bluuebunny/crossref_metadata_2025_split huggingface dataset:
Expression of the 9G1 antigen in the apical cap of axolotl regenerates requires nerves and mesenchyme
Authors: Onda Hiroaki , Tassava Roy A. 
Published: June 2005

AbstractMonoclonal antibody 9G1 (mAb 9G1) is reactive to the wound epithelium of axolotl larvae and therefore provided the opportunity to examine the interaction between the wound epithelium, nerves, and blastemal mesenchyme during axolotl limb regeneration. In unamputated limbs, mAb 9G1 is reactive to most or all cells of the dermis, skeletal elements, blood vessels, and nerves, to a few unidentified cells in muscle, and to none in epidermis. During regeneration of axolotl limbs, mAb 9G1 reacts strongly to an intracellular antigen of the blastemal mesenchyme and of the distal‐most portion of the wound epithelium, the so‐called apical epithelial cap (AEC). Because this thickened wound epithelium of regenerating amphibian limbs has been suggested as functioning in a manner similar to the apical ectodermal ridge (AER) of embryonic limb buds, it was of interest to further examine the reactivity of mAb 9G1 during various stages of regeneration. Whether mAb 9G1 reactivity in the AEC depended on mesenchyme and/or nerves was also tested. Monoclonal antibody 9G1 reactivity appears in the AEC of regenerating limbs prior to outgrowth of the blastema and persists throughout blastemal stages. Apical epithelial cap reactivity to mAb 9G1 is nerve dependent during early stages of blastema development and becomes nerve‐independent at later stages. When epithelium‐free blastemal mesenchyme is grafted onto injured flank musculature, ectopic limb regeneration occurs and the AEC derived from flank epidermis exhibits mAb 9G1 reactivity. These results show that a mAb 9G1 reactive AEC is characteristic of regenerating limbs and that expression of the 9G1 antigen by the AEC is dependent upon underlying blastemal mesenchyme and nerves.
Effects of thyroid hormone deficiency in eggs on early development of the medaka, Oryzias latipes
Authors: Tagawa Masatomo , Hirano Tetsuya 
Published: June 2005

AbstractTo examine the biological significance of thyroid hormones contained in eggs, the hormones were depleted from eggs by treating the mother fish with thiourea. Constantly spawning medaka (Oryzias latipes) were reared in fresh water containing 0.03% thiourea. The plasma thyroxine (T4) and triiodothyronine (T3) concentrations in the mother fish were about 8 and 5 ng/ml, respectively, before the treatment, and decreased to 1/5 of the initial levels within 1 day. Initial concentrations of T4 and T3 in eggs just after fertilization were about 4 and 1 ng/g, respectively, and decreased to less than 1/4 when the mother was treated with thiourea for 7 days. Minimum effective concentration of thiourea to decrease the hormone concentrations in mother's plasma and the eggs was 0.003%. During the course of normal development, egg thyroid hormones are maintained at the initial levels during the first 4 days, and continuously decrease toward hatching (10 days after fertilization). There was no difference between the normal eggs (derived from the mother fish without thiourea treatment) and hormone‐deficient eggs (hormone concentrations were less than 1/10 of the control) in hatchability, the time of hatching, and survival under starvation. No difference was seen between the two groups in body weight, body length, condition factor, and survival rate 16 days after hatching. These findings indicate that more than 90% of the hormones contained in eggs are not essential for early development in medaka.
Evidence for a role of Na+,K+‐ATPase in the hydration of Atlantic croaker and spotted seatrout oocytes during final maturation
Authors: LaFleur G. J. , Thomas P. 
Published: June 2005

AbstractDuring final maturation the oocytes of many marine teleosts swell four to five times their original size due to uptake of water. The involvement of active inorganic ion transport and Na+,K+‐ATPase in oocyte hydration in Atlantic croaker (Micropogonias undulatus) and spotted seatrout (Cynoscion nebulosus), marine teleosts which spawn pelagic eggs, was investigated by examining changes in the inorganic ion content of ovarian follicles containing mainly oocytes, by performing in vitro incubations of the follicles with ion channel blockers, and by assaying membrane preparations of ovaries containing hydrating and non‐hydrating oocytes for Na+,K+‐ATPase activity and content. There were marked increases in the contents of K+, Mg++, and Ca++, but not Na+, in oocytes of M. undulatus and C. nebulosus during hydration. Incubation of follicle‐enclosed oocytes in K+‐free medium or with ouabain or amiloride, inhibitors of Na+, K+‐ATPase and Na+ channels, respectively, blocked gonadotropin‐induced oocyte hydration in M. undulatus. In addition, Na+,K+‐ATPase activity increased threefold and the concentration of the enzyme increased 50% in ovarian tissue during oocyte hydration. These results strongly suggest a major role for active ion regulation by a ouabain‐sensitive Na+,K+‐ATPase system in oocyte hydration in two species of sciaenid fishes.
Sources of calcium, magnesium, and phosphorus for embryonic softshell turtles (Trionyx spiniferus)
Authors: Packard Mary J. , Packard Gary C. 
Published: June 2005

AbstractEggs of softshell turtles (Trionyx spiniferus) were incubated on wet (water potential = −150 kPa) and dry (water potential = −1,500 kPa) substrates at 29°C. The rigid, heavily calcified eggshells restricted exchanges of water between eggs and their environment, but eggs exposed to wet substrates nonetheless contained more water at the end of incubation than eggs in the drier environment. However, differences in the amount of water contained by eggs had no demonstrable effect on patterns of metabolism and growth by embryos. The embryos in both treatments obtained about 75% of their calcium from the eggshell, but acquired all of their magnesium and phosphorus from the yolk. Residual yolk removed from hatchlings contained minimal quantities of all three elements. Thus, all the calcium mobilized during development was deposited in the carcass, and yolk was depleted of almost its entire store of this element. This pattern of mobilization and deposition of calcium is similar to that observed in embryos of other chelonians and in those of oviparous lepidosaurinas. In contrast, embryonic crocodilians and birds store some of the calcium mobilized from the eggshell in the yolk, and residual yolk consequently contains a substantial reserve of calcium. Our results indicate that the pattern of mobilization and deposition of calcium documented for birds and crocodilians probably is an attribute of the archosaurian lineage and not a simple result of embryos developing in rigid, heavily calcified eggshells.
Early devlopmental profile of ornithine decarboxylase in the frog, Microhyla ornata and its regulation by polyamines
Authors: Joseph Kusumam , Baby T. G. 
Published: June 2005

AbstractOrnithine decarboxylase (ODC) activity and polyamine levels were measured during early development of the frog, Microhyla ornata. ODC activity was found to be high and it showed three major peaks during the first 60 hr of development. Putrescine and spermidine levels increased gradually during the above period with little change in spermine. Treatment of developing embryos with exogenous putrescine and spermidine prevented the normal increase in ODC activity. Spermine did not have any significant effect. Addition of ornithine also prevented the increase in ODC activity. Experiment using exogenous ornithine and α‐methylornithine revealed that formation of putrescine and/or spermidine from ornithine is necessary for the suppression of ODC to occur. Suppression of ODC takes place even if conversion of putrescine to spermidine is blocked, indicating that putrescine, independent of its conversion to spermidine, also plays a role in ODC regulation.
Purinergic receptors as a regulatory process of luminescence in Porichthys' luminous organs
Authors: Rees J. F. , Kaouass M. , Baguet F. 
Published: June 2005

AbstractThe effects of exogenous adenosine and adenine phosphorylated derivatives were tested on the adrenergic luminescence of isolated luminous organs of the fish Porichthys. Adenosine triphosphate, at concentrations ranging from 10−5M to 10−2M, strongly inhibited the two peaks of the biphasic‐shaped light emission induced by adrenalin. Adenosine diphosphate mimicked the effects of ATP, whereas adenosine monophosphate (AMP) and cyclic‐AMP were ineffective. Adenosine had no inhibitory effect but potentiated the first peak of light whose intensity was five times increased. It is concluded that P2‐purinergic receptors might be present on photocytes and exert a negative control on the luminescent system. Adenosine‐induced potentiation might be related to an intracellular effect of this compound.
Hepatic 5′‐deiodinase activity of Japanese quail using reverse‐T3 as substrate: Assay validation, characterization, and developmental studies
Authors: Freeman Thomas B. , McNabb F. M. Anne 
Published: June 2005

AbstractUsing rT3 as substrate, an in vitro 5′D assay was validated for use with liver tissue from adult Japanese quail, by defining conditions under which activity is proportional to enzyme (protein) concentration and is linear with incubation time. Activity was measured as the release of 125I from labeled rT3. Using validated assay conditions we found the following 5′D characteristics: maximal activity from 10 to 50 mM dithiothreitol (cofactor), an apparent Km of 0.52 μM rT3, pH optimum of 7.6‐8.5, complete inhibition by 1 mM propylthiouracil and by 1.0 mM iopanic acid, and substrate “preference” of rT3 > T4 > T3. Based on these characterizations the quail hepatic 5′D activity is like the Type I 5′D activity found in mammalian liver and kidney and embryonic chicken liver. To determine how previous unvalidated assays, that used high tissue and relatively low substrate (T4) concentrations, influenced 5′D studies we reevaluated 5′D development using an assay validated for each developmental stage with rT3 as substrate. We found extreme quantitative differences in the activities measured and in the proportional relationships between stages, and only limited qualitative similarity in the pattern of 5′D development when unvalidated T4 assay results were compared with validated rT3 assay results. Our data in this paper show good correspondence between whole liver 5′D activity per unit body weight and plasma T3/T4 ratios for the developmental stages sampled.
Reversal of postmortem degeneration of mouse oocytes during meiotic maturation in vitro
Authors: Schroeder Allen C. , Johnston Daniel , Eppig John J. 
Published: June 2005

AbstractThe developmental capacity of oocytes matured in vitro following isolation at the germinal vesicle stage from freshly killed mice (control) was compared with that of oocytes isolated from the carcasses of mice killed 3, 6, 9, and 12 hr earlier. The yield of intact, cumulus cell‐enclosed oocytes decreased as the interval between death of the animal and removal of the ovary increased. After 15–16 hr of culture of medium containing follicle‐stimulating hormone, the frequency of germinal vesicle breakdown, extrusion of a polar body, and cumulus expansion was equivalent in oocytes of all groups. The frequency of development of inseminated ova to 2‐cell stage embryos in the control, 3, and 6 hr postmortem groups was the same but declined markedly in the 9 and 12 hr groups. There was also no difference in the frequency of blastocyst development from 2‐cell stage embryos between the control, 3, 6, and 9 hr postmortem groups, but the 2‐cell embryos in the 12 hr postmortem group did not develop to blastocysts. Thirty‐six percent of the 2‐cell stage embryos from the 6 hr postmortem group did not develop to blastocysts. Thirty‐six percent of the 2‐cell stage embryos from the 6 hr postmortem group developed to live young after transfer to foster mothers. Follicles of 6 hr postmortem ovaries showed degeneration manifested as prominent crystalline inclusions within the oocytes and many pyknotic granulosa cells. The crystals disappeared within 1 hr of culture and the secondary oocytes appeared normal. The cultured oocyte–cumulus cell complexes, therefore, reversed degenerative changes induced by the death of the animal. This study demonstrates the feasibility of recovering developmentally competent oocytes from valuable recently deceased zoological, agricultural, and endangered mammals.
Trehalose accumulation in the tardigrade Adorybiotus coronifer during anhydrobiosis
Authors: Westh Peter , Ramløv Hans 
Published: June 2005

AbstractChanges in the trehalose level in the tardigrade Adorybiotus coronifer were observed during induction of, and arousal from, anhydrobiosis. A trehalose accumulation surpassing 1.6% dry weight (d.w.) in anhydrobiotic animals collected dry on their biotope was rapidly reduced on rehydration, reaching the level of active animals (0.1–0.2% d.w.) after 6 hours. Tardigrades dried while embedded in sand in the laboratory accumulated trehalose from 0.1% to 2.3% d.w. within 5–7 hours.Induction of aerobic acidosis in arousing tardigrades by CO2 perfusion reversibly arrested reactivation for at least 36 hours and induced a reduction in anabolic and catabolic activities, measured as a significant reduction in trehalose degradation, and a sevenfold reduction in the rate of protein synthesis.These data support the hypotheis that trehalose generally serves a protective role in desiccationtolerant Metazoa, but indicate that tardigrades require only a moderate level for efficient protection.
Culture of intact sertoli/germ cell units and isolated seroli cells from Squalus testis: I. Evidence of stage‐related functions in vitro
Authors: Dubois Wilfrid , Callard Gloria V. 
Published: June 2005

AbstractAs part of an ongoing program of research using the testis of the dogfish shark (Squalus acanthias) to characterize morphologic and functional changes during spermatogenesis, we have developed procedures for culturing intact spermatocysts (germ cell/Sertoli cell clones) and isolated Sertoli cells from premeiotic, meiotic, and postmeiotic stages of development. Phase contrast and light microscopy confirmed the stage and cellular composition of spermatocysts and showed that they retained their closed, spherical configuration for at least 15 d in culture. Stagerelated variations in [3H] thymidine incorporation (premeiotic ≫ meiotic = postmeiotic) were observed, a pattern that was the same quantitatively and qualitatively after one or seven days of culture. [3H] Leucine‐labeled protein synthesis was twofold greater in cultures with premeiotic spermatocysts than in cultures with more mature stages, whether medium or cysts were analyzed. Sertoli cells isolated from spermatocysts of different stages differred in size, shape, cytological appearance, ability to from flattened monolayers, and rate of DNA synthesis. One day after seeding, [3H] thymidine labeling of Sertoli cells corresponded to the pattern obtained with intact spermatocysts (premeiotic ≫ meiotic = postmeiotic); however, 7 days in culture effected a 40‐ to 200‐fold increase in this parameter and altered the stage‐dependent pattern (premeiotic = meiotic < postmeiotic). Also, when [3H]leucine‐labeled macromolecules secreted by Sertoli cells from premeiotic versus meiotic stages were analyzed by polyacrylamide gel electrophoresis (PAGE), banding patterns differed. Initial results demonstrate the feasibility and potential of this in vitro system for studying qualitative and quantitative changes during spermatogenesis.
The meiotic response of cumulus cell‐enclosed mouse oocytes to follicle‐stimulating hormone in the presence of different macromolecules
Authors: Downs Stephen M. , Dow Mark P. D. , Fagbohun C. Funsho 
Published: June 2005

AbstractExperiments were carried out to determine the effect of different macromolecules on the follicle‐stimulating hormone (FSH)‐induced maturation of mouse oocytes in culture. Cumulus cell‐enclosed oocytes (CEO) were isolated from gonadotropin‐primed mice and maintained in meiotic arrest for 17–18 h with the cAMP analogue, dibutyryl cAMP (dbcAMP). Germinal vesicle breakdown (GVB) was stimulated by the addition of FSH. Medium was supplemented with either no macromolecule or with varying concentrations of polyvinylpyrrolidone (PVP), polyvinylalcohol (PVA), crystallized bovine serum albumin (BSA), or fetal bovine serum (FBS). Oocyte maturation in all FSH‐free cultures occurred at a frequency of about 30% or below. High frequencies of maturation were achieved when FSH was added to macromolecule‐free medium or to cultures containing PVP, PVA, or BSA. Crystallized BSA was the most effective of these in supporting stimulation of maturation (94% GVB at 3 mg/ml, compared with 72–74% with synthetic polymer‐supplemented or macromolecule‐free media). The BSA effect was not due to contaminating fatty acids, and a less pure fraction V BSA was not as effective in supporting FSH‐induced maturation. FBS suppressed FSH stimulation of maturation in a dose‐dependent fashion. Sera from pigs, goats, horses, and rats were also inhibitory, but bovine calf serum (BCS) permitted a high maturation frequency (80% GVB). When added to medium containing either FBS or BCS, crystallized BSA had no effect on FSH‐stimulated maturation, but fraction V BSA suppressed maturation in both serum‐supplemented media. Under no conditions did FSH stimulate maturation in cumulus cell‐free oocytes. These results demonstrate that hormone‐induced oocyte maturation is supported in vitro by nonprotein polymers as well as BSA and that the behavior of the oocyte–cumulus cell complex depends on the purity of the BSA sample. In addition, serum contains inhibitory factors that suppress the positive response to FSH. Thus, the choice of macromolecular supplement is of critical importance when testing the hormone responsiveness of isolated cumulus cell‐enclosed oocytes in culture.
Trypsin inhibitors prevent the progesterone‐initiated increase in intracellular calcium required for the human sperm acrosome reaction
Authors: Pillai Muralidharan C. , Meizel Stanley 
Published: June 2005

AbstractInhibitors of trypsin‐like enzymes, benzamidine hydrochloride and 4′‐acetamidophenyl 4‐guanidinobenzoate (also an inhibitor of other serine proteases), were tested for their effects on the acrosome reaction (AR) of human sperm initiated by progesterone or the calcium ionophore ionomycin. The AR was assayed by indirect immunofluorescence and transmission electron microscopy. The trypsin inhibitors, when added 10 min prior to stimulation by progesterone, significantly inhibited the AR in comparison with progesterone treatement alone. Transmission electron microscopic examination of the sperm after progesterone treatment indicated that the inhibitors blocked the membrane fusion events of the AR. By contrast, when ionomycin (at final concentrations of 3μM) was added to sperm preincubated in inhibitors, sperm underwent morphologically normal AR, acrosomal matrix loss was not inhibited, and the percentage of acrosomereacted sperm was the same as that obtained in the absence of inhibitors. Using the cell calcium indicator fura‐2, we further demonstrated that both trypsin inhibitors prevented the progesterone stimulated rise in intracellular Ca2+ ([Ca2+]int) required for the AR, but did not affect [Ca2+]int in unstimulated sperm. These results suggest that sperm trypsin‐like activity may be directly or indirectly involved in increasing sperm [Ca2+]int during stimulation by progesterone.
Egg exudate‐induced reduction of sperm lysin sensitivity in the vitelline coat after fertilization of Bufo japonicus and its participation in polyspermy block
Authors: Yamasaki Hisashi , Katagiri Chiaki 
Published: June 2005

AbstractThe jellyless eggs of Bufo japonicus or those from which the vitelline coats (VCs) had been removed (denuded eggs) were electrically activated. The exudate that accompanied egg activation (AEX) was collected to study its role in preventing polyspermy. When dejellied (but VC intact) eggs were treated with AEX, the eggs lost not only fertilizability but also the sensitivity of their VCs to the sperm lysin. By contrast, denuded eggs treated with AEX were fertilizable; even activated eggs were highly fertilizable, provided they were deprived of their VCs and inseminated 30 min after activation. The loss of sensitivity to sperm lysin occurred in VCs 3–5 min after activation either in De Boer's or 1/20 De Boer's solution. The activity of AEX to reduce the sensitivity of VCs to sperm lysin was heat‐sensitive and dependent on Ca2+, but it was not affected at all by the variety of protease inhibitors used. The activity was lost by the preincubation of AEX with fragmented VCs in the presence of Ca2+, suggesting Ca2+‐dependent binding of AEX molecules to the VC at fertilization. Immunocytochemical studies employing anti‐AEX rabbit serum showed that the pertinent antigens were localized in the cortical granules of unfertilized eggs and in both the inner surface of VCs and the perivitelline space of fertilized eggs. We conclude that the AEX‐induced loss of lysin sensitivity in VCs and the deposition of cortical granule materials on the inner wall of VCs constitute a slow and permanent block to polyspermy.
The distribution of tenascin and its transcript in the developing avian central nervous system
Authors: Tucker Richard P. 
Published: June 2005

AbstractI have studied the temporal and spatial regulation of the expression of the extracellular matrix protein tenascin in the developing chick brain using immunological and in situ hybridization methods. Tenascin is barely detectable by immuno‐slot blot analysis in the E4 telencephalon, but increases rapidly in abundance until E14, when the level of expression tapers off. The late appearance of tenascin was confirmed by immunohistochemistry. Tenascin can not be detected at E4, but at E7 is distributed homogeneously in most parts of the central nervous system. Tenascin is much less abundant in the retina than in other brain areas. As the avian retina is devoid of both vasculature and fibronectin, this supports the notion that tenascin may mask fibronectin from migrating growth cones and cell bodies. I have also used in situ hybridization with a cDNA probe to determine the origins of tenascin in the developing nervous system. Tenascin transcript is found in regions of glial proliferation and the cell bodies of radial glia. In contrast, tenascin appears to be made by neurons in the retina. As a low‐molecular weight splice variant of tenascin is detected on western blots of retina homogenates, different cell types may be responsible for generating the multiple forms of tenascin found in whole brain homogenates.
The striated body: A new structure in the sperm head of the rabbit spermatozoon
Authors: Courtens J. L. , Biggiogera M. , Gabbiani G. , Fakan S. 
Published: June 2005

AbstractThe striated body, a new structure lying in the perinuclear substance of rabbit spermatozoa, is described. It is composed of protein cords displaying a perpendicular periodic arrangement of dark and light bands. It appears in late spermatids, immediately prior to spermiation and is still present in epididymal spermatozoa, mostly, but not exclusively close to the perforatorium. The nature of this component has been analysed using a series of cytochemical techniques, as well as various antibodies and immunocytochemistry. The absence of RNA and of DNA favours a nonviral origin for this structure. The striated body is devoid of actin, differing in that respect from the rest of the perinuclear substance.