摘要:

AbstractMale green anole lizards,Anolis carolinensis, were kept for 22 days on one of five temperature regimes: constant 20°C, constant 30°C, or a thermoperiod (8 h at 30°C, 16 h at 20°C) with heat onset at 0, 8, or 16 h after light onset. Groups of animals on each temperature regime were sacrificed at one of six times of day, every 4 h, for 24 h. The experiment was repeated at three different times of year: April (animals were kept on a photoperiod of LD 13:11), August (LD 13.5:10.5), and December (LD 10.5:13.5). Weight gain, testes weights, reproductive stage, and abdominal fat body weights varied with the temperature treatment and with the season. Depending on the time of day lizards received the warm temperature phase of the thermoperiod, increased heat could be stimulatory to weight gain and reproductive indexes in comparison to heat treatment at other times of day. The effect of constant temperatures on testis state and body weight gain was different from that of the thermoperiod regimes and of the natural environment on these processes.There were also diel variations in both testis DNA synthesis and fat body lipogenesis in the green anole. The photoperiod appeared to set the daily variation of DNA synthesis in the testis, whereas the thermoperiod phased the daily variation of fat body lipogene

ISSN:0022-104X    

DOI:10.1002/jez.1402260202

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

年代:1983

数据来源: WILEY

摘要:

AbstractMale Gulf killifish,Fundulus grandis, were held on various photoperiodic and thermoperiodic regimens for 2 to 4 weeks and examined with respect to body fat stores and testes weights. Groups offish kept on a 24‐hr (LD 12:12) photoperiodic regimen were provided a water temperature of 28°C except for a 4‐hr daily interval of 20°C given at one of six different times during the photocycle. Similarly, fish kept on a 48‐hr (LD 12:36) photocycle and 28–30°C were provided 4‐hr cryophases (20°C) once during each photocycle in various phase relations to the photoperiodic regimen. In addition, some groups were held at 20°C and provided 4‐hr thermophase (28–30°C) interruptions. Fat stores and gonad weights varied among the groups as a function of the time of day when the temperature interruptions occurred. The photoperiod appears to entrain a circadian rhythm of thermosensitivity, so that the coincidence of a temperature change with a thermosensitive phase alters metabolic and reproductive indices. The circadian mechanism in thermoperiodism appears similar to that involve

ISSN:0022-104X    

DOI:10.1002/jez.1402260203

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

年代:1983

数据来源: WILEY

摘要:

AbstractA calcium‐binding phosphoprotein has been isolated from the extrapallial fluid of clams where it occurs as discrete particles 30–40 nm in diameter at a concentration of 1.5–6.0 mM with respect to organic phosphate. The particles were isolated by nitration and differential centrifugation procedures. In particles obtained fromRangia cuneata, 90 mole % of the amino acid residues are aspartic acid (21.7%), serine (29.1%), histidine (34.6%), and lysine (4.6%). InMercenaria mercenariaparticles 95% of the residues are aspartic acid (20.1%), serine and threonine (26.9%), histidine (36.0%), and glycine (11.4%). The serine and threonine residues may be fully phosphorylated.Particles fromRangiacontain 1.45 moles of calcium plus magnesium and 0.24 moles of inorganic phosphate per mole of organic phosphate, and inMercenariaparticles these values are 1.29 and 0.164 respectively. Calcium and magnesium probably bind to organic phosphate and aspartic acid residues, and inorganic phosphate may bind secondarily through calcium and magnesium.InRangia, the innermost shell lamella (ISL) is a single continuous layer which forms the inner surface of the shell dorsal to the pallial attachment. It contains no crystalline mineral but is firmly attached to the mineral in the underlying calcined layer. The presence of phosphoprotein particles in the ISL was demonstrated by electron microscopy and amino acid analysis. Phosphoprotein particles are not present in the bulk shell; however, their occurrence in the extrapallial fluid and ISL coupled with their affinity for mineral ions suggests that the particles have an intermediary roll in shell deposition or dissol

ISSN:0022-104X    

DOI:10.1002/jez.1402260204

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

年代:1983

数据来源: WILEY

摘要:

AbstractThis study quantitatively analyzed the distribution and abundance of the lysosomal enzyme markers, acid phosphatase (AP), nonspecific esterase (NE), and peroxidase (PO) within and between the phagocytes (hemocytes) of two strains of the snail,Biomphalaria. Glabrata, vector host for the human blood fluke,Schistosoma mansoni. Discrete subpopulations of AP‐, NE‐, and PO‐staining cells were found in the glass‐adherent hemocyte population of both schistosome‐resistant (10‐R2) and susceptible (PR albino) strains of the snail. Furthermore, there were significant differences in the distribution and abundance of the different enzymes defining the subpopulations within and between the snail strains. Generally, 10‐R2 hemocytes have a higher enzymatic activity than PR albino cells, which, in part, can be attributed to larger NE‐only, AP‐only, and AP + NE‐staining hemocytes in the 10‐R2 strain, and a larger subpopulation of negative cells in PR albino snails. Moreover, these differences in hemocyte enzyme content are further augmented by the fact that the 10‐R2 strain has nearly twice as many circulating, glass‐adherent blood cells when compared to PR albino snails. These findings may be of additional significance, since previous studies have implicated hemocyte lysosomal enzymes in the killing of schistosome larvae in naturally resistant 10‐R2 snails, although accurate measurements of strain‐specific enzyme levels in these cells have not been conducted. The present study provides direct evidence that 10‐R2 snails naturally possess a much greater lysosomal enzyme content than do those of the PR albino strain, which, in turn, may be related to the observed resistance or susceptibility

ISSN:0022-104X    

DOI:10.1002/jez.1402260205

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

年代:1983

数据来源: WILEY

摘要:

AbstractAs a part of studies on the reproduction of laboratory maintained frogs, wild‐caughtRana pipienswere ovulated and maintained a t 22–27°C for up to 18 months. Vitellogenic oocytes were periodically staged and counted, and a “maturity index” was calculated to assess the progress of the vitellogenic cycle. The initial cycle was similar to that of wild frogs except that the first oocytes to reach stage 5 (mature eggs) usually began to degenerate before later starting oocytes became mature. In addition, a second cycle began before the first was completed. After more than 1 year at room temperature, abnormal cycles were common. Ovaries of such animals contained very few mature eggs. Many of their oocytes were in early stages of vitellogenesis or, if pigmented, had begun to degenerate. These deficiencies were partially corrected in females placed in 4°C for 4–6 weeks. The average number of mature eggs increased 15‐fold and ovary weights more than doubled. Oviduct weights almost doubled. Although the rates of cooling, photoperiod, and nutritional status could be important influences, the results imply that cold treatment alone increases estrogen secretion. We suggest that low estrogen secretion may account for the reproductive deficiencies seen inR. pipienscultured at roo

ISSN:0022-104X    

DOI:10.1002/jez.1402260206

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

年代:1983

数据来源: WILEY

摘要:

AbstractIn an attempt to impede the inductive communications between the apical ectodermal ridge (AER) of the wing bud and its underlying mesoderm, we lined the apex of the trypsin‐isolated ectodermal hull of the chick limb bud with stage 23 or 25 quail back‐skin ectoderm or nonridge limb ectoderm. We then inserted a stage 21 chick wing‐bud mesodermal core into this hull with its apex against the putative barrier. Reciprocally, quail limb components were united with a barrier of chick nonridge limb ectoderm. Such composites, grafted to host chick embryos, usually formed wings comparable in perfection to those obtained when ectodermal and mesodermal elements are recombined and grafted without a lining ectodermal layer. The reestablishment of a normal vascular pattern in the composite limbs was delayed compared to controls, suggesting that the interposed layer of cells interferes, initially at least, with the communication between the AER and subjacent mesoderm, and that this interference delays the development of, particularly, the veinous channels draining the limb bud.Histological study of Feulgen‐stained preparations showed that the interposed ectodermal cells begin moving into the overlying ectoderm as early as 6 h after grafting, populating the AER and adjoining ectoderm. By 48–50 h the ridge and adjacent ectoderm are composed entirely, or almost so, of cells of the interposed type. The original ridge cells are apparently displaced into the amniotic fluid, and the cells invading from below take over the functional attributes of the AER, inducing the growth of terminal l

ISSN:0022-104X    

DOI:10.1002/jez.1402260207

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe temporal coordination of histone and DNA synthesis in mouse eggs and preimplantation embryos were examined. In unfertilized mouse eggs arrested at metaphase II, histone synthesis was observed, but at lower rates than previously reported for fertilized zygotes. Cytosine arabinoside, an inhibitor of DNA synthesis, was used to study the relationship between DNA and histone synthesis during cleavage stages of mouse development. Cytosine arabinoside (50 μM) inhibited by 90% the incorporation of [3H]thymidine into DNA by two‐cell embryos and blastocysts. At this concentration, cytosine arabinoside inhibited incorporation of [3H] lysine into blastocyst histones by only 30% and had no effect at the two‐cell stage. These results are interpreted to show that DNA synthesis and histone synthesis are not coordinated temporally during early development of the mouse, but may become more so as development proc

ISSN:0022-104X    

DOI:10.1002/jez.1402260208

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

年代:1983

数据来源: WILEY

摘要:

AbstractMelanophores of wild‐type and periodic albino mutants ofXenopus laeviswere successfully cultured in vitro. They proliferated in the presence of α‐melanocyte‐stimulating hormone (α‐MSH) or cyclic adenosine monophosphate (cAMP) at a doubling time of 8–10 days. These proliferating melanophores retained their phenotypes, ability to synthesize melanin, and melanin‐dispersing response to MSH stimulation. Neither depigmentation nor selective cell death of periodic albino melanophores was observed for at least 4 months during th

ISSN:0022-104X    

DOI:10.1002/jez.1402260209

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe blastoderm of the medaka embryo contracts rhythmically during epiboly; the time for a contractile wave to move over the entire blastoderm is about one minute at 25°C. The primary objective of this study was to determine which layer(s) of the blastoderm participate in these contractions. We watched changes in the shape of wounds in the enveloping layer (a simple epithelium that covers the blastoderm), contractions of embryos in which the segmentation cavity had been inflated with saline media, and the movement of embryos from which the enveloping layer had been surgically removed. We conclude that both the enveloping layer and the underlying yolk syncytial layer participate in the contractions. The contractions were inhibited by cytochalasin B (5 or 10 μg/ml), by introducing 100 mM K+into the segmentation cavity, and by bubbling carbon dioxide through the bathing medium. Elevating the [K+] in the external medium had no apparent effect on the contraction nor did adding the cholinergic antagonists, atropine and d‐tubocurarine, to either the bathing medium or the segmentation cavity. We conclude that microfilaments are involved in the contractions, and we discuss the possibilities that changes in the membrane potential of the cells may precede or accompany the contractions and that the contractile waves may be preceded by signals propagated through gap junctions. We conclude, furthermore, that acetylcholine has no role in either the initiation or the propagation of the contractile waves. An improved method for dechorionating medaka embryos, based on previously published protocols, is described. With this method, embryos can be dechorionated in 3 hours and can be obtained as young as blastu

ISSN:0022-104X    

DOI:10.1002/jez.1402260210

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

年代:1983

数据来源: WILEY

摘要:

AbstractEnergy‐dispersive x‐ray microanalysis was used to analyze changes in the subcellular distributions of Na, Mg, P, S, Cl, K, and Ca associated with the acrosome reaction of sea urchin sperm. Within 5 sec after induction of the acrosome reaction, nuclear Na and mitochondrial Ca increased and nuclear and mitochondrial K decreased. Uptake of mitochondrial P was detected after several minutes, and increases in nuclear Mg were detected only after 5–10 min of incubation following induction of the reaction. The results suggest that sudden permeability changes in the sperm plasma membrane are associated with the acrosome reaction, but that complete breakdown of membrane and cell function does not occur for several mi

ISSN:0022-104X    

DOI:10.1002/jez.1402260211

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

年代:1983

数据来源: WILEY