bluuebunny/crossref_metadata_2025 huggingface dataset:
Distribution of lectin binding sites in the oviducts of cycling and hormone‐treated pigs
Authors: Raychoudhury S. S. , Suarez S. S. , Buhi W. C.
Published: June 2005

Gamete transport, fertilization, and early embryonic development take place in different regions of the oviduct and under different hormonal conditions. The objective of this study was to use lectins to detect variation in the distribution of glycosylated molecules on the surface of the epithelia that influence these events. Oviducts were collected from gilts on day 1 (estrus) and day 16 (diestrus) of the estrous cycle, and from gilts that were bilaterally ovariectomized on day 4 of the estrous cycle, and were subsequently treated with estradiol valerate (100 μg/day), progesterone (200 mg/day), or corn oil vehicle for 11 days. Six biotinylated lectins, Triticum vulgaris (WGA), Arachis hypogaea (PNA), Ulex europeus (UEA‐I), Dolichos biflorus (DBA), Ricinus communis (RCA‐I), and Canavalia ensiformis (Con A), were used to probe tissue from the isthmus and ampulla using peroxidase‐conjugated avidin as the marker. In cyclic gilts, WGA and DBA stained more strongly in the isthmus than the ampulla on both cycle days. Staining with PNA was patchy, but greater on the apical surface of isthmic epithelium on day 16 than day 1. With UEA‐I, staining was more intense in the ampulla on day 16 than day 1. Staining by PNA and UEA‐I was suppressed in both the ampulla and isthmus with estradiol treatment. DBA staining was suppressed in the isthmus with both estradiol and progesterone treatments. Cilia were labelled by all lectins except WGA and PNA. Thus glycosylation patterns vary in the porcine oviduct with region and hormonal state, reflecting the variety of events that may be influenced. © 1993 Wiley‐Liss, Inc.
Temperature‐dependent sex determination in the leopard gecko, Eublepharis macularius
Authors: Viets Brian E. , Tousignant Alan , Ewert Michael A. , Nelson Craig E. , Crews David
Published: June 2005

The leopard gecko, Eublepharis macularius, has temperature‐dependent sex determination (TSD). Previous reports have shown that females are produced predominately at cool incubation temperatures and males are produced predominately at warm incubation temperatures (Pattern Ib). We report here that incubation at even higher temperatures (34 and 35°C) produces mostly females (Pattern II). The lethal maximum constant incubation temperature for this species appears to be just above 35°C. Although a previous study indicated that females from a warm incubation temperature (32°C) failed to lay eggs, we found that 12 of 14 mature females incubated at 32.5°C, and 5 of 6 mature females incubated at 34°C produced fertile eggs and viable hatchlings. © 1993 Wiley‐Liss, Inc.
Regulation of hepatic vitellogenin synthesis in the little skate (Raja erinacea): Use of a homologous enzyme‐linked immunosorbent assay
Authors: Perez Lorelei E. , Callard Ian P.
Published: June 2005

An enzyme‐linked immunosorbent assay (ELISA) was developed to detect vitellogenin in skates. The antibody raised against the yolk protein lipovitellin was shown to recognize a sexspecific, estrogen‐inducible 205 kD protein in plasma, previously identified in skate as vitellogenin. The detection limit of the assay was 31.3 ng/ml, similar to that of radioimmunoassays for vitellogenin detection in other species. Using the assay, vitellogenin levels were shown to be highest (241.8 ± 26.5 ug/ml) in the ovarian follicular phase, decreasing approximately 1‐2 days before ovulation to a low (173.1 ± 22.9 ug/ml) during the luteal phase. Vitellogenin levels increased again approximately 1‐2 days before oviposition to 259.8 ± 38.8 ug/ml.

The effects of estrogen and progesterone on hepatic vitellogenin production in normal and hypophysectomized male skates were also investigated. Plasma vitellogenin was not detectable in either intact or hypophysectomised male skates, but increased with estradiol treatment (intact: 48.2 ± 4.9 ug/ml vs. hypophysectomised 252 ± 10.6 ug/ml at day 8). Progesterone treatment significantly (P < .01) attenuated the effect of estrogen on plasma vitellogenin levels in both intact (17 ± 2.1 ug/ml) and hypophysectomized (44.0 ± 9.4 ug/ml) male skates. © 1993 Wiley‐Liss, Inc.
Movement of spermatozoa and changes in micropyles during fertilization in medaka eggs
Authors: Iwamatsu Takashi , Ishijima Sumio , Nakashima Seiko
Published: June 2005

In the medaka, movement of spermatozoa and changes in the egg micropyles during fertilization were observed through a video camera and recorded with a video recorder to analyse sperm movement. Movement of spermatozoa as they entered micropyles in both intact and isolated chorions was compared before and after fertilization of the eggs. The inner one third of the micropyle was completely closed and the micropylar vestibule became shallow by 5 min after sperm attachment. Spermatozoa did not increase in swimming speed in the vicinity of the micropyle and were not attracted to it. The majority of spermatozoa entering the micropyle were rotating at an average frequency of 8 Hz in the right‐hand direction. The rotation direction did not correspond to the left‐hand spiral structure of the micropylar wall, though a small amplitude of the beating sperm flagellum corresponded with the narrow micropylar canal. The frequency of sperm entry into the micropyle decreased significantly in intact eggs and isolated chorions following fertilization, independent of artificial occlusion of the micropylar canal. Moreover, in isolated chorions before fertilization, spermatozoa rarely entered the micropylar canal from its inner aperture. The present data suggest the existence of some substance in the micropyle which guides spermatozoa into the micropylar canal, although the perimicropylar depression might also play a role in the guidance of spermatozoa. © 1993 Wiley‐Liss, Inc.
Effects of epidermal growth factor, insulin‐like growth factor‐I, and dialyzed porcine follicular fluid on porcine oocyte maturation in vitro
Authors: Reed Michael L. , Estrada Jose L. , Illera Maria J. , Petters Robert M.
Published: June 2005

Undefined follicular factors that may influence nuclear maturation and/or cytoplasmic maturation are required during in vitro maturation of pig oocytes. Epidermal growth factor (EGF), insulin‐like growth factor‐I (IGF‐I), and dialysed porcine follicular fluid (dpFF) were evaluated for their effects on porcine oocyte nuclear maturation in vitro. In Experiment I, eight different maturation media were made in a split‐plot factorial design with dpFF (0% vs. 10% v/v dialyzed pFF) as the whole plot component, and EGF (0.0 vs. 50 ng/ml) and/or IGF‐I (0.0 vs. 100 ng/ml) as the factorial subplot component. Experiment II was a complete factorial design with dpFF and EGF. Pig follicular granulosa‐cumulus‐oocyte complexes (GCOC) were obtained from slaughterhouse ovaries, washed, and cultured at 38.5°C in a humidified incubator with 5% CO2 in air for 42 h. Following culture, GCOC were mechanically stripped of granulosa‐cumulus cells and evaluated for nuclear maturation by light microscopy. In Experiment I, the percentage of Metaphase II oocytes for control, IGF‐I, EGF, and IGF‐I + EGF treatments without pFF were 50.7%, 52.6%, 80.9%, and 84.3% (control and IGF‐I groups significantly less, P<.001). The same treatments in the presence of pFF were similar and high (84.2, 84.9, 82.1, and 86.8%, respectively). Experiment II gave similar results. These results demonstrate that EGF, in the absence of pFF, promotes a similar level of oocyte nuclear maturation as does pFF alone or pFF with EGF and/or IGF‐I. IGF‐I does not appear to influence nuclear maturation of GCOC. © 1993 Wiley‐Liss, Inc.
Possible involvement of pertussis toxin‐sensitive GTP‐binding protein in the α2‐adrenoceptor‐mediated melanosome‐aggregation response of goldfish melanophores
Authors: Morishita Fumihiro , Hashito Katsuhiko , Fujimoto Masaaki , Yamada Koji
Published: June 2005

The signal‐transduction system involving α‐adrenoceptors, which controls the aggregation of melanosomes, was investigated in the melanophores of the black‐moor goldfish, Carassius auratus.

The order of effectiveness of α‐subtype‐specific agonists and antagonists indicated that the major subtype of α‐adrenoceptor in these cells is α2. After a 12‐hr treatment, pertussis toxin markedly attenuated the melanosome‐aggregation response to norepinephrine (NE), but it failed to inhibit the Li+ ‐induced aggregation of melanosomes.

Pertussis toxin catalyzed the [32P]‐ADP‐ribosylation of a 43‐kDa protein in a crude preparation of membranes from the goldfish melanophores. The radioactivity incorporation into the protein was much reduced by the presence of an analog of GTP, guanosine‐5′‐(3‐O‐thio)‐triphosphate, in the presence of NE. When the membranes were prepared from cells that had been pretreated with pertussis toxin, [32P]‐ADP‐ribosylation of the protein was not observed. These observations indicate that the 43‐kDa protein is the α subunit of a regulatory GTP‐binding protein, and that pertussis toxin inhibits the action of NE on the cells via ADP‐ribosylation of the protein.

From these results, it is concluded that stimulation of α2‐adrenoceptors of goldfish melanophores induces the aggregation of melanosomes in a process mediated by a pertussis toxin‐sensitive GTP‐binding protein. © 1993 Wiley‐Liss, Inc.
Novel female protein with biological activities of C‐reactive protein and lectin in a viviparous rockfish, Sebastes taczanowskii
Authors: Takemura Akihiro , Nunomura Wataru , Takano Kazunori , Hirai Hidematsu
Published: June 2005

A novel sex‐limited protein (FS3) was purified from the serum of female viviparous rockfish, Sebastes taczanowskii, and its physicochemical properties and biological activities were investigated. By using a phosphorylcholin (PC)‐Sepharose column, two types of FS3 could be isolated. Their molecular weights were estimated to be 160,000 and 152,000 by gel filtration. Subunits of 30,000 and 26,000 were found on SDS‐PAGE. Each fragment was glycosylated. In the presence of Ca2+, FS3 agglutinated Streptococcus pneumoniae and rabbit red blood cells (rRBC). The agglutinating activity against the bacteria was inhibited with PC or EDTA, and that of rRBC was inhibited with some sugars. The results indicate that FS3 shares activities of both C‐reactive protein and lectin. FS3 was induced in the serum of males by estrogen administration. The serum levels in the females during the vitellogenic and gestation periods were about 1,000 times higher than those in the normal males. Therefore, the appearance of FS3 is correlated with the active reproductive periods of the female fish and may be related to the peculiar reproductive systems of this species, such as the deposition of spermatozoa and/or developing embryos in the ovary. © 1993 Wiley‐Liss, Inc.
Effects of prolactin, growth hormone, and triiodothyronine on prolactin receptors in larval and adult tiger salamanders (Ambystoma tigrinum)
Authors: Bres Odd , Nicoll Charles S.
Published: June 2005

The effects of porcine growth hormone (pGH) or ovine prolactin (oPRL) alone and in combination with triiodothyronine (T3) on renal PRL receptors were determined in both pre‐ and post‐metamorphic tiger salamanders (Ambystoma tigrinum). The protein hormones were given at a dose of 1.0 μg/gm body weight/day and the T3 was given at 10.0 ng/gm body weight/day. The duration of treatment was 7 days. Effects on growth, and plasma thyroid hormone levels were also determined. Ovine PRL increased growth in both larvae and adults and reversed metamorphic changes. Administration of T3 increased the plasma T3 concentration, as measured by radioimmunoassay, and when given alone caused weight loss at both stages. The GH decreased plasma T4 and increased plasma T3 concentrations, indicating that it caused an increase in T4 deiodination. In adults the renal PRL receptor affinity of 2.9 ± 0.7 × 1010 L/mol and capacity of 160 ± 22 fmol/mg protein were higher than the corresponding values of 1.8 ± 0.3 × 1010 L/mol and 29.2 ± 3.8 fmol/mg in larvae. In adults only, there is an additional low‐affinity, high capacity PRL binding site. The oPRL treatment decreased the binding capacity to 33.2 ± 1.2 and 5.9 ± 4.9 fmol/mg in adults and larvae, respectively. By contrast, pGH increased the capacities to 249 ± 18 and 62.1 ± 6.8 fmol/mg in adults and larvae, respectively. Treatment with T3 alone doubled the oPRL binding capacity to 58.3 ± 4.7 fmol/mg in larvae, but there was no effect in adults. In both developmental stages the effects of oPRL and pGH on the receptors were not changed by the simultaneous T3 treatment. Porcine GH treatment both with and without T3 reduced the PRL binding affinity, but the effect was significant only in larvae. The effect of oPRL on binding affinities could not be determined, because the binding capacity was so low. In adults the low‐affinity site was detectable in all treatment groups, but none of the treatments caused the appearance of the low‐affinity binding site in larval kidneys, even when they increased the binding capacity to adult levels (T3, pGH, or both together). It therefore seems likely that some other factors are involved in the development of the adult binding pattern. The increased oPRL binding capacity caused by pGH in larvae and adults may be secondary to its effect on serum T3 levels. However, the reduction in Ka values in the larvae may be caused by GH itself, possibly due to an increase in the number of the low‐affinity sites. © 1993 Wiley‐Liss, Inc.
Chorioallantoic placentation in squamate reptiles: Structure, function, development, and evolution
Authors: Blackburn Daniel G.
Published: June 2005

Allantoplacentae in lizards and snakes form during the evolution of viviparity through apposition of the chorioallantois and a vestige of the shell membrane to the uterine lining. Generalized squamate allantoplacentae are epitheliochorial, diffuse, adeciduate, and highly vascular, accomplish maternal‐fetal gas exchange, and possibly transfer small quantities of organic and inorganic nutrients. Placental gas exchange presumably is enhanced by the thinning of tissues lying between fetal and maternal capillaries, a progressive increase in placental vascularity, and in some species, by differences in oxygen affinity of fetal and maternal blood. A few saurian genera (e.g., Chalcides, Mabuya, and Pseudemoia) include species with specialized placentae that transfer large quantities of nutrients. Specializations of the allantoplacentae of these lizards include interdigitating, hypertrophied uterine and chorioallantoic tissues, and enlarged absorptive chorionic epithelia. South American Mabuya are further specialized by the presence of chorionic areolae and a distinctive placentome. Weekes' 1935 classification of placental morphotypes is reviewed, and a few minor modifications are proposed, in addition to recognition of a fourth morphotype. Phylogenetic analyses suggest that placental organs have originated on more than 100 occasions among squamate reptiles, and indicate that three separate lineages have converged on substantial placentotrophy through the evolution of specialized histotrophic placentae. © 1993 Wiley‐Liss, Inc.
Yolk sac placentation in reptiles: Structural innovation in a fundamental vertebrate fetal nutritional system
Authors: Stewart James R.
Published: June 2005

The extraembryonic membranes of amniote vertebrates are shared structures that have a brief, yet substantive role in the ontogeny of the organism. The yolk sac, which is the first of these structures to develop, has an important function in regulation and mobilization of nourishment to embryos of oviparous species and additionally contributes to maternal‐fetal exchange in many viviparous species. Yolk sac placentation has been described in all major taxa of viviparous amniotes. The yolk sac of viviparous reptiles contributes to three categories of placentation, the choriovitelline placenta, which also occurs in marsupial and eutherian mammals, and the omphaloplacenta and omphalallantoic placenta, which occur only among squamate reptiles (lizards and snakes). The fetal contribution to the omphaloplacenta includes a structure termed the isolated yolk mass, which forms in all Squamata independent of reproductive mode, and is produced by a morphogenesis of extraembryonic mesoderm that is unique to this reptilian order. For some viviparous squamates, the allantois contributes to the inner margin of the isolated yolk mass and this structural arrangement constitutes the omphalallantoic placenta. The isolated yolk mass is bordered externally by a bilaminar omphalopleure. Epithelial cells of the bilaminar omphalopleure of the omphaloplacenta and omphalallantoic placenta are hypertrophied. The apposed uterine epithelium likewise contains enlarged cuboidal or columnar shaped cells and the underlying lamina propria is richly vascularized. This epithelial cell structure suggests that the region of the isolated yolk mass is a site of placental specialization in viviparous reptiles. Further, since these features of omphaloplacentation or omphalallantoic placentation commonly occur in species without apparent morphological specialization in other areas of fetal‐uterine contact, it is likely that the bilaminar omphalopleure of the isolated yolk mass is evolutionarily the initial site of placental specialization among viviparous reptiles. © 1993 Wiley‐Liss, Inc.
Diapause, pregnancy, and parturition in Australian marsupials
Authors: Renfree Marilyn B.
Published: June 2005

Marsupial pregnancy is characterised by a long lactation and a relatively short gestation. Marsupials have, in effect, exchanged the umbilical cord for the teat. However, gestation can be extended for up to 11 months by the imposition of a period of developmental arrest known as embryonic diapause. Diapause may be under either lactational or seasonal control, and in the kangaroos and wallabies these effects are mediated by prolactin and melatonin, respectively. At the other end of gestation, namely parturition, it appears that marsupials are fairly typical mammals and require all the same physiological and behavioural cues essential for the delivery of a viable young. Parturition depends on a synchronised cascade of hormonal events triggered by the fetus itself. Prostaglandin and prolactin concentrations pulse around the time of birth and progesterone falls. Successful parturition also depends on the adoption of the appropriate behaviour and birth posture by the mother. Despite the fact that the entire period of gestation is accomplished in such a short time, the neonate has perfectly adapted its growth and development to influence its mother's physiology to induce the change from nurturing the young in its uterus via a placenta, to a precise synchronisation of the birth process resulting in completion of its growth within the pouch sustained by a milk tailor‐made for each developmental stage. © 1993 Wiley‐Liss, Inc.
Implantation and decidualization in rodents
Authors: Abrahamsohn Paulo A. , Zorn Telma M. T.
Published: June 2005

This article reviews the main events of embryo‐implantation and decidualization in rodents. In common laboratory rodents the embryo attaches to the uterine epithelial lining, usually on days 4 to 6 of pregnancy. A progressive degree of proximity between trophoblast and epithelium occurs until the epithelial cells undergo apoptosis and detach from the basement membrane. During the attachment stage, the spindle‐shaped connective tissue cells that underlie the epithelium next to the embryos transform into polyhedral and closely packed decidual cells. Following the epithelial detachment and the breaching of the basement membrane the embryo is thus in direct contact with decidual cells. These cells accumulate organelles associated with synthesis of macromolecules, intermediate filaments, and eventually lipid droplets and glycogen. Another remarkable feature of decidual cells is the establishment of gap and adherens intercellular junctions. Differentiation of fibroblasts into decidual cells advances antimesometrially and mesometrially, creating in the endometrium several regions of cells with different morphology. The whole phenomenon of decidualization which is normally triggered by the embryo can be artificially induced in pseudopregnant or hormonally‐prepared animals with the use of diverse stimuli. The uterine epithelium is probably responsible for the transduction of the initial stimulus. Prostaglandins have been shown to be important in the induction of decidualization. More recently other substances such as leukotrienes, platelet‐activating factor (PAF), and transforming growth factor (TGF) have been thought to play a role in induction. Much evidence points to prostaglandin production by the decidual cells. New proteins such as a luteotropic factor, desmin, and other molecules were shown to be produced after rat stromal cells undergo decidual transformation. The extracellular matrix of the mouse decidua contains very thick collagen fibrils. Mouse decidual cells are also very active in phagocytosing the thick fibrils, contributing to the remodeling and involution of the decidua that accompanies embryonic growth. Radioautographic data indicates that mouse decidual cells produce and secrete collagen and sulfated proteoglycans. © 1993 Wiley‐Liss, Inc.
New insights into the anhydrobiotic phenomenon: The effects of trehalose content and differential rates of evaporative water loss on the survival of Aphelenchus avenae
Authors: Higa Lynne M. , Womersley Christopher Z.
Published: June 2005

The effects of differential rates of evaporative water loss on the survival capabilities of small aggregates (ca. 10 mg wet wt) of Aphelenchus avenae were assessed. This was achieved using a comparative approach between rapid (direct transfer of preconditioned nematodes to successively compounds accumulated were also assessed during the induction process. Glyecrol and glucos levels remained low (< 1% dry wt)) while trehalose levels increased dramatically during preconditioning (8–10% dry wt), but the elevated levels were unable to support survival during periods of rapid water loss. Survival was directly related to the rate of evaporative water loss, with the highest level of survival being afforded by the most gradual dehydration regime. In addition, the water loss curves identified a critical period where hydration levels ranged from 40% to 12% H2O. During this time, slow drying was essential if the nematodes were to successfully survive the dehydration process. Survival curves also revealed the existence of a transition phase in the dehydration process, where nematodes required further dehydration before revival could occur. These results are discussed in relation to the adaptive significance of polyhydroxy compound accumulation and the probable role that specific hydration levels play in the implementation of other adaptations at the cellular and subcellular levels. © 1993 Wiley‐Liss, Inc.
Prostaglandin E2 and prostaglandin F2α involvement in the corticosterone and cortisol release by the female frog, Rana esculenta, during ovulation
Authors: Gobbetti Anna , Zerani Massimo
Published: June 2005

Interrenal and ovarian tissues of Rana esculenta were incubated in vitro during the preovulatory, ovulatory and postovulatory phases to study the basal release of prostaglandin E2 (PGE2), prostaglandin F2α, (PGF2α), corticosterone, and cortisol. The effects of exogenous PGE2 and PGF2α on interrenal and ovarian corticosteroid release were also studied. In addition, the plasma values of these four hormones were assessed during the same phases. During in vitro interrenal incubations, PGE2α PGF2α, corticosterone, and cortisol basal releases were higher in the postovulatory phase, PGE2, and PGF2α treatment in vitro increased corticosteroids during the ovulatory phase. During in vitro ovarian incubations, PGE2 basal release was higher in the preovulatory phase and PGF2α and corticosteroids in the ovulatory phase; PGE2 treatment in vitro decreased corticosteroids in the ovulatory phase, and PGF2α increased corticosteroids in the preovulatory and postovulatory phases. PGE2, corticosterone and cortisol plasma values were higher during the postovulatory phase, while PGF2α, was elevated during the ovulatory phase. These findings suggest that ovarian corticosteroids could be considered one of the factors inducing ovulation and that their synthesis may be modified by PGs. © 1993 Wiley‐Liss, Inc.
Pedicle and antler development following sectioning of the sensory nerves to the antlerogenic region of red deer (Cervus elaphus)
Authors: Li Chunyi , Sheard Philip W. , Corson Ian D. , Suttie James M.
Published: June 2005

Sensory nerves supplying the deer antlerogenic region were sectioned about 60 days prior to pedicle initiation to determine the extent of neural influence on pedicle and first antler growth. Our results from a combination of histological examination and immunohistochemical localization showed that all 12 antlerogenic regions were successfully deprived of sensory nerve supply, but in 10 of 12 cases there was partial regeneration during the experimental period. In the two cases where no sensory reinnervation occurred, pedicle growth did not show any differences compared with partially sensory reinnervated or intact pedicles. With or without reduced sensory nerve supply, first antlers were initiated, grown, cleaned of velvet, cast, and regenerated in the normal way, but they were smaller than controls. Consequently, we conclude that a sensory nerve supply is not necessary for normal pedicle formation and for the first antler cycle, but plays a role in determining antler size. © 1993 Wiley‐Liss, Inc.
Characterization of equine oviductal proteins synthesized and released at estrus and at day 4 after ovulation in bred and nonbred mares
Authors: McDowell Karen J. , Adams Mary H. , Williams Neil M.
Published: June 2005

Proteins synthesized and released in vitro by oviducts collected from horse mares during estrus and at day 4 after ovulation for bred and nonbred mares were examined by two‐dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis (2‐D SDS PAGE) and fluorography. Ampullary and isthmic regions both produced a wide array of nondialyzable proteins in culture. Major proteins or groups of proteins identified according to relative molecular weight (kDa) and apparent isoelectric point (pI) were at 100kDa, PI8; 100–200 kDa, PI6; 150 kDa, PI4.5;60–100 kDa, PI 4; and an array of polypeptides at 21–22 kDa, pI 5–6. Oviductal secretory activity, measured by incorporation of radiolabeled amino acids into nondialyzable macromolecules released into incubation medium, was greater (P <.01) for the ampullary than the isthmic oviductal region. No consistent differences were observed in fluorograms between estrus vs. day 4 after ovulation, ampulla vs. isthmus, ipsilateral vs. contralateral to the corpus luteum or largest follicle, oviducts from bred vs. nonbred mares, or mare ages. Dialyzed medium from ampullary and isthmic regions of oviducts was subjected to 1‐D or 2‐D SDS PAGE followed by western blotting utilizing an antiserum directed against human retinol binding protein (RBP). The family of 21–22 kDA polypeptides was identified as immunoreactive RBP. © 1993 Wiley‐Liss, Inc.
Problems in the understanding of cell volume regulation
Authors: Macknight A. D. C. , Gordon L. G. M. , Purves R. D.
Published: June 2005

The constancy of cell volume under physiological conditions is generally thought to reflect a balance between solute influx and efflux and is therefore critically dependent on the properties of the plasma membrane. Despite a number of unanswered questions, a large amount of experimental data can be accommodated within this pump‐leak framework and can by analysed using the simple assumptions of osmotic equality between cells and their surrounding fluid, and fluid electroneutrality. Experimentally, cell volume may be altered in vitro either by changing cell solute content under isosmotic conditions or by changing medium osmolality. Exposure to anisosmotic media may provoke a variety of cell responses that minimise the volume change. However, much of this experimental work has been performed under extreme conditions in vitro that would never be experienced by vertebrate cells in vivo; its relevance to pathophysiological situations is questionable. It is argued that regulation of cell volume should not be seen in isolation but as part of the process, cell homeostasis, by which cells attempt to minimise changes in composition when faced with perturbations in their environment. Given the variety of processes and the large numbers of membrane transporters, an understanding of how cells respond to such perturbations requires a combination of modelling and experimentation. A simple example of this approach is presented. © 1994 Wiley‐Liss, Inc.
Evidence for the role of actin filaments in regulating cell swelling
Authors: Mills John W. , Scwiebert Erik M. , Stanton Bruce A.
Published: June 2005

Actin filaments could play a role in regulation of cell swelling by two distinct mechanisms. One is by a tensile mechanism involving the coordinated interaction of actin and actin‐associated proteins with all plasma membrane domains. The actin‐membrane linkage would restrain cell swelling in the event of the influx of water. In shark rectal gland cells, conditions that cause massive cell swelling (i.e., high K medium, exposure to mercurials) are associatd with disruption of membrane‐associated actin filaments. Under conditions that result in only moderate swelling (Na‐pump inhibition, Li substitution) the actin filaments remain associated with the cell membrane. Thus, in this cell type, disruption of the actin‐membrane organization is correlated with increased swelling. Another mechanism by which actin could limit cell swelling is via regulation of ion transport proteins that are activated by cell swelling. This could be accomplished by a vesicle transport and insertion mechanism that delivers ion transport units to the cell membrane or by interaction with transport proteins already present in the membrane. Cell‐attached patch clamp studies of RCCT‐28A cells exposed to hypotonic medium demonstrated the activation of Cl‐channel activity coincident with an alteration in actin. Activation of the channel was mimicked by stretching the membrane. Exposure of inside‐out patches to cytochalasins also increased Cl‐channel activity. Treatment of isolated patches with phalloidin inhibited stretch‐induced activation. Thus, regulation of a volume‐sensitive Cl‐channel appears to be directly related to the state of organization of actin filaments. © 1994 Wiley‐Liss, Inc.
Volume‐activated amino acid transport and cell signaling in skate erythrocytes
Authors: Goldstein Leon , Musch Mark W.
Published: June 2005

Skate (and other fish) erythrocytes show a rapid efflux of taurine in response to volume expansion upon exposure to hyptonic medium. Taurine and other small amino acids appear to be released from the cells down their concentration gradients via a channel which might involve the anion exchange protein Band 3. Hypotonicity alters the cell permeability to taurine coincident with generation of diacylglycerol from phosphatidylcholine by stimulating the activity of phospholipase D. This diacylglycerol can then activate protein kinase C, stimulating the phosphorylation of specific protein targets. Three phosphoprotein targets have been identified; one is the Band 3 molecule itself, while the other two have molecular weights of 67 and 34 kDa. The precise way in which phosphorylation alters the permeability of the cell to taurine is as yet unknown. It is possible that phosphorylation of Band 3 changes the molecule so that it acts as an amino acid channel. © 1994 Wiley‐Liss, Inc.
Molecular basis for osmoregulation of organic osmolytes in renal medullary cells
Authors: Burg Maurice B.
Published: June 2005

Renal medullary cells are naturally exposed to extremely high and variable interstitial concentrations of NaCl and urea, consequent to operation of the urinary concentrating mechanism. They respond by accumulating large and variable amounts of sorbitol, glycerophosphocholine (GPC), glycine betaine (betaine), myo‐inositol (inositol), and taurine both in vivo and in cell cultures. Sorbitol is synthesized from glucose, catalyzed by aldose reductase. Hypertonicity increases aldose reductase activity by raising this enzyme's transcription, mRNA level, and translation, and thereby increases production of sorbitol. GPC is synthesized from choline via phosphatidylcholine. A combination of high NaCl plus urea does not increase GPC synthesis, but does reduce its degradation by inhibiting GPC:choline phosphodiesterase. Betaine, inositol and taurine are taken up into the cells, each by a different sodium‐dependent transporter. Hypertonicity increases mRNAs of all three transporters. This is due to increased transcription (at least of the inositol and betaine transporters). The eventual result is greater betaine, inositol and taurine uptake and accumulation. Osmoregulation of net sorbitol and GPC synthesis and of betaine, inositol and taurine transport is slow, requiring hours to days. However, following an acute fall in tonicity, these organic osmolytes exit from the cells within minutes, via specialized efflux mechanisms. As demonstrated by cloning efficiency studies, renal cell survival and growth following hypertonicity depend on the sum of all organic osmolytes that are accumulated; altering one experimentally changes the others to maintain a nearly constant total. Methylamine accumulation protects these cells against high urea; the methylamine that is preferentially accumulated in response to high urea is GPC. © 1994 Wiley‐Liss, Inc.

This article is a US Government work and, as such, is in the public domain in the United States of America.
Frequency and amplitude tuning of nematocyst discharge by proline
Authors: Watson Glen M. , Hudson Renee R.
Published: June 2005

In sea anemone tentacles, discharge of nematocysts into vibrating targets is regulated by hair bundles. N‐acetylated sugars are known to induce hair bundles to elongate while tuning nematocyst discharge to low frequencies and small amplitudes corresponding to movements produced by calmly swimming prey. Proline is known to induce hair bundles to shorten while tuning nematocyst discharge to higher frequencies. In this report, we provide evidence suggesting that proline linearly tunes nematocyst discharge. Nematocyst discharge is tuned by increases of 10−18 M proline above background levels ranging from 10−12 M to 10−8 M proline, but only after anemones adapt to the background levels of proline. Anemones adapt more rapidly to 10−12 M proline than to 10−10 M, followed by 10−8 M proline. L‐proline and D‐proline comparably tune nematocyst discharge. Proline tunes discharge to higher frequencies and/or to larger amplitudes at the same lower frequencies produced by prey. We propose that N‐acetylated sugars tune nematocyst discharge to the movements of calmly swimming prey. After the prey is wounded by nematocysts, it releases proline into the seawater. This proline tunes nematocyst discharge to higher frequencies and/or larger amplitudes at low frequencies corresponding to movements produced by struggling, wounded prey. Thus, the greatest numbers of nematocysts may be discharged into calmly swimming, fresh prey and into vigorously struggling, wounded prey. © 1994 Wiley‐Liss, Inc.
Effect of air exposure on ammonia excretion and ammonia content of branchial water of the crab Cancer pagurus
Authors: Regnault Michèle
Published: June 2005

C. pagurus (mean weight 280 g) was exposed to air for 18 h at 16–18°C in presence of a small volume of filtered seawater (FSW = 45 ml) and then reimmersed. Ammonia excretion rate was measured and the amount of ammonia that accumulated in branchial water and haemolymph during emersion was evaluated. During the whole emersion period, ammonia that was released into both FSW (42 μmoles·crab−1) and branchial water (< 11 μmoles·crab−1) amounted to 6% of the pre‐emersion release, at the very most.

In the first 5 min immediately following reimmersion, a large burst of ammonia output (203 μmoles·crab−1) was observed. Neither ammonia stored in branchial water and haemolymph nor breakdown of urate accumulated in haemolymph can account for it. As this burst was not the result of an increase in metabolism only, its potential sources are discussed. Following this burst, ammonia excretion rate returned to its pre‐emersion value within the next 1 h. Then, ammonia excretion rate again increased; this second increase was relatively moderate and lasted for 2–3 h. Recovery was fully achieved within 8 h. The ammonia excess that was excreted during recovery was mainly released at the onset of re‐immersion. © 1994 Wiley‐Liss, Inc.
Immunological identification and biochemical characterization of a glucose transporter in the posterior gills of the crab Carcinus maenas (L.)
Authors: Welcomme L. , Devos P.
Published: June 2005

The euryhaline crab Carcinus maenas when adapted to hyposmotic medium shows an ion transporting‐type epithelium in the three posterior gills. When they are perfused in hyposmotic conditions, there is highly specific sodium‐independent glucose transport activity. This saturable transport activity is inhibited by phloretin and diethylstilbestrol.

Immunological data obtained with the utilization of the antibody RaIRGT (antibody anti‐glucose transporter found in rat adipocytes) reveals the existence of a single bound protein of 38 Kd. This protein can specifically bind to cytochalasin B which has a high affinity for the glucose transporter found in numerous tissues of vertebrates.

These biochemical and immunological data point to the existence of a glucose transporter of 38 Kd in the branchial tissue of this species of crab. © 1994 Wiley‐Liss, Inc.
Spinal cord neurite growth response to target tissue in a dose‐dependent manner in vitro
Authors: Somasekhar Thummala , Pollack Emanuel D.
Published: June 2005

Neurite outgrowth from larval frog spinal cord explants in tissue culture previously has been shown to be enhanced and oriented in the presence of mesenchymal limb target tissue. Evidence that suggests the limb mesenchyme is the source of a motor neuron growth factor has prompted consideration of a possible target dose relationship in eliciting spinal neurite growth. Whereas typical experimental paradigms incorporate a single target explant in cocultures of neural and target tissues, we have challenged spinal cord explants with dual limb targets. Both the spinal cord explants and mesenchymal limb tissue segments were derived from young stage V Rana pipiens tadpoles. In comparison to cultures with a single limb, the spinal neurite density in the presence of two limbs increased more than twofold. Accompanying the increase in neuritic quantity was a substantial increase in the average length of the neurites. Over a two‐week culture period there was little change in the relative differences between the single and double target cultures. Even though the double target tissues were placed adjacent to one another on one side of the cord explant, greatly enhanced neurite growth occurred on the contralateral side as well. The dramatic increase in neurite outgrowth in the presence of an additional target tissue provides further evidence that undifferentiated mesenchymal limb tissue is the source of a spinal neurite growth‐promoting factor that may act in a dose‐dependent manner with implications for both motor axon growth regulation and regeneration. © 1994 Wiley‐Liss, Inc.
Mouse trophoblast cell invasion of extracellular matrix purified from endometrial tissue: A model for peri‐implantation development
Authors: Armant D. Randall , Kameda Shogo
Published: June 2005

We have investigated the invasive activity of mouse trophoblast cells during embryo implantation in vitro by culturing blastocysts with extracellular matrix (ECM) purified from mouse endometrium obtained on day 4 of pregnancy Endometrium was dissected from lyophilized mouse uteri, and intact ECM was isolated by sequential precipitation in nonionic detergent and high salt. Electron microscopic examination of the ECM revealed typical collagen fibers plus an amorphous material resembling basement membrane. Electrophoretic analysis of the ECM revealed an enrichment of high molecular weight proteins, and immunoblotting indicated the presence of fibronectin, laminin, entactin, and type IV collagen, but not the intracellular proteins 2′,3′‐cyclic nucleotide‐3′‐phosphodiesterase or vimentin. Mouse blastocysts cultured with this ECM attached to it within 3 days, and the trophoblast cells began to migrate through the matrix in a manner resembling trophoblast invasion in utero. Unlike blastocysts cultured on plastic surfaces, the trophoblast did not flatten and become disorganized, but retained a polarized, spherical structure. Fluorescent microscopy with fluorescein isothiocyanate‐labeled phalloidin revealed a high degree of microfilament organization and established that actin was absent from the ECM preparation. In the presence of a serum substitute, differentiation continued through yolk sac formation. Without serum components, yolk sac did not form; however, light and electron microscopic examination indicated that the invasive behavior of trophoblast cells persisted and was comparable to that of trophoblasts cultured in the presence of the serum substitute. A three‐dimensional model for investigating trophoblast behavior in ECM from the endometrium should be of great value in elucidating the cellular and molecular events surrounding the process of blastocyst implantation. © 1994 Wiley‐Liss, Inc.
Gravity in mammalian organ development: Differentiation of cultured lung and pancreas rudiments during spaceflight
Authors: Spooner Brian S. , Hardman Patricia , Paulsen Avelina
Published: June 2005

Organ culture of embryonic mouse lung and pancreas rudiments has been used to investigate development and differentiation, and to assess the effects of microgravity on culture differentiation, during orbital spaceflight of the shuttle Endeavour (mission STS‐54). Lung rudiments continue to grow and branch during spaceflight, an initial result that should allow future detailed study of lung morphogenesis in microgravity. Cultured embryonic pancreas undergoes characteristic exocrine acinar tissue and endocrine islet tissue differentiation during spaceflight, and in ground controls. The rudiments developing in the microgravity environment of spaceflight appear to grow larger than their ground counterparts, and they may have differentiated more rapidly than controls, as judged by exocrine zymogen granule presence. © 1994 Wiley‐Liss, Inc.
Role of epidermal–dermal tissue interactions in regulating tenascin expression during development of the chick scutate scale
Authors: Shames Rose B. , Bade Belinda C. , Sawyer Roger H.
Published: June 2005

During normal chicken development tenascin begins to accumulate in the dermis of anterior metatarsal skin at the time of scutate scale ridge formation, and is localized in a distinct pattern along the outer scale surface. Anterior metatarsal skin from scaleless (sc/sc) embryos, which do not form scutate scales, begins to accumulate tenascin 4 days later than normal skin. This study shows that normal and scaleless anterior metatarsal dermis accumulate the same tenascin isoforms and undergo the same isoform changes in the post‐hatch period, but there is less tenascin accumulated in scaleless dermis and there is no pattern to its distribution. In both normal and scaleless anterior metatarsal skin, tenascin mRNA is localized in the dermis and is distributed in the same way as the protein. Thus, scaleless skin is defective in the ability to accumulate appropriate amounts of tenascin and to maintain the tenascin in the patterned manner of normal. Recombinant skin cultures show that epidermal–dermal interactions are required for tenascin accumulation. The dermis specifies the way that tenascin is organized, but interaction with epidermis is required to maintain this organization. The epidermal role appears to be permissive because in heterotypic recombinants, neither scaleless anterior metatarsal epidermis nor normal footpad epidermis changes the way that tenascin appears in the normal anterior metatarsal dermis; and in reciprocal recombinants, normal anterior metatarsal epidermis does not change the way tenascin is accumulated in either scaleless anterior metatarsal dermis or normal footpad dermis. © 1994 Wiley‐Liss, Inc.
Onset of DNA synthesis in experimentally activated ascidian eggs
Authors: Patricolo E. , Mansueto C.
Published: June 2005

DNA synthesis was studied autoradiographically in unfertilized ascidian eggs (Ascidia malaca and Ciona intestinalis) that had been artificially activated by a K+‐free external medium or a Ca‐ionophore. Naked eggs of A. malaca were incubated in K+‐free seawater that contained [3H]‐thymidine for 30 min, and naked eggs of C. intestinalis were incubated in seawater supplemented with a Ca‐ionophore and [3H]‐thymidine for 15 min. The observations revealed limited activation in eggs treated with K+‐free seawater. Activation consisted of surface modifications and the onset of DNA synthesis. Incorporation of [3H]‐thymidine was detected in female nuclei of treated eggs which had not ejected their polar bodies. In eggs treated with the Ca‐ionophore, a known activating agent, the rate of incorporation of [3H]‐thymidine was higher and nuclear duplication was also observed. Comparison of activation under the two different sets of artificial conditions indicated that, in K+‐free medium, the early calcium‐dependent events, such as deformation of egg shape, extrusion of the polar bodies, and ooplasmic segregation, do not occur, while DNA synthesis is initiated. The results are discussed on the basis of the hypothesis that, in Ascidians, egg‐activation events are only partly regulated by an intracellular increase in levels of calcium ions. DNA synthesis appears to be an independent process that is initiated by changes in the egg plasma membrane. © 1994 Wiley‐Liss, Inc.
Combined gonadal and photic influences on 2‐[125I] iodomelatonin‐binding level changes in some brain areas of the quail
Authors: Canonaco Marcello , Tavolaro Renata , Facciolo Rosa Maria , Artero Cristina , Franzoni Maria Fosca
Published: June 2005

Quantitative receptor autoradiography was used to study the binding of 2‐[125I] iodomelatonin in the brain of the castrated and gonadally intact male Japanese quail Coturnix japonica exposed to both long‐ and short‐day photoperiod cycles. The distribution study displayed that these conditions were responsible for a heterogeneous binding pattern as shown by elevated receptor levels being located in visual brain centers, such as the stratum opticum, nucleus pretectalis, and nucleus geniculatus lateralis, pars ventralis, while lower values were found in the nucleus lateralis hypothalami and nucleus isthmi pars magnocellularis. Closer examination of the 2‐[125I] iodomelatonin–binding pattern following the different gonadal and photic influences showed that combination of the gonadally intact condition and a 16L:8D (long‐day) photoperiod cycle was required for the greater binding changes. These differences occurred in brain sites such as the area preoptica, paleostriatum primitivum, and nucleus ectomamillaris. Saturation binding studies, which were carried out only in some of the above areas, revealed that the combined gonadal and photic‐induced changes are basically due to the modifications of total number of binding sites. The importance of a gonadal steroid modulatory role in the photic‐dependent melatonin binding activity suggests that other types of neuronal mechanisms might be involved in the regulation of neuroendocrine and socio–sexual behaviors in nonmammalian vertebrates. © 1994 Wiley‐Liss, Inc.