bluuebunny/crossref_metadata_2025 huggingface dataset:
Red cell metabolism in buffaloes and camels
Authors: Agar N. S. , Suzuki T.
Published: June 2005

Red cell GSH, GSH regeneration rates, and the activities of ten enzymes were measured in the red blood cells of camels and buffaloes. The activity of G6PD was found to be much higher in both the species compared to that found in other ruminants such as sheep, goats, and cattle. Although there were no significant differences in the level of red cell GSH in the two species, there was a striking difference in the rate of GSH regeneration, the mean rate of 0.162 ± 0.009 μmoles/min/gHb in the camels was significantly higher than the 0.082 ± 0.011 μmoles/min/gHb observed in the buffaloes.
Effects of gravidity on the metabolism of the reproductively bimodal lizard, Sceloporus aeneus
Authors: Guillette Louis J.
Published: June 2005

The metabolic rates of gravid and nongravid females of two subspecies of Sceloporus aeneus exhibiting different reproductive modes (oviparity and viviparity) were compared. Both oviparous and viviparous gravid females exhibited a significant increase in oxygen consumption over that of nongravid females of either reproductive mode. Weight‐specific oxygen consumption also is greater in gravid than in nongravid females. The alteration in metabolic rate in gravid females is attributed to a fetal–maternal difference in this parameter‐that is, an altered maternal physiology associated with pregnancy.key words weight‐specific metabolism, reproduction,oxygen consumption,Sceloporus aeneus reptilia, squamata,iquanidae
Development of peroxisomes in amphibians. II. Cytochemical and biochemical studies on the liver, kidney, and pancreas
Authors: Dauca M. , Calvert R. , Ménard D. , Hugon J. S. , Hourdry J.
Published: June 2005

The ontogeny of catalase‐containing organelles was studied by cytochemical and biochemical methods in the liver, kidney, and pancreas during the development of Rana catesbeiana. The biochemical differentiation of peroxisomes in the liver and kidney was compared to that of Xenupus laeuis. Catalase activity was localized after incubation in DAB medium and studied biochemically by a spectrophotometric method. In Rana catesbeiana the number of catalase‐pos‐itive organelles per cell section is low in all three organs during premetamorphosis; their number increases substantially in the liver and kidney of froglets, while it remains almost stable in the pancreas. No further increase is observed in the adult. Biochemically, the liver, kidney, and pancreas of tadpoles exhibit, respectively, 12, 22, and 63% of the catalase activity found in the adult tissues. After metamorphosis an important increase of catalase activity is particularly noted in liver and kidney, the activity being, respectively, 43 and 77% of that of adult bullfrogs. On the other hand, no change in catalase activity in the liver and kidney is noted during the entire development of Xenopus laeuis. The present study illustrates the very different developmental pattern of catalase activity observed during the development of two anuran amphibians. The different developmental pattern of the same enzyme within the small intestine, liver, kidney, and pancreas in Rana catesbeiana is also stressed.
Measurement of enolase molecules in the single preimplantation rat embryo by an enzyme lmmunoassay system
Authors: Watanabe Tomomasa , Suzuki Fujiko , Kato Kanefusa
Published: June 2005

The amount of enolase (EC 4.2.1.11) molecules in a single preim‐plantation rat embryo was determined by an enzyme immunoassay system. An advantage of this assay system is its ability to distinguish each isozyme (αα, αγ and γγ forms) by using the specific antisera to a and y subunits. The isozyme of enolase was mostly the aa form through one‐cell to blastocyst stages, whereas the αγ and γγ forms were scarcely detected. Since the immunoassay system is highly sensitive, the minimum amount detectable being 1 amol(1 × 10−18 mole), the amount of aa form enolase could be determined in single embryos in all preimplantation stages. The results have revealed that the amount of aa form enolase molecules does not change through one‐cell to morula stages, but increases remarkably between morula and blastocyst stages.
Histologic evaluation of the sympathectomy induced by guanethidine sulfate in neonatal rats
Authors: Herskovits M. S. , Singh I. J.
Published: June 2005

Guanethidine sulfate was administered to rats from birth to 14 days of age. Cell counts were carried out in the superior cervical sympathetic ganglion at 30, 45, and 90 days of age. Massive, permanent destruction of sympathetic ganglionic cells was demonstrated during the experimental period. Evidence for a natural loss of neurons during the morphogenesis of the superior cervical sympathetic ganglion is presented.
The regional distribution of poly (A) and total RNA concentrations during early Xenopus development
Authors: Phillips Carey R.
Published: June 2005

Xenopus laevis embryos were oriented and sectioned into six regions along one of three axes: animal‐vegetal, dorsal‐ventral, or right‐left. Total RNA (predominantly ribosomal RNA) and poly riboadenylate [poly (A)] were measured for each region during early embryogenesis. The concentrations of both total RNA and poly(A) are nonuniformly distributed during early development. Total RNA is approximately four‐fold more concentrated in the more animal portions than the more vegetal portions of the embryo. The dorsal‐most region contains a 1.5‐fold higher concentration than in the other five regions of the four‐celled embryo along the dorsal‐ventral axis. Poly(A) concentrations show temporal and regional specific changes in concentration during early development with higher concentrations more generally found in the animal‐most regions.
A study on melanogenesis and catecholamine biosynthesis during Bufo bufo development
Authors: Miranda Michele , Botti Dario , Ragnelli Anna Maria , Cola Mario Di
Published: June 2005

Tyrosinase and L‐DOPA decarboxylase activities have been investigated during Bufo bufo development since catecholamines and melanin are formed from common substrates in homologous cells. Catecholamines first appear at stage 13 (neural plate), but tyrosinase, at a very low level, and L‐DOPA decarboxylase are present throughout all of prior development. Hence, L‐DOPA decarboxylase activity is not likely to be correlated with the control of catecholamine synthesis, although at stage 17 it is mainly localized in the nonneural part of the embryo. The distribution of young melanosomes and L‐DOPA decarboxylase suggest a separation between melanogenesis and catecholamine synthesis.
Sperm nuclear decondensation in mammals: Role of sperm‐associated proteinase in vivo
Authors: Perreault Sally D. , Zirkin Barry R.
Published: June 2005

Previous studies from this (Zirkin et al., '80) and other (Marushige and Marushige, '78) laboratories have shown that proteinase associated with mammalian sperm nuclei is involved in thiol‐induced sperm nuclear decondensation and protamine degradation in vitro. The results of these in vitro studies suggested the exciting possibility that the sperm nucleus itself might contribute proteinase involved in its subsequent in vivo decondensation during fertilization. In the present study, microinjection methods were used to test this possibility directly. Control hamster sperm nuclei, which exhibited proteinase activity, decondensed when incubated in vitro with disulfide reducing agent. As expected, these nuclei also decondensed when microinjected into ovulated hamster oocytes and formed morphologically normal pronuclei. When the proteinase associated with isolated sperm nuclei was removed with 0.5 M salt or inhibited with nitrophenyl‐p‐guanidinobenzoate, the nuclei were rendered incapable of decondensing in response to disulfide reducing agent in vitro. However, when these nuclei were microinjected into eggs, they decondensed and transformed into pronuclei. These results provide direct evidence that sperm‐associated proteinase is not required for sperm nuclear decondensation and formation of the male pronucleus during fertilization.
Isolated osteoclasts and their presumed progenitor cells, the monocyte, in culture
Authors: Osdoby Philip , Martini Mary C. , Caplan Arnold I.
Published: June 2005

Osteoclasts were isolated from the endosteal surface of day 19 embryonic chick tibias by mild trypsinization. Osteoclast enrichment was achieved by passing cell suspensions through Nitex screening of selective sizes, including the eventual selective retention of osteoclasts on 12 μm polycarbonate filters or by sequential sieving through Nitex screens and fractionation on Percoll gradients. The enrichment procedures produced osteoclast populations of 50–75% based on morphological criteria with the latter isolation method providing populations with less matrix debris. The results of light microscopy, transmission and scanning electron microscopic observations indicate that osteoclasts can be maintained in culture for up to 10 days with retention of osteoclast morphology. This morphology includes a specialized ruffled plasma membrane, large numbers of mitochondria, lysosomes, as well as a multinucleated cytoplasm. Furthermore, acid phosphatase and butyrate esterase histochemical measurements support these morphological observations. In addition, chick hatchling circulating monocytes were isolated and purified by Ficoll‐hypaque gradient centrifugation with subsequent adhesion to glass petridishes. With time in culture, these cells form multinucleated cells, but lack the ultrastructural complexity of the isolated osteoclasts. This report describes a unique culture system to study osteoclast function and illustrates the similarities and differences of this system to the monocyte‐to‐giant cell culture system.
Protein synthetic requirements for the outgrowth of trophoblast cells from mouse blastocysts
Authors: Blake Emily J. , Schindler Joel , Sherman Michael. I.
Published: June 2005

Mouse blastocysts cultured under optimal conditions attach to the surface of the culture dish and subsequently give rise to outgrowths of trophoblast cells. The migration of trophoblast cells appears to be analogous to their behavior during the invasive phase of implantation in utero. In these studies, we have attempted to determine the time of synthesis and nature of the products required for trophoblast outgrowth. Fourth‐day blastocysts were cultured in two different media: cNCTC, a nutrient medium supplemented with fetal calf serum, and PCMF, a simple preimplantation medium lacking amino acids and serum. Trophoblast outgrowth occurs in the former, but not in the latter, medium. Most blastocysts will give rise to outgrowths following as little as 12 hr of exposure to cNCTC at the appropriate time, even if they are subsequently placed in PCMF. Outgrowth fails to occur if blastocysts are treated with cycloheximide during the interval of exposure to cNCTC, whereas treatment with the antimetabolite after the period of culture in cNCTC does not block outgrowth. These observations are consistent with the view that protein(s) essential for trophoblast outgrowth are synthesized many hours prior to the actual event.
Decondensation of human sperm nuclei by glycosamineglycan‐sulfate from sea urchin egg
Authors: Delgado Néstor M. , Reyes Rosalina , Huacuja Luis , Carranco Armando , Merchant Horacio , Rosado Adolfo
Published: June 2005

Decondensation of human and sea urchin spermatozoan nuclei has been induced by exposure of intact spermatozoa to glycosamineglycan‐sulfate (GAGs) extracted from eggs of the sea urchin, Toxopneustes roseus. Swelling of human spermatozoan nuclei commenced about 60 min after the addition of GAGs and, depending on the extract concentration, the proportion of swollen nuclei reach 90% after 6 h of incubation when 20 mg of GAGs per ml was used. Swelling of sea urchin spermatozoan nuclei could be induced also with GAGs and/or with heparin. Swelling commenced about 10 min after the addition of GAGs/heparin reaching 90–92% after 60 min of incubation with 5 mg GAGs/500 USP heparin per ml. Preincubation of spermatozoa with 10 mg/ml of trypsin soybean inhibitor did not interfere with the swelling action of the GAGs.
Recurrent germ‐line transmission of the teratocarcinoma genome from the METT‐1 culture line to progeny in vivo
Authors: Stewart Timothy A. , Mintz Beatrice
Published: June 2005

Mouse teratocarcinoma stem cells cultured in vitro provide the unique prospect of obtaining new strains of mice with genetic changes that have been predetermined, preselected, and precharacterized. This possibility rests upon the demonstrated capacity of the stem cells, after injection into blastocysts, to produce lineal cell descendants that are functional gametes. Thus far, only one in vitro line of teratocarcinoma cells has been founa capable of forming germ cells in vivo. The line, established in this laboratory from a 129 (agouti‐strain) embryo, was designated METT‐1 and was shown in previous reports to be karyotypically normal and chromosomally female (X/X); after introduction of the cells into C57BL/6 (non‐agouti‐strain) blastocysts, one mosaic‐coat female (out of nine that were test‐mated) had some offspring from the teratocarcinoma cell source. We report here results from an extension of this study. The new series was initiated in part to clarify the frequency of mosaic individuals with some reproductive cells of the tumor strain, as an indication of the practicability of the proposed genetic manipulation experiments. From among the first eight mice produced, a single female with a mosaic coat was test‐mated to a C57BL/6 male and produced progeny. An agouti (dominant‐color) 129‐derived male appeared in her second litter. The teratocarcinoma lineal provenance of this F1 animal was confirmed by its heterozygosity for the hemoglobin electrophoretic variants (Hbb locus) due to the 129 (diffuse‐type) and C57BL/6 (single‐type) strains. Thus, in our two series combined, the METT‐1 cell line has given rise to normal germ‐line progeny in a substantial frequency (2/10, or 20%) of tested females.
J10 lactate‐induced polycythemia in newts
Authors: Frangioni Giuliano , Borgioli Gianfranco
Published: June 2005

Specimens of Triturus cristatus carnifex (Laurenti) raised for about 3 weeks in a 3 gm/liter solution of sodium lactate present a slight alkalosis and a mean increase of about 35% in the red blood cell count in comparison to control animals raised in identically oxygenated water; analogous treatment with an equal molar concentration of sodium pyruvate produces only alkalosis. Since lactate alone determines an increase in the number of erythrocytes as does hypoxia, and hypoxia always induces an increase in plasma lactate levels, it can be deduced that erythropoietin (ESF) production is stimulated by an increase in plasma lactate and not directly by a lack of oxygen. The hypothesis that ESF in newts is produced by the “lactate‐sensitive cells” of the renal corpuscles, which hypertrophy after experimental anaemia or treatment with lactic acid salts, is indirectly confirmed.
Neuromuscular relationships in the asymmetric claws of Californian snapping shrimp
Authors: Stephens Philip J. , O'Connor Kathleen , Leferovich John M.
Published: June 2005

The asymmetric claws of Californian snapping shrimp (Alpheus californiensis) are comprised of a smaller pincer claw and a larger snapper claw. The present paper describes the morphology of the single closer muscle and the facilitation properties of an excitatory motor axon for both claws. In the snapper claw the closer muscle fibers are composed of uniformly long sarcomeres, measuring 10–15 μm in length. In the pincer the closer muscle fibers are of a smaller diameter and can be divided into two groups on the basis of sarcomere length. One group has short (2 and 3 μm) sarcomeres, while the other has intermediate (7 and 8 μm) sarcomeres. Microelectrode recordings from single closer muscle fibers showed that all fibers are supplied by the fast excitatory motor axon. The slow excitatory motor axon innervates only fibers on the dorsal and ventral surfaces of the closer muscle. Facilitation of excitatory junctional potentials (ejps), produced by stimulation of the fast axon with pairs of brief electrical shocks, revealed that at intervals above 100 ms no facilitation was recorded from either claw. At intervals below 100 ms, however, facilitation was recorded from pincer closer muscle fibers, but defacilitation or depression was recorded from the snapper. This was confirmed by making extracellular recordings of synaptic potentials from snapper closer muscle fibers.
Roles of ectodermal and endodermal epithelial cells in hydra morphogenesis: Analysis of chimeras
Authors: Wanek Nancy
Published: June 2005

Chimeric hydra were constructed from ectoderm of one strain and endoderm of a morphologically different strain. Body size and budding rate were assayed in three pairs of ectoderm/endoderm chimeras, which were chosen on the basis of their differences in size and budding rates. Reciprocal chimeras of one parental pair were the same size as their endodermal parent, while chimeras of another pair were closer to the ectodermal parents in size. Chimeras of the third pair were similar to one another in size, and intermediate in size between the parental strains. The budding rates of the three reciprocal pairs were similar to their ectodermal parents. This suggests that ectoderm exerts more influence than endoderm on budding rate, while both ectoderm and endoderm are capable of influencing the size of a hydra. The morphology of these three pairs of reciprocal chimeras and of a fourth pair of chimeras constructed from normal H. attenuata and a mutant strain which produces multiple basal discs were compared to the parental morphologies. Both ectoderm and endoderm contribute to the morphology of the chimeric strains.
Origin of permanently altered epithelial cells of the vagina in neonatally estrogen‐treated mice
Authors: Mori Takao , Iguchi Taisen , Takasugi Noboru
Published: June 2005

In adult mice, neonatal injections of estrogen induce persistent, estrogen‐independent cornification of the vaginal epithelium. Since the occurrence of nodules composed of affected epithelial cells (B cells) is a prodromic phenomenon of the irreversible vaginal alterations, the relationship between the occurrence of B‐cell nodules and the time of DNA synthesis in the vaginal epithelial cells was examined by means of the techniques of serial mapping and autoradiography. B‐cell nodules appeared in the epithelium of mullerian vagina 3–5 days after the initiation of neonatal estrogen treatment, without spatial continuity to cuboidal epithelial cells of the sinus vagina. The time of DNA synthesis was different in B cells from that in both columnar mullerian and cuboidal sinus cells, suggesting that the mother cells of B cells.
Effect of an estrogen antagonist on development of blastocysts and implantation in the hamster
Authors: Sengupta Jayasree , Paria Bibhas C. , Manchanda S. K.
Published: June 2005

CI 628 citrate, an estrogen antagonist, was given as a single intraluminal injection (5 μg) on day 3 to ovariectomized, progesterone‐treated hamsters. This significantly reduced embryo cleavage rate, transformation of morula into blastocyst, and completely inhibited implantation. The effects of the drug could be reversed by estradiol‐17B (1 μg) but not estradiol‐17α (1 μg) injected intraluminally with CI 628 citrate. Our finding suggests a role of estrogen present in hamster preimplantation embryo in the triggering of embryonic differentiation and implantation of the blastocyst.
Gene expression during mammalian spermatogenesis. II. Evidence for stage‐specific differences in mRNA populations
Authors: Gold Bert , Stern Leslie , Bradley Francis M. , Hecht Norman B.
Published: June 2005

Gene expression during murine spermatogenesis has been studied using highly enriched populations of cells obtained by velocity sedimentation at unit gravity and further purified by density gradient centrifugation through Percoll. Polypeptides whose synthesis was directed by total cytoplasmic RNA from round spermatids, pachytene spermatocytes, primitive type A spermatogonia, and Sertoli cells in cell‐free translation systems have been compared by two‐dimensional polyacrylamide gel electrophoresis, followed by fluorography. At the level of detection provided by the electrophoretic methods used, each population of cells contained mRNAs encoding over 200 polypeptides, many of wich were present in high abundance in all four cell types. However, for each cell type examined, a minimum of 5–10% of these polypeptides appear to be either specific to or greatly enriched within a particular cell type. Analysis of the polysomal and nonpolysomal cell fractions from pachytene spermatocytes and round spermatids revealed that the two compartments share many identical mRNAs but specific mRNAs are selectively compartmentalized between the cell fractions and between the two cell types. Movement between compartments was seen; e.g., some polypeptides encoded by mRNA found primarily in the nonpolysomal fraction of pachytene cells were later seen in the polysomal fraction from round spermatids. Virtually every other combination was also observed. These results suggest that the control of gene expression at the level of selective production of mRNA and selective utilization of mRNA are among the mechanisms involved in regulation of spermatogenic cell differentiation.
Videotape analysis of hamster ovulation in vitro
Authors: Talbot Prudence
Published: June 2005

Videotape recordings were made of hamster follicles ovulating in vitro. These recordings were analyzed to characterize the morphological changes occurring in ovulating follicles and to time various events in the ovulation sequence. Before rupture, the shape of the follicle is transformed from a low to tall profile as shown previously (Martin and Talbot, '81). The complete transition from a low to tall profile required about 22.5 min. During the profile transition, the smooth muscle cells (SMC) in the base of the follicle contract (Martin and Talbot, '81), and the following events were observed. The base of the follicle moved apically. This pressed the cumulus and oocyte against the apical follicle wall, which appeared granular rather than smooth. The size of the antrum decreased presumably due to obliteration of the basal part of the antrum and movement of follicular fluid through the developing rupture site in the apex. The pressing of the cumulus against the apical wall appeared to cause final thinning and opening of the rupture site. The cumulus was extruded in two phases. Phase 1 was rapid (10–60 sec) and resulted in evacuation of about 25% of the cumulus and usually the oocyte from the antrum. Phase 2 required 2–10 min for completion and was accompanied by collapse of the follicle wall. After collapse, the cumulus remained with its follicle and could not be removed by pulling with Watchmaker's forceps. These observations provide new information on the role of SMC in hamster ovulation and characterize extrusion of the cumulus as a two‐phase event.
Nocturnal rhabdom cycling and retinal hemocyte functions in crayfish (Procambarus) compound eyes. I. Light microscopy
Authors: Piekos W. Barry , Waterman Talbot H.
Published: June 2005

In addition to the previously known photoreceptor membrane cycle coupled to light and dark adaptation, detailed study of the late‐night period (24:00 to 06:00 h) in Procambarus compound eyes demonstrates that a second cycle of degradation (about 14% decrease in maximum rhabdom diameter) and resynthesis takes place completely in the dark between midnight and dawn.

Invasive granular hemocytes are present in the retina throughout the latenight period in winter. Their distribution around the retinulas during the degradative phase (24:00 to 02:00 h) of the turnover cycle differs significantly from that characteristic of both the synthetic (02:00 to 04:00 h) and resting (04:00 to 06:00 h) phases. This correlation provides an important way of identifying retinal areas in the process of net photoreceptor membrane degradation. Retinal hemocytes are highly significantly more numerous in the resting stage than in either of the other two.

Certain associated changes differ between winter and summer series. Total hemocyte numbers in our winter experiments show a positive linear correlation with rhabdom diameters. In the summer series, retinal hemocytes are rare or absent, and rhabdom diameters are significantly smaller than in winter. No hemocytes are associated with the smallest (June) rhabdoms. Yet the latter do show the late‐night breakdown and regeneration. Correlation between hemocyte numbers and rhabdom size becomes almost perfect if our summer and winter series are pooled.
Regulation of tadpole spinal nerve fiber growth by the regenerating limb blastema in tissue culture
Authors: Richmond Mary J. , Pollack Emanuel D.
Published: June 2005

Explants of frog tadpole spinal cord cocultured with blastemas of regenerating hindlimbs provide in vitro evidence that the mesenchymelike cells of the blastema may serve to elicit nerve fiber growth and sprouting into the limb stump. The present study indicates that (1) blastemal mesenchyme results in enhanced, directed nerve fiber growth and its extended survival in defined tissue culture medium; (2) the amount of nerve growth decreases in the presence of blastemas from limbs incapable of complete regeneration; and (3) the quantity of nerve fiber outgrowth decreases as the developmental stage of the spinal cord increases. It is hypothesized that one of the requisites for limb regeneration is the production of a distal population of dedifferentiated cells capable of eliciting nerve fiber outgrowth from competent neural tissue in an amount that is sufficient to promote nerve‐dependent regeneration.
Epigenesis in developing avian scales. I. Qualitative and quantitative characterization of finite cell populations
Authors: Tanaka Shoji , Kato Yoshihiro
Published: June 2005

Throughout a period from day 8.5 to day 12.5 of incubation of a chick embryo, a finite cell population of scale epidermis was characterized from various view points such as cellular organization, position, shape, area, number of constituent cells, density, and cell proliferation activity. In this study, the preparation of whole mount specimens was found to be quite valuable. On day 8.5, cells in the prospective scale region could be morphologically distinguished in the tarsometatarsus at a certain distance proximally away from the tarsometatarsal–phalangeal joint.

—On day 9.25, about 1,100 cells became highly columnar in shape and densely associated, forming a placode structure. In both distally and proximally adjacent regions of this placode, the cells were semiquadrate in shape and loosely associated, leading to the formation of the interplacode structures. Such contrasting difference in cell organization between placode and interplacode was preserved from day 9.25 to day 11. During this period, both the area and number of constituent cells increased greatly in the placode and only slightly in the interplacode. However, cell proliferation activity was completely suppressed in the placode, and quite active in the interplacode. The activity in cell proliferation proved to be inversely correlated with the density of basal cells. Throughout the present study, it has been demonstrated that the early development of scale epidermis is achieved through a coordinated activity of the two discrete cell populations: the placode and interplacode.
Availability time of tritium‐labeled DNA Precursors in newt eyes following intraperitoneal injection of 3H‐thymidine
Authors: Reyer Randall W.
Published: June 2005

Following intraperitoneal injection of 3H‐thymidine into host newts, iris together with a regenerating lens was transplanted from a donor eye into a lentectomized host eye at frequent intervals for 20 hours and then every 1 or 2 days for 14 days. The eyes were fixed 2 hours and 1 or 2 days after implantation and autoradiographs prepared. Following fixation 2 hours after operation, incorporation of 3H‐thymidine into DNA, as evidenced by grain counts over nuclei, fell rapidly for 3.5 hours after injection and was no longer apparent after 4.5 hours. However, almost one‐half of the implants were lightly labeled when they remained in the host eyes for 1 or 2 days beginning from 1 to 14 days after isotope injection. When these implanted, regenerating lenses were left in the host eyes for longer periods of time, then a light label was found over nuclei in most of the implants remaining in the eye for 3 to 24 days. When 3H‐thymidine was injected from 1 to 3 days after extirpation of both lens and neural retina, before DNA synthesis had been initiated in the pigmented retinal epithelium or iris, there were numerous cases of labeled nuclei among depigmenting cells of the pigmented retinal epithelium which was regenerating a new neural retina from 2 to 25 days after isotope injection. Depigmenting cells of the dorsal iris and regenerating lens were similarly labeled. These results provide evidence for the continued availability of small amounts of tritiated DNA‐precursor molecules which can be incorporated in DNA of proliferating cells long after the initial injection of 3H‐thymidine.
Thermoperiodism in the Gulf killifish, Fundulus grandis
Authors: Weld Madeline M. , Meier Albert H.
Published: June 2005

Male Gulf killifish, Fundulus grandis, were held on various photoperiodic and thermoperiodic regimens for 2 to 4 weeks and examined with respect to body fat stores and testes weights. Groups offish kept on a 24‐hr (LD 12:12) photoperiodic regimen were provided a water temperature of 28°C except for a 4‐hr daily interval of 20°C given at one of six different times during the photocycle. Similarly, fish kept on a 48‐hr (LD 12:36) photocycle and 28–30°C were provided 4‐hr cryophases (20°C) once during each photocycle in various phase relations to the photoperiodic regimen. In addition, some groups were held at 20°C and provided 4‐hr thermophase (28–30°C) interruptions. Fat stores and gonad weights varied among the groups as a function of the time of day when the temperature interruptions occurred. The photoperiod appears to entrain a circadian rhythm of thermosensitivity, so that the coincidence of a temperature change with a thermosensitive phase alters metabolic and reproductive indices. The circadian mechanism in thermoperiodism appears similar to that involved in photoperiodism.
Proliferation in vitro of melanophores from Xenopus laevis
Authors: Fukuzawa T. , Ide H.
Published: June 2005

Melanophores of wild‐type and periodic albino mutants of Xenopus laevis were successfully cultured in vitro. They proliferated in the presence of α‐melanocyte‐stimulating hormone (α‐MSH) or cyclic adenosine monophosphate (cAMP) at a doubling time of 8–10 days. These proliferating melanophores retained their phenotypes, ability to synthesize melanin, and melanin‐dispersing response to MSH stimulation. Neither depigmentation nor selective cell death of periodic albino melanophores was observed for at least 4 months during the cultivation.
Changes in subcellular elemental distributions accompanying the acrosome reaction in sea urchin sperm
Authors: Cantino M. E. , Schackmann R. W. , Johnson D. E.
Published: June 2005

Energy‐dispersive x‐ray microanalysis was used to analyze changes in the subcellular distributions of Na, Mg, P, S, Cl, K, and Ca associated with the acrosome reaction of sea urchin sperm. Within 5 sec after induction of the acrosome reaction, nuclear Na and mitochondrial Ca increased and nuclear and mitochondrial K decreased. Uptake of mitochondrial P was detected after several minutes, and increases in nuclear Mg were detected only after 5–10 min of incubation following induction of the reaction. The results suggest that sudden permeability changes in the sperm plasma membrane are associated with the acrosome reaction, but that complete breakdown of membrane and cell function does not occur for several minutes.
Male fertility in Drosophila melanogaster: Lesions of spermatogenesis associated with male sterile mutations of the vermilion region
Authors: Dybas Linda K. , Harden Kathryn K. , Machnicki Joy L. , Geer Billy W
Published: June 2005

Of the four male sterile, ms, loci that have been identified in the vermilion region, 9F4 to 10C2, of Drosophila melanogaster, one specifically affects male fertility, whereas three influence male and female fertility and viability. Mutations at a testis‐specific locus (10A2‐5; 1‐33.44) blocked postmeiotic spermatid maturation at or before the coiling stage. Improper associations of the axonemal sheath with the axoneme and with the mitochondrial derivatives were common to spermiogenesis in adult ms (l)v3/Y and ms (l)v 6/Y males representing the locus. Abnormalities in premeiotic events of spermatogenesis were detected in the testes of ms (l) v7/Y (9F4 to 9F8‐9; 1‐32.82), ms (l) v1/Y (1‐B4‐5 to 10B16; 1‐34.61), and ms (l) v22/Y and l (l) v73/Y males (10B4‐5 to 10B16; 1‐35.31). Differences in the characteristics of the premeiotic ms mutations suggested that each influences spermatogenesis in a unique way.
Increase in mitotic activity of regenerating axolotl limbs by growth factor‐impregnated implants
Authors: Chew Keith E. , Cameron Jo Ann
Published: June 2005

This study was designed to investigate the effects of pituitary fibroblast growth factor (FGF), endothelial cell growth supplement (ECGS), and human serum albumin (HSA) on the mitotic indices of dedifferentiating stump cells in regenerating limbs deprived of a wound epidermis. These cells would normally contribute to blastema cell formation but have been prevented from doing so by the placement of a full thickness skin flap over the amputation site. FGF, ECGS, and HSA were released from copolymer implants inserted between full thickness skin flaps and tibia‐fibula amputation sites in axolotls, Ambystoma mexicanum. The implants were plain or contained either FGF or ECGS or HSA. After 2 wk the mitotic indices of the area of dedifferentiation within these experimental limbs were determined and compared to the mitotic indices of normal regeneration blastemas. Histological analysis revealed that the technique of suturing the full thickness skin flaps into position prevented the formation of dermis‐free areas that can permit, regeneration. Full thickness skin flaps alone, or with a plain implant, or with an HSA‐impregnated implant completely inhibited blastema formation in axolotl hindlimbs. The mitotic indices of these animals showed significant decreases compared to mitotic indices of normal regeneration blastemas. The mitotic indices of animals treated with full thickness skin flaps and implants impregnated with either FGF or ECGS showed significant increases compared to those of normal regeneration blastemas. Precocious cartilage development was found in limbs which contained FGF implants.
An electrophoretic and immunological reinvestigation of the cytosolic di‐ and tripeptidases of the guinea pig
Authors: Frick Lloyd
Published: June 2005

Electrophoretic and immunological techniques have been used to analyze the cytosolic di‐ and tripeptidases of guinea pigs. In contrast to previous reports utilizing intestinal mucosa extracts, cavian peptidases were found to be similar to peptidases described in other mammals and in fishes. Earlier papers are in error owing to coelectrophoresis of enzymes and to impure enzyme preparations. Guinea pigs are unusual in that they appear to lack peptidase C.
Muscle and cartilage differentiation in axolotl limb regeneration blastema cultures
Authors: Hinterberger Timothy J. , Cameron Jo Ann
Published: June 2005

A tissue culture system is described for explants of mesenchyme from Ambystoma mexicanum limb regeneration blastemas. Explants were cultured on collagen substrate for 3 weeks in minimal essential medium supplemented with the hormones insulin, thyroxine, somatotropin, and hydrocortisone, plus beef embryo extract (EE), 2%. This medium supported extensive cell migration onto the substrate followed by cell proliferation and differentiation of both cartilage matrix and myotubes. Cultures on plastic substrate, rather than on collagen, displayed similar cell outgrowth and cartilage formation, but relatively little myotube formation. Differentiation in EE‐supplemented medium was compared with that in two defined media: Explants in medium containing only the hormones showed little outgrowth or cartilage development and never formed myotubes; medium containing the hormones plus fibroblast growth factor, 50 ng/ml, supported an intermediate degree of outgrowth and cartilage development and occasional myotube formation. Explant size was also a factor: Smaller explants survived and formed myotubes less frequently, even when on collagen in EE‐supplemented medium.
Experimental studies on a lethal gene (t) in the Mexican axolotl, Ambystoma mexicanum
Authors: Armstrong John B. , Gillespie Laura L. , Cooper Gillian
Published: June 2005

In the Mexican axolotl, Ambystoma mexicanum, the developmental mutation lethal t is inherited as a simple Mendelian recessive. Mutant larvae failed to feed and died, on the average, 17 days after hatching. Unfed wild‐type larvae died an average of 23 days after hatching. By 15 days, forelimb development had progressed further in the wild type; a cartilaginous scapula and humerus were present, but no cartilage was seen in the mutant limb. Histological examination indicated that the visceral cartilage may also be abnormal, and the rectus cervicus muscle was found to have fewer and smaller fibers. Though the mutant was not rescued by parabiosis with wild‐type embryos, transplants of presumptive gill and limb tissue to wild‐type hosts survived, indicating that the mutaion is not an autonomous cell lethal.
Fertilizability of in vitro matured oocytes from golden hamsters
Authors: Leibfried M. Lorraine , Bavister Barry D.
Published: June 2005

The fertilizability of hamster oocytes matured in vitro was examined along with two factors potentially affecting nuclear maturation in culture. The four amino acids (isoleucine, methionine, phenylalanine, and glutamine) necessary for nuclear maturation of cumulus‐free oocytes (Gwatkin and Haidri, '74) were not required if oocytes recovered on the morning of proestrus (day 4) were cultured with intact cumuli. Although follicular oocytes recovered on day 3 of the estrous cycle (late diestrus) had somewhat lower frequencies of maturation in vitro compared to those recovered on day 4 (76 vs. 95%, respectively), they still had a substantial frequency of spontaneous maturation.

Follicular oocytes recovered on day 3 and matured in vitro were fertilized at frequencies equivalent to oviducal oocytes (80 vs. 82%, respectively) when incubation of oocytes with precapacitated sperm was continued for 6 h. Penetration of follicular oocytes was lower (37.4%) after only 4 h of sperm/egg incubation, indicating a delay in sperm penetration with follicular oocytes matured in vitro. Incubation for 4 h is sufficient time for penetration of 80% or more of oviducal oocytes. While 98% of penetrated oviducal oocytes were fertilized normally, only 2% of penetrated follicular oocytes were normal. The majority (85%) of follicular oocytes, unlike oviducal oocytes, were unable to cause decondensation of sperm nuclei after 6 h of sperm/egg incubation. Use of a highly defined system for in vitro fertilization of hamster gametes has provided rigorous proof that isolated cumulus‐oocytes complexes do not undergo complete maturation in vitro.
Hydration‐induced modulation of feeding responsiveness in terrestrial slugs
Authors: Prior David J.
Published: June 2005

In various species of animals the level of body hydration is known to affect feeding responsiveness. In order to understand the mechanisms that underlie this form of behavioral modulation, hydration‐induced changes in feeding have been examined in the terrestrial slugs Limax pseudoflavus and Lehmannia valentiana. Air‐dehydration of slugs to 70–60% of initial body weight (%IBW) abolishes feeding. Feeding responsiveness is rapidly restored in these slugs after they are allowed to rehydrate in contact with a moist surface. Injections of hyperosmotic mannitol or sucrose solution also result in abolition of feeding, thus suggesting that hemolymph osmotic pressure is involved in modulation of the feeding response. Correspondingly, if mannitol‐injected or air‐dehydrated slugs are injected with 0.1 × saline, feeding is restored in a manner similar to that observed following contact‐rehydration. Feeding was restored, however, only in those slugs whose hemolymph was diluted to at least 180–190 mOsm/kg H2O, which is the hemolymph osmolality of slugs at 75–70% IBW. The present results are consistent with the hypothesis that hydration modulation of feeding in slugs is mediated by hemolymph osmotic pressure.
Thermal acclimatization of hepatic polysubstrate monooxygenase and UDP‐ glucuronosyltransferase of mature rainbow trout (Salmo gairdneri)
Authors: Koivusaari Ulla
Published: June 2005

The thermal acclimatization of hepatic cytochrome P‐450‐dependent polysubstrate monooxygenase (PSMO) and UDP‐glucuronosyltransferase of mature rainbow trout (Salmo gairdneri) was studied.

The results indicate that the PSMO system, 7‐ethoxycoumarin and benzo(a)pyrene as substrates, shows almost ideal acclimatization pattern in autumn during water cooling. The enzyme activities were identical if measurements were carried out at acclimatization (=environmental) temperatures which were 20°C in August and 5°C in November. If a constant incubation temperature (18°C) was used, the PSMO activities were significantly higher in cold (5°C)‐acclimatized fish. The acclimatization process could be seen both in specific and total activities. The content of cytochrome P‐450 remains at constant level from August to November.

In early summer during water warming the PSMO activities increased considerably in both sexes in all incubation conditions.

The specific and total UDP‐glucuronosyltransferase activities were significantly higher in warm‐acclimatized fish both in the autumn and in the spring if the activities were measured at environmental temperature. No differences could be detected if the measurements were carried out at constant experimental temperature (18°C).
Unusual glucose phosphate isomerase isozyme patterns in lymphocytes from two C57BL/6J ↔ A/J allophenic mice
Authors: Balinsky Doris , Spannaus Donna J. , Yang Han‐Yi , Briggs Carol J. , Meyer Terry E. , Warner Carol M.
Published: June 2005

Analysis of C57BL/6J ↔ A/J allophenic mice for their lymphocyte composition, using H‐2 antigens as external markers, and glucose phosphate isomerase (GPI) isozymes as internal markers, has led to the discovery of two unusual mice. Both mice showed heterodimers of GPI isozymes upon electrophoresis of the lymphocyte lysate. Specific anti‐H‐2 antisera confirmed that the cells of the mice were of C57BL/6J and A/J origin, as expected, but that the “A/J” cells seemed to behave as F1 hybrids containing the Gpi‐1a and Gpi‐1b alleles. Possible origins of the Gpi‐1b allele in the “A/J” cells are discussed.
Experimental evidence for the accumulation of egg pigment in the brain cavities of Xenopus tadpoles
Authors: Kordylewski Leszek
Published: June 2005

The origin and fate of darkly pigmented clusters of cells that float freely in the brain cavities of the tadpoles of Xenopus laevis have been experimentally investigated. The results point to the conclusion that the clusters are the sites of egg pigment accumulation, which remain within the brain cavities or at its walls until metamorphosis.
Electron microscopic observations on sperm entry into eggs of the rose bitterling, Rhodeus ocellatus
Authors: Ohta Tadayuki , Iwamatsu Takashi
Published: June 2005

Morphological studies on gametes and sperm entry into the egg of Rhodeus ocellatus were conducted using transmission and scanning electron microscopy. The spermatozoon has a round head, a mitochondrion, and a flagellum but no acrosomal structure. The egg is enclosed in a chorion that has a micropyle at the animal pole. After a spermatozoon attaches to the well‐developed microvilli of the egg surface facing the micropyle, it is covered by the microvilli and incorporated into the egg cytoplasm with membrane fusion occurring between gametes. The egg cytoplasm just beneath the micropyle swelled a little while incorporating the spermatozoon and promptly plugged the micropyle. The nuclear envelope of the spermatozoon disappeared first at the apical region of the head and then progressed posteriorly through a process of vesiculation. The nucleus of the sperm head at once initiated decondensation upon incorporation through the effects of the egg cytoplasm. The mechanism of block to polyspermy in Rhodeus eggs is discussed.
Progesterone induces incubatory changes in the brooding pouch of the frog Gastrotheca riobambae (Fowler)
Authors: Del Pino Eugenia M.
Published: June 2005

Progesterone induces closure, vascularization, and the formation of embryonic chambers around inert beads in the brooding pouch of the frog Gastrotheca riobambae (Fowler). These changes of the pouch resemble those occurring during normal reproduction. In contrast to progesterone, human chorionic gonadotropin induces pouch closure only in females with large ovaries. The results suggest that pituitary gonadotropin indirectly induces the incubatory changes of the pouch by stimulating the secretion of a progesterone‐like hormone from the ovary.
Myosin expression in the developing ascidian embryo
Authors: Meedel Thomas H.
Published: June 2005

Myosin accumulation was examined in developing ascidian embryos by measuring its ATPase activity and by resolving myosin heavy chains on polyacrylamide gels. Both procedures used a myosin‐enriched fraction that was prepared by exploiting the unusual solubility properties of this protein. Myosin ATPase was first observed at neurulation and increased 25‐ to 50‐fold by the time of larval hatching, a sequence similar to that found previously for muscle acetylcholinesterase. This similarity to acetylcholinesterase, and the finding of at least two‐thirds of the ATPase activity in the larval tail, imply that most of the myosin studied was muscle myosin. The pattern of expression based on ATPase assays was confirmed in part by gel analysis, but since this technique was less sensitive the appearance of myosin heavy chain was not demonstrated unambiguously until later in development. As found earlier with acetylcholinesterase, actinomycin D treatment only interfered with accumulation of myosin ATPase during early stages of increasing enzymatic activity. Despite certain similarities noted in their ontogeny, differences in the initial increase in the activity of these enzymes and the time of their first response to actinomycin D suggest that the events concerned with the expression of acetylcholinesterase occur 1 hour before those of myosin ATPase. The appearance of these two proteins, representing different enzymes of the muscle cell, is probably controlled independently.