bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of membrane‐associated actin in boar spermatozoa
Authors: Peterson R. N. , Bozzola J. J. , Hunt W. P. , Darabi A. 
Published: June 2005

AbstractBiochemical, immunological, and electron microscopic methods have been used to provide semi‐quantitative estimates and to localize actin in membranes of boar spermatozoa. Immunoblots, using a monoclonal antibody raised against actin from chicken gizzard, detected the protein in caput and cauda sperm plasma membranes. Immunoassay indicated that approximately 1% of the total plasma membrane protein was actin. Monomeric actin accounted for more than onehalf of the membrane actin. Approximately 30–40% of plasma membrane actin was insoluble in Triton X‐100, and approximately 10% of the total actin remained insoluble after treatment with guanidine hydrochloride. The presence of F‐actin in sperm plasma membranes and in plasma membrane detergent‐insoluble proteins was detected by fluorescence microscopy using the specific probe NBD phallacidin. When S1 myosin subfragments attached to colloidal gold were used to localize F‐actin by electron microscopy, the label was restricted to the outer acrosomal membrane of intact epididymal and ejaculated sperm. Filaments appeared in short arrays along the anterior region of the membrane. S1/gold labeled detergent‐insoluble plasma membrane fractions but did not label the plasma membrane in intact sperm. Filaments were least prominent in intact caput spermatozoa and most prominent in ejaculated spermatozoa. We conclude that most actin associated with sperm membranes is in monomeric form in boar spermatozoa, but that actin filaments or protofilaments are components of the outer acrosomal membrane. These filaments may also associate with the plasma membrane overlying the acrosome.
Method for measuring submicrogram quantities of Cl− in minute tissue samples
Authors: Quinn R. H. , Pierce S. K. 
Published: June 2005

AbstractMethods for measuring submicrogram quantities of Cl− are not as widely used by biologists as analogous measurements for small quantities of inorganic cations such as Na+ or K+. A portion of a project measuring osmolyte change during cell volume regulation in molluscan ganglia required Cl− measurement in minute tissue samples. We applied two methods to the determination of Cl− in these samples. Using ion chromatography on a high‐performance liquid chromatograph, submicrogram quantities of Cl− were measured in circumesophageal nerve rings from an opistobranch mollusc, Elysia chlorotica, with quantities of tissue as small as 0.0600 mg dry weight. Cl− was also measured in the range of 3–6 μ from larger quantities of ganglia by a less sensitive method, mercuric nitrate titration with a visual endpoint. Estimates of intracellular Cl−, calculated by subtracting estimates of extracellular Cl− from total tissue Cl−, showed that intracellular Cl− in the ganglia is reduced in response to a reduction in salinity. Thus Cl− loss contributes to osmotic readjustment of the ganglia cells during low‐salinity stress.
Enzymatic and immunological properties of alkaline phosphatase of bullfrog
Authors: Goseki M. , Oida S. , Sasaki S. 
Published: June 2005

AbstractEnzymatic and immunological properties of alkaline phosphatase (ALPase) in several tissues of bullfrog (Rana catesbiana) were investigated. Inhibition and thermal inactivation studies showed that bullfrog ALPases in kidney, liver, and intestine had similar enzymatic properties. In addition, mouse antiserum against bullfrog liver ALPase cross‐reacted with kidney and intestine enzymes as well as with liver enzyme. These results suggest that a single phenotype of ALPase exists in all tissues of bullfrog in contrast to two or three isoenzymes in mammals.
Seasonally occurring lectins from the bryozoan Bugula neritina
Authors: Colon‐Urban Rita , Oppenheim Joel D. 
Published: June 2005

AbstractTwo different lectins (termed BnA‐I and BnA‐II) with distinct carbohydrate specificities were identified and subsequently isolated from the marine bryozoan Bugula neritina. BnA‐I hemagglutinating activity was inhibited by N‐acetylated hexosamines, their polymers, and glycoproteins rich in these moieties. BnA‐II‐induced hemagglutination was not blocked by any simple sugars but could be inhibited by several complex glycoproteins (e.g., thyroglobulin and orosomucoid). Both lectins required the presence of Ca+ + for reactivity and were purified by affinity chromatographic procedures. Purified BnA‐I was determined to have a native molecular weight of 240 Kd and appeared to be a hexameric homopolymer while BnA‐II was shown to be a 65–70 Kd monomer. Both lectins showed seasonality in expression, BnA‐I appearing in animal extracts prepared in the spring and fall while BnA‐II was expressed only during the summer and winter.
Fully differentiated Xenopus eye fragments regenerate to form pattern‐duplicated visuo‐tectal projections
Authors: Wunsh Lauren M. , Ide Charles F. 
Published: June 2005

AbstractIn order to determine if differentiated Xenopus retina is capable of undergoing regeneration and duplicative pattern formation, we devised a new surgical technique for removal of the temporal two‐thirds of the retina. In a series of progressively older larval eyes starting with late tailbud stage embryos (stage 38) and extending to limb‐bud stage tadpoles (stage 48), nasal onethird‐sized eye fragments successfully regenerated to form nearly normal sized eyes over 75% of the time. Histological preparations showed that early wound healing involved the formation of a neuroepithelium at the ventro‐temporal region of the fragment. The pigmented retinal epithelium and associated retinal tissue appeared to be involved in this process. Animals from each stage were reared through metamorphosis and electrophysiologic techniques were employed to determine visuo‐tectal projections. Seventy percent of stage 38 animals showed evidence of pattern‐duplicated projections. Ninety percent of their responding tectal points showed duplicate innervation from two retinal regions. Older animals (stages 44 to 48) showed less duplication. Only 52% of their responding tectal points duplicated (P < 0.001). Thus, fully differentiated Xenopus retina can undergo regeneration and duplicative pattern formation similar to that shown by embryonic retinal tissue.
Microvasculature of the nasal salt gland of the duckling, Anas platyrhynchos: Quantitative responses to osmotic adaptation and deadaptation studied with vascular corrosion casting
Authors: Hossler Fred E. , Olson Kenneth R. 
Published: June 2005

AbstractThe three‐dimensional microvasculature of the nasal salt gland of the duckling was studied by vascular corrosion casting and scanning electron microscopy. Changes in the vascular volume of the gland in response to osmotic stress were also determined using cast weights and densities. The richly vascularized gland is supplied on its medial surface by large branches of the supraorbital and ethmoidal arteries. Numerous arterial branches enter the gland and distribute to lobes via the interlobar connective tissue. Lobar arterioles penetrate to the periductal areas of the lobes before dividing into capillaries supplying the ductal epithelium and secretory tubules. Capillaries envelope the secretory tubules and run radially from the ducts toward the lobe periphery, so that blood flows counter to the tubular secretion. Blood is collected via venous plexuses seen as distinct drainage units on the periphery of each lobe. Veins exhibit large numbers of bicuspid valves. Following 1 day and 4 days of osmotic loading (feeding 1% NaCl), vascular volume of the gland increased fivefold and ninefold, respectively, a response that precedes and exceeds that of the gland weight or Na,K‐ATPase activity. When salt water‐adapted ducklings were fed fresh water for only 24 hr (deadaptation), vascular volume fell to 2.8 times the control level. Changes in blood flow to the gland during osmotic adaptation and deadaptation are rapid and dramatic and may represent the initial steps in the control of gland secretion.
Oogenesis in Fundulus heteroclitus. VI. Establishment and verification of conditions for vitellogenin incorporation by oocytes in vitro
Authors: Kanungo Jyotshnabala , Petrino Teresa R. , Wallace Robin A. 
Published: June 2005

AbstractA procedure was developed for studying vitellogenin (VTG) incorporation by vitellogenic oocytes of Fundulus heteroclitus in vitro. Since homologous VTG can be obtained from this animal only with great difficulty, the use of [32P]VTG from Xenopus laevis was explored as an alternative. Vitellogenic as well as maturational‐stage oocytes were found to sequester X. laevis [32P]VTG from the medium, and incorporation was found to be linear with time for at least up to 12 hr. Once incorporated into the oocyte, [32P]VTG did not appear to undergo turnover. The effect of different [32P]VTG concentrations on incorporation indicated that the uptake mechanism was saturable. Unlabeled F. heteroclitus VTG and X. laevis VTG were also found to compete effectively with X. laevis [32P]VTG, whereas bovine serum albumin did not. These results represent the first documentation of a successful culture system for receptor‐mediated VTG incorporation by teleost oocytes.
Neurotransmitter‐related enzyme acetylcholinesterase in juveniles of Concholepas concholepas (Mollusca; gastropoda; muricidae)
Authors: González M. , Perelman A. , Fuentes M. E. , Castilla J. C. , Labarca R. , Brandan E. , González‐Plaza R. , Inestrosa Nibaldo C. 
Published: June 2005

AbstractWith the aim of understanding the organization of the nervous system in the Prosobranchia gastropod Concholepas concholepas, we studied the properties, specificity, sedimentation coefficient, and solubility of the cholinergic enzyme, acetylcholinesterase (AChE). It was found that 95% of the esterase was inhibited by BW284c51 dibromide but not by iso‐OMPA, which is consistent with the specificity of AChE. The calculated Km 0.22 mm is eight to ten times higher than are the Kms for AChE of other invertebrates and similar to the values reported for fishes and vertebrates.The AChE shows a maximal activity around 22°C, has a glycoproteic character, and presents sedimentation coefficients of 6.5 S and 10.5 S. Most of this AChE activity is soluble under low ionic strength conditions; however, the enzyme aggregates in the absence of detergents.In conclusion, our evidence indicates the presence of a well‐recognized molecular marker that could be useful for the study of the development of Concholepas concholepas.
Effects of osmolality and solutes on performance of shark heart mitochondria
Authors: Lea Malcolm , Hillman Stanley 
Published: June 2005

AbstractDogfish shark heart mitochondria isolated from Squalus acanthias were exposed to increasing concentrations of mannitol/sucrose, trimethylamine oxide (TMAO), betaine, and urea. For all but urea, respiratory control ratios (RCR) and rates of oxygen uptake (V̇O2) in the presence of malate/glutamate were low in basal medium (220 mOsm), increased with solute concerntration to about 420–870 mOsm, and declined in the highest concentrations (1,150 mOsm). Increasing urea concentration up to about 1,150 mOsm had relatively little effect on RCR or V̇O2. The results were not changed significantly by prolonged incubation in these media or by the addition of 0.3 M urea to either mannitol/sucrose or TMAO media. We conclude that, like mannitol/sucrose, betaine, and probably TMAO permeate shark heart mitochondria slowly or not at all, but that urea readily permeates the mitochondria and is thus osmotically inactive. The highest V̇O2 values were obtained in media at 580 mOsm, hypoosmotic to shark blood (897 mOsm) and to local seawater (879 mOsm) but approximately isoosmotic to blood without the osmotic contribution of the permeant urea. We conclude that V̇O2 is superior to RCR as a comparative measure of mitochondrial activity.
Induction of maturation of atlantic croaker oocytes by 17α,20β,21‐trihydroxy‐4‐pregnen‐3‐one in vitro: Consideration of some biological and experimental variables
Authors: Patiño Reynaldo , Thomas Peter 
Published: June 2005

AbstractWe characterized the in vitro control of germinal vesicle breakdown (GVBD) by 17α,20β,21‐trihydroxy‐4‐pregnen‐3‐one (20β‐S) in intact ovarian follicles of gonadotropin‐primed Atlantic croaker. 20β‐S‐induced GVBD was determined in relation to ovarian (oocyte) morphology, duration of incubation, steriod metabolism, and interaction with other steroids. The rate of GVBD in vitro in the absence of exogenous steriod was positively correlated with initial stage of ovarian morphological development. Maximal responsiveness to 20β‐S was seen in ovaries with oocytes showing the first signs of morphological maturation. Dose‐response experiments with 20β‐S and 17α,20β‐dihydroxy‐4‐pregnen‐3‐one (17α,20β‐P) over a range of incubation times yielded similar results for both steriods, suggesting that conversion of 17α,20β‐P to 20β‐S is not required for 17α,20β‐P‐induced GVBD. The ED50 of these steroids markedly decreased with increasing incubation times. Comparisons between patterns of follicular transformation of various radiolabelled steroids to 20β‐S and their respective activities (using unlabelled steroids) in the GVBD bioassay suggested that, in addition to 17α,20β‐P, progesterone has some intrinsic maturational activity. However, the maturational effects of 11‐deoxycortisol and pregnenolone may be explained by their conversion to 20β‐S. For the first time in any vertebrate, we showed that the proposed maturation‐inducing steroid (20β‐S) is not significantly transformed to any extractable, potentially active metabolite by intact, maturing ovarian follicles. These findings strongly suggest that 20β‐S is the terminal product of the MIS biosynthetic pathway in Atlantic croaker ovaries. Estradiol had no acute effects on 20β‐S‐induced GVBD. However, testosterone decreased and cortisol augmented the maturational activity of 20β‐S. Excess progesterone reduced the activity of a maximally effective dose of 20β‐S, but pregnenolone was without effect. The effects of these steroids on 20β‐S‐induced GVBD are discussed in relation to their possible interactions with 20β‐S at the MIS receptor level.
Analysis of myosins from lobster muscles: Fast and slow isozymes differ in heavy‐chain composition
Authors: Li Youlin , Mykles Donald L. 
Published: June 2005

AbstractThe contractile speed of striated muscle is correlated with myosin adenosine triphosphatase (ATPase) activity. In crustaceans, ATPase activity in fast muscle is about four‐fold greater than that in slow muscle. Slow and fast myosins were purified from the crusher claw closer and the deep abdominal muscles, respectively, of teh American lobster, Homarus americanus, and analyzed by peptide mapping, chymotryptic digestion, and two‐dimensional polyacrylamide gel electrophoresis (PAGE). Peptide mapping of myosin heavy chains with Staphylococcus aureus V8 protease produced seven peptides unique to slow‐muscle myosin and 11 peptides unique to fastmuscle myosin. Heavy‐chain fragments produced by chymotryptic digestion of native myosin differed in molecular weight and isoelectric point between the two muscle types, suggesting possible differences in the flexible hinge region in the rod portion of the molecule. In contrast, twodimensional PAGE showed that the corresponding light chains of both fast and slow myosins were identical in size and net charge. Therefore, the molecular basis of the difference in ATPase activities between fast‐ and slow‐muscle myosins can be attributed solely to heavy‐chain isoform composition.
Inhibition of serotonin‐induced oocyte maturation by a Spisula factor
Authors: Kadam Arjun L. , Koide Samuel S. 
Published: June 2005

AbstractA factor that blocks serotonin (5‐hydroxytryptamine, 5‐HT)‐induced maturation of Spisula oocytes was purified from Spisula oocytes by ultrafiltration through a PM‐10 membrane, charcoal adsorption, and reversed‐phase HPLC on a Partisil ODS‐3 column, The oocyte factor is a heat‐stable, non‐proteinaceous compound with an estimated Mr of less than 1,000 Da. It blocked 5‐HT‐induced maturation of Spisula ooctyes at concentrations ranging from 10 to 100 μg/ml. It did not influence KCl‐ or potassium‐ glutamate‐induced maturation of Spisula oocytes or the maturation of mouse, Chaetopterus, Xenopus, or Asterias oocytes. The oocyte substance may function as a modulator of 5‐HT action and/or be the endogenous meiotic arresting factor in Spisula oocytes. At concentrations exceeding 100 μl/ml, the oocyte factor induced formation of blebs and cytoplasmic droplets.
Biosynthesis of 17α,20α‐dihydroxy‐4‐pregnen‐3‐one from 17α‐hydroxyprogesterone by spermatozoa of the common carp, Cyprinus carpio
Authors: Asahina Kiyoshi , Barry Terence P. , Aida Katsumi , Fusetani Nobuhiro , Hanyu Isao 
Published: June 2005

AbstractIsolated sperm of the common (Cyprinus carpio) were incubated with 4‐14C‐labeled 17α‐hydroxyprogesterone at 22°C for 60 min; the medium was extracted, and the products were separated by thin‐layer chromatography (TLC). An autoradiogram of the TLC plate showed that a single major metabolite was produced, which had an Rf value lower than that of 17α,20β‐dihydroxy‐4‐pregnen‐3‐one (17α,20β‐diOHprog) but which was identical to that of its isomer, 17α,20α‐dihydroxy‐4‐pregnen‐3‐one (17α,20α‐diOHprog). The metabolite behaved identically on thin‐layer chromatograms to authentic 17α,20α‐diOHprog after both acetylation and oxidation, and had the same retention time as authentic 17α,20α‐diOHprog when separated by highperformance liquid chromatography (HPLC). The identity of the metabolite was confirmed by recrystallizing it to a constant specific activity after repeated crystallization with authentic 17α,20α‐diOHprog. These results indicate that the sperm cells of common carp contain the enzyme 20α‐hydroxysteroid dehydrogenase and have the capacity to produce high levels of 17α,20α‐diOHprog in the presence of 17α‐hydroxyprogesterone.
Fatty‐acyl coenzyme A pool in liver of rainbow trout (Salmo gairdneri): Effects of temperature acclimation
Authors: Hazel Jeffrey R. , Livermore Rochelle C. 
Published: June 2005

AbstractThe size and composition of the hepatic acyl‐CoA pool were determined in quickly frozen liver tissue of rainbow trout (Salmo gairdneri) acclimated to 5° and 20°C. Concentrations of 14:0‐, 16:1‐, 18:3‐, 20:2‐, 20:3‐, and 24:1‐CoA were significantly higher while proportions of 18:0‐, 18:1‐, 20:1‐, and 20:4‐CoA were significantly lower in warm‐ than cold‐acclimated trout. In spite of these differences, neither the size (although 28% larger in warm‐ than cold‐acclimated trout), total content of unsaturated acyl‐CoAs, average chain length, nor the degree of unsaturation of the acyl‐CoA pool was significantly influenced by acclimation temperature. Arachidonic acid (20:4n6) was the only polyunsaturated fatty acid present in significantly higher quantities in the acyl‐CoA pool of cold‐ than warm‐acclimated trout. Levels of n‐3 acids were similar in both acclimation groups, while proportions of n‐9 and n‐6 acids increased and decreased, respectively, with cold acclimation. It is concluded: 1) that the composition of the acyl‐CoA pool is unlikely to influence significantly the acyl chain composition of membrane lipids and 2) that the temperature dependence of substrate preference for the enzymes of phospholipid biosynthesis and turnover is likely to play a major role in determining which molecular species of phospholipid will accrue as environmental temperature changes.
Role of sialic acid in exogenous protein accumulation and water retention by the egg jelly of the salamander Ambystoma macrodactylum
Authors: Berner Nancy J. , Ingermann Rolf L. 
Published: June 2005

AbstractThe jelly coat of eggs from the salamander Ambystoma macrodactylum is capable of binding and accumulating a high concentration of exogenous protein from a dilute incubation medium. This binding appears to be due to negatively charged moeities of the jelly structure. To examine whether sialic acid was responsible for the binding of exogenous protein as well as water retention, and thus the structural rigidity of the jelly, sialic acid was chemically removed from the jelly. There appeared to be a linear relationship between the sialic acid content of the jelly and the amounts of exogenous protein and water retained by the jelly. Furthermore, removal of about 90% of the sialic acid was associated with 89% and 70% decreases in accumulated hemoglobin and water content, respectively. The data are therefore consistent with the hypothesis that sialic acid is the exogenous protein binding site. The data are also consistent with the hypothesis that sialic acid is responsible for most of the water retention and thus the swollen state of the egg jelly.
Length‐tension and histochemical properties of select shoulder muscles of the savannah monitor lizard (Varanus exanthematicus): Implications for function and evolution
Authors: Young B. A. , Magon D. K. , Goslow G. E. 
Published: June 2005

AbstractWe explored the mechanical properties of four shoulder muscles of the Savannah Monitor Lizard (Varanus exanthematicus) and related these to locomotion. We studied the biceps brachii, supracoracoideus, two parts of the latissimus dorsi, and two parts of the pectoralis muscles by measuring twitch contraction time, peak tetanic tension, and contractile fatigue resistance to repetitive stimulation. In addition, we generated length‐passive and length‐active tension curves at those muscle lengths used during slow and moderate speed walking. Finally, we used conventional histochemistry to identify anatomical compartments within these muscles. Major findings include (1) the length‐active tension of the biceps brachii, supracoracoideus, both parts of the latissimus dorsi, and the pectoralis remains near peak value over a range of muscle lengths associated with normal limb movement, (2) all muscles possess a mean twitch contraction time of between 65 and 70 msec (24°C), (3) all muscles are relatively fatiguable, and (4) evidence for anatomical compartments exists for the latissimus dorsi, pectoralis, and supracoracoideus.We compared the data for the pectoralis of V. exanthematicus to that for the domestic pigeon (Columba livia) in an effort to identify features of musculoskeletal design which may have accompanied the evolution of flight. We conclude that at least two factors were important: (1) the development of a capacity for sustained, aerobic contraction, and (2) a rearrangement of some of the anterior pectoralis fascicles so that they arise from the furcula. The latter provides for a distinct protractive component to the humerus, which is important during downstroke in some forms of flapping flight.