bluuebunny/crossref_metadata_2025 huggingface dataset:
Myosin isoforms and their subunits in the lungfish Protopterus annectens: Changes during development and the annual cycle
Authors: Chanoine Christophe , El‐Attari Ahmed , Guyot‐Lenfant Michèle , Ouedraogo Lazare , Gallien Claude‐Louis
Published: June 2005

Myosin isoforms and their light and heavy subunits were analyzed, in a comparison with the profile of myosin ATPase during the development and annual cycle of the African lungfish Protopterus annectens. Axial muscle of the larvae contained three isoforms of larval myosin. In adult animals, larval isomyosins were shown to coexist with small amounts of fast isomyosins in axial muscle. By contrast, fin muscles displayed essentially the fast isomyosins and a slow myosin isoform. No significant differences were noted in myosin content between swimming, cocooning, and water‐readapted animals. Larval and fast myosin isoforms were composed of two different heavy chains, HCI and HCf, respectively, in association with fast light chains. The slow myosin isoform was characterized by a distinct heavy chain, HCs, which was associated with two slow light chains. Analysis of the profile of myosin ATPase revealed only type IIC fibers in the axial muscles of larvae, while the adult muscles were composed of type IIC fibers in the central part and adult type IIA, IIB, and I fibers in the peripheral part. This study shows that P. annectens resembles the neotenic urodelan amphibian Ambystoma mexicanum at the level of the distribution of muscle fiber types and the expression of myosin isoforms. © 1994 Wiley‐Liss, Inc.
Effects of impregnation on maturation, spawning, and ecdysis of female shrimp Penaeus indicus
Authors: Peeters L. , Diter A.
Published: June 2005

Impregnation of females (i.e., spermatophore transfer) is known to occur soon after ecdysis in closed thelycum penaeids, while no sign of female maturation is visible yet. The influence of impregnation on maturation, spawning, and intermoult duration was assessed in Penaeus indicus females with or without unilateral eyestalk ablation. Impregnation, when occurring in unablated females, was found to significantly increase the percentages of maturing females (93–100% vs. 40–47%) and spawning females (86–100% vs. 20%), the number of spawns per female (1.46–1.91 vs. 0.26–0.40), and the intermoult duration (13.16–13.53 vs. 11.36–11.86 days). No remnants of impregnation was detected since its effects on the various parameters studied were restricted to the moult cycle where it occurred. Unilateral eyestalk ablation induced effects similar to those of impregnation on the reproduction parameters studied, but did not extend the length of the moult cycle. Impregnation of females that have been previously unilaterally ablated induced no change in any parameter studied including the intermoult duration. These findings suggest that impregnation interacts with certain physiological processes controlled by the X organ‐sinus gland neuroendocrine complex, located in the eyestalk. © 1994 Wiley‐Liss, Inc.
Experimental conditions for oocyte maturation in the zebrafish, Brachydanio rerio
Authors: Selman Kelly , Petrino Teresa R. , Wallace Robin A.
Published: June 2005

An in vitro protocol was established for studying oocyte maturation in the zebrafish, Brachydanio rerio. When appropriate size follicles (0.575–0.625 mm diameter) were incubated at 26°C for 8–24 h in 60% Leibovitz L‐15 medium containing 1 μg/ml of 17α,20β‐dihydroxy‐4‐pregnen‐3‐one (DHP), their oocytes underwent maturation. Under these conditions, but in the absence of exogenous steroid, control follicles remained arrested in prophase I. Germinal vesicle breakdown was used to indicate that maturation had occurred, and this event was readily visible in living follicles viewed through a dissecting microscope. Furthermore, as maturation takes place, the rather opaque prematurational follicles became translucent. In the process of establishing a reliable in vitro bioassay for oocyte maturation in the zebrafish, we compared the effects of gonadotropin (human chorionic gonadotropin) and a steroid hormone (DHP) on the in vitro stimulation of maturation, over a range of doses and incubation times. Finally, the relative effectiveness of several steroids and their metabolites in eliciting oocyte maturation in vitro was determined, and DHP appeared to be most effective. © 1994 Wiley‐Liss, Inc.
Pathways of regeneration of Haller's sensory organ during the life cycle of the tick Hyalomma asiaticum
Authors: Belozerov Valentin N. , Leonovich Sergei A.
Published: June 2005

A study of regeneration in nymphs and adults of the Asiatic desert tick, Hyalomma asiaticum, from which forelegs had been amputated during the previous instar, revealed that regenerated Haller's sensory organs exhibited significant changes in structure. Adult regenerates possessed atavistic features in terms of the number and topography of different sensillar types. Regularity in these changes was similar to that demonstrated in regenerates of Ixodes ricinus (Leonovich and Belozerov [1992] Exp. Appl. Acarol., 15: 59–79). Nymphal regenerates, by contrast, had larval features of the parent species. An hypothesis is presented about the ontogenesis of the complete, peripheral, polymodal sensory organ as a process in which the initial cell differentiation of cells begins at different starting points. © 1995 Wiley‐Liss, Inc.
Fluctuations in the biosynthetic activity of the prothoracic gland in recessive trimolters of the silkworm, Bombyx mori: Their modulation by juvenile hormone and physiological significance
Authors: Gu Shi‐Hong , Chow Yien‐Shing , Lin Fei‐Jann
Published: June 2005

Changes in the steroidogenic competence of prothoracic glands and their modulation by juvenile hormone (JH) were examined in recessive trimolters(rt)of the silkworm, Bombyx mori. These rt mutants have four larval instars rather than the five larval instars of normal silkworms. A small peak of prothoracic gland activity was found to occur during the early stage of the last (fourth) larval instar. The activities of both the prothoracic gland and the corpora allata (CA) were, however, greatly inhibited during the third instar after the third instar larvae have been treated with an imidazole compound (KK‐42). No small peak of prothoracic gland activity was detected during the early stage of the last instar in these treated larvae. The pattern of secretion from the prothoracic gland during the third instar was not significantly affected when hydroprene was applied to the KK‐42‐treated larvae during the prolonged third instar. However, the same small peak of activity, as found in untreated rt larvae, was detected during the early last instar. A model was developed from the results of the present study which clearly shows how the slight fluctuations in the activity of the prothoracic gland are regulated. By treating newly ecdysed last instar larvae with KK‐42 and by the addition of 20‐hydroxyecdysone to the food supplied to these larvae, we conclude that the decrease after small increase in the ecdysteroid titers and subsequent low ecdysteroid levels during the early last larval instar play an important role in initiating the decline of the JH biosynthetic rate and in directing precocious metamorphosis. © 1995 Wiley‐Liss, Inc.
Regulation of ovarian recrudescence: Different effects of corticotropin in small and large female lizards, Anolis carolinensis
Authors: Summers Cleff H.
Published: June 2005

Subcutaneous injection of 50 mU of ovine adrenocorticotropic hormone (ACTH) stimulates an increase in plasma corticosterone in Anolis carolinensis, after 30 min equivalent to maximum levels of stress‐induced plasma corticosterone. Plasma corticosterone returned to noninjection levels by 4 h. Injection of 50 mU ACTH, daily at 1630, into female A. carolinensis treated with stimulatory temperature and light, effected ovarian recrudescence; however, the effect depended upon the size of the lizard. Ovarian growth in small lizards (≥2.6 g) was inhibited by ACTH. In these animals ovaries regressed in size and oviducts remained quiescent. In larger females (<2.6 g) ovarian recrudescence continued in spite of ACTH administration and the consequent stimulation of higher levels of plasma corticosterone. Oviducts were significantly heavier in this group as well, indicating that ovaries were not only larger and heavier, but were secreting estrogens as well. The results of these experiments suggest that differently sized females of this species respond to hormones of the adrenal axis differently, and perhaps to stress as well. Specifically, Whereas ACTH administration inhibits ovarian growth in small anoles as it does in other vertebrates, it appears to have no effect or to enhance ovarian growth in large female A. carolinensis. © 1995 Wiley‐Liss, Inc.
Tubulin and microtubule‐associated protein pools in unfertilized and fertilized eggs of the trout Oncorhynchus mykiss
Authors: Farías Gustavo , González Mauricio , Maccioni Ricardo B.
Published: June 2005

A molecular characterization of tubulin and microtubule‐associated proteins (MAPs) along with their intracellular pool distributions in both unfertilized and fertilized oocytes of the trout Oncorhynchus mykiss was carried out. In vitro assembly of microtubular proteins was obtained by cycles of assembly‐disassembly and by taxol‐induced polymerization, thus allowing identification of the protein components of isolated microtubules from the oocyte. Extraction procedures were developed in order to separate molecular components of the egg vitelum prior to purification steps. The use of antibodies that specifically tag tubulin and a set of site‐directed probes against repetitive binding sequences on MAPs provided data on the presence of tubulins and enabled the identification of an 85‐kDa protein that shares common functional epitopes with mammalian MAPs. An enzyme‐linked immunosorbent assay analysis of the free soluble tubulin pools revealed a significant decrease in the pool extent during fertilization as compared with unfertilized oocytes controls. Interestingly, this decrease in free tubulin in the fertilized trout oocyte appeared to be accompanied with a concomitant increase of the assembled tubulin pools. Within the context of the known effects of heat shock in oocyte fertilization, temperature changes from 4 to 26.5°C of fertilized eggs resulted in a transient increase in the soluble tubulin pools during the initial 5‐min heat incubation, decaying after 10 min treatment, to reach at 15 min the levels of soluble tubulin pools of untreated controls. Total tubulin pools remained constant during the heat incubations of fertilized eggs. The distribution of MAPs pools in the oocyte was also investigated using the specific immunological probes. In contrast to tubulin no major differences were found between free MAPs pools of the fertilized oocytes as compared with unfertilized controls. However, heat shock treatment of fertilized oocytes also induced a transient increase in free MAP pools during the first 5 min followed by a mobilization of immunoreactive MAP components from the soluble to the assembled pools. © 1995 Wiley‐Liss, Inc.
Photoperiod‐induced changes in the proteins secreted by the male genital tract of the rodent Octodon degus
Authors: Carballada Rosa , Bustos‐Obregón Eduardo , Esponda Pedro
Published: June 2005

The proteins secreted by the male genital tract were analyzed in the seasonally breeding rodent Octodon degus. The protein patterns from the fluids collected from sexually active animals were compared with those from animals in resting period, with others which were previously castrated, and with castrated animals which received testosterone replacement treatment. Fluids from cauda epididymides (CE), seminal vesicles (SV) and prostate glands (PG) were collected, and analyzed by polyacrylamide gel electrophoresis followed by different staining methods and densitometry. Modifications were detected in the protein patterns of resting or castrated animals. In CE fluid, the decrease of one protein band (45 Kda) and the uprising of another (210 Kda) were recognized after castration. In animals during resting period the changes were not as marked as in castrated animals. SV secretion demonstrated a similar response to resting phase and castration, because Protein SVS I (200 Kda) decreased or were not observed when these conditions occurred. PG fluid proteins were also modified after castration. In general, the more severe changes in the protein spectrum were induced by castration, despite radioimmunoassay showing that testosterone fall is even higher in resting period animals than in those castrated. Testosterone replacement resulted in recovery of a protein profile which is very similar to that of sexually active males. Results suggest that the androgenic control of male tract secretions would be rather different in this seasonal hystrichomorph when compared to the regulation system described for myomorph rodents. © 1995 Wiley‐Liss, Inc.
Cortisol stimulates the size and number of mitochondrion‐rich cells in the yolk‐sac membrane of embryos and larvae of tilapia (Oreochromis mossambicus) in vitro and in vivo
Authors: Ayson Felix G. , Kaneko Toyoji , Hasegawa Sanae , Hirano Tetsuya
Published: June 2005

The effect of cortisol and thyroid hormones on the activity of mitochondrion‐rich (MR) cells in the yolk‐sac membrane of tilapia (Oreochromis mossambicus) embryos and larvae was investigated. MR cells were identified by the fluorescent mitochondrial stain DASPEI. Yolk‐sac membranes from 4‐day‐old embryos in fresh water (FW) were incubated for 24 h in medium supplemented with cortisol, thyroxine (T4), or triiodothyronine (T3). Treatment with cortisol at 0.1 μ/ml and higher significantly increased the population of MR cells and the intensity of fluorescence compared with the control, whereas MR cell size was not affected. Treatments with T4 and T3 did not affect MR cell density, size, or intensity of fluorescence.

Four‐day‐old embryos in FW were immersed for 10 days in FW supplemented with cortisol, T4, or T3. A significant increase in MR cell size was observed starting on day 3 after treatment with 100 μ/ml cortisol. Treatment with lower doses of cortisol produced increases in the cell size on later days. Density of MR cells was significantly increased only on day 9. Treatment with T4 produced inconsistent results. Treatment with T3 did not affect MR cell size or density at any time. None of the three hormones affected the intensity of fluorescence of MR cells. The stimulatory activity of cortisol on MR cells in the yolk‐sac membrane suggests that cortisol, present in the yolk of tilapia embryos and larvae, may be involved in osmoregulation during the early life stages of fish. © 1995 Wiley‐Liss, Inc.
Effects of castration on antler growth in fallow deer (Dama dama L.)
Authors: Kierdorf Uwe , Kierdorf Horst , Knuth Susanne
Published: June 2005

Morphology and histological structure of antlers grown after castration (performed on March 25) were studied in six young fallow bucks. In the year after castration, antlerogenesis occurred during the species‐specific time span, and the shape of the antlers, which remained permanently in velvet, was normal. During a cold period in December/January, the distal parts of the antlers suffered from frostbite and were subsequently detached. The process of sequestration was similar to that leading to normal antler casting. The sequestration sites were soon covered with skin, but (limited) regrowth of antler tissue from the stumps was not observed before late April/early May, i.e., the time of normal antler regeneration. Simultaneously, growth of knobby protuberances started on the surface of the antlers. Histological analysis of biopsies taken on December 20 in the year after castration revealed that the central parts of the antlers consisted of cancellous lamellar bone with mainly secondary osteons. Peripheral to this, the bone tissue (forming the protuberances) was of a more immature nature and exhibited larger intertrabecular spaces. The outermost layer consisted of woven bone formed by intramembranous ossification from the periosteum and was undergoing active growth and remodeling at the time of biopsy. Thus, bone formation at these sites occurred during a period when no antler growth is observed in normal fallow bucks. The velvet covering the bony protuberances was of normal appearance. © 1995 Wiley‐Liss, Inc.
Responses to chronic hypoxia in embryonic alligators
Authors: Warburton Stephen J. , Hastings Dulynn , Wang Tobias
Published: June 2005

To investigate developmental responses to chronic hypoxia, we incubated alligator eggs at 17% O2 and 21% O2 for the entire course of embryonic development and for 5 months post‐hatching. Hypoxic‐incubated alligators hatched later and at a smaller size. Hematocrit was significantly higher in hypoxic‐incubated animals immediately post‐hatch. Allosteric modification of hemoglobin oxygen affinity did not appear to play a role in the adaptation to hypoxia, given equal nucleotide triphosphate‐to‐hemoglobin ratios in the hypoxic and normoxic groups. When acutely exposed to 21% O2, hypoxic‐incubated alligators maintained oxygen consumption relative to their normoxic siblings despite their lower mass. © 1995 Wiley‐Liss, Inc.
Vitellogenins of Oreochromis niloticus: Identification, isolation, and biochemical and immunochemical characterization
Authors: Buerano Corazon C. , Inaba Kazuo , Natividad Filipinas F. , Morisawa Masaaki
Published: June 2005

Two native forms of vitellogenin (EIP1 and EIP2) were identified in the plasma of Oreochromis niloticus. They were present in females and were estrogen‐inducible in males. Both were phosphoglycolipoproteins and both immunoreacted with the antiserum raised against egg proteins. Two prominent bands (EIpp1 and EIpp2; corresponding to 185 and 120 kDa, respectively), observed on sodium dodecyl sulfate‐polyacrylamide gels, were induced by estradiol treatment of males and immunoreacted with the antiserum against egg proteins. EIP1 and EIP2 were isolated by precipitation with Mg2+ ions and ethylenediamine tetraacetic acid, preparative polyacrylamide gel electrophoresis, and electroelution. During purification the fractions containing EIP1 and EIP2 also retained EIpp2 and EIpp1, respectively. Immunoblot analyses using affinity‐purified antibodies against EIP1, EIP2, EIpp1, and EIpp2 confirmed that EIP1 and EIP2 were at least composed of EIpp2 and EIpp1, respectively. These results suggest that at least two immunochemically different proteins are induced and are secreted into the blood to serve as vitellogenin and to provide a source of nutrient for the developing embryo of Oreochromis niloticus. © 1995 Wiley‐Liss, Inc.
Calcium, sulfur, and zinc distribution in normal and arthritic articular equine cartilage: A synchrotron radiation‐induced X‐ray emission (SRIXE) study
Authors: Rizzo R. , Grandolfo M. , Godeas C. , Jones K. W. , Vittur F.
Published: June 2005

Calcium, sulfur, and zinc content in normal and arthritic equine cartilage have been studied by synchrotron radiation‐induced X‐ray emission (SRIXE). Ranging from the superficial to the columnar zone of the normal tissue, calcium and zinc concentrations are increasingly higher, whereas sulfur is at its highest concentration in the transitional zone. In the arthritic tissue, calcium concentration is at its maximum in the transitional zone, whereas zinc and sulfur distributions are relatively homogeneous. Sulfur concentration in arthritic cartilage is reduced to about one‐third with respect to that in normal tissue. The possibility that zinc concentration reflects the distribution of the zinc‐containing enzyme alkaline phosphatase is presented. © 1995 Wiley‐Liss, Inc.
Insulin receptors in Xenopus laevis liver and forelimb regenerates and the effects of local insulin deprivation on regeneration
Authors: Cowan Bryce J. , Foty Ramsey A. , Liversage Richard A.
Published: June 2005

As forelimb regeneration in Xenopus laevis is mainly a cell proliferative event which results in a spike‐shaped appendage, we set out to examine the possibility that insulin is a growth‐promoting factor in this process. The objectives were 1) to detect the presence of insulin receptors (IRs) in the liver (a specific target organ for insulin) and IRs in the forelimb regenerates of X. laevis, 2) to determine whether the receptor is similar to IRs identified in other organisms, and 3) to absorb insulin locally by implanting anti‐insulin antibody‐soaked hydrolyzed polyacrylamide beads into regenerating forelimb outgrowths in order to assess the effects of insulin deprivation on regeneration. The results show that IRs are present in Xenopus liver plasma membranes (XLPM) as well as in plasma membranes of 21 day forelimb regenerates. Insulin binding to this receptor is time‐dependent and specific, as unlabeled bovine insulin competes with radioiodinated insulin for binding to XLPM more effectively than insulin‐like growth factor‐I, guinea pig insulin, or glucagon. Scatchard analysis of insulin binding to XLPM describes a two binding site receptor possessing a low affinity (0.16 nM−1), high capacity (3.2 ± 0.9 pM/mg) binding site and a high affinity (2.7 nM−1), low capacity (0.5 ± 0.3 pM/mg) binding site. The holoreceptor has a molecular mass of 380 kDa. The reduced receptor has subunits of 130 kDa and 95 kDa. The 95 kDa subunit undergoes autophosphorylation following insulin stimulation. Implantation of hydrolyzed poly‐acrylamide beads, saturated with anti‐insulin antibody, into regenerating Xenopus Forelimbs significantly impeded development of the regenerates and, therefore, demonstrates that insulin is required for growth of Xenopus forelimb regenerates. © 1995 Wiley‐Liss, Inc.
Purification and characterization of fatty acid‐binding protein from aerobic muscle of the antarctic icefish Chaenocephalus aceratus
Authors: Londraville Richard L. , Sidell Bruce D.
Published: June 2005

Intracellular fatty acid‐binding protein is purified and characterized from aerobic skeletal muscle of the Antarctic icefish Chaenocephalus aceratus. Molecular mass of C. aceratus FABP (CA‐FABP) is 14,936 Da as estimated by electrospray mass spectrometry. CA‐FABP is expressed at an intracellular concentration of 0.984 ± 0.115 mg CA‐FABP g−1 wet weight aerobic muscle and binds 0.859 ± 0.013 moles oleic acid per mole of protein at a physiological temperature of 0°C. Dissociation constants (Kds) for various fatty acid ligands range from 1.38 to 2.71 μM; Kds are not significantly different among palmitic acid (16:0), palmitoleic acid (16:1), and oleic acid (18:1). Competition assays reveal that CA‐FABP does not have preferential affinity for the very‐long‐chain, polyunsaturated fatty acids that are common in Antarctic fish (e.g., docosahexaenoic acid; 22:6). Partial amino acid sequence from CA FABP aligns with mammalian heart‐type FABPs with as high as 74% identity. These data are strikingly similar to mammalian values, yet they are derived from an organism that is distant from mammals in terms of phylogeny, body temperature, and physiology. This suggests that the FABP family is conserved not only in primary sequence, but also in its physiological properties. © 1995 Wiley‐Liss, Inc.
Effect of changing from a short‐day to long‐day photoperiod on the breeding season of the brushtail possum (Trichosurus vulpecula)
Authors: Gemmell Robert T. , Sernia Conrad
Published: June 2005

In Queensland, possums (Trichosurus vulpecula) in the wild and in captivity first give birth during March and April and continue to give birth throughout the year until November. The possum has a gestation length of 17.5 days, gives birth to one young, and lactation continues for approximately 180 days. If the newborn possum is removed during the breeding season, the possum will ovulate approximately 9 days later and give birth approximately 26 days after removal of the pouch young (RPY). Repeated RPY may be used to determine the duration of the breeding season. In this study, the effect on the breeding season of a marked change in photoperiod from a short‐day to a long‐day was examined by comparing three groups of possums in different photoperiods for 13 months. One group of five female and two male possums (group A) was housed in a natural photoperiod and a second group (B) was housed in a short‐day photoperiod (10 h light: 14 h dark) throughout the study. The third group (C) was housed in a short‐day photoperiod until each possum gave birth, the pouch young was removed, and the possum transferred to a long‐day photoperiod room (14 h light: 10 h dark) for the remainder of the study. The possums held in a natural photoperiod, group A, gave birth to a total of 27 births in the one breeding season from March to October. The 5 possums of group B, held in a short‐day photoperiod, gave birth to a total of 28 births, from January through August, no births in September and October, and 3 births again in November and December. With group C, a total of 15 births was observed, 10 of them after transfer to a long‐day photoperiod. All possums gave birth in January and were transferred to the long‐day photoperiod following RPY. There followed four births in February and March and a further six births from July to November. In conclusion, short‐day photoperiods can hasten the onset of breeding activity in possums and are required for the maintenance of the breeding season. © 1995 Wiley‐Liss, Inc.
Entrainment of circadian system under variable photocycles (T‐photocycles) alters the critical daylength for photoperiodic induction in blackheaded buntings
Authors: Kumar Vinod , Kumar B. Sanjay
Published: June 2005

The present study was designed to investigate the photoperiodic responses of blackheaded buntings to various T‐photocycles [T =the period length of light:dark (LD) cycle]. Two series of experiments were performed. In series I, groups of buntings (n =8‐12) were exposed to LD cycles of 22 to 26 hr with photoperiods of 6, 10, or 11 hr (T22 =6L:16D, 10L:12D, 11L:11D; T24 =6L:18D, 11L:13D; T26 =6L:20D, 11L:15D). Among these groups, birds subjected to 11L:11D showed heavy deposition of fat, weight gain, and testicular recrudescence, a response that is characteristic of long day (≥ 12 hr photoperiod per day) photostimulation, indicating that a T‐photocycle of less than 24 hr (T =22 hr) was photoinductive in buntings when presented with a photophase long enough to interact with the photoinducible phase (ϕi), located in the middle of the photocycle. Experiments in series II included an interrupted‐night lighting protocol with a main photophase of 6 hr and 1‐hr light break in photocycles of T =22 hr, T =24 hr, and T =26 hr. The results revealed that a 1‐hr light pulse was inductive when it was introduced in the middle of the photocycles, and, thus, was coincident with the ϕi. It is suggested that the critical daylength for photoperiodic induction in buntings is altered as a result of entrainment to various T‐photocycles. © 1995 Wiley‐Liss, Inc.
The elasmobranch thymus: Anatomical, histological, and preliminary functional characterization
Authors: Luer Carl A. , Walsh Catherine J. , Bodine A. B. , Wyffels Jennifer T. , Scott Thomas R.
Published: June 2005

Thymi from 22 species of elasmobranch fish (class Chondrichthyes) were examined. Information on the anatomical location, organ arrangement, and cellular composition of the thymi as a function of sexual maturation as well as preliminary characterization of thymocyte functional activities are reported. Most of the sharks, skates, rays, and guitarfish reported herein represent species from which thymus had not been previously documented. The elasmobranch thymus is bilateral and situated dorsomedial to both gill regions. Although its size and location relative to the surrounding musculature varied with sexual maturation, thymus was confirmed in every specimen examined. Separate cortical and medullary regions resembling the cortex and medulla of mammalian thymi were consistent features among all elasmobranch thymi examined. Tissue imprints confirmed the presence of thymocytes ranging in size from small, darkly staining cells to large, lightly staining blast‐like cells. Large thymic cells, containing cell debris or intact thymocytes were often observed. In vitro functional assays including cytochemical visualization of lysosomal enzymes characteristic of stage‐specific thymocyte maturation, and the presence of nuclear and cell surface biochemical markers associated with immature thymocytes suggest functional roles for elasmobranch thymi similar to those of the thymi of higher vertebrate classes. Proliferation of senescent nurse shark thymocytes in culture as determined by cell flow cytometry and tritiated thymidine incorporation was also similar to in vitro responses typical of higher vertebrate mitogen‐independent thymocyte proliferation. © 1995 Wiley‐Liss, Inc.
Uptake of high‐density lipoprotein by Y‐organs of the crab Cancer antennarius: III. Evidence for adsorptive endocytosis and the absence of lysosomal processing
Authors: Kang Byoung K. , Spaziani Eugene
Published: June 2005

Ecdysteroid hormones in crustaceans are synthesized from cholesterol in the Y‐organs. Circulating cholesterol is bound to high‐density lipoprotein (HDL). Experiments were conducted to find the mode of cholesterol uptake by Y‐organ cells. The working hypothesis is as follows: Cholesterol is taken up by endocytosis of the entire HDL‐cholesterol complex. HDL was doubly labeled in the apolipoprotein and cholesterol components with 125I and 3H, respectively. The time courses of uptake of the two labels by Y‐organ segments in vitro were parallel throughout 24 hr of incubation. Chloroquine, an inhibitor of lysosomal function, had no effect on the uptake and degradation of HDL. Cycloheximide, an inhibitor of protein synthesis, depressed HDL uptake. Transmission electron microscopy of Y‐organ tissue showed features characteristic of adsorptive endocytosis, including coated pits in the plasma membranes and their invagination and vesiculation. Visualization of HDL with immunogold binding showed profiles consistent with endocytosis. Quantitation of the distribution of HDL‐gold particles indicated that about 75% were associated with cellular formed elements, but not with lysosomes, and significantly more particles overall were present in cells from de‐eyestalked crabs than those from intact crabs. These data demonstrate that (a) cholesterol‐carrying HDL is taken into Y‐organ cells by adsorptive endocytosis, (b) its uptake is dependent on de novo protein synthesis, (c) its intracellular processing is independent of lysosomal enzymes, and (d) its uptake is depressed by the molt‐inhibiting hormone secreted by the eyestalks. © 1995 Wiley‐Liss, Inc.
Age‐dependent changes in thymuses in the European common frog, Rana temporaria
Authors: Plytycz Barbara , Mika Joanna , Bigaj Janusz
Published: June 2005

The thymus of the adult frog Rana temporaria is generally small each winter and grows through the spring to reach a large size each summer. The summer thymus has a cortex full of small thymocytes and a medulla in the centre, whereas the winter atrophy is manifested by a loss of distinction between cortex and medulla, an abundance of cells filled with secretory granules, and the formation of intercellular cysts. These seasonal changes are superimposed on age changes. The thymus grows rapidly in froglets. The differences in weight and cell number between winter and summer organs are strongest in middle‐aged animals (3–6 years old) and decrease in old specimens. The thymus slowly involutes with age, this being connected with increasing winter atrophy, leading to the formation of huge cysts that fill almost the whole organ in the oldest individuals. In senescent frogs (around 10 years old) seasonal differences still concern corticomedullary division but without pronounced fluctuations in thymic size. The skeletochronological technique applied here for age estimation underestimated rather than overestimated the real age of old animals. © 1995 Wiley‐Liss, Inc.
Development of electrical activity in regenerating aggregates of hydra cells
Authors: Itayama Tomoaki , Sawada Yasuji
Published: June 2005

The development of electrical activity in aggregates of dissociated hydra cells was investigated. Both the number of events and the distribution of amplitude of electrical pulses during the process of regeneration were determined. Correlations between electrical pulses at two separate positions on an aggregate were also examined as regeneration progressed. The main results were as follows: From the measured frequency and amplitude of pulses, together with the correlations between pulses at two different sites, we could observe the way in which contraction pulses developed in regenerating aggregates. The percentage of the electrical pulses of large amplitude increased about 20 hr after the start of regeneration. The correlation between electrical pulses measured at two sites separated by 0.3 mm also increased at about 20 hr, reaching about 80% at 40 hr. The results suggest the possible details of the reorganization of the conduction system for contraction pulses among cells in a regenerating aggregate of hydra cells. © 1995 Wiley‐Liss, Inc.
Toward a gene therapy for duchenne muscular dystrophy
Authors: Dunckley Matthew G. , Piper Tony A. , Dickson George
Published: June 2005

Duchenne muscular dystrophy (DMD) is a wasting disease of muscle caused by mutations in a single gene on the X chromosome. Because no effective treatment is available, the disease inevitably is fatal by the third decade of life. Hence, the use of gene transfer technology to correct the biochemical defect (dystrophin‐deficiency) in muscle fibers of DMD patients may provide a promising therapeutic strategy. This review outlines recent progress toward understanding the molecular pathology of DMD, including identification of novel products of the DMD gene expressed in the nervous system and their involvement in neurological defects in DMD patients. We summarize germ‐line (transgenic) and somatic gene transfer studies performed on the mdx mouse model of DMD, using recombinant cDNA molecules. In light of these results, we discuss areas for future study, such as refinement of viral‐mediated gene transfer to muscle, and the prospects for gene therapy for human DMD patients. © 1995 Wiley‐Liss, Inc.
Self‐injurious behavior as endogenous neurochemical self‐administration
Authors: Thompson Travis , Symons Frank , Delaney Dawn , England Cindy
Published: June 2005

The compulsive and deeply disturbing character of self‐injurious behavior (SIB) makes it one of the most difficult behavior problems to understand scientifically and treat clinically. We review evidence implicating endogenous opioid peptides and the neurotransmitter dopamine in SIB. Next, we describe similarities between the self‐administration of cocaine and morphine by laboratory animals and self‐injury by people with mental retardation. We discuss shared behavioral and neurochemical properties that suggest common mechanisms that may be responsible for both the persistent, damaging behavior patterns characteristic of some forms of SIB and the addictive self‐administration of cocaine and morphine. Multifaceted treatment approaches are explored, based on a better understanding of underlying mechanisms. © 1995 Wiley‐Liss, Inc.
The nature and consequences of fragile X syndrome
Authors: Bailey Donald B. , Nelson David
Published: June 2005

Fragile X syndrome, the leading known inherited cause of mental retardation and developmental disabilities, is caused by a trinucleotide repeat expansion in the 5′ untranslated region of the FMR1 gene in Xq27.3 Research during the pat five years has documented the genetic abnormalities that cause this syndrome and described the impairments, disabilities, and disadvantages asslociated with it. Future research is needed to foucs on genetics and neurobiology, screening and early identification, biomedical treatments, psychoeducational interventions, and family adaptation and support. © 1995 Wiley‐Liss, Inc.
Modeling the natural history of the fragile X gene
Authors: Sherman Stephanie
Published: June 2005

Elucidation of the nature of the mutational process that leads to fragile X syndrome and other triplet repeat disorders poses an interesting problem. At present, no experimental model systems are available to study the expansion process. Moreover, data from fragile X family studies reveal only the behavior of the highly expanded form of the mutation. Thus, mathematical modeling of the mutational process has become an important tool for use in examining the nature and fate of the fragile X gene. Such methods can be used to generate predictions that can be tested using empirical data. This article reviews these models and discusses the predicted allele frequencies at equilibrium and the approach to equilibrium. © 1995 Wiley‐Liss, Inc.
Interaction in teratogenesis: Actinomycin D, puromycin and deoxyguanosine
Authors: Pierro Louis J. , Coghill Joanne E.
Published: June 2005

Abnormal development of the embryonic axis is one consequence of injection into the yolk sacs of 48‐hour chick embryos of each of the following teratogens: actinomycin D, puromycin, deoxyguanosine. Rumplessness and trunklessness are consequences of treatment with actinomycin D or puromycin; thoracic constrictions are consequences of treatment with deoxyguanosine. Treatment with both actinomycin D and deoxyguanosine, under certain conditions of dosage and developmental timing, results in an increase in the frequency of rumplessness and trunklessness; the same is true for combined treatment with puromycin and deoxyguanosine. Although deoxyguanosine treatment of 72‐hour embryos is also associated with rumplessness, evidence is presented that deoxyguanosine‐induced rumplessness does not contribute to the effects obtained with embryos treated at 48 hours incubation age with these combinations of teratogens. Treatment with both actinomycin D and deoxyguanosine can result in an increase in the frequency of thoracic constrictions; treatment with both puromycin and deoxyguanosine, in a decrease. These interactions in teratogenesis between deoxyguanosine and actinomycin D and between deoxyguanosine and puromycin indicate that the distribution in the embryo of each teratogen is more widespread than suggested by the morphological consequences associated with each individually.
Teratogenic action of carbonic anhydrase inhibitors in the rat
Authors: Wilson James G. , Maren Thomas H. , Takano Kiichi , Ellison Arthur
Published: June 2005

Acetazolamide and ethoxzolamide incorporated into the diet of pregnant rats at 0.3% or 0.6% level caused localized appendicular malformation typically affecting the distal, postaxial part of the right forelimb. Other malformations and intrauterine death were also more frequent than in the offspring of untreated rats.

Treatment on day 10 or 11 of gestation with 1000 mg/kg of acetazolamide injected subcutaneously also produced a high incidence of typical abnormalities but similar treatment on day 9 or 12 failed to do so. The susceptible period of rat embryos to this agent is thus defined as the tenth and eleventh days.

Analysis of maternal blood after teratogenic treatment revealed that both acetazolamide and ethoxzolamide produced metabolic acidosis but little change in other electrolytes except potassium, which was sharply reduced. It was not possible to prevent the occurrence of characteristic malformations by supplemental dosing with potassium. The production of litters with acetazolamide‐induced defects was associated with loss of maternal weight after treatment exceeding 10% of pretreatment weight. It has not been possible to produce typical defects using the potent diuretic furosemide.

Analysis of embryos from untreated females revealed that carbonic anhydrase does not appear in measurable amounts in the developing rat until the thirteenth day of gestation, making highly unlikely the possibility that the drug's teratogenic action is associated with carbonic anhydrase inhibition in the embryo.
Analysis of trypan blue induced teratogenesis in Rana pipiens embryos
Authors: Greenhouse Gerald , Hamburgh Max
Published: June 2005

Fertilized Rana pipiens eggs were treated with 0.5% solution of trypan blue in spring water. The stage at which the dye was added and the duration of exposure were varied.

The first signs of aberrant development appeared at late stage 13 at which time the neural folds were abnormal and elongation of the body axis was inhibited. Subsequent development resulted in microcephalic larvae with foreshortened trunks and kinked or malproportioned tails. Such embryos never exhibited spontaneous muscular contractions although they may survive for 10 to 12 days and come to resemble stage 21 larvae.

Microscopic analysis revealed that (1) the notochord was either completely absent or present only in the anterior half of experimental embryos, (2) adjacent to the notochordal abnormalities the lateral mesoderm formed an unsegmented mass whose left and right sides fused beneath the neural tube, and (3) malformations of the forebrain included absence of the diencephalon, optic cups, and cranial ganglia.

Trypan blue was never found within the cells of the embryos.

The critical period of response to trypan blue extended from stage 10 through stage 14. Animals growing in dye solution since fertilization but removed to fresh spring water prior to stage 10 differentiated normally.
Direct effects of 6‐aminonicotinamide on the developing rat embryo in vitro and in vivo
Authors: Turbow M. M. , Chamberlain J. G.
Published: June 2005

Graded dosages of the niacin antimetabolite 6‐aminonicotinamide (6‐AN) were incorporated in the culture media of explanted day 10 rat embryos or injected directly into amniotic cavities of day 15 embryos. Regardless of the route of administration the resultant decreased growth and abnormal development were related to the concentration of the antimetabolite. Culturing embryos for 22–26 hours with 5 to 20 μg 6‐AN progressively interfered with subsequent somite growth and cardiovascular function. Addition of nicotinamide (NAM) to the cultures prevented the deleterious effects of the antimetabolite. Following infra‐amniotic injections, 54 to 94% of the implantation sites given 10 to 100 μg 6‐AN exhibited resorbed fetuses or young with abnormal palates, brains, or eyes by day 21 of gestation. The types of defects found in the present study were similar to those observed following maternal treatment with 6‐AN. Direct applications of this teratogen to isolated or in utero rat embryos resulted in decreased growth, increased fetal death, and congenital abnormalities without significant changes in maternal tissues.
Experimental production of congenital cardiovascular malformations in rats by salicylate poisoning
Authors: Takacs Eva , Warkany Josef
Published: June 2005

Congenital cardiovascular malformations were produced in offspring of rats that received salicylates during the organogenetic period of gestation. The most frequent anomalies encountered were transposition of the aorta to the right ranging from “overriding of the aorta” to complete transposition. The doses necessary to produce such malformations in rats are compared with those used in human beings for therapeutic and suicidal purposes.
The role of the time allowed for mating on variability of fetal weight in rats
Authors: Barr Mason
Published: June 2005

In rats variation of fetal weights among litters is significantly greater than variation of fetal weights within litters. This phenomenon is called the litter effect. Twenty litters of Wistar rats were studied to determine whether or not variation in the duration of the period allowed for copulation (1.5 hours versus 15 hours) was a cause of the litter effect. Analyses of variance showed that the duration of the mating period did not significantly influence mean fetal weight, intralitter variability, or interlitter variability. It is concluded that the use of a restricted mating period as opposed to the commonly used overnight mating period offers no advantage from the standpoint of fetal weight variability. The need to consider the sample size of both litters and fetuses in teratologic and fetal growth studies is stressed.
Teratogenesis and inhibition of DNA synthesis induced in rat embryos by cytosine arabinoside
Authors: Ritter Edmond J. , Scott William J. , Wilson James G.
Published: June 2005

Pregnant Wistar rats were injected at day 12 of gestation with 25, 50, 100, or 200 mg/kg cytosine arabinoside. One to 27 hours later 3H‐thymidine was also injected followed 2 hours later by surgical removal of one uterine horn. The remaining horn was left in situ until day 20 for evaluation of embryotoxicity (malformation, death, or growth retardation). Half of the embryos in the removed horn were prepared individually for whole‐embryo scintillation counts and the other half were homogenized and treated with perchloric acid, of which the acid‐insoluble fraction was quantitated for 3H‐thymidine incorporation by scintillation counting. Other pregnant rats were treated with cytosine arabinoside and allowed to continue to day 20 without further treatment.

Twenty‐day fetuses from females given cytosine arabinoside at day 12 showed dose related malformation and growth retardation but not death following 50 to 200 mg/kg. These effects were more severe when treatment was followed by thymidine injection and partial hysterectomy. The latter procedures revealed striking and dose related suppression of DNA synthesis evidenced by 3H‐thymidine incorporation 1 to 27 hours after cytosine‐arabinoside injection. Embryotoxic effects in 20‐day fetuses were more closely related to the cumulative suppression of DNA synthesis caused by a given dosage than with either the level at any one posttreatment interval or the duration of the suppression. Although all dosages caused reduction in the rate of DNA synthesis to less than 25% of control rate 1 hour following treatment, after the smaller dosages recovery to control rate occurred by 15 hours whereas after 200 mg/kg recovery was not complete even after 27 hours. Surprisingly, 12‐day rat embryos exhibited suppression of DNA synthesis of between 25 and 75% of control rate for up to 9 hours with little effect being apparent in 20‐day fetuses.
Induction of cleft palate in rats with antiinflammatory drugs
Authors: Walker Bruce E.
Published: June 2005

Pregnant Holtzman rats were injected subcutaneously with anti‐inflammatory drugs from days 12–15 of gestation. Daily doses producing significant frequencies of cleft palate in the offspring ranged from 0.1–0.8 mg/day for triamcinolone, betamethasone, and dexamethasone. Cleft palate was not induced by methylprednisolone, prednisolone, and cortisone, even by daily doses ranging from 8–75 mg. Similar experiments were performed on A/J mice. The possible significance of these experiments in relation to testing potential teratogens and to the mechanism of palate closure is discussed.