摘要:

AbstractMitochondria isolated fromCrassostrea virginicagill take up14C‐choline and convert it to glycine betaine. Mitochondria from low salinity adapted oysters from both the Chesapeake Bay and Atlantic coast take up choline at similar rates, but the rate of glycine betaine synthesis is up to 4‐fold faster in the Atlantic oyster mitochondria. The choline uptake and glycine betaine synthesis rates are much higher (as much as 5‐fold, depending upon the concentration of choline) in mitochondria from high salinity adapted oysters from both populations compared to the rates found in the low salinity groups. Furthermore, the uptake and synthesis rates in the high salinity adapted mitochondria are similar between Atlantic and Bay oysters up to 5 mM choline. Above that concentration, the uptake and synthesis rates of mitochondria from the Atlantic oysters are greater than the rates in the Bay oysters (2. 5‐fold and 2‐fold, respectively). These results indicate that glycine betaine synthesis is regulated differently both between the two oyster populations and between the two acclimation salinities. © 1995 Wiley

ISSN:0022-104X    

DOI:10.1002/jez.1402710302

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

年代:1995

数据来源: WILEY

摘要:

AbstractIn order to investigate the control of the onset of postecdysial mineralization of the cuticle of the blue crab,Callinectes sapidusRathbun, EDTA‐soluble proteins and glycoproteins were analyzed at short intervals after ecdysis by SDS‐PAGE. Gels were either stained with silver, blotted to polyvinylidene difluoride membranes and stained with periodic acid/Schiff reagent (PAS), or blotted to nitrocellulose membranes and probed with a variety of lectins [particularly the mannose‐binding lectins concanavalin A(Con A) andGalanthus nivalisagglutinin (GNA)]. Pieces of cuticle were also tested for their ability to nucleate calcite in vitro. A major change occurred in the biochemistry of the cuticle between 1 and 3 hr after ecdysis. This change, which we term the post‐ecdysial cuticle alteration (PECA), involved 1) loss of a major 66 kDa glycoprotein band, 2) decrease in Con A binding by a 79 kDa protein band, 3) complete loss of PAS‐reactivity of both 66 and 79 kDa proteins, 4)gain in Con A affinity of an existing band at 73 kDa, and 5) an increase in the intrinsic ability of cell‐free cuticle pieces to mineralize, as measured by the in vitro calcite crystal nucleation assay. © 1995 Wil

ISSN:0022-104X    

DOI:10.1002/jez.1402710303

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

年代:1995

数据来源: WILEY

摘要:

AbstractThe plasma nonesterified fatty acids (NEFA) and free amino acids (AA) of exercised and rested Artic char (Salvelinus alpinus) were measured. Total nonesterified fatty acids, total saturated fatty acids and total monoenes were significantly elevated in the plasma of the exercised group. Plasma levels of palmitate (16: 0) were also significantly elevated in the exercised fish. No significant changes with exercise were observed in the total polyenes.The total plasma free amino acid and total nonessential amino acid levels were significantly elevated in the exercised group. The concentrations of glutamate, alanine, taurine, and tryptophan increased with exercise. The percent contribution of total essential amino acids to total free amino acids in the exercised fish was lower than that of the rested group.It is suggested that mobilization of specific nonesterified fatty acids and amino acids largely reflect increased oxidation of metabolic substrates by exercising red muscle. © 1995 Wiley‐Liss, I

ISSN:0022-104X    

DOI:10.1002/jez.1402710304

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

年代:1995

数据来源: WILEY

摘要:

AbstractQuantification of cholesterol in biological membranes from a variety of sources is an important step toward understanding cholesterol's roles in membranes function. We extend to biological membranes the fluorometric/enzymatic approach (cholesterol oxidase) to measures cholesterol, originally described for whole cells (Heider and Boyett [1978] J. Lipid Res.,19: 514–518; Gamble et al. [1978] J. Lipid Res.,19: 1068–1070) and serum (Huang et al. [1975] Clin Chem.,21: 1605–1608). This method has a detection limit of 0.3 μg cholesterol. As revealed by comparison with high‐performance liquid chromatography, the fluorometric/enzymatic method with biological membranes is accurate (within 4% and 8% for intestinal and hepatic plasma membranes, respectively). The assay may be completed within 3 to 4 hours and requires neither lipid extraction nor chromatographic techniques. Kinetics of the cholesterol oxidase reaction are membrane‐specific, and first‐order rate constants (k) are positively correlated with membrane order. © 1995 Wi

ISSN:0022-104X    

DOI:10.1002/jez.1402710305

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

年代:1995

数据来源: WILEY

摘要:

AbstractA study of regeneration in nymphs and adults of the Asiatic desert tick,Hyalomma asiaticum, from which forelegs had been amputated during the previous instar, revealed that regenerated Haller's sensory organs exhibited significant changes in structure. Adult regenerates possessed atavistic features in terms of the number and topography of different sensillar types. Regularity in these changes was similar to that demonstrated in regenerates ofIxodes ricinus(Leonovich and Belozerov [1992] Exp. Appl. Acarol.,15: 59–79). Nymphal regenerates, by contrast, had larval features of the parent species. An hypothesis is presented about the ontogenesis of the complete, peripheral, polymodal sensory organ as a process in which the initial cell differentiation of cells begins at different starting points. © 1995 Wiley‐Liss,

ISSN:0022-104X    

DOI:10.1002/jez.1402710306

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

年代:1995

数据来源: WILEY

摘要:

AbstractThe objectives of this study were to determine: 1) if the skin of mink might be a target organ for prolactin (PRL) by establishing if PRL binding sites (receptors) exist in the cell membranes of skin, and 2) if PRL receptor concentrations change during onset and progression of the winter fur growth cycle. Skin was collected on October 6, 1992 for characterization of PRL receptors and from July through December 1992 (N = 3 mink/month) to evaluate possible changes in PRL receptor concentrations during the fur growth cycle. PRL receptors were quantified using125I‐ oPRL in a validated radioreceptor assay. Scatchard analysis of saturation data revealed a single class of high‐affinity (Kd=5.21 × 10−11±. 84M), low capacity (Bmax= 27.03 ± 3.37 fmoles/mg) binding sites. Only oPRL (40% displacement) and to a lesser extent oGH (3% displacement) inhibited the binding of125I‐oPRL to mink skin cell membranes. No inhibition of125I‐oPRL binding to membranes occurred in the presence of a 500‐fold excess of bTSH of oLH, indicating that the receptors were hormone specific. Concentrations of125I‐oPRL receptors during the onset and development of winter fur growth (July through November) exhibited no significant change. However, following completion of the winter fur growth cycle (December 1) PRL receptor concentration was significantly higher than all preceding months. The greater binding observed at that time may reflect a change in tissue sensitivity, in preparation for growth of the summer pelage. These data suggest to us that the skin of mink is a target organ for PRL and are consistent with the hypothesis that part of the affects of PRL on fur growth occur directly at the level of the skin. © 199

ISSN:0022-104X    

DOI:10.1002/jez.1402710307

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

年代:1995

数据来源: WILEY

摘要:

AbstractChanges in the steroidogenic competence of prothoracic glands and their modulation by juvenile hormone (JH) were examined in recessive trimolters(rt)of the silkworm,Bombyx mori. Thesertmutants have four larval instars rather than the five larval instars of normal silkworms. A small peak of prothoracic gland activity was found to occur during the early stage of the last (fourth) larval instar. The activities of both the prothoracic gland and the corpora allata (CA) were, however, greatly inhibited during the third instar after the third instar larvae have been treated with an imidazole compound (KK‐42). No small peak of prothoracic gland activity was detected during the early stage of the last instar in these treated larvae. The pattern of secretion from the prothoracic gland during the third instar was not significantly affected when hydroprene was applied to the KK‐42‐treated larvae during the prolonged third instar. However, the same small peak of activity, as found in untreatedrtlarvae, was detected during the early last instar. A model was developed from the results of the present study which clearly shows how the slight fluctuations in the activity of the prothoracic gland are regulated. By treating newly ecdysed last instar larvae with KK‐42 and by the addition of 20‐hydroxyecdysone to the food supplied to these larvae, we conclude that the decrease after small increase in the ecdysteroid titers and subsequent low ecdysteroid levels during the early last larval instar play an important role in initiating the decline of the JH biosynthetic rate and in directing precocious metamorphosis. © 1995 Wiley

ISSN:0022-104X    

DOI:10.1002/jez.1402710308

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

年代:1995

数据来源: WILEY

摘要:

AbstractA study was undertaken to examine the growth and differentiation of secondary palate in a teleostean fish,Oncorhynchus kisutch. The rate, pattern, and time of synthesis of various macromolecules, which play a crucial role during palate development in higher vertebrates were examined in the developing palate of fish. A spurt in DNA synthesis during midmorphogenesis of fish palate appeared to be related to temporal regulation of palate development. RNA synthesis was high during the time of primordial appearance and increased again from day 4 post hatching (PH) to correspond with differentiation of palate. Protein synthesis remained low initially but its trend paralleled that of RNA synthesis after day 4 PH. Glycosaminoglycan synthesis increased initially with the cartilaginous growth and then with the appearance of mucous cells. An increase in collagen synthesis corresponded with the thickening of collagen layer in the basement membrance. Cyclic AMP activity increased initially prior to the increase in DNA synthesis and subsequently remained high indicating its involvement in both growth and differentiation of fish palate. These profiles of synthesis of various macromolecules in teleostean fish differ considerably from that seen in higher vertebrates. On the basis of comparative analysis, it was suggested that the timing of mesenchymal differentiation may be one of the features in determining the characteristics of palate development in different classes of vertebrates. © 1995 Wiley‐Liss, I

ISSN:0022-104X    

DOI:10.1002/jez.1402710309

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

年代:1995

数据来源: WILEY

摘要:

AbstractSubcutaneous injection of 50 mU of ovine adrenocorticotropic hormone (ACTH) stimulates an increase in plasma corticosterone inAnolis carolinensis, after 30 min equivalent to maximum levels of stress‐induced plasma corticosterone. Plasma corticosterone returned to noninjection levels by 4 h. Injection of 50 mU ACTH, daily at 1630, into femaleA. carolinensistreated with stimulatory temperature and light, effected ovarian recrudescence; however, the effect depended upon the size of the lizard. Ovarian growth in small lizards (≥2.6 g) was inhibited by ACTH. In these animals ovaries regressed in size and oviducts remained quiescent. In larger females (<2.6 g) ovarian recrudescence continued in spite of ACTH administration and the consequent stimulation of higher levels of plasma corticosterone. Oviducts were significantly heavier in this group as well, indicating that ovaries were not only larger and heavier, but were secreting estrogens as well. The results of these experiments suggest that differently sized females of this species respond to hormones of the adrenal axis differently, and perhaps to stress as well. Specifically, Whereas ACTH administration inhibits ovarian growth in small anoles as it does in other vertebrates, it appears to have no effect or to enhance ovarian growth in large femaleA. carolinensis. © 1995 Wiley‐Lis

ISSN:0022-104X    

DOI:10.1002/jez.1402710310

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

年代:1995

数据来源: WILEY

摘要:

AbstractStressful conditions inhibit reproductive function. For example, ovarian recrudescence is slower in captive and crowded lizards, and the presence of a dominant individual inhibits reproductive activity in subordinate male lizards. However, individuals so not necessarily respond to stressors equally. This study investigated the role of social stresses on reproductive function in femaleAnolis carolinensis.Groups of five females were placed with a male for 1 month in 25 × 25 × 25 cm aquaria under temperature and light conditions that stimulate reproduction (14L 32°C:10D20°C). Single females sacrificed prior to treatment with simulatory temperature and light regimens, but following acclimation to cages (as initial control, without male present) showed no ovarian recrudescence. Females placed on per cage with individual males (as final control) had significant ovarian growth yielding large yolking follicles when exposed to stimulatory temperature and light. In multi‐female groups two or fewer females per group had significant ovarian recrudescence. These females also had large yolking follicles, significant uterine growth, and always weighed 2. 7 g or more. Any female in a group weighing less than 2.7 g, regardless of the number of actively cycling females in the cage, had quiescent ovaries. Chromatic and behavioral characteristics of reproductively dominant females are not similar to those of dominant males. Dominant males are significantly more often green than brown. Females with cycling ovaries are significantly more often brown. Females which are successful in maintaining ovarian functioning even in crowded conditions acquire this morphological characteristic usually associated with subordinate status in males, which may facilitate courtship behavior. These results suggest that density‐dependent and/or psychosocial stressors inhibit reproductive cycling in this species. © 1995 Wiley

ISSN:0022-104X    

DOI:10.1002/jez.1402710311

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

年代:1995

数据来源: WILEY