bluuebunny/crossref_metadata_2025_split huggingface dataset:
Paracellular, transepithelial permeation of macromolecules in the body wall epithelium of starfish embryos
Authors: Dan‐Sohkawa Marina , Kaneko Hiroyuki , Noda Koichi 
Published: June 2005

AbstractThe body wall epithelium of starfish gastrulae change the barrier property of the septate junction against large molecules in response to hypertonic environment caused by small molecules such as glycine, arabinose, urea, and NaCl. Ultrastructural obesrveations reveal that the septal portion of the junction either becomes diffuse or disappears altogether while the opposing junctional membranes remain unaltered. Under such conditions, Molecules as large as IgG and IgM can penetrate the body wall without causing morphological abnormalities to the embryo. We have devised a method to detect the paracellular permeation by applying fluorescein‐labeled IgG into the stimulation medium and monitoring the fluorescence which penetrated into the blastocoel. Micropreciptiates of LaCl3 were found, in thin sections of embryos treated with glycine, to lie along the intercelluar spaces, showing, although indirectly, that macromolecules flow through this pathway instead of a transcellular one.The possible role of the septal plates in the barrier function of the septate junction is discussed. © 1995 Wiley‐Liss, Inc.
Notochord formation in amphibians: Two directions and two ways
Authors: Novoselov Vladimir V. 
Published: June 2005

AbstractThe formation, structure, and rearrangements of the notochord were studied in Pleurodeles waltlii and Xenopus laevis embryos. We measured length and cross‐sectional area and calculated volume of the notochord at different stages of development. In both species, the notochord emerges as a condensation and a columnarization of dorsal mesoderm along the midsagittal plane in the midgastrula. In P. waltlii embryos, the notochord segregates from archenteron roof by apical cell surface shrinking. The wave of shrinkage begins in the middle of the rudiment and simultaneously extends cranially and caudally. In X. laevis embryos, the notochord elongates in two directions also, but the mode of notochord formation is not identical in anterior and posterior parts of embryo. While anterior development looks similar to that found in P. waltlii, posterior development features closer binding of the notochord rudiment to ectoderm within existing delaminating boundaries from somite mesoderm. Rates of elongation in the different directions are approximately the same in the two species studied: It is 45–47% for the anterior and 53–55% for the posterior direction compared to total length of the notochord. © 1995 Wiley‐Liss, Inc.
Histidine‐rich protein B of embryonic feathers is present in the transient embryonic layers of scutate scales
Authors: Barnes George L. , Sawyer Roger H. 
Published: June 2005

AbstractBased on its amino acid composition and N‐terminal sequence, a polypeptide (HRP‐B) has been identified as a member of the avian histidine‐rich protein (HRP) family. An antiserum against HRP‐B has been used to localize this polypeptide in developing feathers and scales of chick embryos. HRP‐B was first detectable in the barb ridge cells of feathers at 13 days of incubation and progressively appeared in the distal/proximal and peripheral/central gradients observed previously for the feather‐type β keratins in developing feathers. The HRP‐B polypeptide was detected only in the embryonic layers of scutate scales. It first appeared at 16 days of incubation and not found in the differentiated beta strata of these scales. At no time during the development of reticulate scales or apteric skin regions did the epidermal cells or cells of the embryonic layers express HRP‐B. The transient expression of HRP‐B by the embryonic layers of the scutate scale epidermis is discussed in light of the feather‐forming potential of the presumptive epidermis of the scutate scale‐forming region. © 1995 Wiley‐Liss, Inc.
Enhancing zona penetration by spermatozoa from a teratospermic species, the cheetah (Acinonyx jubatus)
Authors: Roth Terri L. , Swanson William F. , Blumer Evan , Wildt David E. 
Published: June 2005

AbstractCheetahs (Acinonyx jubatus) produce poor quality ejaculates that can limit the efficiency of standard assisted reproduction including artificial insemination (AI) and in vitro fertilization (IVF). The purpose of this study was to: (1) further study sperm‐oocyte interaction in this teratospermic species by examining the ability of malformed sperm to interact with various oocyte barriers; and (2) assess the potential of zona piercing for assisting IVF in a teratospermic felid. Zonae of salt‐stored (SS), domestic cat oocytes were mechanically pierced (ZnPd) three times each. Semen was collected by electroejaculation from six male cheetahs and ejaculates were processed for IVF. Sperm aliquots from each ejaculate were assessed for a sperm motility index (SMI) over time. Zona‐intact (ZnIn‐SS) oocytes (n=78) and ZnPd‐SS oocytes (n=74) were coincubated with spermatozoa in vitro for 6 h. The proportion of morphologically abnormal spermatozoa per ejaculate was high for all males (range 81.5% to 95.9% ). SMI values at 0 and 6 h were variable, ranging from 50 to 75 and 0 to 40, respectively. Spermatozoa from all ejaculates bound to and penetrated the outer zona pellucida of ZnIn‐SS and ZnPd‐SS oocytes similarly (P > 0.05). The proportion of oocytes containing spermatozoa within the inner zona layer and the average number of spermatozoa per oocyte in this region were greater (P < 0.05) for the ZnPd‐SS than ZnIn‐SS oocytes (39.2% and 1.0 versus 12.8% and 0.2, respectively). Although zona piercing enhanced sperm penetration, there was no increase (P > 0.05) in pleiomorphic spermatozoa penetrating the inner zona pellucid or PVS. Penetration of both ZnIn‐SS and ZnPd‐SS oocytes was positively correlated (P < 0.05; r =0.91) with SMI at 6 h but not to the proportion of the pleiomorphic spermatozoa ejaculated (P > 0.05). In summary, altering the integrity of the zona pellucida by creating artificial channels increases the number of cheetah spermatozoa entering the inner zona region, but not the PVS. This phenomenon occurs without increasing the number of pleiomorphic sperm entering the zona/oocyte interface, reinforcing the role of the zona pellucida, especially the inner region, as a powerful filter for malformed sperm. © 1995 Wiley‐Liss, Inc.
Cryoprotective effects of thermal hysteresis protein on survivorship of frozen gut cells from the freeze‐tolerant centipede Lithobius forficatus
Authors: Tursman Donald , Duman John G. 
Published: June 2005

AbstractThermal hysteresis proteins (THPs), which depress the freezing point of water by a non‐colligative process, are common in freeze‐avoiding polar marine fish and terrestrial arthropods where they function as antifreezes. However, some freeze‐tolerant arthropods and plants also produce THPs in winter, raising the question of whether these proteins are involved in the abilities of these organisms to survive the freezing of their extracellular fluids. The centipede Lithobius forficatus is one of these freeze‐tolerant, THP‐producing organisms.Cells isolated from the midgut of both winter‐ and summer‐collected L. forficatus were frozen at various temperatures, either with or without the addition of THPs purified from the beetle Dendroides canadensis, and the survival of the cells was evaluated. The presence of THPs (0.02 mg/ml) in the bathing medium produced a statistically significant increase in cell survival, indicating a cryoprotective function for the THPs. The LT50 (temperature of 50% survival) of cells for summer centipedes was shifted from −8.2°C to −15.0°C, and that of cells of winter centipedes was shifted from −12.1°C to −15.1°C by addition of THPs. Also, cells from summer‐collected centipedes which had been incubated in media containing THPs and then washed in buffer without THPs to remove the protein from the media prior to freezing demonstrated significantly increased survivorship after freezing (LT50 = −14.5). Immunofluorescence studies of these cells indicated that the THPs were present in the cells and/or on the cell membrane. The presence of THPs in the medium also provided some protection to cells frozen under conditions designed to promote the potentially damaging process of recrystallization. (THPs are well known for their ability to inhibit recrystallization.) Therefore, THPs do appear to function as a component in the suite of adaptations which permit freeze tolerance in L. forficatus. © 1995 Wiley‐Liss, Inc.
The effect of dexamethasone on the adrenal gland in fetal and neonatal rats
Authors: Hristić M. , Kalafatić D. , Plećaš B. , Jovanović V. 
Published: June 2005

AbstractThe development and regeneration of the adrenal glands were examined by stereological and morphological methods in 20‐day‐old fetal, as well as 3‐day‐ and 14‐day‐old neonatal male rats born to dams treated with dexamethasone (Dx) on day 16 of gestation. In the fetuses and 3‐day‐old rats, zona fasciculata (ZF) and zona reticularis (ZR) were analyzed as one inner zone (IZ), while in 14‐day‐old animals they were analyzed separately. Single Dx treatment (1.5 mg/kg b.w.) of the dams led to atrophic changes in the adrenal cortex of the fetuses. These changes were visible to a certain degree up to the 14th neonatal day.Administration of Dx to pregnant rats induced a significant decrease of both adrenal weight and volume, as well as the volume of zona glomerulosa + capsule (ZG + C) and IZ, both in fetuses and 3‐day‐old rats. This was due to a decrease in the number but not the volume of cortical cells. Also, necrotic cortical cells, infiltrations and resorption zones accompanied by the presence of macrophages, giant cells and lymphocytes were observed. In 14‐day‐old animals, the degree of atrophic changes in the adrenal cortex was reduced. Changes were observed only in ZR which was decreased in volume resulting from both a significant decrease of the volume and number of cortical cells. Then number of macrophages was somewhat increased, while giant cells were not present. However, the total number of parenchyma cells in ZG was increased, pointing to the possibility of renewal of cortical cells within this zone.The results of the present study demonstrate that even a single Dx dose given to pregnant rat during the period critical for the development of the hypothalamo‐pituitary‐adrenal system in the fetuses leads to marked changes in the structure and function of the fetal adrenal glands which are partially maintained up to the 14th day of postnatal life. © 1995 Wiley‐Liss, Inc.
Characterization of adrenal cytochrome P450c21 from the blacktip shark (Carcharhinus limbatus)
Authors: Nunez B. Scott , Trant John M. 
Published: June 2005

AbstractThe characteristics of cytochrome P450c21 (21 hydroxylase; E.C. 1.14.99.10) were determined in interrenal tissue from blacktip shark (Carcharhinus limbatus). Consistent with other vertebrates, 21‐hydroxylase activity was enriched in the microsomal fraction of the interrenal and was dependent upon a source of reducing equivalents. The reduced form of nicotinamide adenine dinucleotide phosphate supported the highest level of activity. Specific activity increased with increasing temperature (Q10 = 2.5) with a maximum at 35°C. At 30°C, maximal 21‐hydroxylase activity reached a plateau around pH 7.5. Elasmobranchs maintain high concentrations of intracellular nitrogenous compounds known to disturb protein function. While urea (400 mM) had no apparent effect upon 21‐hydroxylase activity, trimethylamine oxide (200 mM) inhibited conversion of progesterone to 11‐deoxycorticosterone by 23%. This inhibition was not reversed by urea. Potassium chloride (150 mM) inhibited 21‐hydroxylase activity by 33%. Kinetic parameters of shark 21‐hydroxylase were determined for [3H]progesterone (Km = 80 nM; Vmax = 2.94 nmol/min/mg protein) and [3H]17α‐hydroxyprogesterone (Km = 90 nM; Vmax = 0.89 nmol/min/mg protein). Substituted progestins were used to determine the steric specificity of this enzyme. Of thirteen steroid substrates studied, nine were metabolized, indicating a relatively broad specificity. The addition of trimethylamine oxide did not alter the substrate specificity. Although the blacktip shark homolog of cytochrome P450c21 is similar in some respects to other vertebrate forms, its temperature dependence, preferential use of progesterone and broad substrate specificity are unusual characteristics. © 1995 Wiley‐Liss, Inc.
Glycoconjugates of the surface of the spermatozoa of Drosophila melanogaster: A qualitative and quantitative study
Authors: Perotti Maria‐Elisa , Pasini Maria E. 
Published: June 2005

AbstractThe important roles played by glycoconjugates in the recognition of gametes and in fertilization are well documented. In the present study, the nature and distribution of carbohydrate residues of the plasma membrane of spermatozoa of Drosophila melanogaster were characterized by use of FITC‐conjugated lectins as probes. The plasma membrane bound agglutinins from Concanavalia ensiformis (Con A) and Pisum sativum (PSA), native and succinylated agglutinins from wheat germ (WGA and s‐WGA), the A4 isoform of agglutinin‐I from Griffonia simplicifolia (GSA‐I A4), and, to a lesser extent, the lectins from Dolichus biflorus (DBA), Lotus tetragonolobus (LTA), and Glycine maximus (SBA). Each lectin gave a specific pattern of binding. The extent of binding of Con A, WGA, s‐WGA, and GSA‐I A4 over the acrosomal region was greater than over nonacrosomal regions, indicating the concentration of α‐mannose/α‐glucose, β‐N‐acetylglucosamine, and α‐N‐acetylgalactosamine residues in this area of the plasma membrane. The surface of the sperm failed to react with lectins from Ricinus communis (RCA‐I), Limulus polyphemus (LPA), and Limax flavus (LFA) and with the B4 isoform of agglutinin‐I from Griffonia simplicifolia‐I (GSA‐I B4). The plasma membrane over the nucleus did not react with any of the lectins tested.Quantitative analysis of binding of Con A, s‐WGA, and GSA‐I A4 to spermatozoa showed that only Con A bound consistently to the sperm surface, showing high affinity for the acrosomal area of the plasma membrane. The other lectins tested bound only to limited and variably sized fractions of the total population of sperm. Therefore, only residues of α‐mannose/α‐glucose are a constitutive component of the plasma membrane, and they are characteristic of the acrosomal area. Con A can be used as a marker of the acrosome portion of sperm from Drosophila for visualization and assessment of acrosome status; labelling with FITC‐conjugated Con A provides a simple and reliable method for visualization of the acrosome of Drosophila sperm that is otherwise detectable only by ultrastructural examination. © 1995 Wiley‐Liss, Inc.
Regulatory volume decrease in neurons of Aplysia brasiliana
Authors: Scemes Eliana , Cassola Antônio C. 
Published: June 2005

AbstractAplysia brasiliana is an osmoconforming mollusc; the osmolality of its extracellular fluid follows that of the external media. This investigation analyzes the volume changes of isolated neuron bodies exposed to hypotonic shocks. The abdominal ganglion was isolated, and the volumes of neuron bodies as well as intracellular K+ concentration were measured. Hypotonic shocks induce a rapid swelling followed by a slower restoration of cell volume. The regulatory volume decrease (RVD) restores cell volume to its control value. Ba2+ slows RVD without blocking it. Furosemide (in the μM range) completely and reversibly blocks the regulatory volume decrease. On return to isotonic solution after RVD, cell shrinkage was only detected when furosemide was present. It is concluded that neuron bodies of A. brasiliana display efficient processes for volume regulation, based on a conductive pathway and a furosemide‐sensitive transport mechanism, which is probably the Na‐2Cl‐K cotransporter. A model simulation provides additional support to this hypothesis. © 1995 Wiley‐Liss, Inc.
Light pulses and injection of IP3 induce mating ability in Paramecium bursaria
Authors: Miwa Isoji , Wada Tsuneya 
Published: June 2005

AbstractPopulations of cells of Paramecium bursaria exposed to a light‐dark cycle (LD; 12:12 hr) show mating reactivity during the light period but not during the dark period. After transfer to constant light (LL) or constant darkness (DD), they continue to show a circadian rhythm of mating reactivity. When cells in the non‐reactive phase of DD were exposed to light pulse (from 5 sec to 6 hr in duration), they expressed mating ability 1.5 hr after the light pulse. Three wavelengths (416 nm, 547 nm, 626 nm) of light (5‐sec pulse) were most effective for inducing the mating ability. Light pulses of more than 2 hr were sufficient to shift the phase of the circadian mating rhythm in DD, but phase shifts did not occur after light pulses of less than 1 hr. We obtained a phase response curve (PRC) for light pulses of 6‐hr duration.To investigate the intracellular light‐transduction pathway, we examined whether inositol triphosphate (IP3) could induce the mating activity in DD. Cells in the non‐reactive phase of DD were injected with 10 pl of a solution of IP3 (120 μM) under dim green light (480 nm, 8 μW/cm2) which did not induce mating ability. The cells begin to show mating activity 30 min after the injection and the extent of the activity was greater than that obtained by exposing cells to a 3 hr light pulse. However, injection of IP3 did not cause phase shifting in DD. Thus, circadian clock appeared not to be influenced by the injection of IP3. © 1995 Wiley‐Liss, Inc.
Histogenesis of antlerogenic tissues cultivated in diffusion chambers in vivo in red deer (Cervus elaphus)
Authors: Li Chunyi , Waldrup Kenneth A. , Corson Ian D. , Littlejohn Roger P. , Suttie James M. 
Published: June 2005

AbstractIn a previous study we showed that formation of deer pedicle and first antler proceeded through four ossification pattern change stages: intramembranous, transition, pedicle endochondral, and antler endochondral. In the present study antlerogenic tissues (antlerogenic periosteum, apical periosteum/perichondrium, and apical perichondria of pedicle and antler) taken from four developmental stages were cultivated in diffusion chambers in vivo as autografts for 42–68 days. The results showed that all the cultivated tissues without exception formed trabecular bone de novo, irrespective of whether they were forming osseous, osseocartilaginous, or cartilaginous tissue at the time of initial implant surgery; in two cases in the apical perichondria from antler group, avascularized cartilage also formed. Therefore, the antlerogenic cells, like the progenitor cells of somatic secondary type cartilage, have a tendency to differentiate into osteoblasts and then form trabecular bone. Consequently, the differentiation pathway whereby antlerogenic cells change from forming osteoblasts to forming chondroblasts during pedicle formation is caused by extrinsic factors. Both oxygen tension and mechanical pressure are postulated to be the factors that cause this alteration of the differentiation pathway. © 1995 Wiley‐Liss, Inc.
Spontaneous maturation in Bufo arenarum oocytes: Follicle wall involvement, respiratory activity, and seasonal influences
Authors: Zelarayán L. I. , Oterino J. , Bühler M. I. 
Published: June 2005

AbstractThe various somatic cell layers (surface epithelium, theca, and follicle cells) that envelope the amphibian oocyte were removed one by one. The various follicular preparations thus obtained were tested for their ability to undergo germinal vesicle breakdown (GVBD) in the presence or absence of progesterone during different seasonal periods. Intact follicles, follicles without epithelium, or defolliculated oocytes (without epithelium and theca layers) did not undergo GVBD when cultured in Ringer solution, unless progesterone was added to the culture medium. In contrast, denuded oocytes (lacking all follicular layers) cultured in a medium with no hormones underwent GVBD in percentages similar to those of denuded oocytes incubated with progesterone. This ability of denuded oocytes to undergo spontaneous maturation was found to be related to the respiratory activity of the oocyte, which is in turn a seasonal variable in Bufo arenarum. The different respiratory activity of the full‐grown oocyte according to the seasonal period was expressed by the respiratory control quotient (around 1.0 during winter and 4.0 during summer). In fact, only those oocytes with a respiratory control quotient over 2.0 were able to undergo spontaneous nuclear maturation. The maturation obtained without exogenous hormonal stimulus was genuine as indicated by the ability of these oocytes to induce pronuclear formation after sperm injection. © 1995 Wiley‐Liss, Inc.
Proliferation of newt spermatogonia by mammalian FSH via Sertoli cells in vitro
Authors: Maekawa Kohtaro , Ji Zai‐Si , Abé Shin‐Ichi 
Published: June 2005

AbstractOur previous studies showed that mammalian follicle‐stimulating hormone (FSH) stimulated the proliferation and differentiation of secondary spermatogonia into primary spermatocytes in organ culture of testes fragments from Cynops pyrrhogaster. To elucidate how FSH stimulates spermatogonial proliferation, we studied the interaction of spermatogonia with somatic cells in the presence or absence of FSH in cultures of aggregated cells derived from fractionated cell populations.When spermatogonia or those with somatic cells were cultured, they formed aggregates with themselves or with somatic cells, respectively. Most of the somatic cells in the aggregates were Sertoli cells, judged by the lipid droplets in their cytoplasm.[3H]thymidine incorporation into aggregates and autoradiography demonstrated spermatogonial proliferation that was enhanced in the presence of FSH and somatic cells (most probably Sertoli cells), but not in the absence of FSH or in the presence of luteinizing hormone (LH).To examine whether direct contact between spermatogonia and Sertoli cells is indispensable for the stimulation of spermatogonial proliferation by Sertoli cells, the two cell types were separated by a 0.4 μm pore filter in two compartments of a bicameral chamber. In this case, Sertoli cells did not stimulate spermatogonial proliferation in the presence of FSH, indicating that direct contact between spermatogonia and Sertoli cells is indispensable for the stimulation of spermatognial proliferation by Sertoli cells.Finally, Sertoli cells isolated from the testes from the primary spermatocyte stage did not stimulate spermatogonial proliferation in the presence of FSH. This result indicated that the function of Sertoli cells with respect to their stimulation of proliferation was stage‐specific. © 1995 Wiley‐Liss, Inc.