bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of an antiandrogen treatment on the antler cycle of male fallow deer (Dama dama L.)
Authors: Kierdorf Uwe , Schultz Michael , Fischer Klaus
Published: June 2005

Weekly application of the antiandrogen cyproteron acetate (CA) to 3 adult (group 1, treatment starting 3 weeks prior to the rut) and 4 subadult (group 2, treatment starting after the rut) fallow bucks led to premature antler casting after about 9 weeks (group 1) or 16 to 17 days (group 2). Variation in time span between onset of CA administration and induced casting (in late November/early December) is attributed to age‐ and season‐dependent differences in androgen levels before and during the treatment period. Casting surfaces of the antlers were flat. In all bucks, casting was followed by a complete though shortened antler cycle, occurring under short day conditions. In February/March velvet was shed from the antlers, indicating a rise in plasma androgen levels at that time. At time of fraying, antlers exhibited signs of immaturity and were shorter than normal. In the most pronounced case of immaturity, the antlers consisted mainly of cancellous woven bone, revealing that bone remodeling and antler mineralization had not occurred to a larger extent. These observations prove that onset of fraying behaviour does not depend on prior maturation of antler bone or necrosis of velvet. Occurrence of the additional antler cycle in late autumn and winter had no negative effect on subsequent antler formation starting in the following spring. © 1993 Wiley‐Liss, Inc.
Gestation and placentation in two new world opossums: Didelphis virginiana and Monodelphis domestica
Authors: Harder John D. , Stonerook Michael J. , Pondy Jacqueline
Published: June 2005

Estrus, gestation, and placentation were studied in the Virginia opossum (Didelphis virginiana) and the gray short‐tailed oppossum (Monodelphis domestica), representatives of the prototypic, New World marsupial family Didelphidae. Didelphis is a large (3,000 g), pouched opossum that exhibits a 28‐day estrous cycle, spontaneous estrus and ovulation, and a high ovulation rate (60 ova per cycle). Monodelphis is a small (100 g), pouchless opossum with male‐induced estrus and ovulation and a moderate ovulation rate (12 ova per cycle). Implantation occurs on day 10 of the 13‐day gestation period in Didelphis and on day 12 of the 15‐day gestation in Monodelphis. Gestation and placentation, including the ultrastructural features of trophoblastic apposition to the uterine mucosa, are very similar in Didelphis and Monodelphis. Differences, such as a larger increase in uterine volume and a more highly folded endometrium following implantation in Monodelphis are minor. They appear to be related to the smaller maternal body size and the relatively larger uterine load of embryos in Monodelphis. Because body size is one of the major variables among New World marsupials, the descriptions of gestation and placentation presented here for Didelphis and Monodelphis, provide a basis for comparison in future studies of didelphid marsupials. © 1993 Wiley‐Liss, Inc.
Giant and binucleate trophoblast cells of mammals
Authors: Hoffman Loren H. , Wooding F. B. P.
Published: June 2005

The cellular origin, structure, and function of trophoblastic giant cells (GC) and binucleate cells (BNC) are reviewed. Mammals in which these cells have received the greatest attention include rodents, rabbits, and humans (GCs), and ruminants and equids (BNCs). In almost all cases these cells arise from the cytotrophoblast. All are large cells and contain either two diploid nuclei (BNCs), multiple nuclei (human placental bed GCs), or single nuclei with amplified DNA content (rodent and rabbit GCs). Giant and binucleate cells typically exhibit the capacity for migration or invasion, although the degree of migratory activity varies between species. While most end up within, or at the interface with, endometrial tissue, in some instances the GCs or BNCs contribute directly to the interhemal membrane of the placenta. Hormone production is a property which most GC‐BNC populations have in common. Lactogen or gonadotropin has been documented in almost all cells of this type examined to date, and in some animals they are also steroidogenic (e.g., rats and sheep). In spite of some common features, both structural and functional differences remain and it is suggested that use of terms such as mononuclear giant cells, multinucleate giant cells, and binucleate cells be continued rather than assuming that these cells are all members of a single trophoblastic subtype. © 1993 Wiley‐Liss, Inc.
Structural interactions of trophoblast and uterus during hemochorial placenta formation
Authors: Enders Allen C. , Welsh Alerick O.
Published: June 2005

It is argued that the successful placental arrangements are those that decrease the exposure of the trophoblast to the efferent side of the cellular immune response. Examples are taken from three different groups with hemochorial placentation, to show that their placental morphology places most of the trophoblast in contact with maternal blood, not maternal connective tissue. In addition, maternal cells of the junctional area are modified either before contact with trophoblast (rat) or just after trophoblast invasion (primate), or the region of contact is limited as in the armadillo, in which maternal blood sinuses are expanded to form intervillous spaces. © 1993 Wiley‐Liss, Inc.
Carbohydrate metabolism in the brain of the adult lamprey
Authors: Foster Glen D. , Youson John H. , Moon T. W.
Published: June 2005

Carbohydrate metabolism was examined in brain pieces isolated from spawning (anadromous, New Brunswick, N.B.) and prespawning upstream migrant (landlocked, Toronto) lampreys (Petromyzon marinus). Brain glycogen concentration in the N.B. lampreys was 2.61 μmol mg−1 protein or 286 μmol g−1 tissue wet wt., significantly above that in the Toronto group (0.34 μmol mg−1 protein; 37 μmol g−1 tissue wet wt.). When glucose was added to an incubate of brain pieces, there was no change in glucose concentration, except in the presence of 10−7 M insulin, which resulted in net glucose uptake by the tissue. Glucose was metabolized by the brain pieces to both glycogen and CO2, with 12% (N.B.) and 32% (Toronto) of the glucose converted to glycogen. Insulin significantly increased glucose flux to glycogen, and epinephrine increased glucose flux to both CO2 and glycogen. Total lactate utilization by the brain pieces was greater than glucose utilization. Although only 2% of the utilized lactate was converted to glycogen, glycogen synthesis from lactate was 25–30% of glycogen synthesis from glucose. PEPCK activities were found in the brain, indicating the potential for a traditional gluconeogenic pathway. This study supports the hypothesis that gluconeogenesis from C3 substrates can contribute to brain glycogen synthesis in adult lamprey. © 1993 Wiley‐Liss, Inc.
Scotopic spectral sensitivity of the optomotor response in the green treefrog Hyla cinerea
Authors: King Richard B. , Douglass John K. , Phillips John B. , Baube Charles L.
Published: June 2005

Amphibians are unusual among vertebrates in having two spectral classes of rod photoreceptors, unique amphibian “green” rods and typical vertebrate “red” rods. Although amphibians have been the subject of extensive research on visual function, it is not known whether possession of two classes of rods is a general feature of Amphibia, nor is it clear to what behaviors each class of rods contributes. The Hylidae comprise one of the largest families within Amphibia but have been little studied with respect to visual function. Here, we demonstrate the presence of green and red rods in Hyla cinerea by microspectrophotometry and provide evidence for the contribution of green rods to one visually based behavior, the optomotor response. In addition, we discuss the role of green and red rods in visually based behavior in light of apparently conflicting demands resulting from the need to maximize absolute sensitivity, visual acuity, and color sensitivity. © 1993 Wiley‐Liss, Inc.
Fiber growth initiation in hair follicles of goats treated with melatonin
Authors: Nixon Allan J. , Choy Vernon J. , Parry Althea L. , Pearson Allan J.
Published: June 2005

The sequence of structural changes in goat hair follicles was investigated using melatonin implants to advance and synchronize spring hair growth. Ten pasture fed cashmere wethers each received a controlled release formulation of 70 mg of melatonin on September 1 1989, and showed plasma melatonin elevated above physiological levels over 14 days post‐treatment (914 ± 154 pg/ml [mean ± SEM] on day 14). In ten untreated animals, daytime plasma melatonin was 19.9 ± 4.7 pg/ml. Histological examination of skin biopsies taken over the 14 days from the start of the experiment showed that primary hair follicles of goats with manipulated hormone levels had initiated fiber growth (entered proanagen), whereas primary follicles of untreated goats largely remained in the quiescent phase (telogen). A standardized terminology was used to describe the sequence of events during induced proanagen. Structural reorganization of follicles began in treated animals between days 6 and 12 post‐treatment, and emergent fibers grew by day 24. Advancement of spring fiber growth was associated with a suppression of the normal rise in plasma prolactin concentration. Prolactin levels in untreated goats increased from 7.4 ± 1.8 ng/ml on day 1 to 12.8 ± 1.6ng/ml on day 14, but declined in treated goats from 6.3 ± 2.3 ng/ml to 2.2 ± 0.8 ng/ml over the same period. © 1993 Wiley‐Liss, Inc.
Gaseous ammonia evolution is coupled to reprocessing of urine at the gills of ghost crabs
Authors: De Vries M. C. , Wolcott D. L.
Published: June 2005

Urine of terrestrial and aquatic crabs generally is of neutral pH and contains negli‐gible waste nitrogen. Ammonia is added to urine during its reprocessing by the gills of some terrestrial species. The ghost crab, Ocypode quadrata, produces an acidic urine (pH < 6.0) that is high in ammonia (>100 mM). This prompted us to study the chemical changes which occur during urine reprocessing by this species. Urine and reprocessed urine were collected from fed animals maintained on sand moistened with diluted seawater, and several chemical variables were measured. During urine reprocessing, Cl− was reclaimed, and CO2 concentration and pH increased. Evolution of gaseous ammonia was then measured in crabs which could and could not pass urine onto their gills. Animals with occluded nephropores released gaseous ammonia at a much lower rate (≈︁300 μmol·.kg−1·day−1) than animals with open nephropores (≈︁2,000 μmol·kg−·day−1). We hypothesize that the gaseous ammonia released by control crabs is predominantly due to degassing of NH3 from the fluid (urine) upon the pH increase which occurs during reprocessing by the gills. © 1993 Wiley‐Liss, Inc.
Cold exposure and food restriction facilitate physiological responses to short photoperiod in Djungarian hamsters (Phodopus sungorus)
Authors: Ruf T. , Stieglitz A. , Steinlechner S. , Blank J. L. , Heldmaier G.
Published: June 2005

We investigated the influence of ambient temperature (Ta) and food availability on seasonal timing and extent of physiological responses to short photoperiod (SP), in particular daily torpor, in Djungarian hamsters (Phodopus sungorus). Exposure of hamsters to cold temperature (Ta = 5°C), relative to warm Ta (23°C), resulted in:(1)a significant advance (P < 0.05) of the first occurrence of torpor among cold‐exposed hamsters (days 52–97 vs. days 83–99 in SP); (2) a higher (P < 0.01) incidence of torpor (48% vs. 20% torpid animals/day);(3) a higher (P < 0.05) degree of molt into the winter pelt; and (4) an accelerated reduction of body weights (P < 0.001). However, within SP/cold‐Ta exposed groups, individual hamsters clearly showed different tendencies for torpor (torpor on 0–95% of days observed). Therefore, we evaluated the effects of small changes in Ta on torpor frequency and extension by subjecting the same SP‐adapted individuals to varying temperatures. Lowering of Ta from 15°C to 10°C and 5°C caused significant (P < 0.05) increases in the incidence of torpor (20%, 33%, and 40%, respectively) and lower minimal body temperatures during hypothermia (P < 0.05). When the same animals were subjected to 24–48 h lasting periods of food restriction (60% of the ad libitum intake), torpor frequency further increased 1.8to 2.6‐fold at all Tas.

These results show that Ta and food availability are effective in modifying both seasonal timing and extent of photoperiodically controlled adaptations. This integration of multiple environmental cues, combined with a pronounced within‐species variability of winter adjustments, indicates that Djungarian hamsters are capable of flexible physiological responses towards unpredictable climatic changes in the environment. © 1993 Wiley‐Liss, Inc.
The wound epithelium of regenerating limbs of Pleurodeles waltl and Notophthalmus viridescens: Studies with mAbs WE3 and WE4, phalloidin, and DNase 1
Authors: Tassava Roy A. , Castilla Martha , Arsanto Jean‐Pierre , Thouveny Yves
Published: June 2005

The wound epithelium of regenerating limbs of the American newt, Notophthalmus viridescens (Nv), up‐regulates a number of antigens, including those recognized by mAbs WE3 and WE4. In the present study, we show that the WE3 antigen is up‐regulated in a similar fashion in the wound epithelium of the European newt, Pleurodeles waltl (Pw). mAb WE3 and WE4 reactivities to secretory/transport body cell types, including integumentary glands, perineurium, endothelium, and conjunctiva, are also similar in these two species of newt. However, mAb WE4 reacts to both the epidermis and wound epithelium in Pw, whereas in Nv, mAb WE4 reacts only to the wound epithelium. Because the WE3 antigen is cytoskeleton‐associated and Western blots reveal a 43 kDa species, we compared mAb WE3 reactivity with that of rhodamine‐labeled phalloidin, a known actin‐binding compound. Phalloidin did not react preferentially to the wound epithelium, conjunctiva, or other cell types strongly reactive to mAb WE3. Pretreatment of sections and tissue extracts with DNAse 1, a protein known to bind to actin, nearly abolished mAb WE3 reactivity in tissue sections and both WE3 and WE4 reactivity in ELISA assays, respectively. The results lead to the hypothesis that the WE3 and WE4 antigens are actin‐binding proteins unique to the wound epithelium and other secretory/transport cell types. © 1993 Wiley‐Liss, Inc.
Studies of lysophospholipids related to the hamster sperm acrosome reaction in vitro
Authors: Llanos Miguel N. , Morales Patricio , Riffo Marta S.
Published: June 2005

Phospholipase A2 and lysophospholipids have been implicated in the mammalian sperm acrosome reaction. In this study we further investigated the role of this enzyme and lysophospholipids on the acrosome reaction of hamster spermatozoa. Hamster epididymal spermatozoa were incubated under capcaitation and acrosome reaction‐inducing conditions. After 3.0 and 3.5 h, the spermatozoa were treated with different doses of lysophosphatidylcholine for 12 min. Then the percentage of motility, hyperactivation, and acrosome reaction was evaluated by light microscopy. Lysophosphatidylcholine, 10 μg/ml, was the highest acrosome reaction‐inducing dose without an effect on sperm motility. Lysophosphatidylcholine induced the acrosome reaction only when added to spermatozoa capacitated for a minimum of 2 h. This effect was apparent after 1 min of its addition and reached a plateau after 5 min. Lysophosphatidylethanolamine and lysophosphatidylinositol were also effective in inducing the acrosome reaction. Lysophosphatidylserine did not have any effect on the reaction, but caused an increase in sperm hyperactivation. Sperm treated with the phospholipase A2 inhibitors quinacrine dihydrochloride and p‐bromophenacyl‐bromide showed an inhibition of the spontaneous occurrence of the acrosome reaction. These inhibitors, however, did not block the acrosome reaction induced by lysophosphatidylcholine. The time course of the lysophosphatidylcholine‐induced acrosome reaction was the same whether control or inhibitor treated spermatozoa were used. These results suggest that the membrane events of the acrosome reaction initiate with the activation of the phosphlipase A2, thus producing the fusogen agents necessary for this exocytotic event. © 1993 Wiley‐Liss, Inc.
Spiral patterns in the micropylar wall and filaments on the chorion in eggs of the medaka, Oryzias latipes
Authors: Iwamatsu Takashi , Nakashima Seiko , Onitake Kazuo
Published: June 2005

The relationship between spiral patterns in the inner wall of the micropyle and attaching and non‐attaching filaments on the chorion was investigated by electron microscopy in eggs of the medaka, Oryzias latipes. There were both right‐ and left‐handed spiral patterns of attaching filaments that arose from the chorion at the vegetal pole area. In the majority of eggs examined, however, the prominent folds in the inner wall of the micropylar vestibule descended toward the micropylar canal in a left‐handed spiral. This spiral pattern in the micropyle may reflect surface indentations in the cytoplasmic extension of the micropylar cell during formation of the micropyle apparatus. The present observations suggest that the patterns of these spiral structures of the chorion are casused by the rotation of the oocyte due to the movement of follicular cells during oogenesis. © 1993 Wiley‐Liss, Inc.
Culture of intact Sertoli/germ cell units and isolated sertoli cells from Squalus testis. II. Stimulatory effects of insulin and IGF‐I on DNA synthesis in premeiotic stages
Authors: Dubois Wilfrid , Callard Gloria V.
Published: June 2005

To investigate growth control mechanisms during spermatogenesis, in vitro, [3H]thymidine incorporation into acid‐insoluble macromolecules was used to quantify DNA synthesis in cultured spermatocysts (intact Sertoli cell/germ cell clones) derived from premeiotic (PrM), meiotic (M), and postmeiotic (PoM) regions of dogfish (Squalus acanthias) testis. Forty‐eight hours after seeding in basal medium, DNA synthesis was >7‐fold higher in PrM cysts than in other stages, thus verifying the staging procedure. In autoradiograms, germ cells of PrM cysts (e.g., spermatogonial and preleptotene stages) were labeled all‐or‐none, but not all cysts were labeled, and later developmental stages (e.g., cysts with round or elongating spermatids) were never labeled. Fetal bovine serum (FBS, 10%) and insulin‐transferrin‐selenite (ITS, 10 μg‐10 μg‐10 ng/ml) doubled DNA synthesis in PrM cyst cultures but had no effect at other stages. Bovine insulin (10 μg/ml) and human recombinant insulin‐like growth factor‐I (IGF‐I, 15 ng/ml) also doubled [3H]thymidine uptake in PrM cultures, but lower doses were less effective and estradiol‐17β, transferrin, adult shark serum, purified shark relaxin, and a variety of other known growth factors were neither stimulatory nor inhibitory at the doses and conditions tested.

Sertoli cell monolayers derived from PrM‐ or M‐stage spermatocysts displayed a dose‐response increase in DNA synthesis after addition of IGF‐I (15–75 ng/ml), with a maximal increment significantly greater than with 10% FBS. Using [3H]thyumidine incorporation by PrM cysts as an end‐point, stimulatory bioactivity was detected in the <30, 000 kDa fraction of spent media from PrM Sertoli cells, whereas the low molecular weight fraction of M‐stage Sertoli cells was inhibitory. Gel electrophoretic analysis of the two fractions revealed qualitative and quantitative differences in protein banding patterns, reinforcing the view that secretory activity of Sertoli cells is stage related.

Results of these studies implicate insulin/IGF‐I in mechanisms governing proliferation of male germ cells and support the view that Sertoli cells have an autocrine or paracrine role as both targets and sources of growth regulatory factors. © 1993 Wiley‐Liss, Inc.
Changes in membrane potential associated with cell swelling and regulatory volume decrease in barnacle muscle cells
Authors: Berman D. M. , Peña‐Rasgado C. , Rasgado‐Flores H.
Published: June 2005

Our aim was to test the effect of hypotonicity and extracellular Ca2+ (Cao) on cell volume and membrane potential (VM) in barnacle muscle cells. Under isotonic conditions the resting VM of isolated cells mounted in the experimental chamber exposed to either Ca2+‐free or Ca2+‐containing (11 mM) solutions was − 46.3 ± 1.0mV (n = 24) and − 56.2 ± 0.9 mV (n = 38), respectively. In the absence of Cao, the cells depolarized at a rate of 2.3 ± 0.47 mV/hr; the presence of Cao reduced this rate of depolarization by 2.9‐fold. Both in the absence or presence of Cao, the cells swelled in response to hypotonicity but underwent regulatory volume decrease (RVD) when Cao was present. Addition of the Ca2+ channel blocker, verapamil (0.1 mM), inhibited the Cao‐dependent RVD. The percentage of cells responding with RVD increased with larger hypotonic challenges. There was a Cao‐independent direct relationship between cell swelling and membrane depolarization which can be explained by dilution of the concentration of intracellular K+ ([K+]i). RVD was accompanied by a small hyperpolarization (3.0 ± 0.38 mV/2 hr) which may represent increases in [K+]i during cell shrinking and activation of a conductive pathway. The results indicate the following: (1) the presence of Cao stabilizes VM; (2) cell swelling produces a depolarization which can be explained by dilution of [K+]i; (3) cell swelling activates a verapamil‐sensitive Ca2+ influx responsible for promoting RVD; and (4) RVD is accompanied by a hyperpolarization which may result from activation of a conductive pathway. © 1994 Wiley‐Liss, Inc.
Channels for ions and amino acids in kidney cultured cells (MDCK) during volume regulation
Authors: Roy Guy , Banderali Umberto
Published: June 2005

A cell line from canine kidney (MDCK) was studied in hypotonic conditions to determine the transport mechanisms involved during regulatory volume decrease (RVD). It was found that RVD was related to a loss of K+, Cl− and amino acids. Membrane potential measurements during RVD have shown a hyperpolarization followed by a depolarization, implying that ion fluxes were probably occurring through channels. Quinine was found to inhibit RVD, the ion fluxes and the amino acid losses. A long preincubation in Ca+ + ‐free EGTA medium had no effect on RVD in cells exposed to the hypotonic medium. Single channel experiments with the patch clamp technique have shown that cell swelling rapidly activates K+ channels and, after a 30 sec delay, Cl− channels. The K+ channel was highly selective and had a linear I‐V curve with a conductance of 25 pS. The Cl− channel was an outward rectifier with conductances of 63 and 26 pS. It was not very selective; replacing Cl− with NO3− did not change the I‐V curve and did not affect RVD. The amino acid losses during RVD were studied with HPLC. It was found that three of them, glutamate, taurine and gly‐cine, had large concentrations and were lost at different rates. Their fluxes during RVD depended linearly on their external concentrations, meaning that the transport process was diffusional. Single channel measurements with glutamate, aspartate or taurine in place of Cl− have shown that these amino acid losses occurred through the Cl− channel. © 1994 Wiley‐Liss, Inc.
Osmoregulation in Rhizobium meliloti: Mechanism and control by other environmental signals
Authors: Smith Linda Tombras , Smith Gary M. , D'Souza Marian R. , Pocard Jean‐Alain , Rudulier Daniel Le , Madkour Magdy A.
Published: June 2005

Bacteria commonly adapt to increases in the osmolarity of the environment by the intracellular accumulation of small organic solutes (osmolytes) that function by restoring turgor. We have investigated the mechanism of osmotic regulation in Rhizobium meliloti, the root nodule symbiont of alfalfa. As a soil microbe, this organism is subjected to variable osmolarity and a number of other environmental conditions to which it must respond appropriately. Natural abundance 13C nuclear magnetic resonance spectroscopy was used to identify the osmolytes accumulated by osmotically stressed R. meliloti. The complement of osmolytes and their concentrations were found to depend on the level of osmotic stress, growth phase of the culture, carbon source, and the presence of osmolytes in the growth medium. The osmolytes accumulated by 22 different bacterial strains are presented and compared to those of R. meliloti 102F34. © 1994 Wiley‐Liss, Inc.
Structure and optics of the eye of the hawk‐wing conch, Strombus raninus (L.)
Authors: Seyer Jan‐Olof
Published: June 2005

The hawk‐wing conch, Strombus raninus, possesses extremely well developed camera‐type (simple) eyes. Light and electron microscopy were used to generate an accurate scale model of the eye, which was then used for predictions of its optical performance. The eye‐bulb measures approximately 1.6 × 1.9 mm and features a spherical lens, a large vitreous body, and a retina. The lens has a diameter of 950 μm and its centre consists of a seemingly homogeneous core with an approximate radius of 215 μm. The image produced by the lens is apparently aberration‐free and has a short focal length (950 μm). The ratio of the focal length to lens radius is approximately 2, and thus lower than the “Matthiessen ratio” of 2.5 frequently found in aplantic lenses of many marine animals. The crisp images produced by the lens imply the presence of a refractive index gradient despite an apparently homogeneous core. In the central retina, the inter‐receptor angle is 0.47° and the rhabdom diameter is 7.8 μm (5.7 times wider than the diffraction blur circle), indicating a retinal array coarser than that necessary to sample all the information contained in the image. The large aperture (850 μm) means that rays have the opportunity of striking the retina with incident angles of up to 41°, possibly degrading resolution further due to spread of light between rhabdoms (which lack shielding). Different aspects of the eye structure are discussed. © 1994 Wiley‐Liss, Inc.
Development ofGyrinophilus porphyriticus: Identification of the ancestral developmental pattern in the salamander family plethodontidae
Authors: Collazo Andres , Marks Sharyn B.
Published: June 2005

We describe the development, from fertilization to hatching, of the salamanderGyrinophilus porphyriticus(family Plethodontidae; tribe Hemidactyliini).G. porphyriticushas a relatively large clutch size (n = 87 eggs in the clutch examined) and egg diameter (mean = 4.0 mm, S.D. = 0.12, n = 4, range = 3.9–4.1) for a plethodontid. Early cleavage is asymmetrical and asynchronous. Gastrulation and neurulation are typical of that described for other species of plethodontids, particularly those with large, heavily yolked eggs. We present a normal table of development from tailbud to hatching divided into nine stages. Development of somites, pigmentation pattern, gills, tail fins, eyes, and limb buds is described. We use data from outgroup taxa, such as non‐plethodontid salamanders and frogs, to polarize nine characters chosen to define the ancestral developmental pattern of plethodontids: (1) developmental mode (direct or larval), (2) timing of oviposition, (3) clutch size, (4) percentage of egg volume contributing to embryonic structures, (5) timing of appearance of the front limb buds relative to the hind limb buds, (6) extent of gill branching, (7) presence or absence of tail fins, (8) external eye morphology, and (9) the presence or absence of lateral‐line organs. Comparisons ofG. porphyriticusto nine other plethodontid species allow us to hypothesize probable evolutionary transformations for these characters.G. porphyriticushas the ancestral condition for all nine characters. The three species ofDesmognathuswith aquatic larvae are derived for two or three of the nine characters. They each have (1) a clutch size of less than 50 eggs, (2) a relatively low percentage of egg volume contributing to embryonic structures, and/or (3) nearly simultaneous appearance of the front and hind limb buds. Finally, we explore the evolutionary implications of retaining the ancestral developmental pattern in the plethodontid tribe Hemidactyliini and salamanders in general. We propose that the retention of the ancestral developmental pattern has permitted the evolution of a specific type of paedomorphosis, larval paedomorphosis, that correlates with a cave‐dwelling existence. © 1994 Wiley‐Liss, Inc.
Freeze tolerance adaptations in the centipede, Lithobius forficatus
Authors: Tursman Donald , Duman John G. , Knight Charles A.
Published: June 2005

Studies were conducted to investigate the adaptations of the wood centipede, Lithobius forficatus, to winter conditions. During winter centipedes were freeze tolerant. However, inoculative freezing initiated from external ice was required for survival of freezing. Because the lower lethal temperature (after 24 hr exposure) was only −6°C, it appears that the insulation provided by the overwintering microhabitat under large logs is important for survival. Freezing proved lethal to summer animals.

Inoculative freezing points of live specimens remained steady at approximately −1°C throughout the year, as did the melting points of hemolymph. Although the supercooling points of the hemolymph stayed roughly constant at −7 to −9°C, those of live animals rose in winter and decreased in summer, suggesting the presence of nonhemolymph ice nucleators in winter. However, inoculative freezing was still essential for freeze tolerance. Centipedes did not accumulate carbohydrates or polyols in winter.

Winter hemolymph showed marked recrystallization inhibition activity, indicating the presence of thermal hysteresis proteins, but summer hemolymph did not. However, only occasional individuals had measurable thermal hysteresis activity in winter, indicating that the hemolymph concentration of thermal hysteresis proteins is low. © 1994 Wiley‐Liss, Inc.
Plasma ketone, glucose, lactate, and alanine levels in the vascular supply to and from the brain of the spiny dogfish shark (Squalus acanthias)
Authors: De Roos Roger
Published: June 2005

Paired, serial blood samples were collected for a minimum of 6 hr to a maximum of 15 days from cannulae chronically placed in the internal carotid artery (A) to the brain and the anterior cardinal sinus (V) from the brain of the spiny dogfish shark (Squalus acanthias). Previously fed animals were fasted for either 3 to 8 days (short‐fasted) or 20 to 29 days (long‐fasted) before the surgery to implant the cannulae and during the subsequent sampling periods. Plasma β‐hydroxybutyrate, acetoacetate, glucose, lactate, and alanine levels were measured by standard enzymatic procedures. The internal carotid artery plasma β‐hydroxybutyrate and acetoacetate levels were in the approximate ratio of 4 to 6:1, were greater in the long‐fasted than in the short‐fasted animals, and both ketones increased throughout the observation periods. In contrast, plasma lactate and alanine levels declined by postoperative day 2 to levels that, like glucose, remained relatively stable and were characteristic of the individual animal. The A‐V metabolite differences between the short‐ and long‐fasted animals were not significantly different and the data from the two groups of animals were combined for purpose of analysis. β‐Hydroxybutyrate was extracted from the plasma by the brain during both the surgery and recovery period (⩽ 2 days) and the “normal” under the observational conditions period (> 2 days). The small negative A‐V differences in acetoacetate during both periods, and in glucose during the > 2 day period, were not statistically significant. There were no evident A‐V differences in plasma alanine. Lactate was released by the brain during both the ⩽ 2 days and > 2 day periods. The uptake of β‐hydroxybutyrate and the release of lactate indicate that the spiny dogfish brain used both β‐hydroxybutyrate and glucose during the observation periods. The data suggest that the plasma was the immediate source of β‐hydroxybutyrate, but, as proposed by previous authors, the proximate glucose source may have been provided by the mobilization of endogenous brain glycogen stores. © 1994 Wiley‐Liss, Inc.
Effects of excitatory amino acids on in vivo and in vitro gonadotropin and growth hormone secretion in testosterone‐primed immature rainbow trout, Oncorhynchus mykiss
Authors: Flett Peter A. , van der Kraak Glen , Leatherland John F.
Published: June 2005

The present studies were conducted to evaluate the effects of excitatory amino acids (EAAs) on gonadotropin II (GtH II) and growth hormone (GH) secretion in testosteroneprimed immature rainbow trout, Oncorhynchus mykiss. Intraperitoneal injections of N‐methyl‐DL‐aspartate (NMA) elevated both plasma GtH II and GH levels. By comparison, Des Gly10 [D‐Ala6] LHRH‐ethylamide (LHRH‐A) elevated plasma GtH II levels but had no effect on plasma GH levels. The GtH II response to NMA was not evident in sexually regressing adult rainbow trout. GtH II secretion by perifused pituitary glands of testosterone‐primed immature rainbow trout was elevated following NMA or salmon GnRH analogue (sGnRH‐A) challenge. The GtH II response to NMA was eliminated in pituitaries previously exposed to either the NMA receptor antagonist, AP5, or a GnRH receptor antagonist (D‐pGlu1,D‐Phe2,D‐Trp3,6‐LHRH), suggesting that NMA operates by stimulating the secretion of GnRH rather than by direct actions on the pituitary gonadotropic cells. The results of these studies provide evidence of the presence of NMA‐specific receptors in the hypothalamo‐hypophyseal system that when activated led to the release of GtH II. L‐glutamic acid (GLU) also stimulated GtH II secretion from perifused pituitary glands. However, the response to GLU was only partly blocked by AP5, suggesting that GLU exerted some of its effect via non‐NMA type receptors, in addition to its actions on NMA receptors. The results of these studies support the contention that EAA receptor activation may play a role in regulating the onset of sexual maturation in teleosts, as it seems to do in mammals. © 1994 Wiley‐Liss, Inc.
A Xenopus maternal effect mutant gene affects oocyte meiotic reinitiation and fertilization
Authors: de Vantéry Corinne , Schorderet‐Slatkine Sabine , Droin Anne
Published: June 2005

No cleavage (nc) is a maternal effect mutant gene, recessive and sex limited. It affects the eggs laid by homozygous mutant females, independently of the male genotype.

Contrary to normal oocytes, following germinal vesicle breakdown (GVBD) during maturation, the transient microtubular array (TMA) is not formed, nor are the meiotic spindles. Cytoplasmic asters with condensed chromosomes are present in the majority of oocytes, as well as microtubular bundles and sometimes cytoplasmic spindle‐like asters. These mature oocytes exhibit a disturbance in yolk platelet arrangements. The white spot is rather irregular, and the maturation period is longer than normal. Transfers of cytoplasm from nc mature oocytes into normal stage VI oocytes resulted in abnormal maturation of the normal oocytes. Reciprocal transfers (cytoplasm from normal mature oocytes into nc stage VI oocytes) induce the formation of spindles, usually cytoplasmic; this indicates that the deficiency can be partly rescued.

Following fertilization, the nc eggs show neither contraction nor rotation; polyspermy is present in the majority of cases. Even in the same egg, simultaneous spindles and nuclei can be observed, revealing a disturbance in the spatial localization of regulators of the cell cycle. Cytokinesis never occurs. Polyspermy results from the absence of cortical reaction following sperm entry. However, when mature nc oocytes are treated with PMA, they show cortical granule exocytosis and the formation of an altered vitelline envelope.

The different factors possibly involved in these anomalies are discussed in relation to cytoarchitectural disorganization of the cell and abnormal cell cycle regulation. © 1994 Wiley‐Liss, Inc.
Effects of the pineal gland and melatonin on the metabolism of oocytes in vitro and on ovulation in Bufo arenarum
Authors: de Atenor M. S. B. , de Romero I. R. , Brauckmann E. , Pisanó A. , Legname A. H.
Published: June 2005

The pineal gland and the hormone melatonin appear to be responsible to some extent for the metabolic behaviour of Bufo arenarum oocytes during the winter. This assumption is supported by the observation that, in isolated mitochondria, both elements stimulate the rate of oxidation of citrate and inhibit that of fumarate, thus raising the oxidizing ratio that relates these parameters (C/F) to values close to or above 1, which is characteristic of these animals in winter.

The sensitivity of oocytes to melatonin, in terms of the C/F ratio, varies throughout the year. It is maximal in fall and early winter at a dose of 1.8 μg/ml after 30 min treatment, minimal or nonexistent in late winter, and it increases gradually during the spring and summer. The response of oocytes to melatonin is more significant if the animals have been previously injected with a homogenate of homologous hypophysis.

A direct metabolic effect of melatonin on oocytes was observed when coelomic oocytes, without follicle cells, responded to hormonal treatment.

Both an extract of pineal gland and melatonin inhibit in vitro ovulation, the inhibitory effect of the extract being greater than that of the hormone. © 1994 Wiley‐Liss, Inc.
Effects of Ddc cluster lethal alleles on ovary growth, attachment, and egg production in Drosophila
Authors: McCrady Edward , Tolin David J.
Published: June 2005

The Ddc cluster of genes on the left arm of chromosome 2 in Drosophila has been extensively characterized by Wright and coworkers (Wright, '87b). Many of the genes in the cluster are associated with the pigmentation and sclerotization of the cuticle, and at least 12 have been shown to play a role in female fertility. To characterize further the actions of genes in the cluster, we have investigated the effect on fertility of a total of five of the previously untested genes (l(2)37Be, Bb, Bg, Bd, and Cg), and three of the partially characterized genes (l(2)37Ce, Ddc, and amd). Each allele was crossed to Df(2L)TW130 or49h flies in order to make it hemizygous over the 8–12 band deficiency covering the Ddc region, 37B9‐C1,2;37D1‐2. Ovaries taken from larvae produced by this cross were transplanted into female larval hosts of y f mal genotype, that were then mated to v f mal males. The wild type allele of mal in implanted tissue allowed identification and study of surviving implants by staining for the presence of aldehyde oxidase. Of the 18 alleles available, amdH149, l(2)37Bb1, Bb9, Bb11, Bd6, Be1, Bd7, Be2, Be3, Ce4, and Cg1 did not allow enough growth to form transplantable ovaries; l(2)37Bg1, Bg2, and Cgtsl prevented development of transplanted ovaries in their hosts; l(2)37Ce5 allowed implanted ovaries to attach to oviducts and grow, but insufficiently for production of eggs; and DdcN27, amd29, and l(2)37Bd4 appeared not to restrict ovary development. Heteroallelic heterozygotes of Bd7 × Bd4 also produced fully fertile ovaries, but no other heteroallelic combinations did so. No obvious correlation exists between this pattern of effects on ovarian fertility and the overall organization of the gene cluster. © 1994 Wiley‐Liss, Inc.
Embryonic development of the cornea in the eye of the clearnose skate, Raja eglanteria: I. Stromal development in the absence of an endothelium
Authors: Conrad Gary W. , Paulsen Avelina Q. , Luer Carl A.
Published: June 2005

Embryos of the clearnose skate, Raja eglanteria, develop in sea water at 20–22°C, hatching after 82 ± 4 days (Luer and Gilbert, Environ. Biol. Fishes, 13:161–171, 1985). Eyes develop as steadily enlarging spheres whose corneas have the same radius of curvature as the sclera. The cornea begins development as a 2‐cell thick epithelium beneath which by Day 12 there is only a basal lamina and a wispy matrix separating it from the underlying lens. This matrix, modified by Day 16, is displaced on Day 22 by a few orthogonal plies of fibrillar primary stroma. Ply number increases to at least 13 by Day 30, reaching the final number of 20 ± 2 by Day 42. Stromal fibroblasts (keratocytes) appear at the corneal periphery by Day 22, and in increased numbers by Day 30, a time at which no keratocytes are seen in the central stroma. However, by Day 40, many fibroblasts are present at the corneal periphery, invading the primary stroma between plies, occasionally reaching even the central cornea. By Day 53, keratocytes are present between all plies, from corneal periphery to center. Thickness of each ply in this secondary stroma increases, but the number of plies remains the same as in the primary stroma. Bowman's layer, non‐invaded matrix beneath the epithelial basal lamina, is not evident until Day 53. Sutural fibers, first seen on Day 22, originate in the corneal epithelial basal lamina, traversing perpendicularly the plies of the primary stroma. Sutural fibers persist throughout development of the secondary stroma and into adulthood. In contrast to chicks, skate corneas remain transparent throughout development, and never form an endothelium. © 1994 Wiley‐Liss, Inc.
Concomitant effects of sulfide and hypoxia on the aerobic metabolism of the marine oligochaete Tubificoides benedii
Authors: Dubilier Nicole , Giere Olav , Grieshaber Manfred K.
Published: June 2005

Sulfide is toxic for most aerobic organisms and inhibits the key enzyme of aerobic respiration, cytochrome c oxidase, at low μM concentrations. Tubificoides benedii is a ubiquitous marine oligochaete that regularly occurs in polluted, poorly oxidized coastal muds with high sulfide concentrations. The questions posed in this study were: Can T. benedii maintain aerobic pathways despite the occurrence in its habitat of sulfide concentrations that are toxic for many marine invertebrates? What influence does the ambient oxygen concentration have on the sulfide effects? To answer these questions animals were incubated under flow‐through conditions in various sulfide and oxygen concentrations. As an indicator of an anaerobic metabolism succinate was measured, a metabolite which accumulates in high concentrations in T. benedii under hypoxic conditions. The results show that under normoxic conditions, T. benedii can maintain a completely aerobic metabolism at sulfide concentrations up to 175 μM. At 300 μM sulfide, anaerobic pathways are utilized to only a small extent and even at sulfide concentrations as high as 450 μM and 600 μM a partially aerobic metabolism is sustained. However, if ambient oxygen concentrations are decreased, much lower sulfide concentrations cause the animal to utilize anaerobic pathways. At oxygen concentrations as low as 20 μM (= 1.5 kPa O2 or 7% air saturation), where the worms can maintain a fully aerobic metabolism in the absence of sulfide, minimal concentrations of sulfide (40 μM) are sufficient to give rise to an anaerobic metabolism. © 1994 Wiley‐Liss, Inc.
Further characterization of the pituitary‐adrenocortical responses to stress in Chiroptera
Authors: Widmaier Eric P. , Harmer Tara L. , Sulak Adriana M. , Kunz Thomas H.
Published: June 2005

Previous studies on bats from this laboratory have revealed the presence of exceptionally high circulating levels of glucocorticoids in two species of the sub‐order Megachiroptera. In the present study, the following questions were asked: (1) what effect does the routine handling and examination of captive bats have on the activity of their hypothalamic‐pituitary‐adrenocortical (HPA) axis?; (2) are the unusually high plasma levels of cortisol and corticosterone found in Pteropus hypomelanus associated with high levels of circulating adrenocorticotropic hormone (ACTH)?; (3) are there diurnal changes in stress responsivity in this species?; and (4) how do levels of glucocorticoids in P. hypomelanus compare with those found in other species of Chiroptera (both micro and megachiropteran species)? Of five species examined, P. hypomelanus had slightly higher total glucocorticoid levels than P. pumulis, but ∼‐fold higher levels than in three species of Microchiroptera (Artibeus jamaicensis, Carollia perspicillata, and Myotis lucifigus). There was a pronounced diurnal rhythm in glucocorticoid levels in one species (M. lucifigus) for which this was determined. A 1‐h period of restraint stress increased glucose and glucocorticoid levels in P. pumulis, and also increased ACTH and glucocorticoids in P. hypomelanus. Fifteen minutes of routine handling (weighing, measuring, etc.) elicited a significant rise in plasma glucocorticoids in P. hypomelanus to combined peak (cortisol plus corticosterone) levels of over 1,000 ng/ml (100 μg%). There was no significant difference in the response to handling in bats tested in the morning or evening. Basal ACTH levels as detected by radioimmunoassay were low in P. hypomelanus, in spite of high steroid levels. Displacement of labeled ACTH by plasma of P. hypomelanus was roughly parallel to that produced by synthetic human ACTH. The identity of immunoreactive ACTH was confirmed by subjecting separate aliquots of plasma to an immunoradiometric assay (IRMA), which operates on a different principle from the RIA and necessitates an intact molecule closely resembling human ACTH. We conclude that bats possess a “stress response” similar in some ways to that seen in other mammals. The extremely high constitutive and stress‐induced levels of glucocorticoids in the Megachiroptera are nearly unique among mammals. Although high circulating levels of ACTH were detected by IRMA, but not by RIA, it is possible that the Chiropteran adrenal gland is hypersensitive to ACTH or possesses exceptionally active intracellular steroidogenic mechanisms. Finally, the routine daily procedures associated with measuring, weighing, and monitoring bats in captivity constitutes a significant stress to the animal as revealed by pronounced activation of the HPA axis. © 1994 Wiley‐Liss, Inc.
Developmental expression and modulation of the vitellogenin receptor in ovarian follicles of the rainbow trout, Oncorhynchus mykiss
Authors: Lancaster Petrina M. , Tyler Charles R.
Published: June 2005

Ovarian uptake of vitellogenin (VTG) accounts for a considerable proportion of oocyte growth in many oviparous species. The mechanisms controlling the expression and modulation of the VTG receptor, therefore, will be key determinants in effecting oocyte growth. This study documents the expression and modulation of the VTG receptor in follicles of the rainbow trout (Oncorhynchus mykiss) during ovarian development.

SDS‐PAGE and ligand blotting with 125I‐VTG demonstrated the presence of the VTG receptor in rainbow trout follicles throughout the period of ovarian development, known as vitellogenesis. The vitellogenin receptor was also shown to be present in very small follicles (those measuring 0.3 mm or less in diameter) and in ovulated eggs. Filter binding assays followed by Scatchard analyses revealed developmental changes in both the receptor equilibrium dissociation constant, Kd, and the maximum number of binding sites, Bmax. The binding affinity of the VTG receptor for VTG in follicles was highest in the smallest follicles examined (0.4 mm in diameter, Kd = 1.3 × 10−9 M) and in those approaching ovulation (1.8 × 10−9 M). Ovulated eggs also had a high binding affinity for VTG (1.2 × 10−9 M). The Bmax increased almost 4‐fold during early development from 70.8 fmol/mg protein in 0.4 mm follicles to 260.5 fmol/mg protein in 0.6 mm follicles, but subsequent to this there was little change in the Bmax throughout follicle growth. Ovulated eggs had a relatively low binding capacity for VTG. The number of VTG receptors per follicle increased 100‐fold with increasing follicle size, but dropped dramatically at ovulation. The data presented also suggests that the density of VTG receptors (numbers per mm2 follicle surface) changed significantly during follicular development. © 1994 Wiley‐Liss, Inc.