摘要:

AbstractTwo structurally related arthropod neuropeptides, red pigment concentrating hormone (RPCH) and adipokinetic hormone (AKH), are potent excitors of the heart of the clamMercenaria mercenaria.The response is bimodal: whereas the threshold for affected hearts is 1–3 × 10−9M, about 40% of the preparations are virtually unresponsive. Aqueous extracts ofMercenariaganglia contain a substance which concentrates the red pigment in the erythrophores of intact destalkedUca pugilatorand even of its isolated legs. This substance is retained on Sephadex G‐15 and co‐elutes with synthetic shrimp RPCH. The active fractions also concentrate the erythrophores and the leucophores of destalked shrimp (Penaeus). Neither dopamine nor the molluscan neuropeptide FMRFamide had any chromatophorotropic effect in these assays. The activity of the ganglion extracts was abolished by digestion with chymotrypsin. In conclusion, molluscan ganglion extracts contain a peptide factor, possibly an analog of RPCH, that concentrates the pigments of crustacean chromatophores by a direct action on t

ISSN:0022-104X    

DOI:10.1002/jez.1402330302

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractGlycine levels in isolated ribbed mussel (Modiolus demissus) gill tissue increased slightly and decreased markedly when incubated at high and low salinities, respectively. Low levels of the enzymes involved in the biosynthesis of serine from triose phosphate intermediates, the serine hydroxy‐methyltransferase, and serine dehydrase were detected in gill tissue homogenates. Experiments using gill tissue incubated with (U‐14C)‐glycine and (U‐14C)‐serine indicated interconversion between serine and glycine and transfer of label to alanine, asparate, glutamate, CO2, organic acids, and protein. Glyoxylate was metabolized more slowly than glycine and was probably converted to glycine for catabolism. Studies using (1‐14C)‐glycine and (2‐14C)‐glycine with isolated gill tissue and mitochondria indicated that the mitochondrial glycine cleavage enzyme was the major route of glycine catabolism. Metabolic controls activating or inhibiting the glycine cleavage enzyme regulate tissue glycine accumulation and catabolism during hypersalinity or hy

ISSN:0022-104X    

DOI:10.1002/jez.1402330303

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractSecondary cartilage forms on avian and mammalian dermal bones, both during normal ontogeny and during repair of fractures, but it has not been observed in any other vertebrate class. We fractured the left lower jaws of adult spotted salamanders,Ambystoma maculatum, to see whether secondary cartilage would form during fracture repair. It did not. Instead, periosteal hyperplasia produced a callus from which new dermal bone formed to bridge the fracture. Meckel's cartilage underwent superficial dissolution but showed a minimal chondrogenic response. A large callus cartilage did form, but it appeared to arise by metaplasia from connective tissue adjacent to the bone. Thus, the environment within the fracture is conducive to chondrogenesis but the periostea of the dermal bones either are not able to respond to that environment or are unable to synthesize cartilage‐specific products. Among recent vertebrates, the ability to form secondary cartilage is limited to birds and mammals and is not a primitive property of the periostea of dermal bones shared by “lower” vertebrate cl

ISSN:0022-104X    

DOI:10.1002/jez.1402330304

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractCells of scyphistomae, strobilae, and ephyrae were dissociated with trypsin and reaggregated. Clumping was inhibited in low Ca+ +and by puromycin, but not by collagenase or sugars. Reaggregates from the oral end of the polyp developed tentacles and mouths first and basal structures later, whereas the opposite sequence occurred with cells from the lower gastric region. Nile‐blue‐stained cells from hypostome or peduncle did not form specific structures in the reconstructed polyp, but were distributed throughout the animal. Ephyra cell aggregates showed little morphogenesis, whereas cells from presumptive ephyra tissue gave rise to structures with tentacles and multiple oral openings. Mixed reaggregates containing equal proportions of polyp and ephyra cells formed irregular structures with transparent outer layer and opaque inner cell mass, suggesting stage‐specific so

ISSN:0022-104X    

DOI:10.1002/jez.1402330305

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractDevelopment of sucrase in the chick small intestine was studied biochemically and immunologically using antiserum prepared against purified chick intestinal sucrase. Sucrase activity was first detectable at 10 days of incubation and increased with age. After a transient drop at 20 days, the activity rapidly increased to the adult level. Immunodiffusion and polyacrylamide gel electrophoretic studies suggested that the sucrase of the embryonic and hatched chick intestines was identical except for a difference in the content of sialic acids. In immunofluorescence and immunoelectron microscopy, sucrase was found to appear on the luminal surface of epithelial cells at 8–10 days of incubation, soon after the start of morphological differentiation from an undifferentiated thick epithelium to a thin simple epitheliu

ISSN:0022-104X    

DOI:10.1002/jez.1402330306

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractThe objectives of this study were to determine the influence of growth and aging on ploidy, cell number, and protein content of various organs. Tissue homogenates were prepared at 3, 8, 25, 50, and 100 weeks of age. Samples were analyzed for DNA per nucleus (by flow cytofluorometry), nuclei number, and protein content. Livers of 8‐ and 100‐week‐old animals were also perfused with collagenase and the released cells separated into parenchymal and nonparenchymal populations by unit gravity sedimentation. Nuclei of these cells were also analyzed for DNA. In all four zones of the kidney and in thyroid, 4n nuclei diminished in percentage between 3 and 50 weeks and increased at 100 weeks. In the growth phase these probably are cycling cells and after 50 weeks represent an increasing population of nuclei arrested after synthesis of DNA. Constant levels of ploidy were found in brain, heart, rectus abdominis, and adrenal throughout the 3–100 weeks. A dramatic increase in 4n nuclei occurred between 3 and 8 weeks in liver with little change occurring thereafter. Ploidy is a property of only parenchymal cells in liver and this probably is also true in other organs. The 4n nuclei that remain in constant proportion to the total population are established early in life and are not related to aging. They are probably tetraploid and replicate into 4n daughter cells during growth. Cerebrum shows no changes in nuclei number but exhibits a 70% increase in protein between 3 and 100 weeks. Although kidney, liver and adrenal show large increases in number of nuclei (≈ fourfold) with growth, these are not as great as increases in body weight (≈ 11‐fold). With regard to organ protein, only liver shows increases approximating those in body weight. Increases in organ nuclei appear to occur in concert for adrenal, kidney, and liver whereas increases in organ protein bear no relationship to each other. Protein content remains at stable levels in organs of 100‐week‐old animals and little (adrenal, liver) or no (brain, kidney) diminution occurs

ISSN:0022-104X    

DOI:10.1002/jez.1402330307

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractMaternal RNA of mouse eggs and embryos was labeled by exposure of growing ovarian oocytes to3H‐uridine in vivo 8 to 16 days before ovulation and fertilization. Labeled embryos from the 1‐cell stage to the blastocyst stage were collected, fixed, and autoradiographs of plastic sections prepared. The observed grain density was similar in the pronuclei and in the cytoplasm of 1‐cell embryos. Knowing the volumes of nucleus and cytoplasm, it was determined that 3% of the maternal RNA was found in the pronuclei. It is suggested that some of this nuclear RNA may be stable small nuclear RNAs (e.g. U1 RNA) retained from the germinal vesicle stage through meiotic maturation. During the 2‐cell stage and beyond, maternal RNA is degraded and labeled precursor is reincorporated into nuclear RNA, making it difficult to accurately quantitate the amount of nuclear maternal RNA. It is known that about one third of the total maternal RNA is lost between the 8‐cell and blastocyst stages. It was found that cytoplasmic grain densities in inner and outer cells of the morula and blastocyst were not significantly different. Thus, the loss of maternal RNA does not proceed more rapidly in the differentiating trophoblast than in the inner

ISSN:0022-104X    

DOI:10.1002/jez.1402330308

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractSpermatogenesis in many mammalian species requires a temperature a few degrees below body core temperature. Upon ascent through the male tract and deposition in the female tract, the temperature of spermatozoa is increased to body core temperature. This report investigates the effects of temperatures above or below normal body core temperature, which is also the usual temperature of in vitro gamete incubations and fertilization, upon sperm acrosome reacting ability and fertility. Epididymal guinea pig spermatozoa were preincubated in a Ca2+‐free medium at temperatures of 15°C, 25°C, 37°C, or 44°C for increasing periods of time. At 15°C or 25°C, no or very few spermatozoa acquired the ability to acrosome react upon exposure to Ca2+even after 18 hr of culture or warming up to 37°C. A known stimulator of acrosome‐reacting ability, lysophosphatidylcholine, was ineffective in promoting acrosome‐reacting ability in spermatozoa incubated at 15°C or 25°C. At 37°C the percentage of acrosome reaction increased steadily over time, reaching about 65% after 18 hr. At 44°C the time course of acquisition of acrosome‐reacting ability was greatly accelerated with a percentage at 2 hr comparable to that achieved at 37°C only after 18 hr of preincubation. This effect of incubation at 44°C could be reversed by cooling the spermatozoa to 37°C before they were exposed to Ca2+. Spermatozoa induced to undergo the acrosome reaction after preincubation at 44°C were fully capable of fertilizing intact guinea pig eggs. These results are discussed in relation to possible temperature‐dependent or ‐sensitive mechanisms that may be components o

ISSN:0022-104X    

DOI:10.1002/jez.1402330309

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractThe male accessory reproductive gland (ARG) of the house cricket,Acheta domesticus(L.), contains an exceedingly high concentration of cyclic GMP, about 1,000 pmol/mg protein. Immunofluorescent localization and radioimmunoassay measurements show that cyclic GMP is concentrated in a small number of tubules. It accumulates in the tubule lumina where it is protected from degradation by phosphodiesterases. Cyclic GMP is secreted by the ARG and is incorporated into spermatophores. Over 80% of spermatophore cyclic GMP is found in the handle‐capillary tube, a thin conduit through which sperm pass during transfer to the female. The concentration of cyclic GMP in the insemination fluid is about 20 μM but does not appear to be specifically associated with the sperm. Cyclic GMP enters the female spermatheca during insemination but disappears rapidly. Physiological effects of cyclic GMP on sperm were not observed nor was an effect of cyclic GMP observed on egg laying by mated females. Cyclic AMP was localized on sperm flagella in the spermatophore and in the spermatheca. These studies indicate that cyclic nucleotides have important roles in insect reproduction and that the house cricket is a good model for elucidating these functio

ISSN:0022-104X    

DOI:10.1002/jez.1402330310

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractMaturing rainbow trout were immunised with testis plus Freund's complete adjuvant (FCA) to determine when autoantigen(s) appear on germ cells during spermatogenesis. Only testes containing spermatozoa and spermatids developed lesions, and no other germ cell types appeared to be involved. This response was gonad specific, but showed little correlation with antibody titres to spermatozoa. The necessary conditions that allow the development of autoantigen(s) on postmeiotic cells are discussed.

ISSN:0022-104X    

DOI:10.1002/jez.1402330311

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY