摘要:

AbstractSpecimens of the stone crab,Menippe mercenaria, survived severe hypoxia (PO2<8mm Hg) for at least 12 hr at 28–30°C. During the time course of 12 hr of hypoxia, hemolymph L‐lactate levels rose to 30–50 μmoles/g wet wt. There was a slight elevation of L‐alanine levels, whereas succinate was found in only trace quantities in the hemolymph. Pronounced metabolic changes took place in the heart, cheliped closer, and leg socket muscles during severe hypoxia. L‐lactate accumulated to levels ranging from 16–20 μmoles/g wet wt. There were pronounced changes in high‐energy phosphate levels in the cheliped closer and leg socket muscles. Taking into account expected intra‐ and extracellular water content, the calculated intracellular lactate content in the three muscles investigated is substantially less than the hemolymph lactate concentrations. Part of this reverse concentration gradient may be accounted for by the reduction in lactate activity due to cation‐lactate complex formation. Hemolymph calcium and magnesium concentrations rose considerably during severe hypoxia. During recovery from severe hypoxia, approximately 50% of the accumulated lactate in the hemolymph was cleared in 6 hr. Hemolymph lactate and alanine levels returned to near control levels after 24 hr of recovery. This study shows that the stone crab,M. mercenaria, survives severe hypoxia by a reliance on glycogen fermentation to lactate. This species is capable of tolerating high levels of

ISSN:0022-104X    

DOI:10.1002/jez.1402340202

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

年代:1985

数据来源: WILEY

摘要:

AbstractA sequential dissociative extraction scheme was used to extract proteins from developing Blue Shark enameloid. The first extraction solution (4 M guanidine HCl) solubilized the polypeptides, mainly collagenous, not closely associated with the hydroxyapatite. The next extraction solution (4 M guanidine HCl, 0.5 M ethylenediaminetetraacedic acid (EDTA)) solubilized the proteins more closely associated with the tooth mineral component. After extraction, the proteins were separated and isolated with gel electrophoresis. Protein molecular weights were determined and selected proteins were isolated for amino acid composition analysis. The two proteins isolated were tested for mammalian enamel protein antigenic determinants by a “Dot” immunobinding assay. The isolated proteins were enamelinlike by extraction criteria and amino acid composition. Further, the two proteins share antigenic determinants with mammalian enamel prote

ISSN:0022-104X    

DOI:10.1002/jez.1402340203

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

年代:1985

数据来源: WILEY

摘要:

AbstractSalinity tolerance and hypoosmoregulatory ability of anadromous brook trout (Salvelinus fontinalis) were investigated in relation to sex and state of maturation. Seawater survival of mature males was significantly poorer than that of females or immature males. Lowered salinity tolerance of adult males became acute during the autumn photoperiod (normal spawning period) when the gonadosomatic index was high. Plasma [Cl−], [Mg2+], osmolarity and hematocrit were significantly higher in mature males after transfer to seawater, relative to mature females. It is postulated that reduced adult male hypoosmoregulatory ability explains skewed sex ratios in anadromous brook trout populations and may limit the extent of brook trout anadrom

ISSN:0022-104X    

DOI:10.1002/jez.1402340204

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

年代:1985

数据来源: WILEY

摘要:

AbstractTreatment of the killifish,Fundulus heteroclitus, with ovine thyrotropin (oTSH) produced elevations in serum thyroxin (T4) that varied seasonally with a strong inverse correlation to environmental photoperiod (P<0.001). At 20°C, oTSH (0.2 IU) increased serum T4to levels ranging from 1.5 μg/100 ml in midsummer to 7.5 μg/100 ml in midwinter despite relatively stable resting levels throughout the two years of study. Similar rates of clearance of T4in summer and winter suggest that an alteration in thyroid response to oTSH accounts for this change. The serum T4response to oTSH is both photoperiod‐ and temperature‐dependent. In laboratory studies, fish exposed to a short artificial photoperiod (LD 8:16) for one month responded to oTSH with T4levels about twice as high as those in fish exposed to long days (LD 14:10). On the other hand the T4response to oTSH was sharply reduced at 5°C from that seen at 20°C. This suggests that, in nature, seasonal changes in photoperiod and temperature have opposite effects on thyroidal responsiveness to TSH. Overall, the annual variation in the T4response to oTSH appears to be driven by photoperiod, inasmuch as the alterations preceded major temperature changes in the wild and can be shown to occur at constant temperature in captivity. Photoperiodic induction of changes in thyroid sensitivity may aid in the maintenance of basal T4levels under changing thermal co

ISSN:0022-104X    

DOI:10.1002/jez.1402340205

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

年代:1985

数据来源: WILEY

摘要:

AbstractTwo cell types can be distinguished with intracellular recording from the pars intercerebralis of the American cockroach (Periplaneta americana). The first type, which corresponds morphologically to the medial neurosecretory cell, always had spontaneously occurring, overshooting action potentials. These action potentials are probably endogenously produced. Tetrodotoxin experiments revealed that sodium is the dominant ion of the action potential. The action potentials are followed by a relatively long after‐hyperpolarization. The input resistance of these cells ranged from 120 to 390 MΩ. A mathematical model, based on cellular morphology and response to current pulses, revealed a membrane time constant of about 100 msec and an exonal:somatic conductance ratio of approximately 13. Area‐specific membrane resistance was estimated at 33 kΩ cm2. These cells also often had reversible and spontaneous inhibitory postsynaptic potentials. The second cell type, which is non‐neurosecretory, never produced spontaneous action potentials and rarely had synaptic potentials. Action potentials could be evoked by current injection into the cell body or by extracellular stimulation of their axons in the posteroventral portion of the the protocerebrum. These action potentials also depend on sodium ions. Their input resistance ranged from 16 to 35 MΩ. They had a membrane time constant of approximately 15 msec and an axonal:somatic conductance ratio of about 9. Their area specific membrane resistance was estimated at 1

ISSN:0022-104X    

DOI:10.1002/jez.1402340206

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

年代:1985

数据来源: WILEY

摘要:

AbstractElectrophysiologically identified cells of the cockroach pars intercerebralis (Periplaneta americana) were injected with the dye Lucifer Yellow for morphological examination and with horseradish peroxidase for ultrastructural marking. In addition to this, uninjected cells were also studied to elaborate the findings from the injected material. The two electrophysiologically distinct classes of cells (type I and type II) correspond to two distinct morphological and ultrastructural classes. Type I cells are the medial neurosecretory cells of the pars interecrebralis, which project their axons to the retrocerebral neuro‐hemal complex. Their cell bodies have a mean diameter of 17 μm, and they contain neurosecretory granules 200 nm in diameter. Arborizations emanate from the axon in the anterior part of the protocerebral neuropil. The type II cell bodies are larger (38 μm in diameter). Their axons project into the contralateral circumesophageal connective. These cells were usually multipolar, having somatic arborizations in the anterior portocerebral neuropil. The cell bodies contain vesicles 40 nm in diameter, numerous trophospongia, and a multi‐layered glial env

ISSN:0022-104X    

DOI:10.1002/jez.1402340207

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

年代:1985

数据来源: WILEY

摘要:

AbstractCumulus cells were isolated by hyaluronidase treatment of whole cumulus masses from superovulated, non‐mated mice. The cells, in groups of approximately 200, were incubated for up to 4 h in 50 nl medium M2 at 37°C, and serial 3‐nl samples assayed for pyruvate using an ultramicrofluorescence technique. With 5.55 mM glucose, 23.3 mM lactate, or a mixture of the two substrates, the cumulus cells formed pyruvate at rates of 10.2, 9.6, and 8.9 fmol/cell/h, respectively. The concentrations of glucose, pyruvate, and lactate, as measured in 3‐nl aliquots of rabbit oviduct fluid were 1.5 mM, 0.3 mM, and 3.7 mM, respectively. When incubated with 1 mM glucose and 3 mM lactate, mouse cumulus cells formed 7.5 fmol pyruvate/cell/h. The mean number of cumulus cells per ovum within a cumulus mass was 2,060. Intact cumulus masses from mated and non‐mated superovulated mice, incubated with 1 mM glucose and 3 mM lactate, formed 22.6 and 23.3 pmol pyruvate/ovum/h, respectively. The results suggest that pyruvate production by cumulus cells may be important in supporting the nutrition of unfertilized and fertilized ova, and of spermatozoa, within the ovidu

ISSN:0022-104X    

DOI:10.1002/jez.1402340208

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

年代:1985

数据来源: WILEY

摘要:

AbstractRepresentative species of four bivalve subclasses were examined for the presence of mineral‐binding phosphoprotein particles in the physiological fluids. The particles were identified in Heterodont bivalves only, and particles from nine different Heterodont species were isolated and characterized. All phosphoprotein particles are internally cross‐linked via histidinoalanine residues. In all species over 80% of the amino acid residues in the particles are aspartic acid, phosphoserine (and/or phosphothreonine), and histidine. These amino acids are probably the only residues directly related to mineral ion binding, since all phosphoprotein particles bind mineral irrespective of the minor amino acid content, which is species dependent. In their native state the phosphoprotein particles contain large amounts of calcium, magnesium, and inorganic phosphate ions (up to 45 metal ions and 8 phosphate ions per 100 amino acid residues) and trace amounts of transition elements. Evidence for the presence of calcium phosphate complexes in the native phosphoprotein particles was obtained by observing a concomitant increase in the inorganic phosphate and calcium ion content of the particles with pH in v

ISSN:0022-104X    

DOI:10.1002/jez.1402340209

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

年代:1985

数据来源: WILEY

摘要:

AbstractWhite Leghorn chicken embryos were treated at different ages with the insecticide dicrotophos to determine the time period of maximum effect upon notochordal development. Doses of insecticide ranging from 250 μg to 2.0 mg were injected into eggs at 8, 16, 24, 32, 40, 48, 72, or 96 hr of incubation and the eggs allowed to incubate for an additional 48 hr. Dicrotophos treatment caused dorsoventral and lateral folding of the notochord, with the cervical region being most severely affected. Although there was no apparent difference in dose responsiveness at any one age, there was an obvious age relationship. Notochordal responsiveness, expressed as both the number and severity of folds, was low among the 8‐ and 16‐hr treated embryos, increased to a maximum in the 48‐hr treatment group, and then declined among the older embryos. The time of maximum effect correlates closely with the time of sheath deposition and vacuolization of the notochord, but not to initial formation of the notochord from the mesoblast or later extracellular matrix production by sclerotome cells. It is proposed that dicrotophos interferes with some aspect of sheath formation. The pressure exerted by the vacuolization upon a structurally weakened sheath is thought to cause the observed f

ISSN:0022-104X    

DOI:10.1002/jez.1402340210

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe effects of estradiol (E2) and the anti‐E2tamoxifen (tam) on forskolin (F)‐dependent meiotic arrest in hamster oocytes were investigated. The hypotheses tested were that (1) the arresting action of F is enhanced by E2and suppressed by tam and (2) the extent of heterologous metabolic coupling and the concomitant transfer of cumulus cell cAMP into the oocyte is increased and decreased by E2and tam, respectively. E2was tested with the ID25F (where ID25is the dose of F previously shown to arrest the meiosis of 25% cultured oocytes; intact, 3 μM; denuded, 10 μM) and tam was tested with the ID75F (intact, 10 μM; denuded, 100 μM).E2induced reversible dose‐dependent increases in the percent germinal vesicle (%GV; determined cytogenetically) of both intact and denuded oocytes in the presence of ID25F (intact: ID50E2= 18.0 μM; denuded: ID50E2= 17.2 μM) but, in contrast to intact oocytes, E2also exerted a dose‐dependent action on denuded oocytes in the absence of F (ID50= 26.1 μM). E2induced dose‐dependent increases in the cAMP content (determined by RIA) of intact oocytes (cAMP‐oo) and of cumulus masses (cAMP‐cm) and in the ratio of cAMP‐oo:cAMP‐cm but failed to elevate F‐stimulated cAMP in denuded oocytes. Heterologous metabolic coupling, as assessed by determination of the fraction of radiolabeled uridine marker that was transferred from the cumulus cells to the oocyte, was not significantly enhanced by E2. In contrast to denuded oocytes, tam induced dose‐dependent decreases in the %GV and cAMP content of intact oocytes in the presence of ID75F and significantly depressed heterologous metabolic coupling. While tam failed to antagonize the E2action on denuded oocytes in the presence of ID25F, in intact oocytes cultured with E2and the ID25F, the anti‐E2significantly decreased the %GV, the cAMP‐oo and cAMP‐cm, and the extent of heterologous metabolic coupling.These data show that while E2can directly arrest the maturation of denuded hamster oocytes with no associated elevation of cAMP‐oo, E2‐enhancement of arrest in intact oocytes is correlated with both elevation of cAMP within the oocyte‐cumulus complex and maintenance of heterologous metabolic coupling and

ISSN:0022-104X    

DOI:10.1002/jez.1402340211

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

年代:1985

数据来源: WILEY