left or right hemipenis in either of two copulations separated by 1–3 h or in a series of 16 copulations over 16 days. Thus, males did not preferentially use the hemipenis leading to the intact testis. Moreover, unilaterally castrated males showed significant alternation in the use of the hemipenes, not only in the two successive copulations, but also in the series of 16 copulations. The mass of the sperm ducts differed significantly after the last of the copulations. The mass of ducts that led to a testis was significantly greater than that of ducts not leading to a testis. These findings suggest that the pattern of alternation of hemipenis use in male A. sagrei is not determined by sensory input from either the testis or the sperm duct.
Integumentary uptake of short‐chain carboxylic acids by two freshwater oligochaetes, Tubifex tubifex and Lumbriculus variegatus: Specificity of uptake and characterization of transport carrier
Authors: Sedlmeier Ulrich A. , Hoffmann Klaus H. 
Published: June 2005

AbstractThe freshwater oligochaete Tubifex tubifex can take up considerable amounts of dissolved organic material (DOM) from ambient water (Hipp et al. J. Exp. Zool. 1986; 240:289–297). This paper describes evidence that the uptake system is located in the body wall. The system preferentially transports unsubstituted aliphatic monocarboxylic acids with chain lengths of two and three carbons. The proteinaceous nature of the monocarboxylate “carrier” is suggested by results from studies with covalent inhibitors [α‐cyano‐4‐hydroxycinnamate; para‐chlormercuri‐phenyl‐sulfonic acid (PCMBS)] and by the temperature dependence of transport. The characteristics of the uptake system are similar to those of the systems for transporting monocarboxylic acids in mammals. In another freshwater oligochaete, Lumbriculus variegatus, the rates of uptake of DOM were low and no evidence for a mediated transport system was found.
Properties of the muscle and heart lactate dehydrogenases of the New Zealand hagfish, Eptatretus cirrhatus: Functional and evolutionary implications
Authors: Baldwin J. , Davison W. , Forster M. E. 
Published: June 2005

AbstractHagfish possess two lactate dehydrogenase (LDH) subunit types that combine to form only the two homotetramers LDHA4 and LDHB4. Similarities in the kinetic properties of these isozymes from Myxine glutinosa have been attributed to the anaerobic nature of the hagfish heart and the failure of LDHB4 to diverge in function since the ancient A‐B gene duplication. The LDHA4 and LDHB4 isozymes purified from the New Zealand hagfish Eptatretus cirrhatus display more divergent properties which are consistent with the more efficient oxygen delivery system and aerobic lifestyle of this species. This, together with recent reinterpretations of LDH subunit evolution, leads to the conclusion that the unusual properties of hagfish LDH isozymes can be attributed to metabolic adaptation rather than to the conservation of features present in the ancestral LDH of vertebrates.
Transferrin, alpha‐fetoprotein, and albumin in plasma of quail‐chick chimeras during embryonic development
Authors: Martin B. , Denoulet P. 
Published: June 2005

AbstractHeterospecific chimeras obtained by blastoderm recombination between 36h quail embryos and chick yolk sacs were used as an in ovo model to determine the respective contribution of yolk sac and embryo in plasma protein during development. Analysis of quail and chick embryo plasma proteins by 2D‐PAGE and peptide mapping showed that it was possible to readily distinguish both albumin and transferrin from these two avian species. No distinction could be established between chick and quail alpha‐fetoprotein using these criteria. The presence of quail‐ and chick‐type albumin and transferrin was then assayed in chimera blood at two stages of embryonic development. We show that transferrin and albumin of both avian species are found at 7 and 12 days of incubation. This result obtained in ovo suggest that both yolk sac (chick) and embryo (quail) contribute, at least, to albumin and transferrin synthesis during development.
Regeneration of the foreleg tibia and tarsi of Ephippiger ephippiger (Orthoptera: Tettigoniidae)
Authors: Lakes Reinhard , Mücke Alfred 
Published: June 2005

AbstractThe regenerative power of Ephippiger ephippiger (Tettigoniidae) after the experimental removal at hatching of both tibia and tarsi of the foreleg was investigated. The lost leg parts were successively regenerated with increasing degrees of morphological differentiation. This process has an effect on the postembryonic development because, subsequently, the first larval stage is prolonged. In adults, the regenerated limb is one‐quarter of the length of normal tibia and tarsi together, but it often has the gross morphology of a normal leg. The pattern of innervation and the distribution of receptor is completely changed, and the complex tibial organ is not reformed. The tympanic nerve is missing, and the axons of the regenerated receptor cells form new nerves that join the leg nerve.Physiological recordings of acoustic‐vibratory, ventral nerve cord neurons revealed the possibility of excitatory input from the contralateral, intact acoustic receptors. However, the magnitude of the response is not fully restored. Behavioral experiments showed that the operated animals are not able to compensate for the unilateral deprivation of sensory input and fail in localization of the conspecific song.
Mating‐induced release of granules by the endocrine dorsal body cells of the snail Helisoma duryi (Mollusca)
Authors: Saleuddin A. S. M. , Ashton Mary Lou , Khan Hamid R. 
Published: June 2005

AbstractThe hermaphrodite snail Helisoma duryi reproduces preferentially by cross‐fertilization. Virgin and castrated snails lay an insignificant number of egg masses. The fine structure of its endocrine dorsal bodies (DB), which regulate reproduction, has been studied in reproductively inactive virgin and castrated snails and in reproductively active mated snails, using tannic acid staining and autoradiography after injection of [3H]leucine. The DB cells of the mated snails appear synthetically active, containing scattered rough endoplasmic reticulum (RER) and probably smooth endoplasmic reticulum (SER), many Golgi complexes, and putative DB hormone‐containing granules. On the other hand, the DB cells of the virgin and castrated snails appear synthetically inactive, containing RER in circular stacks, few Golgi complexes, many lipid droplets, and scattered glycogen. Mitochondria appear slender in mated snails, whereas those in virgin and castrated snails appear large and spherical. With tannic acid treatment, the processes of the DB cells of mated snails exhibited more released granules than those of virgin and castrated snails. Many silver grains were seen on RER, Golgi complexes, and mitochondria in the autoradiographs of the DB cells of mated snails. It is suggested that the DB cells of the reproductively active snails are synthetically more active than those in virgin and castrated snails and that the DB cells may produce peptide hormone as well as a steroid hormone.
Daily variation in maternal and fetal weight gain in mice and hamsters
Authors: Davis Fred C. 
Published: June 2005

AbstractDaily variation in maternal and fetal weight gain was measured in hamsters (Mesocricetus auratus) and in mice (Mus musculus, C57Bl) with free access to food or under restricted feeding schedules. Pregnant hamsters with free access to food and water were weighed twice a day and fetuses were collected twice a day from 10.5 to 14.5 days after fertilization. In three experiments, pregnant mice were given free access to food and water or were allowed food for 12 hours a day or for 6 hours a day. Pregnant mice were weighed twice a day and in the restricted feeding experiments, fetuses were collected every 6 hours from 12.0 to 14.5 days after fertilization. Pregnant mice and hamsters with free access to food showed a daily rhythm in weight gain with greater gain at night. There was no evidence of a daily rhythm in the weight gain of hamster fetuses. Mouse fetuses showed greater weight gain during two 6‐hour intervals each day, the second half of each night and the second half of each day. The 12‐hour variation was seen in both wet and dry fetal weight. A 24‐hour rhythm in fetal growth was previously described in rats (Barr: Teratology, 7:283–288, 1973). Results in rats and mice indicate that fetal growth is modulated on a daily basis. The different periodicity observed in rats and mice might be related to the different ages of the fetuses examined.
Pineal sensitivity to nighttime swimming stress changes during the active season in Richardson's ground squirrels (Spermophilus richardsonii)
Authors: Tannenbaum Michael G. , Reiter Russel J. , Hurlbut Edward C. , Vaughan Mary K. , Gonzalez‐Brito Aldo , Troiani Maureen E. 
Published: June 2005

AbstractMelatonin synthesis in the pineal gland, which is primarily regulated by the environmental lighting regime, can also be influenced by other factors that elicit modifications in sympathetic tone. The objectives of this study were to determine if forced swimming alters the normal pattern of melatonin production in the pineal gland of the Richardson's ground squirrel (Spermophilus richardsonii). In early June, the squirrels were forced to swim for 10 min during the photophase or during the scotophase. In mid‐July squirrels swam only during the scotophase. Animals were sacrificed 15, 30, or 60 min after the onset of swimming. Activities of pineal N‐acetyltransferase (NAT) and hydroxyindole‐O‐methyltransferase (HIOMT) were assessed by radioenzyme assay, and pineal melatonin content was measured by radioimmunoassay. Daytime swimming elicited no major changes in enzyme activity or pineal melatonin. In June, swimming at night prevented the normal rises in NAT activity and pineal melatonin seen in nonswimming controls. In contrast, the pineals of squirrels that were tested 6 weeks later in mid‐July did not appear to be as sensitive to nighttime swimming, as there were only minor differences in both NAT activity and melatonin content compared to controls. These results demonstrate that forced nighttime swimming, unlike several other aversive stimuli, can evoke changes in the normal pattern of pineal melatonin production in this species. Furthermore, the pineal's response to such stimuli may not be stable over the course of the active season.
Molecular analyses of gene expression during sea star spermatogenesis
Authors: Boom J. D. G. , Smith M. J. 
Published: June 2005

AbstractWe have investigated actin gene expression during the annual spermatogenic cycle of Pisaster ochraceus by Northern blot analyses of testes RNAs pooled from defined spermatogenic stages. Specific probes for cytoplasmic (Cy) and muscle (M) actin gene products detect 2.3 and 2.1 kb transcripts, respectively. In addition, actin‐coding sequence probes detect a third, much larger (3.5 kb) transcript designated FAT. Preliminary sequence analyses of two cDNAs representing portions of the FAT transcript show over 90% homology to Pisaster Cy actin at the amino acid level but only 80% nucleotide identity.The expression patterns of these three transcripts, plus two spermiogenic indicator transcripts (H3 histone and β‐tubulin), were determined over the cycle. The Cy transcript is seen at all stages but is ten‐ to 100‐fold higher early in the cycle when mitotic activity predominates. The M transcript appears at the onset of gonadal growth and is maintained at constant levels through spermatogenesis consistent with the expansion of the muscular sheath surrounding the testes. The FAT, H3 histone, and β‐tubulin transcripts reach their highest levels in ripe testes when spermiogenic activity is maximal. The homology of the FAT transcript to actin, and its pattern of expression, suggest the hypothesis that this transcript may encode acrosomal actin.
Anisotropic gas diffusion in the shell membranes of the hen's egg
Authors: Ar A. , Girard H. 
Published: June 2005

AbstractThe area‐specific diffusive conductances for oxygen and carbon dioxide of the isolated eggshell compound membrane (CSM), in perpendicular direction (the shortest way between hard shell and chorioallantois), on day 16 of incubation, are 3.38 and 2.00 mmol/(cm2·d·kPa), respectively. Calculated Krogh constants of the CSM for oxygen (K) in lateral (parallel to the shell) and perpendicular (to the shell) directions show marked anisotropy in diffusive properties. The lateral K is about 100 times the perpendicular K. Analysis shows that eggshell pore density is closely structured to match the diffusive properties of the CSM, ensuring a quasihomogenization of gas pressures in the CSM among adjacent pores. During incubation regional P (and P) changes within the CSM may occur as a result of covering relatively small fractions of eggshell. The CSM contributes little to the overall O2 transport resistance in the live egg.
Changes in the testicular binding of luteinizing hormone and plasma testosterone concentrations in the Djungarian hamster subjected to different photoperiods and temperatures and effects of long‐term testosterone treatment on the binding
Authors: Tsutsui Kazuyoshi , Kawashima Seiichiro , Masuda Atsuko , Oishi Tadashi 
Published: June 2005

AbstractThe effects of artificial photoperiod, temperature, and long‐term testosterone treatment on testicular luteinizing hormone (LH) binding were studied in adult male Djungarian hamsters. In hamsters transferred to long‐day (LD; 16 hr light, 8 hr dark) photoperiod 8 weeks after adaptation in short‐day (SD; 8 hr light, 16 hr dark) photoperiod of 25°C, testicular growth was associated with an increase in the total LH binding per two testes and a decrease in LH binding per unit testicular weight. Plasma testosterone levels reached a peak 47 days after transfer to LD and tended to decrease thereafter, while the testes continued growing. In contrast, when hamsters reared under LD conditions at 25°C for 12 weeks were transferred to SD, testicular regression was associated with a decrease in plasma testosterone and the total LH binding per two testes and an increase in LH binding per unit testicular weight. A significant decrease in LH binding per unit weight compared to SD controls was observed in those hamsters exposed to SD with continuous testosterone treatment. The testosterone treatment tended to induce decrease in the total LH binding. Scatchard plot analyses of the binding suggested that changes in LH binding were due to changes in the number of binding sites. When sexually mature male hamsters were subjected for 8 weeks to two different ambient temperatures (7°C and 25°C) and photoperiods (LD and SD), the difference between the two temperature groups was statistically not significant regarding the weights of testes, epididymides, and prostates; plasma testosterone levels; and LH binding in either LD or SD group. These results suggest that photoperiod is a more important environmental factor than temperature for the regulation of testicular activity and LH receptors and that testosterone reduces the number of LH receptors per unit testicular weight in adult male Djungarian hamsters.
Embryonic cellular organization: Differential restriction of fates as revealed by cell aggregates and lineage markers
Authors: Bernacki Susan H. , McClay David R. 
Published: June 2005

AbstractCleavage‐stage Lytechinus variegatus embryos were dissociated and the cells were aggregated in an experimental system designed to address questions of embryonic organizational capability. Using monoclonal antibodies against stage‐ and structure‐specific antigens, it was determined that germ‐layer specific molecules were expressed in the expected locations in aggregates and that the germ layers differentiated in the normal temporal sequence, but the dorsoventral axis of the embryo was not reestablished properly. In other experiments individual rhodamine‐labeled blastomeres were incorporated into unlabeled aggregates. Micromeres localized and differentiated normally. Mesomeres, however, which in normal embryos form only ectoderm, were found to change their specified fate and participate in gut formation.The sequence of aggregate organization revealed other properties of the embryo. Ectodermal and endodermal epithelia formed via two temporally distinct epithelialization events. Ectoderm separated from a mass of interior cells at about 12 hrs, and endoderm compacted from the interior cells at about 20 hr. A lathrytic agent that prevents gut formation in normal embryos also prevented gut formation in aggregates; however, it did not affect formation of the ectoderm. Hence, formation of the triploblastic structure in aggregates appears to be dependent upon developmentally regulated, distinct cell adhesion events.