摘要:

AbstractThe phenotypic analysis of a new spontaneous recessive lethal mutation ofDrosophila melanogasteris described. Thelethal(2)thinmutation maps at 85.6 on chromosome 2 and produces a characteristic long, thin puparium due to an inability to shorten the larval form prior to pupariation. Histological examination of larval muscles and behavioural studies support the hypothesis that the mutation affects the striated structure of the larval muscles in late larval stages. Lethality largely occurs due to an inability to perform the movements necessary for pupation, although there is evidence for larval and possibly embryonic lethal phases.

ISSN:0192-253X    

DOI:10.1002/dvg.1020060202

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

年代:1985

数据来源: WILEY

摘要:

AbstractHeat shock uncovers the recessive forked phenotype when heterozygotes betweenf36aand wild‐type are heated during sensitive periods in pupal development. We call the phenocopy of a mutant in such a heterozygote aheterocopy. The heterocopy inf36a/+ is virtually identical to the mutant phenotype; however, bristles on different parts of the body are affected during different sensitive periods. We discuss the hypothesis that the heat shock acts by affecting expression of the wild‐type gene product corresponding to the mutant gene. The sensitive period for heterocopy induction in a specific tissue is proposed to correspond to the normal time of gene expression for the forked gene product in a particular tis

ISSN:0192-253X    

DOI:10.1002/dvg.1020060203

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

年代:1985

数据来源: WILEY

摘要:

AbstractSome of the derivatives of a cross of maize (Zea maysL.) ×Tripsacum dactyloides(L) L (2n = 72) have abnormal development leading to strange and striking morphologies. TheTripsacumchromosomes in these “tripsacoid” maize plants (withTripsacum‐like characteristics) were eliminated and the maize chromosomes were recovered through repeated backcrossing to maize. As an initial attempt to analyze the DNA alterations in tripsacoid maize, we have detected a few restriction site changes in the ribosomal DNA repeat of these plants (Hpa II, Bal I, Sst I, Mbo II, and Sph I) and a new Sph I site was mapped to the spacer region between the 26S and 17S genes. Several possible mechanisms for the generation of a new restriction site are discussed, and we propose that the transient presence ofTripsacumgenome during the backcrossing in some way induced a rapid amplification and fixation of new restriction sites in a relatively short period o

ISSN:0192-253X    

DOI:10.1002/dvg.1020060204

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

年代:1985

数据来源: WILEY

摘要:

AbstractDuring conjugation in the ciliated protozoan,Tetrahymena thermophila, a somatic MAC‐ronucleus develops from the germinal MICronucleus. Ten to 20 percent of the MIC genome is eliminated during this process. Three repetitive families have been identified which have different levels of repetition in the MIC and are eliminated to different degrees in the MAC. Some members of two of these families persist in the MAC. In this study, we have looked at these persistent sequences in the MAC of cell lines from a variety of sources including several inbed strains, two sets of caryonides, caryonidal subclones, and vegetatively aged cell clones. The results suggest that the sequences that remain in the MAC have a genetic predisposition to persist. However, epigenetic variations occur as the MAC develops so that only some of the persistent sequences are actually observed in a particular MAC. Polymorphisms may be generated if alternative processing of a single MIC segment occurs. These polymorphisms can later be resolved by phenotypic assortment during vegetative growth. These facultatively persistent sequences appear to differ from sequences previously described in this organis

ISSN:0192-253X    

DOI:10.1002/dvg.1020060205

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

年代:1985

数据来源: WILEY

摘要:

AbstractOvarian follicle cells of wild typeDrosophila melanogastersimultaneously secrete yolk polypeptides (YP1, YP2 and YP3) and vitelline membrane proteins. In order to understand the relationship between these two secretory activities, we have investigated the ultrastructure of a female sterile mutation that alters YP1 secretion and vitelline membrane deposition. Homozygousfs(1)1163females lay eggs that collapse and contain reduced quantities of YP1. Secretory granules in follicle cells contain an electron‐translucent component that is assembled into the developing vitelline membrane in both mutant and wild‐type ovaries, and an electron‐dense component that disperses after secretion in wild‐type ovaries. Mutant ovaries differ from wild‐type by (1) having larger secretory granules (2) forming clumps of the dense secretory component within the developing vitelline membrane (3) accumulating more tubules in the cortical ooplasm of vitellogenic oocytes, and (4) possessing altered yolk spheres. Mutant ovaries implanted into wild‐type hosts showed no improvement in the secretory granules and slight improvement in the vitelline membrane clumps but amelioration of the oocyte phenotypes. Since genetic evidence suggests that thefs(1)1163mutation resides in or near theYp1gene and biochemical data show that the mutation alters YP1 structure, we conclude that the ultrastructural phenotypes are due to a structurally abnormal YP1 in the mutant. The alteration in vitelline membrane structure caused by the dense clumps could account for collapsed eggs and, hence, the female sterility of

ISSN:0192-253X    

DOI:10.1002/dvg.1020060206

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

年代:1985

数据来源: WILEY

ISSN:0192-253X    

DOI:10.1002/dvg.1020060207

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

年代:1985

数据来源: WILEY

ISSN:0192-253X    

DOI:10.1002/dvg.1020060201

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

年代:1985

数据来源: WILEY