bluuebunny/crossref_metadata_2025_split huggingface dataset:
Parallels of genomic organization and of endogenous retrovirus organization in cat and man
Authors: O'Brien Stephen J. , Reeves Roger H. , Simonson Janice M. , Eichelberger Mary A. , Nash William G. 
Published: May 2005

AbstractA combination of technical advances (most notably heterologous cell fusion, high resolution G‐banding, and molecular cloning) has contributed to an accelerated advance in genetic analysis in mammals. The present human genetic map contains over 400 gene assignments and the map is growing rapidly as each new molecular clone or immunological reagent is developed. In our laboratory, we have developed a panel of rodent X human somatic cell hybrids that have been utilized in chromosome assignment of several classes of genes including oncogenes (ras, raf) and endogenous human retroviral sequences (ERVL, 2, etc). Using similar techniques, a biochemical genetic map of the domestic cat has been derived. The cat has 19 chromosome pairs and, to date, 40 genes have been mapped to 16 linkage or syntenic groups. Comparison of linkage relationships between homologous enzymes has revealed a striking conversation of chromosomal linkage association between cat and man. A comparison of syntenically homologous, highly extended high resoultion G‐banded chromosomes between the two mammalian families revealed that 20–25%, by length, of the human karyotype can be precisely aligned (chromomere to chromomere) between cats and man despite the evolutionary divergence of the species nearly 80 million years ago.Moderately repetitive families of retrovirus‐related DNAs exist within the feline and the human genomes. We have isolated molecular clones of several members of the feline RD‐114 retrovirus family from a genomic library of normal cat cellular DNA. The endogenous sequences analyzed were similar to each other in that they were colinear with RD‐114 proviral DNA, were bounded by long terminal redundancies, and conserved many restriction sites in the gag and pol regions. Several sequences were apparently deleted, relative to the previously characterized inducible RD‐114 genome. The env regions of a number of endogenous RD‐114 sequences examined were substantially deleted or diverged; a subset of these sequences contained information at the position of the env region that was not homologous to inducible RD‐114. The RD‐114 virogenes were dispersed to several cat chrosomes that were localized using a panel of rodent x cat somatic cell hybrids. A comparison of the genetic properties of endogenous human retroviral sequences revealed several similarities between the human and feline status of endogenous retroviruses.
Complex brain and behavioral functions disrupted by mutations in Drosophila
Authors: Hall Jeffrey C. 
Published: May 2005

AbstractReproductive behavior in Drosophila involves a complex series of actions which is perturbed by many different kinds of mutations. Some of the most interesting courtship variants are those originally isolated with respect to disruptions of general learning and memory. Several types of genetically abnormal males have their “conditioned courtship” blocked or attenuated by the learning and memory mutations, some of which, in turn, are known to cause abnormal levels of specific monoamines or cyclic nucleotides. Recent studies of the defective courtship performed by the conditioning mutants involve “mosaic focusing” of the neural tissues affected by the behavioral/biochemical mutations. These experiments address the question of whether there are localized influences of the relevant genetic loci in their control of conditioned courtship, in spite of the fact that the protein products of the genes have a broad tissue distribution. Female responses to courting Drosophila males can also be dependent on the former's prior experiences. This pertains to enhancing aftereffects of prestimulation by the courtship song that is produced by a male; and the same learning and memory mutations, expressed in females, impinge on the normal aftereffects. One element of acoustical communication in courtship is a rhythmic oscillation in a particular component of the song. This short‐term behavioral rhythm is altered in males expressing circadian rhythm mutations. To investigate the neural and cellular mechanisms by which these genes act, a mosaic analysis has been initiated on the ganglia affected by a clock mutation in its disruption of the courtship rhythm and of circadian cycles. A molecular isolation and identification of the normal form of this genecalled period—has also begun, in order to probe the locus's structure and function in detail. Such an investigation will include a comparison of the mosaic results with a direct determination of the various tissues in which the gene's product is expressed. In addition, interspecific transfers of the purified period gene will augment the current studies of species‐specific features of the rhythmic courtship songs.
Molecular polymorphism: How much is there and why is there so much?
Authors: Ayala Francisco J. 
Published: May 2005

AbstractThe evidence for genetic variation can be traced to Mendel's experiments: The discovery of the laws of heredity was made possible by the expression of segregating alleles. Since that time, the study of genetic variation in natural populations has been characterized by a gradual discovery of ever‐increasing amounts of genetic variation. In the early decades of this century geneticists thought that an individual is homozygous at most gene loci and that individuals of the same species are genetically almost identical. Recent discoveries suggest that, at least in outcrossing organisms, the DNA sequences inherited one from each parent are likely to be different for nearly every gene locus in every individual; ie, that every individual may be heterozygous at most, if not all, gene loci. But the efforts to obtain precise estimates of genetic variation have been thwarted for various reasons.
The interaction of bromodeoxyuridine with ribosomal RNA cistron redundancy in Drosophila
Authors: Krider Hallie M. , Levine Bryan I. 
Published: May 2005

AbstractWe demonstrate that Bromodeoxyuridine (BrdU)‐induced reductions of the ribosomal RNA cistrons (rDNAs) are observed in Drosophila virilis, and Drosophila busckii, but not in karyotypically normal adults or larvae of Drosophila melanogaster. However, BrdU does reduce the redundancy of the rDNAs of XO D melanogaster males, in which a compensatory response is evidenced in the untreated XO sibling controls. These results suggest that the BrdU‐rDNA interaction is specific to events which modulate rDNA redundancy. Further, both thymidine and deoxycytidine “reverse” the BrdU effect in D virilis, an observation which is inconsistent with current working hypotheses describing the mechanisms of BrdUs effects.
Cell specificity in the developmental regulation of acid hydrolases by temporal genes
Authors: Paigen Kenneth , Jakubowski Audrey 
Published: May 2005

AbstractThe cell specificity of expression of three distinct trans acting temporal gene systems determining the developmental control of α‐galactosidase, β‐galactosidase and β‐glucuronidase was tested in mouse liver. For α‐galactosidase and β‐galactosidase, expression was limited to hepatocytes; no effect was seen in nonhepatocytes. For β‐glucuronidase the data suggest that expression of the Gus‐t temporal locus is also limited to hepatocytes, and that the smaller enzyme reduction seen in nonhepatocytes of some strains is due to a separate systemic regulatory locus that is also present in the [Gus] gene complex. We conclude that the temporal gene‐determined timing mechanisms initiating switches in rates of enzyme synthesis are intrinsic to the cells themselves and are not communicated to adjacent cells. This conclusion applies to the temporal locus for β‐glucuronidase that is proximate to its structural gene as well as those for α‐galactosidase and β‐galactosidase that are distant from the structural genes that they regulate.
Pupation in drosophila melanogaster and the effect of the Lethalcryptocephal mutation
Authors: Chadfield Colin G. , Sparrow John C. 
Published: May 2005

AbstractThe events of normal pupation in Drosophila melanogaster are described in detail from the time of gas bubble expulsion until the completion of pupation with the eversion of the cephalic complex. The importance of the internal gas bubble for posterior movement of the prepupa is examined and its relation to the expulsion of the larval mouthparts and the creation of the anterior gas space described.The phenotype of lethalcryptocephal homozygotes, which characteristically cannot evert their heads, is re‐examined. Observations of larval lethality and multiple mouthparts in 1 (2)crc larvae and pupae are described. These new aspects of the mutant phenotype are discussed with respect to the abnormalities of pupation. Fristrom's hypothesis that the basic mutant lesion is an increased stiffness of the pupal cuticle due to an excess chitin deposition is re‐evaluated.
Expression of adenylate cyclase and phosphodiesterase in development of temperature‐sensitive mutants with impaired metabolism of cAMP in drosophila melanogaster
Authors: Savvateeva Elena V. , Peresleny Irina V. , Ivanushina Valerya , Korochkin Leonid I. 
Published: May 2005

AbstractThe mode of the developmental expression of adenylate cyclase (AC) and phosphodiesterase (PDE) in D melanogaster indicates that PDE plays the major role in the maintenance of a certain level of cAMP in postembryonic development, while both enzymes function in concert in imago. The ts‐mutants ts155 and ts622, characterized upon their isolation as having an increased cAMP content and normal PDE activity, manifest high levels of AC activity from the third day of imago life. The levels of PDE activity characteristic for adult mutants with altered enzyme activity (low in ts66 and ts980, high in ts398) are manifested in ts980 from larval instar II, and from the larval instar III in ts398 and ts66. Data on the dependence of PDE activity in adults upon temperature of incubation, being in agreement with the expectations for a ts‐mutation in a gene coding for a form of PDE in case of ts66, suggest that ts398 affects not the enzyme‐coding gene but rather one for an activator protein. The fact that in ts398 (the polyphasic ts‐lethal mapping to 1‐38.9) 1) AC activity is somewhat higher than normal at 22°C and is readily activated at 29°C, 2) activity of PDE‐I assayed in heat‐pretreated homogenates is higher than normal, 3) that boiled extracts of ts398 are potent activators of the wild type and of its own PDE‐I indicates that it is a mutation affecting calmodulin, which is known to be stable at boiling and capable of activating both AC and PDE‐I. Data on Ca2+ and EGTA effects suggest that the mutation presumably increases Ca2+‐binding activity of calmodulin, ts980 and ts622, in which ts‐lethality could be produced only by certain doses of haloperidol and triftazine, appear to be lethal in compounds with ts398, thus indicating that these mutations could affect the same calmodulin‐controlling gene.
The axolotl mutants
Authors: Armstrong John B. 
Published: May 2005

AbstractThe Mexican axolotl (Ambystoma mexicanum) has enjoyed wide use in experimental embryology for over 100 yr. Its usefulness has been extended into the area of developmental genetics largely due to the contributions of R. Briggs and R. R. Humphrey at Indiana University. To date over 30 mutants have been described, almost all of which affect development. Some of these have been discovered in inbred strains while others have been uncovered in recent Mexican imports. These mutants can be subdivided into several major classes. Maternal effect mutations lead to deficiencies in informational, structural, or metabolic components of the egg essential to early development prior to the time at which the embryo's own genome becomes active. In contrast, the developmental lethals affect later stages in embryogenesis when both morphogenetic and biochemical events are determined exclusively by the genotype of the embryo. Most lead to death at about feeding stage. Some, the cell lethals, are believed to suffer from fundamental metabolic defects affecting all parts of the embryo. Others affect the development of specific organs or tissues. The developmental nonlethals also affect specific systems, but ones that are not essential to survival. Some affect the development and survival of pigment cells and these, along with isozyme variants, are useful as markers in developmental experiments.A number of the mutants have been studied in detail, but others scarcely at all. The purpose of this review is to bring them to the attention of all developmental biologists in the hope that their potential will be even more widely recognized.
A mutation affecting larval muscle development in Drosophila melanogaster
Authors: Ball Elizabeth , Ball Sarah P. , Sparrow John C. 
Published: May 2005

AbstractThe phenotypic analysis of a new spontaneous recessive lethal mutation of Drosophila melanogaster is described. The lethal(2)thin mutation 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.
Yolk polypeptide secretion and vitelline membrane deposition in a female sterile Drosophila mutant
Authors: Giorgi Franco , Postlethwait John H. 
Published: May 2005

AbstractOvarian follicle cells of wild type Drosophila melanogaster simultaneously 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. Homozygous fs(1)1163 females 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 the fs(1)1163 mutation resides in or near the Yp1 gene 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 the mutant.
Analysis of molting and metamorphosis in the ecdysteroid‐deficient mutant L(3)3DTS of Drosophila melanogaster
Authors: Holden J. J. A. , Walker V. K. , Maroy P. , Watson K. L. , White B. N. , Gausz J. 
Published: May 2005

AbstractThe dominant temperature‐sensitive mutation L(3)3DTS (DTS‐3) in Drosophila melanogaster causes lethality of heterozygotes during the third larval instar at the restrictive temperature (29°C). Temperature‐shift experiments revealed two distinct temperature‐sensitive periods, with lethal phases during the third larval instar (which may persist for 4 weeks) and during the late pupal stage. At 29°C mutant imaginal discs are unable to evert in situ, but did evert normally if cultured in the presence of exogenous ecdysterone or when implanted into wild‐type larval hosts. The only morphologically abnormal tissue present in the lethal larvae is the ring gland, the prothoracic gland being greatly hypertrophied in third instar DTS‐3 larvae. Injection of a single wild‐type ring gland rescued these mutant larvae, indicating that the mutant gland is functionally, as well as morphologically, abnormal. Finally, the mutant larvae were shown to have less than 10% of the wild‐type ecdysteroid levels. These results are all consistent with a proposed lesion in ecdysteroid hormone production in DTS‐3 larvae. A comparison with the phenotypes of other “ecdysone‐less” mutants is presented.
Characterization of revertants of stmF mutants of Dictyostelium discoideum: Evidence that stmF is the structural gene of the cgmp‐specific phosphodiesterase
Authors: Coukell M. Barrie , Cameron Anne M. 
Published: May 2005

AbstractstmF mutants of Dictyostelium discoideum produce long, banded aggregation streams on growth plates and exhibit altered cGMP metabolism. To learn more about the role of cGMP in chemotaxis and the nature of the defect in these mutants, 15 nonstreaming (Stm+) revertants of two stmF mutants were isolated and characterized. Fourteen of the revertants continued to show the elevated cAMP‐induced cGMP response and very low cGMP‐specific phosphodiesterase (cGPD) activity characteristic of their stmF parents. Parasexual genetic analysis revealed that many of these Stm+ revertants carried phenotypic suppressors unlinked to stmF. One Stm+ revertant, strain HC344, exhibited a low, prolonged cGMP response and relatively high cGPD activity throughout development. To determine whether the elevated cGPD activity in this revertant resulted from increased enzyme production or enhanced enzyme activity, cGPDs were partially purified from the wild‐type strain, the stmF parent and revertant HC344, and properties of the enzymes were compared. cGPDs from the stmF mutant and the revertant showed similar differences from the wild‐type enzyme in kinetic properties, thermal stability, and sensitivity to certain inhibitors. These results suggest that stmF is the structural gene of the cGPD. In addition, the unusual cGMP response in revertant HC344 appeared to be due to increased production of an altered cGPD.
Isocitrate dehydrogenase in D. melanogaster imaginal discs: Pattern development and alteration by homoeotic mutant genes
Authors: Kuhn David T. , Cunningham Glenn N. 
Published: May 2005

AbstractThe distribution of the soluble form of NADP+ ‐dependent isocitrate dehydrogenase (ICDH) was examined in Drosophila melanogaster imaginal discs. Development of the enzyme patterns and the specific transformations of the patterns by homoeotic mutants were studied. ICDH pattern formation was followed in eye‐antennal discs and wing discs from the late 2nd instar stage through 3rd instar and 8 hours into prepupal development. The patterns formed gradually in both disc types. The most interesting pattern developed in the eye portion of the eye‐antennal disc complex. ICDH distribution as well as staining intensity correlated well with differentiation of the ommatidia. The spatial distribution of ICDH within the discs was under genetic control. The patterns reflected the state of determination of the disc. When the presumptive tissue type was transformed via mutant homoeotic genes to different determinative states, the ICDH pattern likewise transformed to the pattern characteristic of the newly acquired structure.
A temperature‐sensitive mutant affecting the process of chorion gene amplification in Drosophila melanogaster
Authors: Komitopoulou Katia , Kouyanou Sophie , Kafatos Fotis C. 
Published: May 2005

AbstractK575 is a temperature‐sensitive female sterile mutant which shows abnormal chorion structure and subnormal amounts of the major chorion proteins at the restrictive temperature. These phenotypes apparently result from a temperature‐sensitive defect in amplification. Both clusters of chorion genes are affected, indicating that the gene operates in trans.
Noncoordinate synthesis of the vitellogenin proteins in tissues of Drosophila grimshawi
Authors: Kambysellis Michael P. , Hatzopoulos Polydefkis , Seo Eul Won , Craddock Elysse M. 
Published: May 2005

AbstractIn analyzing the in vitro pattern of protein synthesis by the fat body and ovaries of the Hawaiian species Drosophila grimshawi, we have found that the ovaries synthesize much more protein than the female fat body and that the majority of the synthesized proteins are retained by the ovarian tissues. In contrast, the fat body secretes most of the proteins into the culture medium. Vitellogenins are the major class of proteins synthesized and released into the medium by both tissues. The synthesis of the three vitellogenin proteins (V1, V2, V3,) is noncoordinate in the two tissues. Ovaries synthesize much more of the V2 protein, less V1 and very little V3, whereas fat body synthesies more Vs1 protein with lesser qu antities of the other two. The follicle cells were identified as the site of ovarian vitellogenin synthesis in D. grimshawi, confirming the findings in D. melanogaster. In D. grimshawi, the three vitellogenins are synthesized by the follicle cells in a noncoordinate and developmentally regulated manner. V2 and V1 are the predominant proteins at the onset of vitellogenesis (S8–9); their production peaks together with that of V3 a few hours later (S10) and then decreases to quantitiesequalto that of V3 during early choriogenesis (S11). During active choriogenesis (S12), V2 and V1 cease to be synthesized, but V3 synthesis continues. The vitellogenins synthesized by the follicles in vitro are released into the medium and not incorporated into the oocyte.
Regulation of late gene expression in a temperature‐sensitive cohesion‐defective mutant of Dictyostelium discoideum
Authors: Saxe Charles L. , Firtel Richard A. 
Published: May 2005

AbstractWe have analyzed the expression of a series of developmentally regulated genes in the Dictyostelium discoideum strain JC‐5. This strain has been previously described as a temperature‐sensitive, cohesion‐defective derivative of FR17, itself a temporally deranged mutant of wild‐type NC‐4. At restrictive temperature (27°C), JC‐5 initially acquires EDTA‐resistant cell contacts but at the time of tip formation (12 hr) loses the ability to make specific cell‐cell associations and regresses to an amorphous mound of cells. We have found that genes preferentially expressed in either prespore or prestalk cells are expressed prior to the appearance of the cohesion defect in JC‐5; the specific cell contact system defective in this strain is necessary for neither the proper initiation nor maintenance of expression of either prespore of prestalk genes. We have also found, by use of an in vitro cell suspension system, that JC‐5 is temperature‐sensitive with respect to gene expression several hours before the defect in cell cohesion is observable. Our data suggest that the defect in JC‐5 is due to a specific lesion not in the late cohesion system but rather in a more general component that is required earlier in the developmental process.