摘要:

AbstractWe have studied the organization and development of the eyeantenna imaginal disc ofDrosophila melanogaster. We examined the pattern of gynandromorph mosaicism and determined the “sturt distances” between 42 different structures of the head, antenna, and maxillary palpus. A morphogenetic map based on these sturt distances resembles more closely in size and shape that of a single thoracic segment than that of two or more adjacent segments, suggesting that the eye‐antenna disc is derived from a single embryonic body segment. We examined the morphology of the eye‐antenna discs in situ in late third‐instar larvae in serial cross sections. The two discs are connected medially by a thin cellular membrane that probably serves to join the two discs during evagination and morphogenesis of the adult head. A fate map of the imaginal disc was established by cutting the mature disc into fragments and transplanting the fragments into host larvae for metamorphosis. The peripodial layer of the eye‐antenna disc is thickened in several regions, and our data suggest that these thickened areas represent primordia of adult head structures. A comparison of the location of precursors in the imaginal disc with those of the differentiated structures of the adult head revealed the nature of the morphogenetic movements that must occur during evagination and diff

ISSN:0022-104X    

DOI:10.1002/jez.1402370302

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

年代:1986

数据来源: WILEY

摘要:

AbstractA specialized larval morph, here called the precocious larvae, is present in broods of the polyembryonic encyrtid wasp,Copidosomopsis tanytmemusCaltagirone, an egg‐larval parasite of the Mediterranean flour moth,Anagasta kuehniella(Zeller). The precocious larvae are clonally derived from the same embryonic cells that produce the normal larvae. In contrast to their normal siblings, precocious larvae have well‐developed cranial structures and mouthparts, and are extremely motile. The most unusual feature of precocous larvae, however, is their failure to attain reproductive age; they invariably die in the host hemolymph as untransformed larvae. Competition experiments with the braconidPhanerotoma flavitestaceaFischer or one of the ichneumonidsVenturia canescens(Gravenhorst) andTrathalasp. showed that precocious larvae injured or killed these competitors in 74, 98, and 97%, respectively, of the observed cases of multiple parasitism.Dissection of parasitized host larvae revealed that dead parasite larvae had different fates. Although injured and dead braconid and ichneumonid parasites were encapsulated by aggregations of host lamellocytes, precocious larvae remained unencapsulated, regardless of whether death occurred normally or, rarely, resulted from injury. It is hypothesized that successful avoidance of encapsulation by both precocious and normal larvae ofC. tanytmemusis due to either or both of the host‐produced cyst or the parasite‐produced trophic membrane.The precocious larvae fulfill the requirements for the ultimate altruist predicted by kin‐selection theory. However, because they are genetically identical to the individuals whose survival they enhance, the precocious larvae paradoxically qualify as a completely selfish caste as well. It is thus pointed out that the biological role of the precocious larvae is most appropriately evaluated as that of

ISSN:0022-104X    

DOI:10.1002/jez.1402370303

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

年代:1986

数据来源: WILEY

摘要:

AbstractHuman spermatozoa were demembranated with Triton X‐100 (TX) and injected into the mature eggs ofXenopus laevis. The nuclei of these spermatozoa decondensed and developed into pronuclei. Chromosomes did not appear in the eggs until the end of a 5‐hr incubation period. When the demembranated human spermatozoa were further treated with dithiothreitol (DTT) before they were injected into the eggs, the sperm nuclear decondensation and pronuclear development took place considerably faster than in spermatozoa treated with the detergent alone. By the end of the 5‐hr incubation period, decondensed chromatin threads or chromosome‐like structures appeared, but none of the eggs cleaved. When human spermatozoa were injected into fullgrown ovarian oocytes with intact germinal vesicle (GV) or oocytes which had matured without GV, the nuclei of a proportion of TX‐treated and all TX‐DTT‐treated sperm decondensed but showed no sign of developing into pronuclei. Sperm nuclei injected into maturing oocytes formed condensed chromatin fragments as long as the oocytes were not activated, but they transformed into pronuclei when the oocytes were stimulated with electric shock. These results indicate that the cytoplasmic factors responsible for the decondensation of human sperm nuclei are present in egg cytoplasm independent of GV‐materials. We also suggest that the factors controlling development of decondensed sperm nuclei into pronuclei are dependent

ISSN:0022-104X    

DOI:10.1002/jez.1402370304

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

年代:1986

数据来源: WILEY

摘要:

AbstractThat portion of the lateral mesoderm capable of supporting migration of the pronephric duct was mapped by transplanting secondary ducts ventral to the primary duct. Ducts transplanted more anterior than the primary duct did not migrate, whereas those transplanted more than 2 somitewidths posterior to the primary duct appeared to be delayed in the onset of migration. These transplants thus define an “active” region that extends approximately from the posterior margin of the last‐formed somite to the position of the primary duct tip, about 2 somite‐widths anterior. The anterior boundary of the active region coincides with a wave of shape change that passes in a craniocaudal direction through the lateral mesoderm. In this wave, the mesoderm changes from a two‐cell to a single‐cell layer and then back to a two‐cell layer. The duct tip is always located over the single‐cell layer. We also examined the distribution of extracellular matrix (ECM) between the mesoderm and epidermis. The posterior limit of the ECM was always posterior to the duct tip but did not extend beyond the las

ISSN:0022-104X    

DOI:10.1002/jez.1402370305

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe presence of sucrase in the yolk sac of the chick was studied biochemically and immunologically. The sucrase was partially purified from the yolk sac of hatched chicks and was compared with the sucrase purified from the small intestine. Immunodiffusion with antiserum against intestinal sucrase and characterization of the activity revealed that the two enzymes were almost identical. However, the size of the yolk sac sucrase was found to be slightly smaller than that of the intestinal enzyme by chromatography on Sephadex G‐200 and polyacrylamide gel electrophoresis. Immunocytochemical studies showed that the sucrase was located on the free surface of yolk sac endodermal cells, but the sucrase may also be present in the cytoplas

ISSN:0022-104X    

DOI:10.1002/jez.1402370306

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe present study shows that there is communication between reaggregated asynchronous cleavage stage blastomeres that regulates blastocoele formation. Individual blastomeres from eight‐cell murine embryos were transferred to empty zonae pellucidae, intact two‐cell embryos, or enucleated two‐cell embryos, and were examined over a period of 75 hours for development of cavitation. It was found that the isolated blastomeres cavitated concurrently with intact control eight‐cell embryos, while intact control two‐cell embryos cavitated 24 hours later. However, the embryos resulting from combining a two‐cell embryo and a blastomere from an eight‐cell embryo cavitated at a time in between the eight‐ and tw

ISSN:0022-104X    

DOI:10.1002/jez.1402370307

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

年代:1986

数据来源: WILEY

摘要:

AbstractExamination of major biochemical classes during the spermatogenic cycle provides a definition of the changing chemical microenvironment influencing germinal cells and also suggests temporal relationships among successive spermatogenic events. Testes from sea stars collected throughout the year were homogenized and lyophilized, and aliquots were assayed for DNA, RNA, total protein, free amino acids, total lipids, glycogen, and other carbohydrates; spermatogenic stage was determined by examination of paraffin sections. The resulting data, expressed as 1) mg/g dry mass, 2) mg/mg DNA, and 3) total content, were analyzed by weighted periodic regression and circular‐linear correlation with spermatogenic stage and time of year.With the exception of lipid/DNA, all components show a significant regression against time. DNA concentration increases during the proliferative and differentiative phases, attaining maximal values late in the differentiative phase; DNA synthesis appears to be essentially complete by the end of March. RNA concentration increases in the late aspermatogenic phase, as testicular cells begin preparations for proliferation, and remains high until late in the differentiative phase. Protein accumulates during proliferation, preceding the accumulation of DNA, but then gradually declines during differentiation. Free amino acids, simple sugars, and glycogen all increase during the aspermatogenic phase, possibly as a result of nutritive input.The observed patterns of change correlate closely with cytological variations observed within the germinal epithelium. Biochemical data thus complement existing data on the cytology of the germinal epitheliu

ISSN:0022-104X    

DOI:10.1002/jez.1402370308

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

年代:1986

数据来源: WILEY

摘要:

AbstractWe have devised a procedure for mechanically inserting intact, acrosome reacted spermatozoa under the mouse zona pellucida, and have examined the ability of sperm so inserted to fertilize the mouse oocyte. Sperm immobilized by a variety of different methods are unable to fertilize the egg, despite the fact that electron microscopy confirms that they are acrosome reacted. Control experiments show that the oocytes are capable of being fertilized by motile sperm after the microinjection procedure, and that the immobilized sperm are able to form male pronuclei after injection directly into the ctyoplasm. These results indicate that in addition to its importance for penetration of egg investments, sperm motility is required for fusion of the gametes. Alternatively, the findings suggest that the enzymatic machinery required for sperm motility is very similar to that utilized for gamete fusion, and that destruction of one is likely to lead to inactivation of the other.

ISSN:0022-104X    

DOI:10.1002/jez.1402370309

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

年代:1986

数据来源: WILEY

摘要:

AbstractLiving spermatozoa of seven mammalian species were treated with the thiol‐alkylating fluorescent labelling compound, monobromobimane (MBBR). MB‐labelling alone had no effect on sperm motility, nor on the time course or ability of golden hamster spermatozoa to undergo the acrosome reaction when capacitated in vitro. Exposure of MB‐labelled spermatozoa to ultraviolet (UV) light and excitation of the MB fluorochrome resulted in virtually immediate immobilization of the spermatozoa without affecting acrosomal status. UV exposure of unlabelled spermatozoa for up to 30 sec had no effect upon motility. Immobilization of MB‐labelled spermatozoa depended on the midpiece being irradiated, as irradiation of the head alone, or of the more distal parts of the principal piece, had little or no effect upon motility. Labelling with MB followed by immobilization of individually selected spermatozoa was most useful for detailing the course and site of occurrence of the acrosome reaction during penetration of the cumulus oophorus by golden hamster spermatozoa in vitro. In these often hyperactivated spermatozoa, precise determination of the acrosomal status could not often otherwise be made due to the difficulty in visualizing the acrosomal region of a vigorously thrashing, hyper‐activated spermatozoon. This technique should prove valuable in a variety of studies on sperm motility, capacitation and fertilization, and could also be extended to other cel

ISSN:0022-104X    

DOI:10.1002/jez.1402370310

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

年代:1986

数据来源: WILEY

摘要:

AbstractCauda epididymal spermatozoa of the golden hamster were labelled with the thiol‐alkylating reagent, monobromobimane (MB). Female hamsters underwent uterine insemination with labelled spermatozoa at laparotomy under metofane anesthesia. All 12 females examined between 5 and 54 h postinsemination yielded a total of 83/100 (83%) eggs in the process of fertilization or embryos. Under ultraviolet (UV) exposure all exhibited a fluorescent tail which, in the 4‐ and 8‐cell embryos, could be seen to be fraying or disintegrating. As cleavage progressed, labelled tail components came to be restricted among the blastomeres such that at the 4‐ and 8‐cell stage the tail could be seen in only one to three blastomeres. To study complete development and pregnancy another 12 females received uterine insemination. After recovery from anesthesia (≃ 4 h) these females were mated with a vasectomized male bearing a dominant genetic marker (black eyes) to allow unequivocal determination of paternity in the fetuses and young produced. Seven became pregnant with one female losing her pregnancy about Day 7 of gestation. Two females sacrificed on Day 13 produced 17 normal fetuses and one resorption. Four females delivered 16 young, all normal at birth and in subsequent growth and fertility. In addition, insemination of female rabbits with MB‐labelled spermatozoa yielded normal embryos (50/52 96%) from 3 does on Day 2 and (38/64 60%) from 4 does on Days 4 or 5. Two normal litters (9 bunnies) have delivered from 3 does allowed to carry to term. These results suggest MB‐labelling of the fertilizing spermatozoon does not compromise normal development and may provide a valuable tool to determine the role and fate of some sperm components (non‐nuclear) to the process of development, particularly in the preim

ISSN:0022-104X    

DOI:10.1002/jez.1402370311

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

年代:1986

数据来源: WILEY