bluuebunny/crossref_metadata_2025_split huggingface dataset:
High‐molecular‐weight serine proteinase from lobster muscle that degrades myofibrillar proteins
Authors: Mykles Donald L. 
Published: June 2005

AbstractA latent alkaline serine proteinase (ASP) has been extracted from the soluble fraction of lobster claw and abdominal muscles. The enzyme, which was irreversibly activated 30‐ to 40‐fold by brief (2–3 min) heating at 60°C, had an optimal caseinolytic activity at pH 7.75. Its molecular weight was estimated to be 740,000 by gel filtration chromatography. Serine protease inhibitors (diisopropylfluorophosphate, phenylmethanesulfonyl fluoride, soybean trypsin inhibitor, aprotinin, benzamidine, and chloromethyl ketones) suppressed ASP activity 22 to 70%. In addition, sulfhydryl‐blocking reagents and hemin inhibited activity 69 to 100%; leupeptin and E‐64, however, did not. Pepstatin A, ethylenediaminetetraacetate, and adenosine triphosphate were without effect. These results suggest that the lobster ASP is a serine proteinase that contains one or more sulfhydryl groups essential for catalysis. ASP was stimulated by dithiothreitol and inhibited by CaCl2 and oleic and linoleic acids. The enzyme was partially activated by low concentrations of sodium dodecyl sulfate; 0.05% produced activities 13% of that of preparations heated at 60°C. Neither poly‐L‐lysine, urea, dimethylsulfoxide, oleic acid, linoleic acid, nor N‐ethylmaleimide activated the enzyme. The ASP degraded most myofibrillar proteins, but showed a preferential hydrolysis of paramyosin, troponin‐I and ‐C, and myosin α light chain.
Rapid postembryonic development of a cricket flight muscle
Authors: Novicki Andrea 
Published: June 2005

AbstractThe metathoracic dorsal longitudinal muscle (DLM) of the cricket Teleogryllus oceanicus differentiated and developed rapidly over the last nymphal instar. Within eight days, the muscle mass increased by a factor of 15 and the relative volume of mitochondria quadrupled, while the relative amounts of myofibril and sarcoplasmic reticulum decreased. Tracheoblasts began to invade the muscle fibers immediately before the adult molt. Muscle mass continued to increase until four days after the adult molt, but the relative volumes of the ultrastructural components did not change. Within two weeks following the adult molt, the muscles in some of the animals began to degenerate.
Control of growth and ultrastructural maturation of a cricket flight muscle
Authors: Novicki Andrea 
Published: June 2005

AbstractThe metathoracic dorsal longitudinal muscle (DLM) in the cricket Teleogryllus oceanicus increased in mass and rapidly acquired interfibrillar tracheoles and an increased proportion of mitochondria around the time of the adult molt. Both neural input and juvenile hormone levels were investigated as possible factors controlling this rapid maturation. Motor axons to the muscle were cut early in the last nymphal instar, and muscle growth slowed but ultrastructural maturation continued; the percentage of muscle volume occupied by mitochondria tripled and tracheoblasts invaded the fibers in both the denervated and contralateral innervated muscles. Newly molted last instar nymphs were treated with methoprene, a juvenile hormone analog, and examined four days following the next molt. Muscle growth was slowed but not stopped. Both mitochondrial proliferation and tracheoblast formation were completely blocked by hormone treatment. This study shows that both neural input and low levels of juvenile hormone are required for muscle growth. However, ultrastructural maturation seems to depend exclusively on low levels of juvenile hormone.
Regeneration of the dermoepidermal junction in anuran larval skin
Authors: Kinoshita Tsutomu , Takahama Hideki , Sasaki Fumie , Watanabe Kyozo 
Published: June 2005

AbstractIn anuran larval skin, several ultrastructures are formed at the dermoepidermal interface, and these include half‐desmosomes, basal lamina, and anchoring fibrils. Regional differences in the tadpole skin were assessed in terms of the process of regeneration of the junctional structures. The dermoepidermal interface was specifically destroyed by treatment with a neutral protease at pre‐ (stage V), pro‐ (stage XVIII), and climactic metamorphosis (stage XXI). The regeneration of the junctional structures was then compared between the skin of the tail and the back. Regardless of the metamorphic stages, the back skin regenerated complete structures, which contained the same number of half‐desmosomes as in the control, within 3 days after treatment. In the tail skin from tadpoles at premetamorphosis, basal lamina and half‐desmosomes were regenerated 2 days later than was the back skin. The ability of the tail skin to regenerate decreased as metamorphosis proceeded. When the enzymatic treatment was performed on skin removed at the climax of metamorphosis, the tail skin underwent histolysis without completion of junctional repair. In experiments with heterotypically recombined skins, active regeneration similar to that of the back skin was observed in recombinants of tail epidermis and back dermis. However, the recombinants of back dermis with tail dermis produced only basal lamina and amorphous material beneath the epidermis. These results suggest that a regional difference, with respect to the regenerating ability of the dermoepidermal junction, already exists in the skin of the premetamorphic tadpole and that this difference depends on the dermal components of the skin.
Cross‐fertilization between Syrian and Chinese hamsters
Authors: Roldan E. R. S. , Yanagimachi R. 
Published: June 2005

AbstractThe role of the zona pellucida in the specificity of fertilization was studied by cross‐inseminations between Syrian (Golden) and Chinese hamster gametes. Cumulus‐enclosed eggs from both Syrian and Chinese hamsters were placed together in one dish and inseminated with spermatozoa from either one or the other species. Fertilization always took place between gametes of homologous species. Chinese hamster spermatozoa failed to bind to the zona pellucida of Syrian hamster eggs; hence, fertilization was never observed. However, Chinese hamster spermatozoa could fertilize zona‐free Syrian hamster eggs. In the reciprocal cross, a large number of Syrian hamster spermatozoa could bind to and penetrate the zonae of Chinese hamster eggs. However, fusion of Syrian hamster spermatozoa with the vitellus of zona‐intact Chinese hamster eggs was never observed. After removal of the zona pellucida, only a small percentage (31%) of Syrian hamster spermatozoa could fuse with Chinese hamster vitelli. Thus, in these species, the mechanisms of interspecific gamete recognition and the prevention of interspecies fertilization seem to differ according to the direction of the cross. In Syrian hamster eggs, the block to interspecies fertilization seems to exist at the level of the zona pellucida, while in Chinese hamster eggs the block is at the level of the egg plasma membrane. The implications of these results in analyses of the genetics of spermatozoa, the molecular basis of sperm‐egg recognition, and mechanisms of reproductive isolation leading to speciation, are discussed.
Cultivation and differentiation of satellite cells from skeletal muscle of the rainbow trout Salmo gairdneri
Authors: Powell R. L. , Dodson M. V. , Cloud J. G. 
Published: June 2005

AbstractPostembryonic myogenic satellite cells have previously been identified by microscopic methods in skeletal muscle of the rainbow trout, Salmo gairdneri, and are considered to be responsible for myofiber hyperplasia and hypertrophy during the growth of skeletal muscle. However, methods to harvest satellite cells from fish skeletal muscle tissue and data to demonstrate that fish satellite cells can grow in primary cell culture appear to be lacking. Therefore, the objectives of the present preliminary research were 1) to determine if satellite cells from postembryonic rainbow trout skeletal muscle can be harvested and 2) to determine if these satellite cells can differentiate to produce multinucleated, striated myotubes in vitro. Mononucleated cells were isolated by enzymatic digestion of minced skeletal muscle tissue followed by differential centrifugation. The cells were then cultured at 20°C in Leibovitz's L‐15 medium supplemented with 15% fetal bovine serum and antibiotics. Fusion of satellite cells to form multinucleated tubular structures similar to mammalian satellite cell‐derived myotubes occurred from 3 to 6 days after initial plating; myofibrillar striations began to appear in some of these structures approximately 3 to 4 days after they had developed. Based on these preliminary observations, the authors concluded that viable satellite cells may be harvested from the rainbow trout and that these cells may differentiate to produce multinucleated, striated myotubes in vitro.
Kinetic analysis of cadmium binding to metallothionein and other intracellular ligands in oyster gills
Authors: Roesijadi G. , Klerks P. L. 
Published: June 2005

AbstractIn the oyster Crassostrea virginica the gill was a primary organ for accumulation of Cd from sea water. Gill Cd concentrations measured after 2 weeks of exposure increased as seawater Cd concentrations increased from 0.03 (the control) to 200 μg Cd · liter−1. Both the cytosolic and particulate fractions of gill tissues were involved in sequestering Cd. The cytosolic Cd was bound mainly to metallothionein (MT), which was most effective at binding Cd at the exposure of 50 μg Cd ·liter−1. The relative importance of binding to the particulate fraction was greatest at the lower exposure of 10 μg Cd · liter−1, at which the amount of Cd bound to MT was relatively low, and at the higher exposure of 200 μg Cd · liter−1, at which the capacity for metallothionein to bind Cd appeared to have been exceeded. Gills excised from oysters exposed continuously to 50 μg Cd · liter−1 for up to 24 days were used in a kinetic analysis of the influence of MT induction on intracellular Cd distribution. Short‐term 109Cd‐uptake experiments at this concentration indicated that MT was induced between 1 and 4 days of exposure. Increased binding rates of Cd to MT were attributed to induction of MT and associated with decreased binding to structures in the particulate and to high‐ and low‐molecular‐weight cystolic fractions. The Cd‐binding rates of the different compartments were ranked as MT > particulate fraction > high‐molecular‐weight cytosolic molecules > low‐molecular‐weight cytosolic molecules once MT was induced. The high Cd‐binding rates for MT coupled with the low turnover rates for MT‐bound Cd indicated that MT was the compartment that governed the dynamics of Cd in the whole gill. The intracellular distribution of Cd could be explained on the basis of competitive binding of Cd to intracellular ligands with varying Cd affinities.
Cardiovascular and metabolic responses during anoxic submergence in the bullfrog with and without maintained extracellular pH
Authors: Warburton Stephen J. , Wasser Jeremy S. , Jackson Donald C. 
Published: June 2005

AbstractWe studied metabolic, cardiovascular, and electrolyte responses of paralyzed bullfrogs to 6 hours of submerged anoxia at 15°C, either with or without maintenance of extracellular pH at preanoxic values by NaHCO3 infusion. There were no differences in arterial PCO2 between acidemic and nonacidemic groups. Lactate appearance in arterial blood, as an indicator of anaerobic metabolic rate, was not significantly different between the anoxic groups, although both were significantly elevated over control. Heart rate in both anoxic groups was similar and significantly lower than in control. During anoxia, both systolic and diastolic pressures fell, and the group with maintained pH fell further. Plasma calcium concentration decreased in both anoxic groups, but the fall was more severe in the group in which pH was controlled. Survival was lower in this group, with a rapid decline in survival after 4 hours of anoxia. We conclude that the fall in extracellular pH seen during anoxia has a protective effect on cardiovascular function that may be partially due to maintenance of relatively high extracellular calcium levels.
Protrusion formation in the cell division‐arrested mutant Tetrahymena thermophila cdaA1: Some rules governing cytoskeletal growth
Authors: Bużańska Leonora , Gregory David W. , Wheatley Denys N. 
Published: June 2005

AbstractIn the cdaA1 temperature‐sensitive mutant cell line of Tetrahymena thermophila, growth occurs at the restrictive temperature of 35°C without proper coordination of cytoskeletal structures, resulting in large and irregularly shaped “monsters.” This disturbed development has helped to elucidate some rules governing cortical morphogenesis in this species.Within the cdaA1 cortex, the individual ciliary row may grow independently with respect to other parts of the cortex. Local growth of the cortex is morphologically visualized as a local increase in the rate of basal body proliferation and elongation of the longitudinal microtubular (LM) band. It results in looplike, three‐dimensional projections that appear at various parts of the cell cortex. After the apical break of the ciliary row with the parallel LM band, these projections become long, fingerlike, and sharply pointed structures.During its formation, an individual protrusion does not change its location within the cell latitude and longitude. The row by row autonomy and the intrinsic polarity of growth of the ciliary row have been demonstrated. Analysis of further growth in length revealed that in 90% of cases, the free (‐) end of the anterior segment of the broken ciliary row in a protrusion actively elongates, irrespective of the latitude at which protrusion was located.
Organization of positional information in the axolotl limb
Authors: Gardiner D. M. , Bryant S. V. 
Published: June 2005

AbstractWe have used the phenomenon of position‐dependent growth stimulation, brought about by the confrontation of cells with dissimilar positional values, to reveal the organization of positional information in the center of the upper and lower arms of axolotls. When either humerus or radius was transplanted into either dorsal or posterior positions, extra growth leading to the formation of supernumerary digits occurred following amputation through the graft. However, transplants of humerus or radius into anterior or ventral positions did not lead to the formation of any additional digits. The ulna by contrast was capable of stimulating supernumerary digit formation when transplanted into anterior, posterior, dorsal, or ventral positions. We interpret these results to indicate that the humerus and radius are surrounded by symmetrically arranged anterior and ventral positional values, whereas the ulna is surrounded by a complete asymmetrical set of angular positional values. We use our proposed arrangement for the positional information in the limb center to explain a number of previous experimental findings. In addition, we provide an explanation, in terms of the underlying positional information, for the structural and developmental relationships between the different skeletal elements of the vertebrate limb, and in particular for the anatomical pattern known as Gregory's pyramid.
Major vitelline envelope proteins in pipefish oocytes originate within the follicle and are associated with the Z3 layer
Authors: Begovac Paul C. , Wallace Robin A. 
Published: June 2005

AbstractA method is described for purifying salt‐washed vitelline envelopes of pipefish eggs. Approximately 72% of the envelope dry weight is represented by 2 extractable proteins with molecular masses of 109 and 98 kDa. The 2 proteins are present in a 1:2 ratio, respectively, on 1‐dimensional electrophoretic gels; the 98 kDa protein can be resolved further into a family of peptides by 2‐dimensional gel electrophoresis. A monoclonal antibody raised against vitelline envelope protein recognizes both groups of protein and no other component of the oocyte, plasma, or liver. Immunocytochemistry indicated that the recognized antigen first appears in late cortical alveolistage oocytes, coincident with formation of the Z3 layer of the vitelline envelope; immunogold staining of thin sections confirmed antigen localization to the Z3 layer. Incubation of intact follicles with [35S]methionine in vitro followed by 2‐dimensional gel electrophoresis and immunoblotting demonstrated the synthesis of the vitelline envelope proteins by such preparations. However, isolated follicle cells or denuded oocytes failed to yield convincing evidence of a similar nature. We conclude from these observations that the principal vitelline envelope proteins originate from within the follicle rather than elsewhere, such as the liver, and that the structural integrity of the follicle may be necessary for their elaboration.
Intestinal transfer of growth hormone into the circulatory system of the rainbow trout, Salmo gairdneri: Interference by granule cells
Authors: Le Bail Pierre‐Yves , Sire Marie‐France , Vernier Jean‐Marie 
Published: June 2005

AbstractTo test if growth hormone, well known for its strong effect on fish growth, could be incorporated into the diet, bovine growth hormone (bGH) was introduced into the lumen of the digestive tract of trout yearling (Salmo gairdneri). Radioimmunoassay (RIA) and radioreceptoras‐say (RRA) were used to assess plasma concentration of bGH. In our experimental conditions, the concentration of bGH peaks after 1 hour, in treated fish only, attesting to the intestinal hormone transfer (coefficient of absorption is about 0.2%). Immunocytochemistry is used to follow the hormone transfer process. Most bGH molecules absorbed by enterocytes of the distal segment are found in the vacuoles (phagolysosomes) of the apical hyaloplasm. A small part escapes the intracellular degradation and is found in the intercellular space and in the interstitial space of the lamina propria. At this level, the granule cells trapped the antigenic hormone, as did immune cells.The results of this study indicate that oral administration of GH can be potentially used in fish culture.
Leucine pool sizes in the fat body of ovariectomized and vitellogenically active adult Acheta domesticus (L.)
Authors: Bradley James T. , Harber Gregory J. 
Published: June 2005

AbstractHemolymph and intracellular fat body leucine were extracted from 10‐day‐old ovariectomized adults and sham‐operated females and were isolated by thin layer chromatography. Leucine pool sizes in both tissues were estimated by a double label‐dansylation procedure. Ovariectomy had no effect on the hemolymph leucine pool size, but the total intracellular fat body leucine pool size was greater in intact than in ovariectomized females. The postinduction rates of vitellogenin synthesis in the fat bodies of ovariectomized and sham‐operated females are discussed in the context of these data. A mechanism responsible for the lowered leucine pool size in the fat body of ovariectomized crickets remains to be identified.
Effects of 17α,20β‐dihydroxy‐4‐pregnen‐3‐one on the in vitro production of 11‐ketotestosterone by testicular fragments of the common carp, Cyprinus carpio
Authors: Barry Terence P. , Aida Katsumi , Hanyu Isao 
Published: June 2005

AbstractTesticular fragments of the common carp were incubated with a range of doses of 17 α,20β‐dihydroxy‐4‐pregnen‐3‐one (17,20‐P, 3, 30, 300, and 3,000 ng/ml) in combination with either silver carp gonadotropin (GtH, 0.5 μg/ml), 17α‐hydroxy‐4‐pregnen‐3‐one (17‐P, 100 ng/ml), testosterone (T, 100 ng/ml), or Ringer alone (control). The production of T, 11‐ketotestosterone (11‐KT), 17‐P, and 17,20‐P were measured after 18 hr incubation by specific radioimmunoassay. Gonadotropin, 17‐P, and T all significantly stimulated 11‐KT production above control levels in the absence of 17,20‐P. Addition of 17,20‐P inhibited 11‐KT production in response to these agents in a dose‐dependent manner; doses 30 ng/ml and higher completely eliminated the stimulatory effects of GtH and 17‐P, and only 3 ng/ml 17,20‐P significantly inhibited T‐stimulated 11‐KT production. In the control incubations, there was a trend of decreasing 11‐KT production with increasing dose of 17,20‐P. In the incubations treated with GtH and 17‐P, decreasing 11‐KT levels were not accounted for by corresponding increases in the levels of T. In all incubations, the levels of 17‐P increased in response to 17,20‐P, although this may have been due to the conversion of 17,20‐P to 17‐P. The results indicate that at least one of the two enzymes that converts T to 11‐KT, 11β‐hydroxylase and 11β‐hydroxysteroid dehydrogenase, is inhibited by physiological levels of 17,20‐P. In addition, the activities of other enzymes involved in androgen biosynthesis, such as C‐17,20‐lyase, may also be inhibited by 17,20‐P.
Cell intercalation during notochord development in Xenopus laevis
Authors: Keller Ray , Cooper Mark S. , Danilchik Mike , Tibbetts Paul , Wilson Paul A. 
Published: June 2005

AbstractMorphometric data from scanning electron micrographs (SEM) of cells in intact embryos and high‐resolution time‐lapse recordings of cell behavior in cultured explants were used to analyze the cellular events underlying the morphogenesis of the notochord during gastrulation and neurulation of Xenopus laevis. The notochord becomes longer, narrower, and thicker as it changes its shape and arrangement and as more cells are added at the posterior end. The events of notochord development fall into three phases. In the first phase, occurring in the late gastrula, the cells of the notochord become distinct from those of the somitic mesoderm on either side. Boundaries form between the two tissues, as motile activity at the boundary is replaced by stabilizing lamel‐liform protrusions in the plane of the boundary. In the second phase, spanning the late gastrula and early neurula, cell intercalation causes the notochord to narrow, thicken, and lengthen. Its cells elongate and align mediolaterally as they rearrange. Both protrusive activity and its effectiveness are biased: the anterioposterior (AP) margins of the cells advance and retract but produce much less translocation than the more active left and right ends. The cell surfaces composing the lateral boundaries of the notochord remain inactive. In the last phase, lasting from the mid‐ to late neurula stage, the increasingly flattened cells spread at all their interior margins, transforming the notochord into a cylindrical structure resembling a stack of pizza slices. The notochord is also lengthened by the addition of cells to its posterior end from the circumblastoporal ring of mesoderm. Our results show that directional cell movements underlie cell intercalation and raise specific questions about the cell polarity, contact behavior, and mechanics underlying these movements. They also demonstrate that the notochord is built by several distinct but carefully coordinated processes, each working within a well‐defined geometric and mechanical environment.
Pre‐axonogenesis migration of afferent pioneer cells in the grasshopper embryo
Authors: Bentley David , Toroian‐Raymond Alma 
Published: June 2005

AbstractIn insects, afferent neurons arise primarily from the ectodermal epithelium in the periphery and differentiate at the site of their precursor mitosis. Here we describe ectodermally derived cells that migrate away from their site of origin and initiate axonogenesis at a distant location. In embryonic grasshopper limb buds, the first two pairs of afferents to differentiate are the pair of Ti1 pioneers at the limb tip and the pair of Cx1 cells found at the base of the limb. While the Ti1 pioneers arise from the mitosis of a pioneer mother cell at the limb tip, the Cx1 cells are shown to emerge from the epithelium at circumferential positions that are approximately 150° apart and that belong to different embryonic compartments. The cells migrate into contact with each other before initiating axonogenesis, and their axons then extend in a new direction that is orthogonal to the route of cell migration.