摘要:

AbstractPrevious studies have implicated morphological adaptations as important countermeasures to gravitational stresses on the circulatory systems of arboreal or climbing snakes. Such features include tight skin and relatively non‐compliant tissue compartments that oppose edema formation, but these traits have not been previously studied quantitatively. To provide information on this subject, interstitial fluid pressures were measured in eleven species of snakes using slit‐end catheters positioned in subcutaneous tissue located at the base of the tail. Interstitial pressures in all species were typically 0 to + 2 mm Hg in normally hydrated tissue, but varied widely when snakes were active or when the tail was curved at the site of measurement. Local compliance of the free fluid space was determined from measurements of pressure while saline was infused via the catheter tip. Such measurements varied from 0.18 μl/mm Hg inPhilodryas baroni, an arboreal species, to 2.3 μ/mm Hg inCrotalus adamanteus, a ground‐dwelling, terrestrial species. In general, compliance of the subcutaneous tissue space was greatest (P<0.05) in non‐climbing and aquatic species of snakes that do not face problems of gravitational edema in dependent tissues. Presumably, the compliance measurements reflect adaptive structural differences related to requirements for counteracting gravitational stresses in the various species. © 1993 Wiley

ISSN:0022-104X    

DOI:10.1002/jez.1402670602

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractSpermatozoa of the horseshoe crab,Limulus polyphemus, contained high activities of arginine kinase (AK), the bulk of which was completely solubilized in buffer lacking detergent. Sperm AK, along with the fast isoform of muscle AK, were purified to homogeneity. Sperm AK had similar electrophoretic mobility on cellulose acetate to that of muscle AK. In contrast, sperm AK ran somewhat slower than muscle AK on SDS‐PAGE, indicating that this protein has a higher relative molecular mass (44 kD vs. 41 kD). These two forms also showed different chromatographic behavior on a reverse‐phase HPLC column. Peptide maps of cyanogen bromide cleavage fragments of sperm and muscle AK showed distinct differences. Collectively, these data suggest that the sperm ofL. polyphemuscontain a unique AK isoform. Polyclonal anti‐muscle AK antibodies, which showed strong reactivity against sperm AK, were used to localize AK in sperm. Both indirect immunofluorescence and immunogold transmission electron microscopy showed that AK was present in the midpiece in the vicinity of the mitochondria and also along the length of the flagellum. Given the polarized geometry of these cells, it appears that the AK reaction may play a role in high energy phosphate transport to dynein ATPases in the flagellum. © 1993 Wiley‐L

ISSN:0022-104X    

DOI:10.1002/jez.1402670603

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractWe studied the kinetics of the glucose transporter in mussel mantle cells. The transport is sodium dependent, with a very low uptake of glucose when sodium is replaced with potassium, choline or sucrose. In the presence of phlorizin, a glucose transporter inhibitor, the uptake is greatly diminished, with a low glucose uptake which is probably due to passive diffusion. The Woolf‐Augustinsson‐Hofstee plot obtained with different concentrations of glucose, and the Hill coefficient obtained in studies about the effect of Na+on glucose uptake, indicate that more than one sodium ion was involved in the transport of each molecule of glucose across the membrane in mussel mantle cells, or that positive cooperativity is occurring. The activity of the transporter is not affected by the sodium‐proton pump inhibitor amiloride. © 1993 Wiley‐L

ISSN:0022-104X    

DOI:10.1002/jez.1402670604

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractA clone of a fast isoform of myosin heavy chain (HC) gene was isolated from a cDNAThe sequence data for this cDNA has been submitted to GenBank; the accession number is U03091.expression library made from mRNA purified from the deep abdominal flexor muscle of the lobster,Homarus americanus. The cDNA (1.5 kb) contained the 3′ untranslated region (UTR) and the coding sequence for the last 413 amino acid residues of the carboxyl terminus of the polypeptide. The deduced amino acid sequence showed high homology with that of myosin HCs fromDrosophila(73% identity), nematode (57% identity), and vertebrates (49% identities). Hydropathy plots showed a 28‐amino acid periodicity that is consistent with the α‐helical coiled coil structure of the rod region of native myosin. Northern blot analysis and in situ hybridization showed that the fast myosin HC isoform was expressed only in fast fibers; the probes did not hybridize to mRNA from slow fibers. The message consisted of a single transcript of 6.6 kb. The intracellular localization of the fast myosin mRNA was not uniform. The mRNA was largely confined to the intermyofibrillar spaces and to the subsarcolemmal cytoplasm of the fiber periphery and large infoldings of the cell membrane. Within these regions the mRNA was concentrated in the cytoplasm immediately surrounding the nuclei. This constitutes the first report of the cloning and expression of a myosin HC gene from a crustacean species. © 1993 Wiley‐

ISSN:0022-104X    

DOI:10.1002/jez.1402670605

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractVitellogenin was purified from plasma of estradiol‐17β‐treated cod (Gadus morhua) rainbow trout (Oncorhynchus mykiss), turbot (Scophthalmus maximus), and wolffish (Anarhichas lupus) by precipitation with EDTA:Mg2+, distilled water, and high‐performance ion‐exchange chromatography. Vitellogenin of high purity was obtained by precipitation followed by chromatography, as evaluated by an homologous antiserum developed for each species. The instability of vitellogenin demanded consistent low temperature and the use of protease inhibitor before blood sampling. When the necessary precautions were taken, vitellogenin from rainbow trout, turbot, and wolffish eluted as one regular peak during chromatography. Cod vitellogenin eluted as two peaks and these demonstrated identical migration patterns on SDS‐PAGE. The observed differences in stability between the four species suggest that isolation procedures should be modified according to the requirements for each species. Electrophoresis of plasma from treated fish revealed the presence of several smaller proteins, with a molecular mass around 50 kDa, that were considered to be vitelline envelope proteins. Other minor plasma proteins were immunoreactive to antisera, directed against vitellogenin and therefore judged to be fragments of degraded vitellogenin. © 1993 Wile

ISSN:0022-104X    

DOI:10.1002/jez.1402670606

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractLandlocked larval sea lampreys (Petromyzon marinus) in three size‐groups were treated with two concentrations of potassium perchlorate (0.01 and 0.05% KC104; a goitrogen) for 117 days during the winter to determine if metamorphosis can be induced at a time when it will not occur spontaneously and whether a minimum size (length and weight) and physiological condition, measured as a condition factor (CF), are necessary for induction to occur. Metamorphosis was induced in all size‐groups with both concentrations of KC1O4but not in control animals. Size‐group was the only factor that significantly influenced (P130 mm long. Metamorphosing animals were significantly larger (P<0.05) in size (length and weight) and had significantly higher (P130 mm) and the smallest animal to metamorphose was 84 mm and 0.71 g in size. Minimum size and CF criteria for spontaneous metamorphosis (120 mm, 3.0 g, 1.50 CF) in landlocked sea lampreys are not necessary prerequisites for inducing metamorphosis using KC1O4. The experimental production of metamorphosis in sea lampreys of various sizes creates a valuable tool for studying hormonal and genetic regulation of this developmental strategy in a vertebrate of ancient lineage. ©

ISSN:0022-104X    

DOI:10.1002/jez.1402670607

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractThe epidermis of the body skin in anurans undergoes a metamorphic fate different from that of the tail skin. The former survives metamorphosis and is transformed into the adult type, while the latter is subject to apoptosis. In a search for an explanation for this regional specificity at the cellular level, the epidermis of tadpoles of the bullfrog,Rana catesbeiana, was characterized histologically and immunohistochemically during metamorphosis and was compared between the body and the tail. No histological difference in the epidermis was apparent between the two tissues at stages I and II defined by Taylor and Kollros (Anatomical Record94:7–23, 1946). A clear difference was first noticed at late stage III with respect to basal cells, which are thought to be the progenitor cells of the germinative basal cells of the adult‐type epidermis: basal cells appeared at this stage in the body but not in the tail. At stage X, about 22% of epidermal cells were basal cells in the body, whereas there were still no basal cells in the tail. However, we present histological evidence for the presence of adult‐type cells in the tail at the late stages of climax. Weak but consistent expression of adult antigens in the tail skin was also demonstrated immunohistochemically with antibodies against human blood group A antigen, which cross‐react with an epitope present in adult‐type epidermal cells. We conclude that even the tail epidermis, a larva‐specific tissue, contains a population of cells that can differentiate into adult‐type cells. The different distribution of basal cells between the body and the tail epidermis closely correlates with the difference in metamorphic fate between the two tissues. © 1993 W

ISSN:0022-104X    

DOI:10.1002/jez.1402670608

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractBlood cell‐mediated cytotoxic activity against mammalian target cells by the hemocytes of the solitary ascidianCiona intestinaliswas investigated in vitro by fluorochromasia. Salt‐conditioned target cells were labeled with carboxyfluorescein diacetate and challenged with mixed and separated hemocytes. The assay provided optimal conditions for the functioning of the effector hemocytes while maintaining low background leakage from the target cells. Comparison of different hemocyte populations, separated by density gradient centrifugation, revealed that only cell bands containing the phagocytic and nonphagocytic amoebocytes exhibited cytotoxicity. Experiments to characterize cytolysis demonstrated that activity increased with the effector to target cell ratio, occurred within 15 min, and was maximal at an incubation temperature of 20°C. Both human (K562) and mouse [YAC‐1, P815, WEHI (3B) and L929] target cell lines were killed by the ascidian effector hemocytes. This paper demonstrates a population of nonspecific cytotoxic effector cells in the blood ofC. intestinalisthat are able to spontaneously kill a range of mammalian targets in vitro. © 1993 Wiley‐

ISSN:0022-104X    

DOI:10.1002/jez.1402670609

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractSperm are stored in the ovary ofLacuna (Epheria) uariegata(Carpenter, 1864) between oocytes or oriented with follicle cells singly or in clumps. The sperm develop close associations with follicle cells and in some cases become embedded in invaginations of cell apices. Follicle cells are rich in rough endoplasmic reticulum and are generally considered to provide nutrients to developing oocytes. The storage of sperm in the ovary was previously unknown for any gonochoric gastropod. The existence of sperm storage in the ovary ofL. variegatahas implications for both the site of fertilization and for sperm capacitation in this genus. The subfamily Lacuninae represent a monophyletic clade comprising five genera. This clade was previously characterized partly by a long duct to the seminal receptacle in two genera and by the eventual loss of the seminal receptacle with sperm storage in the oviduct in three others, includingLacuna. Storage of sperm in the ovary is an important new character that will enable further distinction among species of this unusual clade. © 1993 Wiley‐Liss, I

ISSN:0022-104X    

DOI:10.1002/jez.1402670610

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractNeutral, organic molecules with seven or less major atoms permeate erythrocytes of the little skate (Raja erinacea.) Hypotonicity (80%) increased permeation up to 10‐fold. Under both isotonic and hypotonic conditions solute influx occurred with the same size limitation, indicating that the number of permeation sites, but not their size, increases with hypotonicity. The maximum average diameter of these neutral molecules that penetrate the cell membrane is about 5.6 to 6.2 Å. This is similar to that found previously for amino acid permeation, but unlike amino acids, the entry of most of the organic, neutral molecules into skate erythrocytes is not affected by Band 3 inhibitors. These results suggest that the neutral molecules tested may enter the erythrocytes via the same channel as amino acids, but do not interact with the sites blocked by Band 3 inhibitors, or through a separate channel of similar size which is also volume activated. © 1993 Wiley‐Liss

ISSN:0022-104X    

DOI:10.1002/jez.1402670611

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY