摘要:

AbstractThe three‐spined stickleback (Gasterosteus aculeatus) from the St. Lawrence Estuary prefers temperatures between 9 and 12°C, but encounters temperatures ranging from 0 to 30°C. To determine whether despite this preference for cool temperatures this species retains a capacity for metabolic compensation during thermal acclimation, adult sticklebacks were acclimated to 4°C and 20°C for 6 weeks at various ration levels. When food rations were maximal, PFK, CPT, and CS activities were twofold higher in cold‐acclimated sticklebacks, particularly in the pectoral muscle. This pattern of thermal compensation is similar to that shown by eurythermal fish with considerably higher thermal optima. However, at sub‐maximal rations, warm‐acclimated sticklebacks can undergo a decline in condition which confounds the compensatory response. In the field, even though food is abundant, the condition of male sticklebacks also declined as temperatures rose. When the condition factor declined by 30%, the pectoral and axial muscle indices decreased by 40% and 55%, respectively, and the activities of glycolytic and oxidative enzymes in the pectoral and axial muscles dropped by up to 60%. Clearly, a temperature‐induced increase in metabolic rate can confound a compensatory response t

ISSN:0022-104X    

DOI:10.1002/jez.1402580302

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

年代:1991

数据来源: WILEY

摘要:

AbstractLarvae of the Pyrochroid beetleDendroides canadensisproduce hemolymph antifreeze proteins (AFPs) as an adaptation to subzero overwintering temperatures. The AFPs are produced in early autumn in response to various environmental cues (short photoperiod, low temperature, short thermoperiod). The study presented here reinforces and extends the initial finding (Horwath and Duman, '83b) that juvenile hormone is involved in stimulating production of AFPs. Dose response curves showed seasonal variation in the sensitivity of the larvae to topical application of Juvenile Hormone (JH), with late summer larvae being more sensitive than early summer ones. The time response curve for induction of AFP activity in late summer larvae demonstrated that ∼14 days are required after JH treatment for the appearance of a significant increase in AFP activity. The timing of this response to JH induction is similar to that seen previously when larvae were acclimated to a short photoperiod.Studies with cultured fat bodies showed that the fat body is a probable site of production of the AFP, and further emphasized a role for JH in AFP induction. However, stimulation of AFP production by fat body only occurred when the fat bodies were removed from larvae that had been pretreated with JH. The presence of JH in the culture medium did not stimulate fat bodies taken from larvae that had not been pre‐treated. This suggests that an additional hormone(s), or other factor, may be required to induce fat body production of A

ISSN:0022-104X    

DOI:10.1002/jez.1402580303

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe characteristics of two alkaline phosphatases (ALP) in the midgut epithelium of the silkwormBombyx mori(Insecta: Bombycidae) have been investigated further. Distributions of the soluble ALP and membrane‐bound ALP were determined quantitatively by rocket immuno‐electrophoresis with monospecific antibody against the purified soluble ALP and membrane‐bound ALP, respectively. More than 70% of soluble ALP was distributed in the posterior midgut, and the rest of it in the anterior and middle midguts. The membrane‐bound ALP existed at similar levels in all regions of midgut except the most anterior portion. Enzyme‐histochemistry of ALPs could be detected at the apical cell surface of goblet and columnar cells as shown in the previous paper on the immunohistochemistry of ALPs (Azuma, M., and M. Eguchi (1989) J. Exp. Zool.251:108–112). Furthermore, it was shown that the soluble ALP (goblet cell ALP) required Mg2+to express its maximum activity, but the membrane‐bound ALP (columnar cell ALP) was insensitive to Mg2+. By using ATP as the substrate, the purified soluble ALP possessed ATPase action with Mg2+‐ and/or HCO 3−‐dependent manner. From these results, it is concluded that the soluble ALP functions as one of the ATPase at the goblet cell surface, differing from the K+‐ATPase. This ATPase may be a possible component in generating the alkalinization of midgut lumen characteristic

ISSN:0022-104X    

DOI:10.1002/jez.1402580304

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

年代:1991

数据来源: WILEY

摘要:

AbstractChanges in the trehalose level in the tardigradeAdorybiotus coroniferwere observed during induction of, and arousal from, anhydrobiosis. A trehalose accumulation surpassing 1.6% dry weight (d.w.) in anhydrobiotic animals collected dry on their biotope was rapidly reduced on rehydration, reaching the level of active animals (0.1–0.2% d.w.) after 6 hours. Tardigrades dried while embedded in sand in the laboratory accumulated trehalose from 0.1% to 2.3% d.w. within 5–7 hours.Induction of aerobic acidosis in arousing tardigrades by CO2perfusion reversibly arrested reactivation for at least 36 hours and induced a reduction in anabolic and catabolic activities, measured as a significant reduction in trehalose degradation, and a sevenfold reduction in the rate of protein synthesis.These data support the hypotheis that trehalose generally serves a protective role in desiccationtolerant Metazoa, but indicate that tardigrades require only a moderate level for efficient protect

ISSN:0022-104X    

DOI:10.1002/jez.1402580305

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe resumption of development upon light activation ofArtemiaembryos is accompanied by an immediate drop in cyclic adenosine monophosphate (cAMP) concentration. The concentration of cyclic guanosine monophosphate (cGMP) remains unaltered, however. A similar effect is observed when the cysts are treated with H2O2, with which we demonstrated that its action mimics light activation. The demonstrated decrease in cAMP is the earliest observed intracellular event after light induction. Possible regulatory roles of cyclic nucleotides in light‐induced resumption of development are discusse

ISSN:0022-104X    

DOI:10.1002/jez.1402580306

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

年代:1991

数据来源: WILEY

摘要:

AbstractTwo experiments were performed. The first tested the hypothesis that the toad,Bufo marinus, will select a lower ambient temperature under dry environmental conditions. This behavioral response would reduce evaporative water loss and facilitate survival on land. The second experiment measured the effects of temperature on evaporative water loss. In the first experiment, toads were placed in a thermal gradient (11–40°C) for 3 days. On days 1 and 3, water‐filled dishes were placed along the temperature gradient and humid air was circulated through the chamber. On day 2, water dishes were removed, and dry air was circulated through the chamber. Body temperature (Tb) was recorded with a cloacal thermistor. Selected Tbwas approximately 8.6°C lower during the dry conditions than during the humid conditions. The behavioral hypothermia took about 6 h to develop. In the second experiment, a reduction in Tbfrom 17.7 to 12.°C reduced evaporative water loss by 42%. Consequently, behavioral hypothermia of the toad is an important adaptation to dry environmental cond

ISSN:0022-104X    

DOI:10.1002/jez.1402580307

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe morphology and adhesiveness of the presumptive mesodermal cells (PMCs) ofBufo vulgarisembryos were examined before and during gastrulation. Before the late‐blastula stage, the PMCs were in close contact with one another and were polyhedral in shape. Intercellular contacts became loose and cells were round in shape at the late‐blastula stage. At the initial stage of gastrulation, the PMCs began to form hyaline blebs. The blebbing cells appeared to crowd in one region (the bleb‐forming region [BFR]), located in the deep marginal mesoderm: The blebbing cells decreased in number and changed into filopodia‐ and lamellipodia‐forming cells with the start of the migration of PMCs at the early‐gastrula stage.Cells in the BFR and in the presumptive BFR were isolated, and adhesiveness of cells to fibronectin was examined. The results showed that the BFR cells begin to adhere to fibronectin at the early‐gastrula stage when the PMCs start to migrate along the inner surface of the blastocoelic wall.A series of changes (i.e., loosening of intercellular contacts, the formation of hyaline blebs, and the development of the ability to adhere to fibronectin) is thus evident in the PMCs before and during gastrulation. These serial changes are discussed within the context of the way in which PMCs start to migrate at the early

ISSN:0022-104X    

DOI:10.1002/jez.1402580308

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe EGF‐EGF receptor system has been widely examined for signal transduction, control of cell growth and differentiation, and in vivo physiological function and carcinogenesis. The localization of EGF receptors in vivo led to the idea that the system is operative in proliferation and differentiation of cells and tissues. However, a consensus for its distribution and function in human tissues has not yet been determined because of discrepancies in the reported results. Using a highly specific monoclonal antibody against the EGF receptor, we examined various tissues of an infant and adults as well as embryonal carcinoma. We observed restricted localization of EGF receptors in basal cells of epithelial tissues and duct cells of secretory tissues. Fibroblasts express a high level of EGF receptors when they are rapidly growing. Using the monoclonal anti‐EGF antibodies, we observed that EGF is localized to differential cells rather than to stem cells such as glandular tissues. We also observed that some cells express both EGF and the EGF receptor. All histochemical results indicated that in epidermis and various glandular tissues, EGF may be expressed in differentiating cells derived from the stem cells expressing EGF recept

ISSN:0022-104X    

DOI:10.1002/jez.1402580309

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

年代:1991

数据来源: WILEY

摘要:

AbstractCell‐lineage analysis has demonstrated that a pair of the right and left A7.6 cells of a 64‐cell embryo of the ascidianHalocynthia roretzi, descendants of A4.1 cells of an 8‐cell embryo, give rise to trunk lateral cells (TLCs). In this study, in order to investigate cellular mechanisms involved in the specification of TLCs, we have examined the expression of a TLC‐specific antigen in cleavage‐arrested embryos and in quarter partial embryos. Although cleavage arrest of embryos by treatment with cytochalasin B at early stages, prior to and including the 16‐cell stage, inhibited expression of the TLC‐specific antigen, embryos arrested at the 32‐cell stage and at later stages developed the antigen. The only blastomeres exhibiting expression of the antigen were the presumptive TLCs, as predicted by cell‐lineage assignments. When the developmental potential of quarter embryos that originated from four isolated blastomere‐pairs (a4.2, b4.2, A4.1, and B4.1 pairs) of an 8‐cell embryo was examined, the A4.1 quarter embryos, which are developmentally fated to give rise to TLCs, rarely showed evidence of expression of the antigen. Expression of the antigen was not observed in a4.2 and b4.2 quarter embryos, which are not associated with the TLC fate. By contract, expression of the antigen was detected in about a half of the B4.1 quarter embryos which are also not associated with the TLC fate. These results are discussed with reference to the relationship between TLCs

ISSN:0022-104X    

DOI:10.1002/jez.1402580310

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

年代:1991

数据来源: WILEY

摘要:

AbstractThe tails of agouti C3H/HeJmsHir mice are completely pigmented, whereas the tails of black C57BL/10JHir animals possess unpigmented tips. Genetic analysis indicates that white tail‐tipping is due to an autosomal recessive gene, with incomplete penetrance, that segregates independently from the gene for agouti with a maternal influence in the F1generation. To analyze the influence of specific coat‐color genes on the expression of tail‐spotting in mice, five congenic lines of C57BL/10JHir with different coat colors were prepared. No influence was observed on the occurrence of tail‐spotting in agouti (A/A) or dilute (d/d) mice or in F1mice from crosses between black and albino (c/c), or in F1mice from crosses between black and pink‐eyed dilution (p/p). However, the frequency of tail‐spotting was dramatically decreased in brown (b/b) mice. These results suggest that the mutant allele (b) at the brown locus is involved in determining the extent of pigmented areas in the tail tips of mice through an interaction with the tail‐

ISSN:0022-104X    

DOI:10.1002/jez.1402580311

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

年代:1991

数据来源: WILEY