bluuebunny/crossref_metadata_2025 huggingface dataset:
Homoeosis in Drosophila: Maternal effect of the enhancer of Polycomb locus and its interaction with Polycomb and related loci
Authors: Sato Takashi , Hayes Pliny H. , Denell Robin E.
Published: May 2005

A mutation or deficiency of the Enhancer of Polycomb (E(Pc)) locus acts as a dominant enhancer of the adult mutant phenotypes of a group of similar homoeotic loci (Polycomb, Polycomblike, extra sex comb, and lethal(4)29). The E(Pc) mutation has a recessive lethal effect, and homo‐ and hemizygotes die as late embryos or larvae which appear cuticularly normal. E(Pc) also acts as a dominant enhancer of the embryonic homoeotic syndromes associated with Polycomb. Polycomblike, and lethal(4)29 mutations: its effect on the extra sex comb syndrome has not been effectively evaluated. At least for the interaction with Polycomb mutations, evidence is presented that the Enhancer of Polycomb locus has a maternal as well as a zygotic effect, and that its effect on Polycomb expression is not at the level of transcription. We suggest that the Enhancer of Polycomb locus acts specifically to regulate the activities of this set of homoeotic loci, and that E(Pc) recessive lethality results from noncuticular homoeotic defects which arise as a consequence of their reduced activity. In the context of this hypothesis, no present data allow us to distinguish whether Enhancer of Polycomb is a nonhomoeotic locus regulating the function(s) of Polycomb and related genes or is itself a homoeotic locus.
A mutation in Drosophila that appears to accelerate aging
Authors: Leffelaar David , Grigliatti Thomas A.
Published: May 2005

The question as to the role that genes play in determining life‐span is essentially unresolved. Although it is well documented that genotype influences longevity, this is no way demonstrates that life‐span is genetically determined. In the present study we examine five temperature‐sensitive mutations for their effect on the aging process. At the permissive temperature (22°C ), the longevity of each mutant strain is comparable to that of wild type. However, at the restrictive temperature (29°C ) the life‐span of these mutants is severely curtailed. Using behavior loss as a landmark of adult physiological age, we examined each of these strains for its pattern of behavior loss relative to longevity, and compared each to a wild‐type strain. In four of the mutations the pattern of behavior loss relative to longevity was severely altered at one or both temperatures. However, one strain, adl‐16tsl displayed a pattern of behavior loss that was indistinguishable from wild type at both 22°C and 29°C. At 29°C not only was the longevity decreased, the pattern of behavior loss was also compressed into a shorter time period. The compression of the pattern of behavior loss was proportional to the reduction in life‐span. Thus it appears that this mutation, adl‐16tsl, may accelerate the normal aging process when placed at 29°C. The potential utility of these types of mutants for studying the aging process is discussed.
On the evolutionary relationships of Drosophila melanogaster
Authors: Ashburner Michael , Bodmer Mark , Lemeunier Francoise
Published: May 2005

The gene coding for alcohol dehydrogenase (Adh) in Drosophila melanogaster maps to 2:50.1 on chromosome arm 2L. It is expressed in both larvae and adults, coding for an abundant enzyme that plays a role in the detoxification of primary and secondary alcohols. In larvae the gene is most abundantly expressed in the fat body and gut. We have recently shown [49] that the major Adh transcripts differ in larvae and adults, the major adult transcript being initiated from a promotor several hundred pairs 5′ to the promotor from which the major larval transcript is initiated. However the coding region of the “larval and adult” mRNA are identical. We discuss recent studies of the transcriptional organization Adh and compare the structure of this gene in D. melanogaster with that in other species of Drosophila. The entire Adh gene and its surrounds has been sequenced from four species of Drosophila [45,48]. This data has been used not only for the study of phylogenetic relationships, but also of the types of sequence variation seen between species. The constraints on mutational change, especially with respect to codons, will be discussed.
The role of mRNA structure in the regulation of protein synthesis: Implications for studies of development
Authors: Vournakis John N. , Vary Calvin P. H.
Published: May 2005

A method is described for the experimental determination of the secondary structure of RNA using enzymatic cleavage data coupled with computer analysis. The structure‐specific enzymes S1 nuclease and cobra venom ribonuclease are used to locate nonpaired and basepaired nucleotides, respectively. Computer techniques that utilize the enzymatic susceptibility information to generate a minimum free‐energy structure are used to obtain secondary structure models. A second method, using acrylamide‐agarose gel electrophoresis, is described for the determination of the relative protein synthesis initiation rates of endlabeled eukaryotic mRNAs. These methods are applied to the rabbit globin mRNAs as an example of a general approach for relating mRNA structure and function. A discussion of the role of messenger RNA structure in the regulation of translation is included with an emphasis on studies of development.
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

A 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

Reproductive 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

The 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

We 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

The 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

The 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

The 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

The 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

The 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

Ovarian 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

The 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

stmF 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

The 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

K575 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

In 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

We 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.
Analysis of mating type determination by transplantation of O macronuclear karyoplasm in Paramecium tetraurelia
Authors: Koizumi Sadaaki , Kobayashi Sumiko , Mikami Kazuyuki
Published: May 2005

The odd (O) or even (E) mating type in Paramecium tetraurelia is determined during the first cell cycle after new macronuclear development. The present paper demonstrates that mating type E is irreversibly determined at the end of the first cell cycle. Direct evidence comes from transplanting O macronuclear karyoplasm containing O‐determining factor into E autogamous cells during a new postzygotic macronuclear development. Transplantation of O macronuclear karyoplasm into E autogamous cells at 7–8 hr after the origin of the macronucleus from a product of the synkaryon produces nearly 100% O mating type among the exautogamous cell lines but almost none 10–11 hr after the origin of the macronucleus (around the end of the first cell cycle). The macronuclear anlagen at the stage at which mating type E seems to be fixed contains about 20 times as much DNA as the vegetative G1 micronucleus. The O‐determining factor shifting E cells toward O mating type by transplanting O macronuclear karyoplasm is also produced by the newly developed macronucleus in an effective concentration at 10–11 hr after the sensitive period and produced at full levels by the third cell cycle. The level of O factor in the macronucleus then gradually declines with subsequent repeated rounds of DNA synthesis and is finally lost by the eighth cell cycle.
The relationship of relative gene dose to the complex phenotype of the daughterless locus in Drosophila
Authors: Cronmiller Claire , Cline Thomas W.
Published: May 2005

The daughterless (da) gene provides an essential maternally supplied component for Drosophila sex determination and dosage compensation. In this connection, it is required as a positive regulator of a female‐specific master regulatory gene, Sex‐lethal (Sxl). In addition, zygotic da gene function is required for male and female viability. Thus, the phenotype da is complex; it includes both maternal and zygotic aspects, as well as both sex‐specific and nonsex‐specific aspects. Assessment of wild‐type da function has relied on the characterization of only a single leaky mutant da allele. In order to better understand the nature of this allele and the relationships between the various aspects of its complex phenotype, tandem duplications of both the mutant and wild‐type da alleles were isolated and used in a dose study of this gene's function. Three conclusions were reached: (1) by the most stringent genetic criteria, the mutant da allele is a simple hypomorph, an allele with reduced but non‐zero levels of wild‐type functions; (2) since increased dose of da+ had no effect on viability or progeny sex ratio, this gene seems not to be a dose‐sensitive element of the X/A ratio sex determination signal; and (3) expression of the maternal da+ allele does make a contribution to the nonsex‐specific developmental processes that require zygotic da+ function; however, that contribution is clearly minor. In contrast, the zygotic genotype with respect to da appears to have no effect on the expression of Sxl+ in the zygote, the sex‐specific process that requires maternal da+ function.
β‐Glucuronidase activity is present in the microscopic epididymis of the Tfm/Y mouse
Authors: Scott J. Elliott , Blecher Stan R.
Published: May 2005

The sex‐linked recessive gene Tfm in the mouse produces a condition of testicular feminization (androgen insensitivity syndrome, AIS) in hemizygotes, comparable to the condition of the same name in humans. The murine mutant was originally believed to have no derivatives of the mesonephric duct system (MDS), and this absence was ascribed to dependence of these derivatives on androgens for survival. However, microscopical epi‐didymides, retia testes, and vasa deferentia were identified in these animals in our laboratory. These micro‐organs may play a role in meiosis induction in Tfm/Y animals. The present study was designed to determine whether survival of these organs is due to retention of an ability to respond to androgens, or whether they are unique amongst MDS derivatives in being independent of androgens.

Previous studies in our laboratory demonstrated that the enzyme β‐glucuronidase (βG) is androgen sensitive in the epididymis of the normal mouse. In the present investigation we used this enzyme as a marker to study androgen sensitivity in the microscopical epididymides of Tfm/Y hemizygotes and in the epididymides of control +/Y litter‐mate brothers. Both mutant and control animals were studied with and without exogenous androgen stimulation.

Tfm/Y hemizygotes demonstrated low levels of diffuse, cytoplasmic βG activity that appears to be unresponsive to exogenous androgen stimulation. In light of our previous studies, this distribution of βG reaction products suggests some degree of androgen sensitivity. The survival of these micro‐organs and their partial androgen sensitivity may be related to the role of the MDS in inducing meiosis.
Nonreciprocal gonadal dysgenesis in Chironomus thummi hybrids: Temperature sensitivity of female sterility
Authors: Häugele Klaus
Published: May 2005

In nonreciprocal hybrids of Chironomus thummi an environmental factor has been detected which, along with genetic factors, determines gonadal dysgenesis. Female hybrids of the cross Ch' thummi thummi ♂ ♂ × Ch. thummi piger ♀ ♀ show various degrees of rudimentary developed ovaries and sterility. The extent of these abnormalities is dependent on the developmental temperature of the hybrids. At a temperature of 21°C approximately 90% of the females are completely sterile and at 16°C only 30%. The curative effect of a temperature of 16°C on sterility occurs, however, only in those hybrid females which hatch from a specific type of egg mass (class A). Females of another type of egg mass (class B) show nearly as many dysgenic ovaries as do those developed at 21°C. At a developmental temperature of 21°C no such differentiation between the A and B class of egg masses is possible.

Ovarian dysgenesis and sterility is induced during atemperature‐sensitive period which extends from the beginning of embryonic development through the first two‐thirds of the first larva instar stage. The abnormalities observed must be due to a failure in the early development of the germ line and are probably initiated by an inhibition of primordial germ cell divisions.
Evidence of a gene‐dosage effect for the glucocorticoid receptor in trisomy 18 mice
Authors: Vogliolo Daniel , Winking Heinz , Knuppen Rudolf
Published: May 2005

The amount of cytosolic glucocorticoid receptor in liver of Ts18, Tsl6, and Tsl9 vs euploid mouse fetuses was studied after incubation of [3H]dexamethasone with cytosol followed by isoelectric focusing on polyacrylamide gels. In addition, corticosterone concentrations and enzyme activities of alanine aminotransferase and tyrosine aminotransferase were measured in the cytosol of the livers. The amount of glucocorticoid receptor in the cytosol fractions of the livers was always higher in the Tsl8 than in the euploid fetuses of the same litter. It was also significantly (P < 0.0005) higher if pooled data from different litters were analyzed. The ratio of the glucocorticoid receptor in Ts l8 vs euploid mice varied between 1.3 and 4.7, with a mean of 2.1. In contrast, the glucocorticoid receptor levels in Tsl6 and Tsl9 fetuses were not different from the corresponding euploid controls. Comparing the corticosterone levels of the three trisomies tested with the corresponding euploid fetuses, no significant differences were found, indicating that the markedly elevated cytosolic glucocorticoid receptor concentrations in Tsl8 were not due to different corticosterone levels. This finding is consistent with the assignment of the glucocorticoid receptor gene to chromosome 18 in the mouse. There was no correlation betwen glucocorticoid receptor levels and the activity of the two glucocorticoid inducible enzymes tested in the liver of mouse fetuses.
Induction of gastrulation in the chick embryo
Authors: Zagris Nikolas , Matthopoulos Demetrios
Published: May 2005

Interaction between the epiblast and the primary hypoblast in chick blastula results in induction of the primitive streak (PS) in the epiblast. Alpha‐amanitin, a specific inhibitor of poly A‐containing RNA synthesis, inhibits formation of the definitive PS. This inhibition is associated with qualitative changes in the pattern of protein synthesis in the hypoblast but not in the epiblast. The protein pattern of the component areas of the epiblast shows increase in some polypeptides after treatment with α‐amanitin. By contrast, α‐amanitin resulted in a decrease in synthesis of several polypeptides, which are either undetectable or weakly present in the hypoblast. The α‐amanitin‐sensitive translational products of the embryonic genome that are observed in the hypoblast may have specific functions in the control of PS induction and stabilization.
Expression of the differentiation antigen F7D6 in tumorous tissues of Drosophila
Authors: Bedian Vahe , Jungklaus Christine E.
Published: May 2005

The 63‐kDa antigen recognized by the monoclonal antibody F7D6 is present in all Drosophila embryonic cells and disappears from most tissues as each one reaches its final, differentiated state. Larval tissues lose the antigen around the time of hatching, imaginal tissues lose it during metamorphosis, and germ cells lose it during gametogenesis (Bedian et al: Devel Biol 115:105–118, 1986). The nervous system and spontaneously contracting musculature of the gut and gonads are exceptions and remain antigen positive at all stages. The F7D6 antigen appears to be associated with dividing, undifferentiated cells and electrogenic cells. This prompted us to test tumors for antigen presence. We tested four different recessive mutants that give rise to four different types of tumorous transformation: the embryonic tumor Notch, several larval melanotic tumors, the imaginal disc tumor 1(2)gl, and three alleles of the ovarian tumor otu. In all cases, tumorous tissues in homozygotes contained the F7D6 antigen. The electrophoretic mobility of the antigen appeared to be unaltered in tumorous tissues compared to normal cells, but the antigen is expressed at higher levels. The antigen is found on the cytoplasmic surface of plasma membranes and appears to be a marker of undifferentiated normal and tumorous cells. Similarities and differences between the F7D6 antigen and Drosophila c‐src protein are discussed.
Neurochemical characterization of embryonic brain development in trisomy 19 (Ts19) mice: Implications of selective deficits observed for abnormal neural development in aneuploidy
Authors: Saltarelli Mario D. , Forloni Gian Luigi , Oster‐Granite Mary Lou , Gearhart John D. , Coyle Joseph T.
Published: May 2005

In this study, we examined the neurochemical profiles of selected brain regions (cerebral hemispheres, diencephalon/brainstem) in fetal (day 14 to 18 gestation) trisomy 19 (Ts19) mice. The neurochemical characteristics we observed in Ts19 mice were quite different from those we observed previously in Ts16 mice. Choline acetyltransferase (ChAT) activity was reduced significantly in the cerebral hemispheres, but not in the brainstem/diencephalon, of the fetal Ts19 mouse brain, suggesting a selective vulnerability of telencephalic cholinergic neurons. Additionally, the activity of glutamic acid decarboxylase (GAD) was reduced significantly in both hemispheres and diencephalon/brainstem of late gestation Ts19 fetuses, suggesting a selective vulnerability of GABAergic neurons as well. While the levels of catecholaminergic and dopaminergic markers were reduced significantly at late gestational ages, the relative rate of turnover of dopamine (DA), measured by the ratio of DOPAC/DA, was elevated significantly in Ts19 mice. Neither reduction in the thickness of various cellular zones of the cerebral cortex nor reduced cell density of the cerebral cortex accounts for the alterations in neurochemical parameters observed in Ts19 mice. These results suggest that the effects of the triplication of specific genes on the respective chromosomes, rather than a generalized disruption of developmental homeostasis resulting from extra chromosomal material, may produce selective alterations in neurochemical and neuroanatomical markers observed in these two mouse trisomies.
Constitutive transcription of a soybean heat‐shock gene by a cauliflower mosaic virus promoter in transgenic tobacco plants
Authors: Schöffl Fritz , Rieping Mechthild , Baumann Götz
Published: May 2005

Transcription of heat‐shock protein genes in soybean can be induced by high temperature stress leading to a transient expression of heat‐shock proteins. We have tested whether the replacement of a native heat‐shock promoter by a viral promoter results in constitutive transcript levels of the respective gene in transgenic plants. The 35S‐transcript promoter of the cauliflower mosaic virus was linked to the protein‐coding region of the genomic heat‐shock gene hs6831, encoding a 17.6‐kD heat‐shock protein of soybean. After transformation of tobacco plants with this chimeric construction using a disarmed Agrobacterium binary vector, abundant mRNA levels were detected in transgenic plants. The steady‐state level of this mRNA at 25°C was equal to that generated by the native heat‐shock promoter at 40°C; however, it was markedly reduced by heat shock applied to the transgenic plants. These findings suggest a sufficiently high stability of heat‐shock mRNA produced at the normal growth temperature to direct constitutive expression of heat‐shock proteins. The application of constitutive gene expression for the investigation of thermotolerance is discussed.
Chromatin structure and plant gene expression
Authors: Kahl Gönter , Weising Kurt , Görz Andrea , Schäfer Willi , Hirasawa Eiji
Published: May 2005

The nuclear DNA of eukaryotic organisms is associated with a variety of proteins, which together make up what is called “chromatin.” Chromatin serves to package all genes into higher‐order structures such as nucleosomes, solenoids, and loop domains. Tight packing of a particular gene and its regulatory sequences does not allow the approach of RNA I or II polymerase proteins. Before or during the activation of such an inactive gene its chromatin has to adopt a relaxed, more “open” configuration. This altered chromatin can be probed by its higher sensitivity toward nucleases, such as DNAse I or S1 nuclease, and the appearance of DNAse I‐hypersensitive sites. These sites may constitutively be present or may be induced, and they can be mapped to specific DNA sequence motifs. In many cases, such sites are delimited by non‐B‐DNA, notably Z‐DNA, which in turn may form part of enhancer elements. The Z‐DNA configuration may be induced or maintained by methylation of cytosyl residues within underlying sequences.

Two plant gene model systems have been selected to probe their chromatin structure. Constitutively expressed T‐DNA genes of Agrobacterium induced tobacco crown gall tumor cells have been shown to be organized in canonical nucleosomes, to be more sensitive to DNAse I than the bulk of host chromatin, and to contain a series of six constitutive DNAse I‐hypersensitive sites. Inducible ribulose‐1,5‐bisphosphate carboxyl‐ase/oxygenase small subunit (rbcS) genes of pea are rearranged into a nuclease‐sensitive format upon activation by light, especially in their promoter region. The rbcS promoter harbors a series of five constitutive DNAse I‐hypersensitive sites and one light‐inducible site, which is surrounded by potential regulatory sequences (enhancer cores, inverted repeats). The 3′ region of rbcS genes also contains constitutive sites. Methylation/demeth‐ylation of Alu I‐, Fnu4H1‐, HaeIII‐, Sau3AI‐, and Sau 96I sequences in rbcS promoters does not play any role in rbcS gene inactivation/activation.
Plant tubulin genes: Structure and differential expression during development
Authors: Silflow Carolyn D. , Oppenheimer David G. , Kopozak Steven D. , Ploense Sara E. , Ludwig Steven R. , Haas Nancy , Peter Snustad D.
Published: May 2005

Microtubules are important components of the cytoskeleton of plant cells and play key roles in plant growth and morphogenesis. Recent molecular studies have begun to elucidate the structure and expression of plant genes coding for the major components of microtubules, α‐ and β‐tubulin. Tubulin amino acid sequences deduced from the DNA sequences of eight higher plant tubulin genes are 79–87% homologous with constitutively expressed mammalian tubulins. The genome of the model plant system Arabidopsis thaliana contains four dispersed α‐tubulin sequences and at least seven β‐tubulin sequences, only two of which appear to be linked. Of the five A. thaliana genes whose expression has been analyzed, the transcripts of one α‐tubulin and one β‐tubulin gene are constitutively expressed in roots, leaves, and flowers. A second α‐tubulin gene is expressed predominately in flowers; the transcripts of the second and third β‐tubulin genes are found predominately in leaves or in roots, respectively.
Structural and biochemical studies on four sex‐linked chorion mutants of Drosophila melanogaster
Authors: Komitopoulou Katia , Margaritis Lucas H. , Kafatos Fotis C.
Published: May 2005

Four female‐sterile mutants, fs(l)K451, fs(1)K1214, fs(1)K575TS, and fs(1)384, were studied in terms of chorion structure and chorion protein composition. The first three of these mutants cause morphological defects, ie, substantial underproduction and disruption of the endochorion, correlated with underproduction of the six major chorion proteins, s15–s38; the phenotypes are consistent with the observation that these mutants interfere with amplification of the major chorion genes that encode the s15–s38 proteins [Orr et al.: Proc Natl Acad Sci USA 81:3773–3777, 1984; Komitopoulou et al.: Dev Genet 7:75–80, 1986]. The fourth mutant, fs(1)384, and its alleles do not interfere with production of the major chorion proteins and the morphologically detectable bulk of the endochorion but lead to failure of endochorionic organization. Apparently this complementation group is responsible for a minor chorion product, which is evidently important morphogenetically and which is processed posttranslationally in a complex manner [Bauer and Waring: Dev Biol 121:349–358, 1987].
Multiplicity of functions for the otu gene products during Drosophila oogenesis
Authors: Storto Patrick D. , King Robert C.
Published: May 2005

The ovarian tumor gene behaves as if it encodes a product (OGP), which is required durirng several early steps in the transformation of oogonia into functional oocytes. Seventeen ethyl methane sulfonate‐induced mutations have been studied, and their mutant phenotypes can be explained as graded responses by individual germ cells to different levels of OGP synthesized by the mutant germ cells themselves. The lowest and highest levels of OGP appear to be produced by otu10 and otu14, respectively. The 15 mutants with intermediate OGP levels are temperature sensitive; subnormal temperatures improve ovarian development, while above‐normal temperatures suppress it. A subgroup ofthese mutants are unable to form a system of actin microfilament bundles in the cortical cytoplasm of their nurse cells during stage 10B, and these defective nurse cells are unable to transport their cytoplasm to the oocyte, as normally happens between stages 10B and 12. In addition to its role in the actin‐mediated transport of nurse cell cytoplasm, OGP also appears to alter the morphology of giant polytene chromosomes, which form as the nurse cells undergo endocycles of DNA replication. Genetic evidence suggests that otu also encodes a second product (SP) that is utilized late in oogenesis. SP is required for the synthesis in the ooplasm of glycogen‐rich, beta yolk spheres. Products of the otu gene also play a vital but unknown role in embryogenesis.