摘要:

AbstractQuantitative comparison of pinealocyte ultrastructure in 3‐month‐old and 28‐month‐old male white‐footed mice (Peromyscus leucopus) revealed decreases both in the area of the Golgi apparatus and in the number of dense‐core vesicles. In contrast, no differences between these two age groups were noted in the areas of granular endoplasmic reticulum, vacuoles with flocculent content, lysosome‐like bodies, or motochondra. Nor were any changes between groups of mice apparent in pinealocyte nuclear or cytoplasmic areas, nuclear: cytoplasmic ratios, or the number of pinealocyte nuclei per unit area. areas of unusual, annulate lamellae‐like structures were increased in the pinealocytes of a group of 28‐month‐old mice. These observations suggest a possible age‐associated decrease in the neurosecretory‐like (but not ependymal‐like) secretory process in the pinealo

ISSN:0022-104X    

DOI:10.1002/jez.1402240202

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

年代:1982

数据来源: WILEY

摘要:

AbstractMutations bearing morphological alterations in both head and body are reported inCaenorhabditis elegans. Although most dumpy mutants so far isolated have shorter bodies with normal head form, the mutants presented in this paper have rounded heads in addition to dumpy bodies. On examination with light‐ and scanning electron microscopes, defects in organs attached to the tip of head were not detected. The mutations were mapped as alleles of thedpy‐20gene on linkage group IV. Segregation of the head abnormality from dumpy body was not detected upon examination of over 10,000 descendants from heterozygous offspring (F1), produced by crossing mutant hermaphrodites with wild‐type males. Revertants ofdpy‐20(cn142) allele were found to be almost wild‐type in both head and other body morphology, supporting the possibility that both phenotypes in these alleles have been produced by a single mutation. Genetic analyses of two other revertants are also presented in th

ISSN:0022-104X    

DOI:10.1002/jez.1402240203

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

年代:1982

数据来源: WILEY

摘要:

AbstractPrevious work has shown that the anteroposterior axis and the transverse axis of the palleal buds of some botryllid and polystyelid ascidians develop in a predictable manner, depending on the position of the buds on the parental lateral wall. In the present study, three kinds of homopleural and heteropleural bud grafts were performed to invert the presumptive bud axes. The results show that the polarity of the bud A‐P axis can be inverted with relative ease, depending on the duration of the connection of the bud with a host adult zooid. Concurrently with the reversal of this axis, the normal pattern of body asymmetry is reversed. When both the presumptive anteroposterior and transverse axes are inverted, the future zooid develops the same body asymmetry pattern as its parent. Body asymmetry conversion was induced most efficiently (22.8%) when buds were amputated and grafted with reversed proximodistal axis on the host mantle wall. The polarities of zooid body patterns are transmitted through subsequent (asexual) blastogenic generations. This work shows that the future body pattern of a bud depends on the two axial polarities of its paren

ISSN:0022-104X    

DOI:10.1002/jez.1402240204

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

年代:1982

数据来源: WILEY

摘要:

AbstractThe innervation and neuromuscular physiology of the flexor muscles in the legs ofCarcinuswere investigated using a variety of histological and electrophysiological techniques. Slow muscle fibers were found in the proximal and distal regions of the muscle; intermediate‐ and fast‐contracting fibers were found in most regions, but fast fibers predominated in the central regions. Muscle fibers were innervated by one to four excitatory axons. The extent of inhibitory innervation was not determined. The motor innervation showed significant departures from the previously described Brachyuran pattern. The results indicated the need for a thorough reexamination of the patterns of limb innervation of the crustacean tri

ISSN:0022-104X    

DOI:10.1002/jez.1402240205

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

年代:1982

数据来源: WILEY

摘要:

AbstractThree types of muscle fiber were recognized in the leg flexor muscle ofCarcinus maenason the basis of histochemical staining for the oxidative enzyme NADHD and analysis of fiber cross‐sectional area. The distribution of these fiber types within the muscle is described. The oxidative capacity and cross‐sectional area of the fiber was correlated with the fiber type determined physiologica

ISSN:0022-104X    

DOI:10.1002/jez.1402240206

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

年代:1982

数据来源: WILEY

摘要:

AbstractAntifreeze glycopeptides from the Atlantic tomcodMicrogadus tomcod), saffron cod (Eleginus gracilis), and Greenland cod (Gadus ogac) were isolated by ion exchange chromatography. Polyacrylamide gel electrophoresis revealed that fewer sizes of antifreeze glycopeptides are present in the serum ofM. tomcodandE. graciliscompared to the Antarctic nototheniid (Dissostichus mawsoni), Glycopeptide 6 fromM. tomcodandE. gracilisas well as glycopeptide 8 fromG. ogacwere sequenced and compared with known sequences of similar‐sized glycopeptides from Antarctic fishes. It was found that arginine residues in glycopeptide 6 fromE. gracilisandM. tomcodoccur at positions 15 and 18, that proline periodically replaces alanine (ala) at positions 7, 13, and 19. In contrast, none of the antifreeze glycopeptides from Antarctic fishes contain arginine. Threonine (thr) occupies positions 15 and 18 instead. Glycopeptide 8 fromG. ogacwas found to have the same sequence as glycopeptide 8 from the polar cod (Boreogadus saida). The results indicate that the repeating sequence (ala‐ala‐thr) appears to be highly conserved within polar fishes. However, greater variation in antifreeze glycopeptide structure exists within one family of northern cods (Gadidae) than within species belonging to four separate families of Antarctic f

ISSN:0022-104X    

DOI:10.1002/jez.1402240207

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

年代:1982

数据来源: WILEY

摘要:

AbstractA model has been proposed by Silva et al. ('77) to describe the manner by which Cl extrusion occurs across the gills of the eel and seawater fish in general. Aspects of the model include (1) passive distribution of Na across the gill surface, and (2) Cl extrusion dependent on Na‐K‐ATPase and thus dependent on the transport of Na.In order to test various aspects of this model, we examined, using the appropriate radiotracers, the relationship of Na and Cl efflux in the gulf to adfish,Opsanus beta. The model of Silva et al. does not apply to the toadfish because (1) Na cannot be passively distributed across the gills of the toadfish, because the transepithelial potential is several millivolts negative with respect to seawater, and (2) Cl efflux (unlike Na efflux) is not dependent on external K. Additionally, Cl efflux is dependent on the seawater Na concentration, and both Na and Cl efflux are dependent on seawater HCO3. Thus Na and Cl efflux appear to be linked in the toadfish, but not as proposed in the model suggested by Silva et

ISSN:0022-104X    

DOI:10.1002/jez.1402240208

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

年代:1982

数据来源: WILEY

摘要:

AbstractMeasurable amounts of cuticular and hepatopancreas lipids were synthesized by the scorpionParuroctonus mesaensisfrom [14C]‐labeled acetate, propionate, mevalonate, and leucine when animals were acclimated to 35°C and incubated for at least 72 hours. Labeled hydrocarbons comprised less than 1.5% of the activity in lipids, with most of the labeled hydrocarbons associated with the hepatopancreas. The hepatopancreas was also the site of most lipid synthesis in scorpions injected with [3H]H0. Incorporation of the latter into hydrocarbons relative to other lipid classes increased from 0.9% in 72 hours to 8.4% by day 10 in fed animals, with slightly higher values in starved scorpions. After 3 months, activity in cuticular hydrocarbons increased coincident with a decrease in hepatopancreas activity. Scorpions maintained on crickets (Acheta domesticus) which contain fewn‐alkanes showed a marked decrease in cuticularn‐alkanes after 10 weeks, while scorpions maintained on grasshoppers (Trimerotropis pallidipennis) which aren‐alkane‐rich showed a corresponding increase in their cuticularn‐alkanes. Scorpions fed crickets injected with labeledn‐alkanes (C25, C27, C29) incorporated these unchanged into their cuticular hydrocarbons. These results are evidence that lipid synthesis is consistent with the low metabolic rate of the scorpion and that the synthesized hydrocarbons which slowly accumulated in the cuticle were supplemented by diet‐specific branc

ISSN:0022-104X    

DOI:10.1002/jez.1402240209

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

年代:1982

数据来源: WILEY

摘要:

AbstractMouse embryos at day 9 of development were cultured for 24 to 42 h in 50% fetal calf serum and 50% Waymouth's medium containing 0.5 μg/ml insulin supplemented with various amounts of progesterone and estradiol‐17‐β. Unmodified medium contained approximately 0.2% of the normal maternal blood levels for that stage of pregnancy. The addition of 1 × 10−7M progesterone to the medium brought the level near that of the normal maternal circulating amount and appeared to be beneficial for in vitro development. After 24 h of cultivation there was a statistically significant increase in somite number, the number of embryos developing posterior limb buds, and protein accumulation over the control embryos. The addition of small amounts of estradiol‐17‐β (1 × 10−10M) increased the protein accumulation of the embryo over that of progesterone alone and seems to enhance the beneficial effects of proge

ISSN:0022-104X    

DOI:10.1002/jez.1402240210

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

年代:1982

数据来源: WILEY

摘要:

AbstractDue to the close correlation between glucose mobilization and utilization within animal tissues, in this paper, the stages of appearance of phosphorylase, glucose‐6‐phosphatase and hexokinase as well as the levels of some intermediates of glucose metabolism have been investigated duringBufo bufodevelopment. Phosphorylase first appears at stage 13 and is dominant in the neural part of the embryo, but, after this stage, increases relatively more in the nonneural one. Hexokinase appears at stage 17 and glucose‐6‐phosphatase soon after. Phosphorylase appearance at stage 13 is correlated with an increase of lactate content in the embryo; this may indicate a metabolization of hexoses. On this basis, the subsequent appearance of hexokinase and glucose‐6‐phosphatase activities also seems coherent with hexose mobilization and utilization within embryo. No direct causative factor for the changes observed

ISSN:0022-104X    

DOI:10.1002/jez.1402240211

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

年代:1982

数据来源: WILEY