摘要:

AbstractThe relationships between the size of a cell and the number of some compound cortical structures (cirri and membranelles) were studied using cells of a hypotrich ciliateParaurostyla weisseistained with protargol. The length of cells was measured, the number of AZM membranelles, frontal, transverse and left marginal cirri were counted in cells from growing populations and in miniaturized cells obtained by starvation or repetitive regeneration.Changes in the number of cortical elements occur mainly through replacement of the whole ciliature during a morphogenetic process (division, reorganization, regeneration). In growing populations small postdividers and large predividers do not differ with respect to the number of membranelles and cirri despite the differences in size. In miniaturized cells the number of cortical elements formed decreases and is directly correlated with the length of the cell showing a proportional regulation in accordance to the cell size. Different modes of pattern regulation are discussed.

ISSN:0022-104X    

DOI:10.1002/jez.1401950102

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

年代:1976

数据来源: WILEY

摘要:

AbstractWild‐type third instar larvae ofDrosophila melanogasterfed a casein‐sucrose synthetic diet supplemented with phosphatidylcholine (4 mg/ml) possessed 33% more tissue lipid and a modified fatty acid profile compared to larvae fed a fat free‐sucrose diet. The rates of lipid synthesis and pentose shunt activity were 2.1 and 2.2 times greater respectively in larvae fed the fat free‐sucrose diet than in fat‐sucrose fed animals. The tissue concentrations of acetyl‐CoA and acytl‐CoA were 80 and 61% higher respectively, CoA 49% lower, and the NADPH/NADP+ratio greater in fat‐sucrose fed larvae than in larvae fed a fat free‐sucrose diet. Thus, larvae effectively utilized dietary lipid for lipid synthesis and as a supplementary energy source to carbohydrate. Larval oxidative NADP‐enzyme tissue levels were dependent upon the interaction of at least three regulatory systems. Dietary carbohydrate induced high tissue levels of glucose‐6‐phosphate dehydrogenase (EC 1.1.1.49) and 6‐phospho‐gluconate dehydrogenase (EC 1.1.1.43), ostensibly via a glycolytic derivative. High tissue levels of malic enzyme (EC 1.1.1.40) and NADP‐isocitrate dehydrogenase (EC 1.1.1.42) were induced by an acetate derivative postulated to be formed by the Krebs cycle. In contrast, a fatty acid derivative, presumably a product of β‐oxidation, repressed the tissue levels of all four oxidative NADP‐enzymes in larvae. A model of induction and repression regulatory systems that are dependent on re

ISSN:0022-104X    

DOI:10.1002/jez.1401950103

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

年代:1976

数据来源: WILEY

摘要:

AbstractThe volume of the rhabdom in compound eyes of mosquitoes decreases upon illumination. This decrease is probably mediated by a bleaching of the visual pigment, since blue light is most effective in producing the change and red light is least effective. The reduction in rhabdom volume appears to be a result of rhabdomal membrane loss to coated vesicles and multivesicular bodies. These organelles were seen most frequently in blue adapted eyes, markedly less frequently in red adapted eyes, and only rarely in dark adapted eyes.

ISSN:0022-104X    

DOI:10.1002/jez.1401950104

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

年代:1976

数据来源: WILEY

摘要:

AbstractThe amino acid composition has been determined for two of the five subunits of the crayfish lipovitellin. In addition the molecular weight of each subunit has also been ascertained. Most importantly it is demonstrated that following in vitro incubation radioactive amino acids are incorporated into each of three purified subunits. These data strongly support the suggestion that the vitellogenic ovary of the crayfish is capable of in situ synthesis of lipovitellin.

ISSN:0022-104X    

DOI:10.1002/jez.1401950105

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

年代:1976

数据来源: WILEY

摘要:

AbstractPlanarian neoblasts, the only cell type in this organism endowed with mitotic power, decrease in density as total body volume, total cell number, and length increase. Studies on mitosis show that the neoblast mitotic rate is a function of body length, being lower as the organism increases in length. The cephalo‐caudal distribution of mitotic figures in animals of different sizes shows a change towards a more even distribution of mitosis jointly with a mitotic increase in the caudal regions as length increases. However, in the sagittal and dorso‐ventral axes, the distribution of mitosis is always nonuniform, probably due to the uneven distribution of parenchymal tissue along them.The pharynx of animals in all size groups examined shows no mitotic figures except some near its base. This may suggest for this organ a proximal type of growth with some cell migration.Feeding elicits a very rapid increase in mitosis which lasts for almost a week, whereas long periods of starvation do not cause a significant increase or decrease in the basal mitotic rate. All these results stress the need of looking at the planarian neoblast mainly as a stem or replacement cell of most differentiated cell types and not as a mere “regeneration cell.” The implications of the results obtained for the mechanisms of growth and shrinkage are di

ISSN:0022-104X    

DOI:10.1002/jez.1401950106

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

年代:1976

数据来源: WILEY

摘要:

AbstractIn planarian regeneration mitosis occurs in both anterior and posterior blastemas. The mitotic increase is visible as early as one hour after amputation, reaches a rapid first maximum at 5–12 hours, a relative minimum at 24–30 hours, and a higher and longer second maximum at two to four days depending on body size, level of amputation, and on whether blastema is anterior or posterior. The spatial dynamics of mitosis show a rapid and high mitotic increase in the distal regions but not in the proximal regions. Later, the proliferative zone shifts in sucessive mitotic waves to more proximal regions, paralleling the formation of the head ganglia and nerve cords.These results do not agree with theories of blastema formation through neoblast migration or through cell dedifferentiation, in as much as the local proliferation of neoblasts encountered is sufficiently high and early to account for the number of blastema cells found during period of regeneration. Therefore, we suggest that blastema formation during planarian regeneration occurs mainly through local neoblast proliferation.These results and the data obtained on regeneration rates enable us to suggest that nervous tissue may be one of the factors responsible for the differing mitotic increases found. Since neoblasts are the only planarian cells capable of mitosis, we suggest that neoblast proliferation could be under nervous tissue control through some stimulatory substance (s) released from the nerve terminals. The implications of this hypothesis for the maintenance of axial polarity are also discus

ISSN:0022-104X    

DOI:10.1002/jez.1401950107

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

年代:1976

数据来源: WILEY

摘要:

AbstractThe accessory gland of the male cricket,Acheta domesticus, is a polytubular structure which produces a complex mixture of proteins used in the formation of the spermatophore. The synthetic capacity of individual accessory gland tubules has been analysed by micro‐scale SDS‐polyacrylamide gel electrophoresis. For the large and intermediate size tubules (approximately 300 in number), between 29 and 32 distinct protein synthetic patterns have been detected for individual tubules, with most of such patterns assignable to tubules at specific locations in the gland.Analysis of labelled nascent peptide distribution on polysomes confirms regional heterogeneity in protein synthetic capacity and also demonstrates a corresponding regionality in the distribution of active messenger RNAs. Other experiments indicate that tubules with identical products can have different extents of protein labelling, suggesting that a capacity to regulate either precursor uptake or protein synthetic rate exists at the level of the individual tub

ISSN:0022-104X    

DOI:10.1002/jez.1401950108

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

年代:1976

数据来源: WILEY

摘要:

AbstractCleavage of fish (Oryzias latipes) eggs was induced by injection of heterologous (sea urchinHemicentrotus pulcherrimusand oysterCrassostrea gigas) sperm microtubules. Cleavage initiating (CI) activity of microtubules was higher in 3% PVP suspension than in 6% BSA, and not affected significantly by the concentration of microtubules themselves. The CI activity of microtubules suspended in 3% PVP was comparatively stable in the frozen state. Heat‐treatment at more than 55°C resulted in the loss of most or all of their CI activity. Such activity was observed in side‐by‐side aggregates of tubulin linear polymers of sea urchin (Hemicentrotus pulcherrimus) spermatozoa but not in dispersed linear polymers or tubulin dimers. Microtubules with CI activity seem to participate in initiating cleavage as astral centers, or a “seed” for polymerization of ooplasmic tubulins in acti

ISSN:0022-104X    

DOI:10.1002/jez.1401950109

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

年代:1976

数据来源: WILEY

摘要:

AbstractFollowing immunization with human IgG three species of anuran amphibians,Xenopus borealis,Xenopus cliviiandXenopus muelleri, were found to synthesize two molecular populations of antibodies associated with 19S and 7S fractions of the sera. These antibodies, designated high (HMW) and low (LMW) molecular weight immunoglobulins, were isolated and their constituent heavy (H) and light (L) polypeptide chains separated following extensive reduction and alkylation in a relative yield of about 70% and 30% respectively. The molecular weights of H and L chains of the three species were determined by SDS‐acrylamide gel electrophoresis. The L chains from both molecules in the three species had a molecular weight of about 26,000. The H chains of the HMW and LMW immunoglobulins had a molecular weigh of about 73,000 and 63,000 respectively. The two populations of immuno globulins were analysed in immunodiffusion plates using rabbit antisera to LMW immunoglobulins. The HMW immunoglobulins were found to be antigenically deficient with respect to LMW immunoglobulins. From these results it was judged that the two populations in each species belonged to distinct classes. The antigenicities of the LMW and HMW immunoglobulins of different species within the genusXenopuswere compare

ISSN:0022-104X    

DOI:10.1002/jez.1401950110

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

年代:1976

数据来源: WILEY

摘要:

AbstractThe influence of the wound epithelium on the cellular events preceding blastema formation was examined by comparing dedifferentiation, DNA labeling indices, and mitotic indices of the distal mesodermal tissues in control regenerating newt forelimbs and in amputated forelimbs covered with a flap of full thickness skin. Three kinds of results were seen following the skin‐flap graft operations. Epidermal migration across the amputation surface was completely inhibited in 22% (8) of the cases and these limbs repaired the amputation wound but did not form regeneration blastemas. In 11% (4) of the experimental limbs, essentially normal wound epithelia displaced the skin flaps and the limb stumps formed blastemas and regenerated. The majority of the skin grafts (67%) exhibited epidermal migration restricted to the free edges of the flaps. These limbs formed eccentric blastemas on the ventral side of the limb next to the dermis‐free epidermis and regenerated laterally in that direction.Despite these differences caused by the skin‐flap grafts, the experimental limbs all resembled control regenerating limbs one week after the operations in the dedifferentiated appearance of the distal mesodermal tissues and in the DNA labeling and mitotic indices of the mesodermal cells. While the labeling and mitotic indices increased by two weeks after the operations in limbs with wound epithelia, these parameters decreased in limbs with complete skin grafts which lacked dermis‐free epidermis. When labeling and mitotic indices were determined two weeks after the operations in the limbs with partial skin flaps, these values had increased over those a week earlier in the areas next to the lateral wound epithelia, but decreased in the opposite areas contacting the complete skin of the graft.These results suggest that the epidermal influence in promoting blastema formation may serve to keep the dedifferentiating cells in the cell cycle and prevent their early redifferen

ISSN:0022-104X    

DOI:10.1002/jez.1401950111

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

年代:1976

数据来源: WILEY