bluuebunny/crossref_metadata_2025 huggingface dataset:
Proliferative activity of somatic cells during gonadal development in the Japanese pond frog, Rana nigromaculata
Authors: Tanimura Akihiko , Iwasawa Hisaaki
Published: June 2005

Proliferative activities of gonadal somatic cells were examined autoradiographically during gonadal development in Rana nigromaculata. Both the germinal epithelium and the sexual cord appeared to be of coelomic epithelial origin, as indicated ultrastructurally by the observation that the 2 regions were covered with a common basal lamina. Cell‐proliferative activity was higher in the sexual cord than in the germinal epithelium at stage 29, suggesting that topographically specific active proliferation of coelomic epithelial cells contributed to the formation of the sexual cord. In the course of testicular development, high proliferative activity of the sexual cord was recognized until stage 32 (just after gonadal sex differentiation). At stage 43 (during metamorphosis), higher proliferative activity was noted in the germinal epithelium than in the sexual cord, and the germinal epithelium differentiated into seminiferous cords. There were no differences in proliferative activity between the germinal epithelium and sexual cord at stages 32 and 34 in the ovaries. At stage 43, there was higher proliferative activity in the germinal epithelium than in the sexual cord, and the germinal epithelium differentiated into follicular cells. These results suggest that both seminiferous cords and follicular cells are derived from germinal epithelium and that both pass through similar processes of development.
Zinc‐protein from rat prostate fluid binds epididymal spermatozoa
Authors: Sansone G. , Abrescia P.
Published: June 2005

The detection and the isolation of a zinc‐protein from the secretion of the rat dorsolateral prostate is described. The purification procedure, based on gel filtration and cationic exchange chromatography, allowed to separate a minor protein (Mr ≈︁ 66,000) from free zinc ions and other secretory components. Two zinc ions were estimated to be associated with one molecule of isolated protein. The zinc‐protein was labelled with 125I and then incubated at 37°C with spermatozoa from rat epididymal cauda. Time‐dependent in vitro binding of the radioactive protein to sperm cells was demonstrated. This binding was not affected by the presence of proteins from the seminal vesicle during the incubation, while it was blocked in the presence of an excess of unlabelled zinc‐protein. After binding, the labelled spermatozoa were treated with a buffer containing 0.5% sodium deoxycholate and 40 mM EDTA; only very small amounts of label were removed from the cells, thus suggesting that the zinc‐proteins were kept on the plasma membrane by interactions which do not involve merely hydrophobic bonds.
Metabolic consequences of exercise in organs of rainbow trout
Authors: Storey Kenneth B.
Published: June 2005

The effects of exhaustive swimming on a number of metabolic parameters were assessed in six organs of rainbow trout (Oncorhynchus mykiss). Glycogen phosphorylase was activated in four organs (liver, gill, heart, and white skeletal muscle), the largest increases in phosphorylase a activity being 5.3‐ and 6‐fold in liver and white muscle, respectively. Exhausted fish showed elevated lactate levels in all organs except brain with absolute increases of about 12 μmol/g wet weight in white and red skeletal muscles but only about 1 μmol/g in internal organs. ATP content dropped dramatically in skeletal muscles after exercise but remained constant in other organs. Fructose‐2,6‐bisphosphate levels rose in liver and brain but dropped in gill and heart during exercise. Kinetic properties of trout liver 6‐phosphofructo‐1‐kinase and pyruvate kinase were assessed in control versus exhausted fish. Neither enzyme showed changes in substrate affinities, ion cofactor affinities, or sensitivities to metabolite inhibitors or activators as a result of exercise, giving evidence that these liver enzymes (unlike glycogen phosphorylase) were not modified by reversible protein phosphorylation in response to muscle exercise. Exhaustive exercise also resulted in major changes in the levels of various free amino acids in trout organs. Alanine content rose by 9–11 μmol/g in heart, gill, and brain. Glycine increased by 12 μmol/g in white muscle and by 0.4–2 μmol/g in liver, heart, and gill. Several organs also showed significant changes in glutamate and glutamine contents and free histidine content increased in others, most notably by 2.8 μmol/g in white muscle. Organ‐specific patterns of response to the exercise stress are indicated.
Calcium regulation of epidermal cell differentiation in the frog Xenopus laevis
Authors: Shimizu‐Nishikawa Keiko , Miller Leo
Published: June 2005

Adult frogs have a stratified epidermis with a keratinized stratum corneum. Since the extracellular calcium concentration is known to regulate differentiation of mammalian epidermal cells in vitro, we studied the effects of calcium on the terminal differentiation of frog epidermal cells. Exposure of the epidermal cells to a high concentration of calcium (> 0.2 mM) induced cornification and the synthesis of a 51 Kd acidic keratin. These data are very similar to the results from mammalian epidermal cell cultures, suggesting that the mechanism of terminal differentiation is conserved throughout the evolution of terrestrial vertebrates.
Timed daily injections of neurotransmitter precursors alter the gonad and body weights of spotted munia, Lonchura punctulata, maintained under short daily photoperiods
Authors: Chaturvedi C. M. , Prasad S. K.
Published: June 2005

The present study was designed to examine the role of circadian organization in the control of seasonality in the seasonally breeding spotted munia, Lonchura punctulata, which does not utilize photoperiod to time its reproduction under natural day‐length conditions.

Daily injections of L‐dihydroxyphenylalanine (L‐DOPA, precursor of dopamine) given 12 hr and 8 hr after administration of 5‐hydroxytryptophan (5‐HTP, precursor of serotonin) alter the gonadal and body‐weight responses of the spotted munia, when it is maintained under short‐day conditions (LD 6:18). The 12‐hr interval was stimulatory and the 8‐hr interval was inhibitory for both gonadal and body‐weight responses while other intervals (0, 4, and 16 hr) had no effect. A 20‐hr interval was stimulatory only for gonadal growth and had no effect on body weight.

These findings support the suggestion that the endogenous seasonal mechanism is determined by circadian organization (i.e., by changes in the phase relationships of two neural oscillations and their many other circadian expressions). The results also indicate that interaction between these two systems does not produce any pharmacological effect but actually affects the seasonality of the birds, as indicated by the different gonadal and metabolic conditions that followed differently timed daily injections of drugs that influence serotonergic and dopaminergic activities. Furthermore, the mechanism of regulation of seasonality seems to be similar in species that do and do not utilize day length as the primary regulator with which to time their seasonal reproductive and metabolic cycles.
Reduced calcium and inhibition of protein kinase C mimic the enhancement of ornithine decarboxylase activity by prolactin in Ambystoma tigrinum tissues
Authors: Ibrahim Ragaa H. , Platt James E.
Published: June 2005

We previously reported that prolactin (PRL) could increase the activity of ornithine decarboxylase (ODC) in liver slices taken from larval tiger salamanders (Ambystoma tigrinum). This action of the hormone was inhibited by oxytocin (OT), the calcium ionophore A23187, and diacyglycerol (DG) and was duplicated by 10 μM verapamil (VML), a calcium channel blocker. Here, we expand these results to show that 1) a higher dose of VML (50 μM) produces an additive effect with PRL; 2) addition of small amounts of calcium (0.1 mM) to the liver culture medium blocks PRL action; 3) neither nifedipine (NIF), a different type of calcium channel blocker, nor EDTA alter PRL action; and 4) gossypol, a reported inhibitor of protein kinase C, mimics PRL action. Additionally, we show that PRL increases ODC activity in tiger salamander tail skin in vitro, a tissue previously demonstrated to be a PRL target tissue in this species. The same set of treatments which we have shown to modify PRL effects on ODC in liver slices affects PRL action in the tail skin in a parallel manner. Thus, the mechanism whereby PRL enhances ODC activity appears to be the same in both these tissues. These results are discussed in conjunction with the findings from similar studies using mammalian tissues in an attempt to assess the current picture of the mechanism of PRL action and the possible role of inositol phospholipid turnover, calcium, and protein kinase C in the action of this hormone.
Initiation of placental lactogen‐I production by blastocysts growing on a two‐dimensional surface and in hanging drops
Authors: Nieder Gary L. , Nagy Frank
Published: June 2005

The mouse blastocyst undergoes a program of protein secretion during the periimplantation period including the initial production of placental lactogen‐I (mPL‐I) on day 6 of pregnancy. Although blastocysts collected on day 5 also produce mPL‐I when cultured to form outgrowths on plastic dishes, it was not known if embryos have an intrinsic ability to produce mPL‐I during culture in vitro, or if a specific uterine influence is necessary. Earlier experiments also suggested that attachment of the trophoblast to a stable surface may be a prerequisite for synthesis of mPL‐I. Both questions were addressed by examining mPL‐I production by day 3 and day 4 embryos cultured either on a two‐dimensional tissue culture dish surface or in hanging drops. The presence of intracellular mPL‐I was assayed by immunohistochemistry, while the secreted hormone was detected by its known position in two‐dimensional electrophoresis gels. These experiments demonstrated that these earlier stage embryos do have an intrinsic program for mPL‐I production which proceeds in vitro under various culture conditions. Synthesis of mPL‐I occurred in embryos suspended in hanging drops as well as in those spreading on a solid two‐dimensional surface, thus showing that adhesion to a surface is not required for production of this hormone. Although some mPL‐I synthesis was seen in embryos cultured in medium containing BSA as the sole macromolecule, the inclusion of fibronectin either in dishes, where it supports attachment, or in the hanging drop system stimulated mPL‐I secretion. Serum supplementation in both culture systems further increased growth and differentiation of the embryo, as well as mPL‐I secretion, compared to fibronectin supplementation.
Variations in urinary output of the lobster
Authors: Cheng Jin‐Hua , Chang Ernest S.
Published: June 2005

Urinary rates were studied in cannulated juvenile lobsters. If animals were in intermolt and unfed, urinary rates were constant at daily rates of 2% and 20% of body weight in 100% and 75% seawater (SW), respectively. More than 4% of the body weight could be rapidly excreted as urine upon either feeding, forced drinking, or low salinity acclimation. These results indicate that the urinary bladders are usually filled with urine and that they are part of the body volume‐regulating system.

At ecdysis, however, urinary flow ceased when drinking rate increased, suggesting that the intermolt mechanism regulating body volume may have been altered. In 100% SW, drinking was necessary for lobsters to gain sufficient water to withdraw their claws at ecdysis. While in 75% SW, osmotic entry of water across the body surface alone was sufficient to permit a successful molt. These results indicate that water influx across the body surface may contribute to much of the water intake at ecdysis if the osmotic gradient is substantial and that the cessation of urinary flow contributes to the overall water balance at ecdysis.
At least half of capacitated, motile mouse sperm can fertilize zona‐free mouse oocytes
Authors: Ivani K. A. , Seidel G. E.
Published: June 2005

The percentage of individual sperm capable of fertilizing zona pellucida‐free mouse oocytes was investigated by placing motile sperm near zona‐free oocytes with a micromanipulator. Incubation with one or two capacitated sperm per oocyte resulted in 50% and 70% fertilization, respectively, compared to 88% for cumulus intact (105 sperm/ml) and 87% for zona‐free (2 × 103 sperm/ml) control oocytes. When sperm were treated with .1 μM calcium ionophore A23187 to facilitate the acrosome reaction, fertilization rates for single motile sperm were markedly lower than for capacitated, nontreated single sperm (4% and 35%, respectively). Similar fertilization rates resulted when one sperm was incubated per two ova (4% and 48% per sperm for A23187‐treated and controls, respectively). When a lower dose of A23187 (.001 μM) was used to treat sperm, 7% of oocytes incubated with single sperm were fertilized. These experiments demonstrate that at least half of motile, capacitated mouse sperm are capable of fertilizing zona‐free mouse oocytes in vitro, and that motile, A23187‐treated mouse sperm resulted in poor fertilization rates.
Cyanide detoxification in the mudskipper, Boleophthalmus boddaerti
Authors: Chew S. F. , Ip Y. K.
Published: June 2005

The tolerance of the mudskipper, Boleophthalmus boddaerti, to cyanide is higher than those of other fishes reported elsewhere. The 24 h, 48 h, and 96 h LC50 for B. boddaerti were 0.37 mg HCN/liter, 0.34 mg HCN/liter, and 0.29 mg HCN/liter, respectively. The tolerance of B. boddaerti to cyanide does not involve a reduction of metabolic rate or an enhanced anaerobic metabolism, or a cyanide‐insensitive respiratory pathway. Instead, it is a result of the presence of a surplus of cytochrome oxidase and inducible cyanide‐detoxifying mechanisms in this mudskipper. Although cytochrome oxidase activities in the various tissues of the fish exposed to 0.23 mg HCN/liter were inhibited by more than 50%, no reduction in the O2 consumption rate was observed. B. boddaerti could detoxify cyanide to thiocyanate. The activity of rhodanese in the liver extract of fish exposed to cyanide increased significantly compared to that of the control. The activities of cysteine amino‐transferase (CAT) and 3‐mercaptopyruvate sulfurtransferase (MPST) in the extracts from the liver and the muscle of B. boddaerti exposed to cyanide also increased significantly compared to those of the control fish. Glutamate formed in the reaction catalyzed by CAT could undergo transamination leading to the accumulation of aspartate in the muscle of the fish exposed to cyanide.
Effects of gonadotropin‐releasing hormone variants on plasma and testicular androgen levels in intact and hypophysectomized male frogs, Rana esculenta
Authors: D'Antonio Mauro , Fasano Silvia , de Leeuw Renato , Pierantoni Riccardo
Published: June 2005

The effects of vertebrate gonadotropin‐releasing hormone (GnRH) variants on plasma and testicular androgen level in intact and hypophysectomized (PDX) male frogs, Rana esculenta, have been investigated. In intact animals, mammalian (m)‐GnRH, m‐GnRH analog (buserelin), salmon (s)‐GnRH, chicken (c) I‐GnRH, cII‐GnRH, D‐Arg6‐cII‐GnRH (cII‐GnRHA), and lamprey (l)‐GnRH (1.5μg and 6μg, total dose given on alternate days for 5 days) were able to enhance androgen production showing that specificity of pituitary responsiveness to GnRH variants appears to be low. Chicken II‐GnRH was more effective than s‐GnRH in eliciting testicular and circulatory androgen level increase. Moreover, in animals treated with 6μg of cII‐GnRH and s‐GnRH in combination, androgens decreased as compared with animal treated with cII‐GnRH only, suggesting that GnRH receptors bind preferentially the s‐GnRH form. In PDX animals, buserelin (1.5 and 6μg), cII‐GnRH, and its analog (6μg) were able to increase plasma androgen levels whereas testis androgen concentrations were increased by cII‐GnRH (1.5 and 6μg), D‐Arg6‐cII‐GnRHA, and buserelin (6μg). Since androgen production in PDX animals is influenced especially by peptides sharing cII‐GnRH structure, it is suggested that a testicular cII‐GnRH‐like material play a role as local modulator of the gonadal activity in Rana esculenta.
Evolutionary modification of regenerative capability in vertebrates: A comparative study on teleost pectoral fin regeneration
Authors: Wagner G. P. , Misof B. Y.
Published: June 2005

The regenerative ability of the pectoral fins of 14 species from 6 euteleostean families was tested. Blastema formation and distal outgrowth was observed in all species, indicating the initiation of regeneration in all species tested. Interspecific variation exists with respect to the frequency of malformations and the patterns produced by heteromorphic regeneration. Taking into account published reports on pectoral fin regeneration, the systematic distribution of homo‐ and heteromorphic regeneration leads to the following conclusions: 1) regenerative ability of pectoral fins is a property inherited from the common ancestor of euteleosteans. Whether it is also the ancestral condition for the whole teleostean group cannot be determined, because reports on more primitive teleosteans like the herring and the osteoglossimorphs are missing. 2) A propensity to produce high frequencies of heteromorphic regenerates originated independently at least three times in Cypriniformes, Scorpaeniformes, and Perciformes. 3) Impaired regeneration is most commonly found in bottom fishes, although not all ground fish groups show heteromorphic regeneration. This suggests that impaired regeneration is not directly related to bottom dwelling, but most probably originated as a side effect of other adaptive changes. Hence, neither the presence nor the loss of faithful regeneration can be associated with particular adaptive scenarios in this group, since regeneration seems to be ancestral to all major euteleost groups and its loss has no clear adaptive significance. Whether there are adaptive reasons to maintain regenerative capability or whether there are cases of reestablishment of regeneration after it was lost cannot be decided on the basis of recent evidence. More observations on phylogenetically closely related species with variable regenerative capability are necessary to assess adaptive explanations of regeneration.
Developmental changes in the incidence of chromosome anomalies of bovine embryos fertilized in vitro
Authors: Iwasaki S. , Hamano S. , Kuwayama M. , Yamashita M. , Ushijima H. , Nagaoka S. , Nakahara T.
Published: June 2005

In total, 196 two‐ to 32‐cell bovine embryo and 104 blastocysts were obtained by the in vitro fertilization of follicular oocytes matured in vitro, and 15 blastocysts fertilized in vivo were used. Chromosomal anomalies in these embryos and the inner cell mass (ICM) separated immunologically were investigated. Chromosomal anomalies were observed in 12.1% (5/41) of 2‐cell embryos, 20.0–36.4% of 4‐ to 16‐cell embryos, 7.1% (1/14) of 17‐ to 32‐cell embryos, 44.2% (15/34) of blastocysts, and 18.6% (13/70) of ICM cells derived from in vitro fertilization. These anomalies were mainly 3N and 4N at 2‐cell stage, 1N and 1N/2N at 4‐ to 32‐cell stages, and 2N/4N in blastocysts and in their ICM cells. Chromosomal anomalies of blastocysts from in vivo fertilization and their ICM were observed in 20.0% (1/5) of blastocysts and 33.3% (3/9) of ICM cells and these compositions were mainly 2N/4N. These results indicate that the abnormalities at early and blastocyst stages of embryos derived from in vitro fertilization were caused by abnormal fertilization in vitro and abnormal cleavage, respectively. Furthermore, a definite location of the chromosomal anomalies was observed in the trophectoderm of blastocysts derived from in vitro fertilization.
Chordate testis: The extracellular matrix hypothesis
Authors: Grier Harry J.
Published: June 2005

Testis structure in the chordates has been evaluated based upon relationships between primary spermatogonia, Sertoli cells, and the changes in the chronological secretion of the extracellular basement membrane. Prespermatocystic, polyspermatocystic, lobular, and tubular testicular types are described. In all chordates, germinal and interstitial compartments are separated by a basement membrane. The timing of the formation of this separation varies with the chordate class. Although primary spermatogonia are not initially separated from the interstitial tissue in agnathans and elasmobranchs, a basement membrane forms around secondary spermatogonia and associated Sertoli cells before meiosis. The spermatocyst so formed is a unit of testicular evolution. In fishes and amphibians, Sertoli cells, primary spermatogonia, and the subsequent stages of germ cell development reside in spermatocysts. They are always sequestered from interstitial tissues by a basement membrane. Sertoli cells rest upon the basement membrane and their processes form the borders of spermatocysts. I propose the Extracellular Matrix Hypothesis to explain how changes in the chronological formation of basement membranes resulted in the evolution of lobular and tubular testes from spermatocystic testes.
Plasticity of gonadal development and protandry in fishes
Authors: Shapiro Douglas Y.
Published: June 2005

Sexual differentiation in eutherian mammals follows a simple governing paradigm: development proceeds in a female direction unless a masculinizing mechanism intervenes. Sexual development in fishes is much more plastic than in mammals. It permits the intervention of environmental factors and follows several different types of sequences that produce successive hermaphrodites and alternative pathways for the development of the same final sex. In spite of this plasticity, the primacy of female development is suggested by the initial ovarian phase in the development of gonads of both sexes in some gonochoristic fishes and by protogynous sex change. One barrier to the application of this principle to fishes generally is the existence of protandric hermaphrodites. Recent evidence suggests a reinterpretation of gonadal differentiation in a protandric anemonefish and a protandric sparid. In both cases, testicular development is both preceded and followed by ovarian development. These patterns are interpreted to mean that female development is primary and that male development is a temporary phase initiated by a masculinizing mechanism and terminated by its cessation.
Male reproductive system as sex pheromone producer in teleost fish
Authors: van den Hurk R. , Resink J. W.
Published: June 2005

Male zebrafish, Brachydanio rerio, have paired testes and no additional reproduction glands. Incubation experiments with 3H‐labeled steroid precursors showed the capacity of testes to synthesize seven steroid glucuronides. Enzyme histochemical studies demonstrated interstitial (Leydig) cells as steroid and steroid glucuronide producing sites. Male holding water, testis homogenates, and testis fractions containing steroid glucuronides were able to induce ovulation in female zebrafish. Deglucuronidation of these fractions led to a loss of ovulation inducing potency, indicating steroid glucuronides as ovulation inducers. The chemical substances are perceived by the recipients by means of olfaction, as anosmic females do not have an ovulatory response after administration of male holding water. In African catfish, Clarias gariepinus, the male reproductive organ system consists of two paired structures, the testis and the seminal vesicle. Histochemical enzyme investigations pointed to interstitial cells as sites of steroid and steroid glucuronide production both in testis and seminal vesicle. Glucuronidation of steroids may also take place in the epithelium lining and seminal vesicle tubules. Biochemical studies showed the seminal vesicle as the main source of steroid glucuronides. Eight conjugated steroids were identified. Electrophysiological studies demonstrated that these compounds, especially 5β‐pregnane‐3α, 17α‐diol‐20‐one‐glucuronide are olfactory stimulants in female conspecifics. Males with enlarged seminal vesicles, caused by compensatory growth after castration, were more attractive to ovulated female catfish in a two‐choice test, using a U‐shaped tank. Males lacking seminal vesicles were less attractive. The steroid glucuronide fraction of seminal vesicle fluid appeared to be responsible for the attraction effect. A synthetic mixture of steroid glucuronides resulted in a dose dependent attraction effect. The data are indicative of a pheromonal function for steroid glucuronides that are produced by the reproductive organ system of male zebrafish and African catfish.
Drosophila single‐minded gene and the molecular genetics of CNS midline development
Authors: Crews Stephen , Franks Robert , Hu Song , Matthews Beverley , Nambu John
Published: June 2005

Our goal is to understand the molecular mechanisms that govern the formation of the central nervous system. In particular, we have focused on the development of a small group of neurons and glia that lie along the midline of the Drosophila CNS. These midline cells possess a number of unique attributes which make them particularly amenable to molecular, cellular, and genetic examinations of nervous system formation and function. In addition, the midline cells exhibit distinctive ontogeny, morphology, anatomical position, and patterns of gene expression which suggest that they may provide unique functions to the developing CNS. The single‐minded gene encodes a nuclear protein which is specifically expressed in the midline cells and has been shown to play a crucial role in midline cell development and CNS formation. Genetic experiments reveal that sim is required for the expression of many CNS midline genes which are thought to be involved in the proper differentiation of these cells.

In order to identify additional genes which are expressed in some or all of the midline cells at different developmental stages, a technique known as enhancer trap screening was employed. This screen led to the identification of a large number of potential genes which exhibit various midline expression patterns and may be involved in discrete aspects of midline cell development. Further molecular, genetic, and biochemical analyses of sim and several of the enhancer trap lines are being pursued. This should permit elucidation of the genetic hierarchy which acts in the specification, differentiation, and function of these CNS midline cells.
Specificity of VIIIthnerve regeneration in lower vertebrates
Authors: Davis Robin L.
Published: June 2005

From the initial studies of Sperry (Am. J. Physiol, 144:735–741, 1945) to more recent investigations, the regenerative capacity of the VIIIthcranial nerve in nonmammalian vertebrates has been noted for its robust and accurate recovery of functional connections after transection. The VIIIthcranial nerve contains nerve fibers that link functionally distinct sensory epithelial to various areas within the central nervous system (CNS), yet after transection these multiple components of the nerve navigate back to their original central target areas, without innervating inappropriate nuclei. A number of factors may be required to establish and direct VIIIthnerve regeneration. Cellular interactions appear to be necessary for the initiation of outgrowth and the maintenance of neural connections. The release of chemotropic substances from target cells has been postulated as the most likely mechanism guiding the reinnervation of central targets. Furthermore, the growth characteristics of these neurons in tissue culture, without target cells present, indicates that intrinsically regulated growth features may also contribute to the process of VIIIthnerve regeneration.
Functional regeneration and recovery of locomotor activity in spinally transected lamprey
Authors: McClellan Andrew D.
Published: June 2005

Spinally transected lamprey recovery locomotor function within 3–6 weeks, and recovery is due, in part, to functional regeneration of neural pathways in the central nervous system (CNS). Our data demonstrate for the first time in the lamprey that descending axons arising from brainstem command neurons can functionally regenerate and restore locomotor initiation below a healed spinal transection site. Immediately after behavioral recovery (3–6 weeks) the locomotor pattern was incomplete but returned to normal during the remainder of the recovery period (6–40 weeks). Initially, the extent of regeneration of descending axons was limited but increased to at least 30–50 mm at recovery times of 24–40 weeks. Regenerated giant Muller axons do not contribute significantly to recovery of locomotor function; rather, regenerated axons of smaller reticulospinal neurons appear to restore locomotor initiation. The restoration of locomotor coordination across a spinal lesion is dependent on two mechanisms: regeneration of spinal coordinating neurons and mechanosensory inputs. Comparisons are made to spinal cord regeneration in other lower vertebrates and to the relative lack of CNS regeneration and behavioral recovery in higher vertebrates.
Secondary sex characteristics and related physiological values in male fallow deer (Dama dama L.) and their relationships to changes in the annual cycle of daylengths: Frequency alterations to 4‐ and 3‐month photoperiodic cycles, and subsequent re‐synchronisation under natural conditions
Authors: Schnare H.
Published: June 2005

Five adult male fallow deer were maintained in a barn with artificial light control. In a previous experiment, three 6‐month photoperiodic cycles entrained morphogenetic and associated physiological values that revealed typical relationships to the antler cycle.

Presented here, the light cycle was accelerated to three 4‐ and one 3‐month photoperiods in the same group. Each artificial photoperiod generally resulted not only in an almost complete antler cycle but also in an entire cycle of seasonal fluctuations in neck girth. Increases in plasma levels of alkaline phosphatase (AP), total‐, LDL‐ and HDL‐cholesterol, were generally entrained and the maxima revealed positive correlations with antler formation, but the relationships slightly diverged. In neck girth and creatinine, positive correlations to the hard antler period as well as to each other prevailed but diverged. In the 3‐month photoperiodic cycle, these relationships were out of synchrony. In the second 4‐month cycle, two bucks “missed” shedding and subsequent casting, but commenced antler growth in the following cycle with an in‐time shedding. The possibility of desynchronisation of physiological conditions and the question of an endogenous circannual mechanism interacting with daylight are discussed.

At the end of the 3‐month cycle, experimental indoor and natural outdoor casting was coincident so the group was transferred to outside conditions for re‐synchronisation. After spending altogether 36 months in frequency altered photoperiods, the represented values were neither synchronized nor revealed their typical relationships to the antler cycle, except of AP and neck volume. In the second cycle of re‐synchronisation, all parameters, except of creatinine, appeared to be resynchronized.
Presence of a trypsin‐like protease in starfish sperm acrosome
Authors: Sousa Mário , Moradas‐Ferreira Pedro , Azevedo Carlos
Published: June 2005

Marthasterias glacialis sperm cells were treated with ionophore A23187, centrifuged, and the supernatants were assayed for esterase activity. With N‐benzoyl‐L‐arginine ethyl ester‐HCl (BAEE) as substrate, a net activity was determined which was not detectable when N‐acetyl‐L‐tyrosine ethyl ester (ATEE) was used. The BAEE trypsin‐like activity was inhibited by soybean trypsin inhibitor (SBTI), N‐α‐p‐tosyl‐L‐lysine chloromethyl ketone‐HCl (TLCK), and phenyl methyl sulfonyl fluoride (PMSF), but not by L‐1‐tosylamido‐2‐phenylethyl chloromethyl ketone (TPCK). The presence of proteolytic activity in acrosomal exudates was further demonstrated by gelatin‐sodium dodecyl sulfate‐polyacrylamide gel electrophoretic zymography (gelatin‐SDS‐PAGE). The presence of several bands of low proteolytic activity and of one band of high proteolytic activity, which also has the lower molecular weight, together with the fact that all are inhibited by benzamidine, suggests the existence of a trypsin‐like proteinase system. The effect of the acrosomal exudate on the oocyte jelly coat was investigated by SDS‐PAGE analysis. All jelly proteins appeared to be digested by the acrosomal enzymes. Furthermore, if SBTI is added shortly after insemination, the sperm fail to fertilize the oocytes. These results indicate that the starfish sperm acrosomal vesicle contains a trypsin‐like protease which may be involved in sperm penetration through the oocyte jelly coat.
Tissue‐specific metabolism during normothermy and daily torpor in deer mice (Peromyscus maniculatus)
Authors: Nestler James R.
Published: June 2005

Previous work with deer mice (Peromyscus maniculatus) has demonstrated that a significant acidosis occurs during daily torpor. In addition, carbohydrate levels are significantly lower, whereas fatty acid and ketone levels are significantly higher during torpor. The present study examined the effects of these in vivo acid‐base and metabolite adjustments on in vitro 14C‐glucose metabolism in tissues taken from normothermic and torpid deer mice. Glucose oxidation in liver and vastus lateralis taken from normothermic animals was reduced by a change in incubation temperature from 37°C to 25°C (liver, 0.44 to 0.23 μmoles/g.h; vastus, 0.66 to 0.25 μmoles/g.h), whereas heart from normothermic mice exhibited an increase from 0.57 to 0.99 μmoles/g.h at the lower temperature. Altering acid‐base conditions or metabolite levels had no effect on glucose metabolism in the heart or liver. However, both of these factors significantly influenced metabolism in vastus. Vastus taken from normothermic mice had an increased glucose oxidation rate under the more acidic torpor conditions (0.25 to 0.33 μmoles/g.h), whereas a reduction in oxidation occurred when incubated with torpor substrate concentrations (0.33 to 0.22 μmoles/g.h). In vastus taken from torpid mice, changing acid‐base state and metabolites to torpor levels resulted in a significant reduction in glucose oxidation (0.26 to 0.12 μmoles/g.h). Under most incubation conditions, glucose oxidation was significantly lower in tissues taken from torpid mice than in these tissues from normothermic mice, suggesting that adjustments in addition to changes in acid‐base and substrate parameters may be necessary to account for metabolic modifications during daily torpor. © 1992 Wiley‐Liss, Inc.
Thyroid hormone stimulates gastric development in flounder larvae during metamorphosis
Authors: Miwa Satoshi , Yamano Keisuke , Inui Yasuo
Published: June 2005

To elucidate the hormonal regulatory mechanisms of gastric development of the flounder, Paralichthys olivaceus, premetamorphic flounder larvae were treated with either 100 ppb of L‐thyroxine sodium salt (T4), or 30 ppm of thiourea (TU, a goitrogen) by dissolving drugs in ambient seawater. Control fish were reared in untreated seawater. Measurement of gastric gland volume with an image analyzing system revealed that the T4 treatment markedly increased the volume of the glands. Immunocytochemistry using an antiserum raised against purified quail pepsinogen as the primary antibody showed precocious appearance of pepsinogen‐like immunoreactivity in the gastric glands of the larvae treated with T4. In contrast, the gastric glands of the larvae treated with TU remained undifferentiated throughout the experiment. The volume of the glands of TU‐treated larvae was very small and immunoreactivity for antiquail pepsinogen was very weak even at the end of the experiment (4 weeks after the start of the experiment) when control fish had well‐developed gastric glands. These results strongly suggest that thyroid hormone stimulates differentiation of gastric glands during metamorphosis of the flounder. © 1992 Wiley‐Liss, Inc.
Relationship between cell size and nuclear volume in nucleated red blood cells of developmentally matched diploid and tetraploid mouse embryos
Authors: Henery C. C. , Kaufman M. H.
Published: June 2005

Analysis of control diploid and polyploid amphibia indicated that cell and nuclear volumes were closely related to their ploidy, so that an increase in ploidy was generally associated with an increase in cell size. This relationship is also believed to occur in mammalian polyploids. However, since the latter are only rarely encountered spontaneously, or only occasionally following experimental manipulation, no detailed morphometric studies have been carried out to date to confirm whether such a relationship exists. In this study, the cellular and nuclear volume of primitive red blood cells was analyzed in carefully developmentally matched control diploid mouse embryos and tetraploid embryos produced by the technique of electrofusion. All of the cells and/or nuclei studied had a characteristic spherical shape which greatly simplified the morphometric analysis. A defined and predictable relationship between ploidy and cellular and/or nuclear volume was observed in the red blood cells between 8.25 and 14.5 days of gestation. During this period the primitive red blood cells are gradually replaced by the definitive erythrocytes. The ratio of control values to tetraploid values was found to be close to the theoretical value of 1:2 when comparable cells and/or their nuclei were analyzed in carefully developmentally matched material. © 1992 Wiley‐Liss, Inc.
Serosa ontogeny in two embryonic morphs of Copidosoma floridanum: The influence of host hormones
Authors: Baehrecke E. H. , Grbić M. , Strand M. R.
Published: June 2005

The embryos of 2 larval morphs of the insect parasitoid Copidosoma floridanum (Ashmead) (Hymenoptera: Encyrtidae) were readily distinguished on the basis of temporal and morphological characters. Although larvae of the 2 morphs diftered in morphology and timing of hatch, both morphs derived a serosal membrane just prior to embryonic morphogenesis. Nuclei of the serosa increased in diameter and ploidy during development. Serosa polyploidy was similar in both morphs at identical stages of morphogenesis. Host endocrine perturbations that blocked C. floridanum morphogenesis also affected serosa development. Serosa ontogeny was blocked when the host was ligated at 7 h of the 4th stadium. Daily application of the juvenile hormone analogue methoprene starting at 20 h of the host's 3rd stadium resulted in serosal nuclei with greater diameters and ploidy values than those of untreated embryos. Treatment of the host with methoprene beginning at 20 h of the 3rd stadium followed by ligation at 7 h of the 4th stadium arrested serosa ontogeny and embryonic growth of the parasitoid. These data indicate that embryos of both morphs of C. floridanum formed a serosa just prior to morphogenesis and that serosa ontogeny required host head factors. Furthermore, host juvenile hormone did not influence serosa ontogeny but stimulated polyploidy of membrane nuclei. © 1992 Wiley‐Liss, Inc.
A highly repetitive interspersed sequence isolated from genomic DNA of the Medaka, Oryzias latipes, is conserved in three other related species within the genus Oryzias
Authors: Naruse Kiyoshi , Mitani Hiroshi , Shima Akihiro
Published: June 2005

A highly repeated interspersed sequence (OLR1) was isolated from a genomic DNA library of the Medaka, Oryzias latipes. The OLR1 was about 160 base pairs (bp) in length. As judged from the results of colony hybridization experiments, OLR1 is one of the major repeated DNA sequences in the Medaka genome and is present in every 136 kb on average. Results of Southern and colony‐hybridization analyses indicate that OLR1 is a small interspersed repetitive element (SINE). OLR1‐related sequences were conserved in other three species (O. luzonensis, O. curvinotus, and O. mekongnensis) within the genus Oryzias as a repetitive sequence. These results lend support at the DNA level to the hypothesis that these four species form one group in the genus Oryzias, as has been suggested from an analysis of their karyotypes (Magtoon and Uwa, '85, Proc. Jpn. Acad., Ser. B, 61:157–160). © 1992 Wiley‐Liss, Inc.
Tissue‐specific and dietary control of alpha‐amylase gene expression in the adult midgut of Drosophila melanogaster
Authors: Thompson D. Bruce , Treat‐Clemons Lynda G. , Doane Winifred W.
Published: June 2005

The regulatory effects of allelic substitution at the trans‐acting mapP locus and of dietary glucose on the expression of the duplicate genes for alpha‐amylase (Amy) in Drosophila melanogaster were examined in the anterior midgut and posterior midgut regions of mature flies. The levels of amylase activity and amylase protein, as well as the abundance of amylase‐specific RNA, were quantified. All 3 parameters of Amy expression were concordant. Results indicate that the effects of both mapP and dietary glucose are exerted at the level of amylase RNA. However, the tissue‐specific effects of mapP are restricted to the posterior midgut and can therefore be distinguished from the effects of glucose in food medium, which influences amylase RNA levels in both the anterior and posterior midgut regions. Our data suggest that, in large part, strain‐specific effects of dietary glucose can be explained on the basis of alternate alleles at the mapP locus in different homozygous strains of flies.

Levels of amylase RNA in tissue extracts of flies from an amylase‐null strain were also measured. Low levels were observed in both anterior and posterior midgut extracts. These were unresponsive to dietary conditions. © 1992 Wiley‐Liss, Inc.
The role of microtubules in contractile ring function
Authors: Conrad Abigail H. , Paulsen Avelina Q. , Conrad Gary W.
Published: June 2005

During cytokinesis, a cortical contractile ring forms around a cell, constricts to a stable tight neck and terminates in separation of the daughter cells. At first cleavage, Ilyanassa obsoleta embryos form two contractile rings simultaneously. The cleavage furrow (CF), in the animal hemisphere between the spindle poles, constricts to a stable tight neck and separates the daughter cells. The third polar lobe constriction (PLC‐3), in the vegetal hemisphere below the spindle, constricts to a transient tight neck, but then relaxes, allowing the polar lobe cytoplasm to merge with one daughter cell. Eggs exposed to taxol, a drug that stabilizes microtubules, before the CF or the PLC‐3 develop, fail to form CFs, but form stabilized tight PLCs. Eggs exposed to taxol at the time of PLC‐3 formation develop varied numbers of constriction rings in their animal hemispheres and one PLC in their vegetal hemisphere, none of which relax. Eggs exposed to taxol after PLC‐3 initiation form stabilized tight CFs and PLCs. At maximum constriction, control embryos display immuno‐localization of nonextractable α‐tubulin in their CFs, but not in their PLCs, and reveal, via electron microscopy, many microtubules extending through their CFs, but not through their PLCs. Embryos which form stabilized tightly constricted CFs and PLCs in the presence of taxol display immuno‐localization of nonextractable α‐tubulin in both constrictions and show many polymerized microtubules extending through both CFs and PLCs. These results suggest that the extension of microtubules through a tight contractile ring may be important for stabilizing that constriction and facilitating subsequent cytokinesis. © 1992 Wiley‐Liss, Inc.
An autoradiographic time study during regeneration in fully differentiated Xenopus eyes
Authors: Underwood Lauren Wunsh , Ide Charles F.
Published: June 2005

Nasal one‐third sized fragments were created from fully differentiated larval Xenopus eyes (stage 47). At various times post‐surgery, animals were injected with tritiated thymidine. All animals were fixed 1 day post‐injection. Animals injected 1 day post‐surgery showed limited healing and thymidine labeling in the retina. In animals injected 1 week post‐surgery, heavy thymidine label was localized in the ventrotemporal retina in a “thickened” neuroepithelium internal to the extending pigmented retinal epithelium. In contrast, the dorsal retina showed no apparent extra labeling, but rather resembled normal ciliary margin. In animals injected 1 month post‐surgery, the eye fragment regained normal size and retinal layering, and the label was restricted to the ciliary margin. Regenerative growth associated with healing appeared to have been completed by this time.

This extra cell division that occurs during the 1st month post‐surgery may underlie novel axonal targeting properties shown by nasal one‐third sized fragments. For example, these findings are consistent with the idea that pattern duplication of the visuotectal projection in nasal one‐third sized eye fragments occurs via intercalary cell division during healing and regeneration. © 1992 Wiley‐Liss, Inc.
In vitro allogeneic cytotoxicity in the solitary urochordate Styela clava
Authors: Kelly Karen L. , Cooper Edwin L. , Raftos David A.
Published: June 2005

Hemocytes from the solitary urochordate Styela clava can effect allogeneic cytotoxicity in vitro. Spectrophotometric and microscopic quantification of eosin‐y dye exclusion revealed significantly greater frequencies of cell death in allogeneic hemocyte cultures when compared to autogeneic controls. This cytotoxic response was characterized by 1) transient activity such that specific cytotoxicity could be detected for only 4 hours of culture though continued specific killing may have been obscured by spontaneous cell death; 2) a necessity for cellular interaction demonstrated by the elimination of allogeneic cytotoxicity in the absence of cell contact; 3) killing of multiple targets by effector cells due to high levels of response at low allogeneic ratios; 4) insensitivity to altered temperature; 5) increased cytotoxicity in the absence of autologous plasma; 6) an absence of xenogeneic reactivity; 7) the presence of three hierarchical levels (low, intermediate, and high) of response. These data reflect events involved in the recognition of allogeneic cellular determinants resulting in specific cytotoxicity effected by immunocompetent cells. Such in vitro recognition and cytotoxic recognition and cytotoxic reactivity may be responsible for adaptive reactions caused by histoincompatibility in solitary tunicates. © 1992 Wiley‐Liss, Inc.
Length regulation in the Dictyostelium discoideum slug is a late event
Authors: Breen Edmond J. , Eliott Susannah , Vardy Phil H. , White Angela , Williams Keith L.
Published: June 2005

Time‐lapse video light microscopy was used to study the emergence and maturation of the migratory slug from a D. discoideum aggregate. The anterior part, the tip of this simple multicellular organism, establishes migration prior to the definition of the rear, and hence the length of the slug. It was found that newly formed slugs of wild‐type strain WS380B can reach lengths greater than 1 cm, yet mature slugs of this strain are rarely longer than 2–3 μmm. Often the tip extended out of the aggregation mound upon an arching pillar of cells. After the tip first touched the substratum, it commenced migration with a rapid succession of movement steps. Here we show that at the initiation of migration, a differential rate of cell movement along the developing slug axis results in a series of complicated changes, before the stable and mature shape of the slug is formed. Our results lead to new conclusions about D. discoideum slug formation and shape maintenance. Evidence is presesnted for regulation of slug length. © 1992 Wiley‐Liss, Inc.