摘要:

AbstractDiploidOrnithonyssus bacotifemales from an inbred laboratory colony are more variable in more external morphological characters than haploid males maintained under identical colony conditions. Prejudiced selection of characters or use of a small sample size can provide data suggesting greater variability in males. When large numbers of characters on many mite specimens are compared by F‐tests of variances, coefficients of variation, generalized variances (determinant of variance‐covariance matrices) and tests of homogeneity of variance‐covariance matrices, general phenotypic variation is greater in females. The agreement between univariate and multivariate tests allows additional confidence in the conclusion (tables

ISSN:0022-104X    

DOI:10.1002/jez.1401890302

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

年代:1974

数据来源: WILEY

摘要:

AbstractRates of T3‐ and T4‐induced metamorphosis in sexually mature and immature tiger salamander larvae (Ambystoma tigrinum) from a single local population were proportional to daily injected doses (1.0, 101, 102, or 103μg T3, or T4). Larvae were maintained at 16° C on 12L:12D photoperiod, and were fed beef liver daily. Metamorphic rates were compared as the mean number of days to achieve 50% resorption of the gills (GR50). Saline‐injected and untreated control larvae exhibited no metamorphic tendencies during the experiments. Immature larvae were induced to metamorphose with as little as 0.05 ng T3or T4/g body weight/day. Small, sexually mature larvae were less sensitive to a given dose of T4, especially at the lowest doses. Large sexually mature larvae did not differ from small larvae. It is presumed that the observed differences in sensitivity would not account solely for the observations of neoteny in this species. Metamorphosis was not influenced by sex. T3and T4are equipotent inducers of metamorphosis in immature larvae under conditions of this experiment except that some animals receiving the lowest dose of T3did not undergo metamorphosis. Larvae receiving 10−1μg T4/day did not metamorphose at 5° C, and gill resorption was slower for larvae at 10° C as compared to 16° C. GR50for larvae maintained at 21° C was not differ

ISSN:0022-104X    

DOI:10.1002/jez.1401890303

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

年代:1974

数据来源: WILEY

摘要:

AbstractAn in vitro bioassay for hyaluronidase activity has been developed based on cumulus dispersion rate. It was found that the logarithm of the time for complete cumulus dispersion and the logarithm of hyaluronidase activity are linearly related in three incubation media. These data have been used in constructing standard curves for the prediction of hyaluronidase activity from the observed time for complete cumulus dispersion. The technique is sensitive to low levels of hyaluronidase activity, is compatible with complex incubation media, and requires small volumes of test solution.

ISSN:0022-104X    

DOI:10.1002/jez.1401890304

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

年代:1974

数据来源: WILEY

摘要:

AbstractHamster sperm incubated in vitro were used to determine: (1) when hyaluronidase is released from sperm undergoing acrosome detachment, i.e., either a degenerative or normal acrosome reaction, and (2) what ultrastructural changes occur in the acrosomes of living sperm during hyaluronidase release. Sperm were incubated up to 4 hours in normal saline, Ham's F‐10, or heat pretreated blood serum. At hourly intervals, the percentages of live (motile) and acrosome reacted sperm were counted, and the supernatant from each sperm sample was assayed for hyaluronidase activity. In normal saline, sperm died during the incubation period, underwent a degenerative acrosome reaction, and gradually released hyaluronidase. In Ham's F‐10, sperm lived throughout the incubation period, did not undergo acrosome detachment, and did not release detectable amounts of hyaluronidase. In heat pretreated blood serum, sperm death did not occur during the incubation period, a surge of hyaluronidase release was complete by 1 hour of incubation, and additional hyaluronidase activity was not detected in the incubation medium between 3 and 4 hours when the normal acrosome reaction was observed. The fine structure of the acrosome was unaltered immediately after the release of hyaluronidase in serum. It was concluded that more than 50% of the mechanically extractable hamster sperm hyaluronidase was released by a factor present in serum and that this release occurred prior to and independently of the normal acrosome reaction. The partial release of hyaluronidase in serum prior to the occurrence of a normal acrosome reaction may indicate that this enzyme has a bifunctional role in reproduct

ISSN:0022-104X    

DOI:10.1002/jez.1401890305

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

年代:1974

数据来源: WILEY

摘要:

AbstractGroups of earthworms(Eisenia foetida)were injected either with 1% methyleholanthrene (MCA), 0.5% 7–12, Dimethylbenz (a) anthracene (DMBA) or 3 × 10−4mg of N‐methyl‐N‐nitrosoguanadine (NMNG), After one week, the posterior ten segments were removed from all worms. Twenty‐five days after amputation the mumber of regenerated segments were counted. A statistically significant overgrowth of segments occurred in MCA‐treated worms as compared to controls. DMBA treatment failed to alter the mumber of regenerating segments and worms treated with NMNG had statistically fewer regenerating segments than controls. An overgrowth of segments also occurred in certain groups of vehicle‐injected control worms. The groups receiving oil‐based vehicles had significantly greater growth than Hank's Balanced Salt Solution injected controls. A new theory of the mechanism of regeneration is offered to explain the seemingly p

ISSN:0022-104X    

DOI:10.1002/jez.1401890306

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

年代:1974

数据来源: WILEY

摘要:

AbstractThe experiments reported in this paper demonstrate that ependymal cells can stimulate a regenerative outgrowth when implanted into the limb of a lizard. Simple limb amputation, amputation followed by a sham operation, and amputation followed by the implantation of a cartilage tube from a tail regenerate were ineffective in causing the hind limbs ofXantusia vigilisto regenerate. However, amputation followed by the implantation of a cartilage tube containing ependyma caused regenerative outgrowths in 82% of the treated limbs. These results show that ependymal cells, in addition to initiating tail regeneration in their normal location, can when transplanted to the limb, initiate limb regeneration.

ISSN:0022-104X    

DOI:10.1002/jez.1401890307

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

年代:1974

数据来源: WILEY

摘要:

AbstractRat epididymal spermatozoa were preincubated for various times in concentrated (9.6–14.9 × 106sperm/ml) or diluted form (0.7–1.2 × 106sperm/ml) and mixed at similar concentrations with eggs recovered from superovulated immature rats. When the eggs were examined at various times after insemination, the penetration rates, the time of sperm penetration, and the fertilizing capacity of sperm were greatly reduced following the preincubation of spermatozoa in a concentrated form for 5–7.5 hours. By preincubation of sperm in diluted form, capacitation of spermatozoa was achieved in 3–5.5 hours, the penetration rates were increased, and the interval between insemination and sperm penetration was progressively reduced as the duration of preincubation increased up to 7.5 hours. It appears that the sperm concentration plays an important role for the capacitation of rat spermatozoa in vitro and the maintenance of their fertilizing

ISSN:0022-104X    

DOI:10.1002/jez.1401890308

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

年代:1974

数据来源: WILEY

摘要:

AbstractThe importance of the pigmented retinal epithelium (PRE) for photoreceptor maturation during retinal development was evaluated inRana pipiens.Retinal rudiments with or without an enveloping PRE were isolated from stage 18 embryos and allowed to develop in a non‐nutrient culture medium for up to 19 days. A set of morphological features with which to evaluate the degree of differentiation occurring in cultured material was obtained through examination of eyes of normal embryos, stages 18–25.Some photoreceptor outer segment material first appeared after 7 days in culture. The number of well‐ordered outer segment discs per receptor increased progressively with age in PRE‐covered retinas. However, photoreceptors of retinas lacking PRE contained little disc membrane material and this quickly lost proper orientation. Electroretinograms could first be elicited from PRE‐containing cultures after 7 days, but none were produced by retinas lacking a PRE. In PRE‐covered retinas a progressive differentiation of photoreceptor synaptic complexes was seen between 7–19 days; in retinas lacking a PRE, synaptic ribbons appeared after 7 days in culture, but no further maturation of the synapse was observed.The PRE itself underwent sequential differentiation and achieved the tadpole appearance after 17 days in culture. Both PRE and retina developed at the same rate in cultured material, and this rate was about one‐third that observed in eyes of embryos raised at the same temperature. These findings indicate that the PRE plays a critical role in photorecep

ISSN:0022-104X    

DOI:10.1002/jez.1401890309

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

年代:1974

数据来源: WILEY

摘要:

AbstractAntarctic nototheniid fishes have red muscle which is restricted to the pectoral girdle region of the body. The muscle masses articulate the pectoral fins whose movement propels the fish during sustained low speed cruising. Both the rate of oxygen consumption and lipid content are higher in the red muscle masses than in white muscle. Electron microscope observations reveal large numbers of lipid droplets and mitochondria arranged in close association with one another. These findings support the hypothesis that red muscle is used for long, sustained swimming motion, and that lipid, rather than glycogen, is the main energy source for this activity.

ISSN:0022-104X    

DOI:10.1002/jez.1401890310

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

年代:1974

数据来源: WILEY

摘要:

AbstractThe induced expulsion of a condensed chromosomal strand from equine sperm head pieces by the combined action of guanidine HCl (0.35M) and β‐mercaptoethanol (5 × 10−3M) is documented by scanning electron microscopy. The circular dichroism spectrum of a disordered gel state of this expelled sperm chromatin is shown and suggests that the DNA component of this chromosomal material may be in the compact ψ‐DNA state, The possible role of ‐S‐S‐reductive breakdown in the sperm chromatin expulsion mechanism during fertilizatio

ISSN:0022-104X    

DOI:10.1002/jez.1401890311

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

年代:1974

数据来源: WILEY