摘要:

AbstractThe tetrameric lactate dehydrogenases (LDH) of vertebrates contain several different subunits that arose by gene duplication. While the A and B subunits occur in all classes of gnathostomes, the enzymes of agnathans appear to represent two stages in the evolution of vertebrate LDH. Lampreys of the family Petromyzontidae have a single enzyme classified as LDHA4, while hagfish possess both A and B subunits which form only the two homopolymers LDHA4and LDHB4. It is generally assumed that the original vertebrate LDH was an A4type, that duplication to give the B subunit occurred prior to the divergence of lampreys and hagfish, and that modern lampreys subsequently lost expression of the B gene. Lactate dehydrogenases were purified from representatives of all three lamprey families, and it was confirmed that members of the Mordaciidae and Geotriidae also possess single tetrameric LDH enzymes containing one subunit type. The kinetic properties of the lamprey LDH enzymes were compared with the LDH homopolymers of hagfish, skate, and sardine. These properties did not allow the lamprey enzymes to be unequivocally identified as either LDHA4or LDHB4. Immunochemical titration using antisera against lamprey and hagfish LDH homopolymers demonstrated that the lamprey LDH enzymes showed greater immunochemical similarity to LDHB4than to LDHA4of hagfish. It is concluded that there is little evidence for the claim that the original vertebrate LDH was an A4rather than B4type.

ISSN:0022-104X    

DOI:10.1002/jez.1402410102

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe inactivation by hydrostatic pressure of muscle‐type lactate dehydrogenase (M4‐LDH, EC 1.1.1.27; L‐lactate: NAD+oxidoreductase) homologues from five shallow‐living and six deep‐living marine teleost fishes was compared. The pressures which inactivate these enzymes are much higher than the pressures experienced by any of the species. To determine whether hydrostatic pressure effects on protein aggregation state and conformation might influence proteolysis, the inactivation of LDH by the proteases, trypsin (EC 3.4.21.4) and subtilisin (EC 3.4.4.16) was determined at atmospheric pressure and 1,000 atm pressure. At 10°C and atmospheric pressure, the enzymes of the shallow‐living fishes are inactivated four times faster by trypsin and three times faster by subtilisin than are the homologues of the deep‐living species. At 1,000 atm pressure, the homologues of shallow‐occurring fishes were inactivated 28 to 64% more than predicted from the summed effects of denaturation by 1,000 atm pressure and tryptic inactivation at atmospheric pressure. In contrast, the homologues of the deep‐sea species were inactivated by trypsin 0 to 21% more than expected. At 1,000 atm, inactivation by subtilisin increased to a similar degree for enzymes from both deep‐ and shallow‐living species. However, at 1,000 atm, the M4‐LDH homologues of the deep‐sea species lost less activity (55.3%) than did the homologues of the shallow species (86.4%). In comparisons made at 200 atm, a pressure typical of the habitat of the deep‐occurring species, tryptic inactivation of the LDH of the shallow‐livingSebastes melanopswas increased 14%. No pressure inactivation of the enzyme is evident at 200 atm. Two hundred atm pressure does not increase the tryptic inactivation of the enzymes of the two deep‐living macrourids. Increased structural stability of the enzymes of deep‐sea species may be an adaptation which prevents too rapid protein turnover, which would be energeticall

ISSN:0022-104X    

DOI:10.1002/jez.1402410103

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

年代:1987

数据来源: WILEY

摘要:

AbstractNear‐term embryos of two goodeid species (Xenotoca eiseniandGirardinichthys viviparus) have been exposed to horseradish peroxidase (HRP) and/or cationized ferritin (CF) within the ovarian cavity. The trophotaenial absorptive cells (TACs) ofX. eisenihave an apical endocytotic complex and, therefore, readily ingest tracer molecules from ambient proteinaceous liquids. Internalized solutes accumulate in large apical storage vacuoles. In double‐tracer experiments, the two proteins are mostly sorted each into separate vacuolar compartments. After exposure for several hours, reaction product of HRP can be localized in a lamellar membranous complex, which underlies the peripheral plasma membranes and communicates with the intercellular space. Some vesicles carry small portions of ferritin molecules to the basal or basolateral cell surface and eventually exteriorize their contents. No activity of an acid phosphatase (AcPase) is testable in elements of the endocytotic system before and after exposure to tracer proteins. InG. viviparus, the TACs are lacking an endocytotic apparatus. Consequently, the rate of solute movements into the cells is relatively low, and the total amounts of ingested proteins remain rather moderate, even after 24 h of continuous exposure. The binding of CF to cell surface components apparently stimulates micropinocoytotic activity. During the endocytotic process, an apical canalicular system is formed, which subsequently develops into multivesicular bodies (MVBs). These were seen to arise more numerously if the tracer medium contains CF. The effect of a sorting mechanism, resulting in differently labeled storage compartments, is not observable in the TACs ofG. viviparus. Some of the internalized ferritin is transferred to the basal and basolateral plasma membranes. The vesicular or short tubular transport vehicles seem to contain only ferritin granules, even when the marker medium is composed of CF and HRP. Clusters of CF molecules can be seen fairly regularly in the lamina lucida of the basement membrane and in erythrocytes of the underlying capillary plexus. A scheme is presented that depicts the mechanisms of protein uptake and transport of either HRP or CF by TACs of bothG. viviparusandX. eis

ISSN:0022-104X    

DOI:10.1002/jez.1402410104

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe pattern of adrenergic innervation to melanophores in split tail fins of the goby,Tridentiger obscurus, and the guppy,Lebistes reticulatus, was investigated using3H‐norepinephrine (3H‐NE) by light microscopic autoradiography. In goby fins, comparatively thick nerve bundles labeled with3H‐NE ran approximately parallel to fin rays. Thin varicose fibers which branched out from the thick bundles formed rough plexuses around individual melanophores. In guppy fins, no thick nerve bundles could be observed, but numerous thin varicose fibers ran between fin rays, forming dense nerve plexuses on individual melanophores. In setioned preparations of guppy fins, the3H‐labeled neural elements were observed to be in close contact with both surfaces of the cells (i.e., those facing the epithelial cell layer and the split side of fins), while in goby fins, the neural elements could be found only on the epithelial surface of the cells. Usually, melanophores in freshly isolated guppy fins responded with a full aggregation of pigment to isotonic KCl and maintained the state during the repetitive administration of the medium. Meanwhile, the degree of pigment‐aggregation response of goby melanophores to isotonic KCl decreased considerably during the treatment. The difference in the mode of melanophore response to K+between two fish species was considered to be due to the difference in the density of neural elements around each melanophore and, probably as a consequence, in the amount of released neurotransmiter which acts on

ISSN:0022-104X    

DOI:10.1002/jez.1402410105

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

年代:1987

数据来源: WILEY

摘要:

AbstractRomalea micropteracorpus cardiacum (RCC) contains large quantities of peptide material that is capable of eliciting strong hyperlipemic (maximum increase, 26 mg/ml; locusts) and hypertrehalosemic (maximum increase, 27 mg/ml; cockroaches) responses in test species. Calculation indicate that RCC contain more than an order of magnitude more bioactive material than eitherLocustaorPeriplanetacorpus cardiacum.R. micropteraitself shows no response to injections of synthetic locust adipokinetic hormone I (AKH I) at doses of up to 100 pmol, although injection of RCC at high concentrations (up to 1.0 gland‐equivalents) causes moderate hyperlipemia (maximum increase, 3 mg/ml). StarvedR. micropterado not exhibit the metabolic hyperlipemia observed in starvedL. migratoria, but starvation does block the RCC‐stimulated hyperlipemia. Neither fed nor starvedR. micropterashow a hypertrehalosemic response to RCC or AKH I. Reversed‐phase high‐performance liquid chromatography (RP–HPLC) shows the adipokinetic/hypertrehalosemic bioactivity to be concentrated in two peaks, which are present in the ratio of 6:1 Peak I: Peak II. Further RP–HPLC studies suggest that Peak II is identical to the adipokinetic hormone from the cricketGryllus bimaculatus, while Peak I appears to be a previously unknown n

ISSN:0022-104X    

DOI:10.1002/jez.1402410106

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe purpose of this study was to determine the localization of calmodulin in the developing mouse testis by the indirect immunoperoxidase method. In addition, the amount of calmodulin in pachytene spermatocytes, spermatids, and residual bodies isolated from the mouse testis and epididymal spermatozoa was quantitated by the adenylate cyclase activation assay and by enzyme immunoassay. The relative levels of calmodulin in the developing mouse testis and in the isolated testicular germ cells were confirmed by western transfer staining. The level of immunoreactive calmodulin was very low in the testes from immature animals. In testes from the mature mouse, calmodulin was found to be localized in spermatocytes and spermatids, but was not found in spermatogonia, Sertoli cells, and interstitial cells. By contrast, immunochemical staining of tubulin was extremely intense in Sertoli cells. Biochemical determinations also showed that pachytene spermatocytes, round spermatids, spermatozoa, and residual bodies contained 14.9μg, 15.8μg, 2.3μg and 5.2μg of calmodulin per mg of protein, respectively. Both the immunochemical and the biochemical studies revealed that levels of calmodulin were high in the spermatocytes and in the round spermatids, as compared to the level in spermatozoa. This fact strongly suggests that the large amount of calmodulin in mammalian testes may be associated primarily with meiotic divisions and/or spermatogene

ISSN:0022-104X    

DOI:10.1002/jez.1402410107

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

年代:1987

数据来源: WILEY

摘要:

AbstractFull‐grown stage VIXenopus laevisoocytes (1,200 to 1,300μm) respond to progesterone stimulation by undergoing a series of physiological and morphological changes that are referred to as meiotic maturation. Oocytes in earlier stages of oogenesis (I through V) do not undergo these changes and remain in prophase arrest when exposed to this steroid. We have found that oocytes ranging from 850 μm (stage IV) to 1,000 μm (stage V) are capable of responding to progesterone under the appropriate conditions. Oocytes ≥ 850 μm in diameter underwent germinal vesicle breakdown (GVBD) after 10–12 hr of exposure to progesterone when ouabain was added to the medium at a concentration>2.5 × 10−6M. Under this culture condition, progesterone was now able to induce a 0.3‐ to 0.4‐unit increase in the intracellular pH of stage IV–V oocytes, a 4‐ to 5‐fold increase in 40s ribosomal protein S‐6 phosphorylation, and a 2.3‐fold increase in their rate of protein synthesis. All of these physiological changes are characteristic of full‐grown stage VI oocytes undergoing meiotic maturation. In addition, we have found that oocytes ≥ 750 μm are capable of amplifying maturation promoting factor (MPF) in their cytoplasm leading to GVBD. Therefore, stage IV–VXenopusoocytes have the potential for undergoing meiotic maturation, but they are blocked at a point in prophase that appears to be alleviated by the combin

ISSN:0022-104X    

DOI:10.1002/jez.1402410108

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

年代:1987

数据来源: WILEY

摘要:

AbstractUnder ultraviolet illumination, eggs of the ascidiansCiona intestinalisandC. savignyiwere found to emit specific autonomous fluorescence in the myoplasmic region of egg cytoplasm, the vacuoles of test cells, and the follicular vesicles of follicle cells. The fluroescent egg cytoplasm formed a crescent after ooplasmic segregation and was distributed mainly to presumptive muscle cells. The fluorescence of the test cells appeared at early stages of oogenesis and remained constant during oogenesis and embryogenesis. The number of test cells within the perivitelline space ofCionaunfertilized eggs was estimated to be 1,154 ± 182 (S.D.); at the tailbud stage the number was 1,089 ± 149 (S.D.). These counts suggest that there is no proliferation of test cells from fertilization to at least the tailbud stage. The fluorescence of follicle cells also appeared at early stages of oogenesis and did not change during embryogenesis. The number of follicle cells attached to the chorions of eggs was estimated to be 63 ± 8 (S.D

ISSN:0022-104X    

DOI:10.1002/jez.1402410109

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

年代:1987

数据来源: WILEY

摘要:

AbstractCircadian levels of melatonin (M) were determined in plasma of four male white‐tailed deer sampled hourly in September for 24 h via indwelling jugular catheter. Concentrations of M, detected by the radioimmunoassay rise with the onset of darkness, peak at 1.00 h (265 pg/ml) and then quickly decline to baseline levels (60 to 70 pg/ml) maintained during the scotophase. Orally administered M (5 mg, given at 13:00 h) induced a rapid elevation of plasma M (peak 980 pg/ml at 15:00 h) followed by a decline to baseline (100 pg/ml) reached at 22:00 h. The usual midscotophase peak was abolished by exogenous M administration. Seasonal midscotophase levels of M (determined in three samples taken 45 min apart between 23:00 and 1:00 h reach maximum in December (1530 pg/ml) followed by decline to minimum (69 to 90 pg/ml) observed between May and July. The data indicate that: 1) similarly to other mammals, deer exhibit peak level of M during the dark phase; 2) 5 mg of M given orally caused a rapid elevation of M levels in blood followed by a depression of the normally present night‐time peak; and 3) midscotophase levels of M exhibit very pronounced seasonal fluctuations which might be related to yearly cycles, such as the reproduction, hair molt, and antler gro

ISSN:0022-104X    

DOI:10.1002/jez.1402410110

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

年代:1987

数据来源: WILEY

摘要:

AbstractMale farm‐reared alligators were injected with mammalian FSH, LH, hCG, prolactin, or saline. A blood sample was taken immediately prior to injection of hormone and at 24 h postinjection. Testosterone concentrations in the plasma were then determined by radioimmunoassay. Only the alligators injected with FSH showed a significant increase in plasma testosterone. In a second series of experiments male alligators were injected with ovine LH, ovine FSH, or saline and bled at 0, 2, 4, 16, and 24 h postinjection. Again, only the alligators injected with FSH showed significant increases in plasma testosterone at 16 and 24 h postinjection. Mammalian LH does not appear to stimulate testosterone secretion in male alligator

ISSN:0022-104X    

DOI:10.1002/jez.1402410111

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

年代:1987

数据来源: WILEY