bluuebunny/crossref_metadata_2025_split huggingface dataset:
Antisense inhibition of nuclear‐encoded cytochrome C oxidase subunits IV and VIIc activity in the pre‐implantation embryo
Authors: Ao Asangla , Erickson Robert P. , Rosenthal Nancy H. , Grossman Lawrence I. 
Published: May 2005

AbstractIt had not previously been known whether synthesis of nuclear‐encoded mitochondrial subunits occurs in pre‐implantation embryos. We have used cytoplasmic injections of antisense RNA transcribed in vitro to study this question. Capped, in vitro transcribed RNA antisense to either cytochrome coxidase subunit IV or VIIc injected into each cell at the two‐cell stage markedly inhibited synthesis of adenine nucleotides by the 8‐ to 16‐cell stage, whereas injection of the cognate sense RNAs gave levels similar to those previously published for normal embryos. These results strongly suggest that translation of nuclear‐encoded mRNAs for mitochondrial subunits is required during pre‐implantation development. It was of additional interest that, not only was ATP decreased, but ADP and AMP as well, with the effect that the charge ratio remained constant. The results also suggest, therefore, that the mechanism by which cells normally regulate their charge ratio, thought to be with adenylate deaminase, is already in place. © 1993Wiley‐Liss, Inc.
Sea urchin maternal mRNA classes with distinct developmental regulation
Authors: Kelso‐Winemiller Leslie , Yoon Joonwon , Peeler Margaret T. , Winkler Matthew M. 
Published: May 2005

AbstractPrevious studies of newly synthesized proteins during early development in sea urchins have revealed several different patterns of synthesis that can be used to predict the existence of mRNA classes with distinct regulatory controls. We have identified clones for abundant maternal mRNAs that are actively translated during early development by screening a cDNA library prepared from polysomal poly(A) + RNA isolated from 2‐cell stage (2‐hour) Strongylocentrotus purpuratus embryos. Probes prepared from these cDNA clones and several previously characterized maternal mRNA cDNAs were used to compare relative levels of individual mRNAs in eggs and embryos and their translational status at various developmental stages. These abundant mRNAs can be classified into two major groups which we have termed cleavage stage‐specific (CSS) and post cleavage stage (PCS) mRNAs. The relative levels of the CSS mRNAs are highest during the rapid cleavage stage and decrease dramatically at the blastula stage (12‐hours). In contrast, PCS mRNAs are present at relatively low levels during the rapid cleavage stage and then increase at the blastula stage. Polysome partition profiles reveal that CSS mRNAs are translated more efficiently than PCS mRNAs in the unfertilized egg, at fertilization, and during the cleavage stages. Following the blastula stage, some CSS transcripts move out of polysomes and accumulate as untranslated RNAs, while newly transcribed PCS mRNAS are recruited into polysomes. These data suggest that the rapid cell cycles following fertilization require high levels of specific cleavage stage proteins, and the synthesis of these proteins occurs preferentially over PCS mRNAs. © 1993Wiley‐Liss, Inc.
Gene regulation in Drosophila spermatogenesis: Analysis of protein binding at the translational control element TCE
Authors: Kempe Elisabeth , Muhs Beate , Schäfer Mireille 
Published: May 2005

AbstractWe have previously identified a 12 nucleotide long sequence element, the TCE, that was demonstrated to be necessary for translational control of expression in the male germ line of Drosophila melanogaster (Schäfer et al., 1990). It is conserved among all seven members of the Mst(3)CGP gene family, that encode structural proteins of the sperm tail. The TCE is invariably located in the 5′ untranslated region (UTR) at position + 28 relative to the transcription start site. In this paper we analyse the mode of action of this element. We show that protein binding occurs at the TCE after incubation with lestis protein extracts from Drosophila melanogaster. While several proteins are associated with the translational control element in the RNA, only one of these proteins directly crosslinks to the sequence element. The binding activity is exclusively observed with testis protein extracts but can be demonstrated with testis extracts from other Drosophila species as well, indicating that regulatory proteins involved in translational regulation in the male germ line are conserved. Although binding to the TCE can occur independent of its position relative to the transcription start site of the in vitro transcripts, its function in vivo is not exerted when shifted further downstream within the 5′ UTR of a fusion gene. In addition to being a translational control element the TCE also functions as a transcriptional regulator. Consequently, a DNA‐protein complex is also formed at the TCE. In contrast to the RNA‐protein complexes we find DNA‐protein complexes with protein extracts of several tissues of Drosophila melanogaster. © 1993 Wiley‐Liss, Inc.
Regulated polyadenylation of clam maternal mRNAs in vitro
Authors: Standart Nancy , Dale Martin 
Published: May 2005

AbstractDuring meiotic maturation of Spisula oocytes, maternal mRNAs undergo changes in translation and in the length of their poly(A) tails. In general, those mRNAs that are translationally activated, i.e., unmasked become polyadenylated, while deactivated mRNAs lose their poly(A) tails. The activated class of mRNAs encode ribonucleotide reductase, cyclins A and B and histone H3, while the proteins that stop being made include tubulin and actin. Previously, we demonstrated that mRNA‐specific unmasking can be brought about in vitro by preventing the interaction of protein(s) with central portions of the 3′ noncoding regions (masking regions) of ribonucle‐otide reductase and cyclin A mRNAs. In this report, we show that clam egg extracts are capable of sequence‐specific polyadenylation of added RNAs since the 3′ untranslated regions (UTRs) of ribonu‐cleotide reductase and histone H3 mRNAs are polyadenylated, while that of actin mRNA is not. In contrast, oocyte extracts, as in vivo, are essentially devoid of polyadenylation activity. We present an initial characterisation of the cis‐acting sequences in the 3′ UTR of ribonucleotide reductase mRNA required for polyadenylation. The results suggest that the sequences for cytoplasmic polyadenylation are more complex and extensive than those determined in vertebrates and that they may partly overlap with the masking regions. © 1993 Wiley‐Liss, Inc.
Homeotic gene expression in the locustSchistocerca: An antibody that detects conserved epitopes in ultrabithorax and abdominal‐A proteins
Authors: Kelsh Robert , Weinzierl Robert O. J. , White Robert A. H. , Akam Michael 
Published: May 2005

AbstractTo investigate what role homeotic genes may play in morphological evolution, we are comparing homeotic gene expression in two very different insects,Drosophila(Diptera) andSchistocerca(Orthoptera). In this paper we describe a monoclonal antibody, FP6.87, that recognizes the products of both theUltrabithorax (Ubx)andabdominal‐A (abd‐A)genes inDrosophila, via an epitope common to the carboxy terminal region of these two proteins. This antibody recognizes nuclear antigens present in the posterior thorax and abdomen ofSchistocerca.We infer that it recognizes theSchistocercahomolog of UBX protein, and probably also of ABD‐A. As the distribution ofSchistocercaABD‐A protein is already known, we can use this reagent to map the expression ofSchistocercaUBX in the thorax and anterior abdomen, where ABD‐A is not expressed. Both the general domain, and many of the details, of UBX exp ression are remarkably conserved compared withDrosophila.Thus UBX expression extends back from T2 in the ectoderm (including the CNS), but only from A1 in the mesoderm. As noted for other bithorax complex genes inSchistocerca, expression begins in the abdomen, at or shortly before the time of segmentation. It only later spreads anteriorly to the thorax. For much of embryogene‐sis, the expression of UBX in the thoracic epidermis is largely restricted to the T3 limb. Inthis limb, UBX is strikingly regulated, in a complex pattern that reflects limb segmentation.Reviewing these and earlier observations, we conclude that evolutionary changes affect both the precise regulation of homeotic genes within segments, and probably also the spectrum of downstream genes that respond to homeotic gene expression in a given tissue. Overall domains of homeotic gene expression appear to be well conserved between different insect groups, though a change in the extent and timing of homeotic gene expression may underlie the modification of the posterior abdomen in different insect groups. © 1994 Wiley‐Liss, Inc.
Expression patterns of twist and snail in Tribolium (Coleoptera) suggest a homologous formation of mesoderm in long and short germ band insects
Authors: Sommer Ralf J. , Tautz Diethard 
Published: May 2005

AbstractThe mesodermal region in Drosophila is determined by a maternally derived morphogenetic gradient system which specifies the different cell fates along the dorsoventral axis, including the prospective mesodermal cells at the ventral side of the embryo. There are at least two zygotic target genes, twist and snail, which are required for mesoderm formation in Drosophila. To analyze whether a similar mode of mesoderm specification might also apply to short germ band insect embryos, we have cloned twist and snail‐ related gene fragments from the flour beetle Tri‐bolium and have analyzed their expression pattern. Both genes are expressed in a ventral stripe at early blastoderm stage, which is restricted to the region of the developing germ rudiment. The cells expressing the two genes are those that invaginate during gastrulation, indicating that the early stages of mesoderm specification are indeed very similar between the two species. Interestingly, both genes are also expressed during germband extension in a subregion of the growth zone of the embryo which forms the mesodermal cells. This suggests that the expression of the two genes is required for mesoderm formation both at early blastoderm stage and during germband elongation until the end of the segmental growth process. © 1994 Wiley‐Liss, Inc.
Heterochronic expression of an adult muscle actin gene during ascidian larval development
Authors: Swalla Billie J. , White Mary E. , Zhou Jing , Jeffery William R. 
Published: May 2005

AbstractAdultation is a hetercchronic mode of development in which adult tissues and organs differentiate precociously during the larval phase. We have investigated the expression of an adult muscle actin gene during adultation in the ascidian Molgula citrina. Ascidians contain multiple muscle actin genes which are expressed in the larva, the adult, or during both phases of the life cycle. In ascidian species with conventional larval development, the larval mesenchyme cells, which are believed to be progenitors of the adult mesoderm, remain undifferentiated and do not express the muscle actin genes. In M. citrina, the mesen‐chyme cells differentiate precociously during larval development, suggesting a role in adultation. An adult muscle actin gene from M. citrina was obtained by screening a mantle cDNA library with a probe containing the coding region of SpMAl, a Styela plicata adult muscle actin gene. The screen yielded a cDNA clone designated McMAl, which contained virtually the complete coding and 3′ noncoding regions of a muscle actin gene. The deduced McMAl and SpMAl proteins exhibit 97% identity in amino acid sequence and may be encoded by homologous genes. The McMAl gene is expressed in juveniles and adults, but not in larval tail muscle cells, suggesting that it is an adult muscle actin gene. In situ hybridization with a 3′ non‐coding region probe was used to determine whether the McMAl gene is expressed during adultation in M. citrina. McMAl mRNA was first detected exclusively in the mesenchyme cells during the late tailbud stage and continued to accumulate in these cells during their migration into the future body cavity and heart primordium in the hatched larva. The McMAl transcripts persisted in mesenchyme cells after larval metamorphosis. It is concluded that an adult muscle actin gene shows a heterochronic shift of expression into the larval phase during adultation in M. citrina.
Establishment of the dorsoventral axis in nemertean embryos: Evolutionary considerations of spiralian development
Authors: Henry Jonathan Q. , Martindale Mark Q. 
Published: May 2005

AbstractThe Nemertea represent one of a number of invertebrate phyla that display a highly conserved pattern of cell division known as spiral cleavage. The fates of the early blastomeres are known for representatives of some spiralian phyla (i.e., molluscs and annelids) and in these species there appears to be a high degree of conservation in the ultimate fates of particular embryonic cells. The first two cleavage planes bear an invariant relationship to the symmetry properties of the future larval and adult body plan. To investigate whether these properties of spiralian embryo‐genesis are shared (conserved) amongst members of other spiralian phyla, individual blastomeres in two‐ and four‐cell embryos of the nemertean, Nemertopsis bivittata, were microinjected with bi‐otinylated dextran lineage tracers. N. bivittata is a direct‐developing hoplonemertean that forms a nonfeeding larva. When individual blastomeres are injected at the two‐cell stage, two sets of complementary labeling patterns (a total of four different patterns) were observed in the ectoderm of the larvae. When cells were injected at the four‐cell stage, four different patterns were observed that represented subsets of the four patterns observed in the previous experiment. Unlike the case in the annelids and molluscs, in which the first cleavage plane bears a strict 45° angular relationship to the future dorsoventral axis, the first cleavage plane in N. bivittata can bear one of two different relationships relative to the larval/adult dorsoventral axis. In half the cases examined, the first cleavage plane corresponded roughly to the plane of bilateral symmetry, and in the rest, it lay along a frontal plane. A similar result was observed for the embryos of the indirect‐developing heteronemertean, Cerebratutus lacteus. These results indicate that the fates of the four cell quadrants in nemerteans are not directly homologous to those in other spira‐lians, such as the annelids and molluscs. For instance, no single cell quadrant appears to contribute a greater share to the formation of ectoderm, as is the case in the formation of the post‐trochal region by the D‐cell quadrant in annelids and mol‐luscs. Rather, two adjacent cell quadrants contribute nearly equally to the formation of dorsal or ventral ectoderm in the larvae. Possible explanations for the determination of dorsoventrality in nemerte‐ans, as well as implications of these findings regarding the evolution of spiralian development, are discussed. © 1994 Wiley‐Liss, Inc.
IME1 gene encodes a transcription factor which is required to induce meiosis in Saccharomyces cerevisiae
Authors: Mandel Silvia , Robzyk Kenneth , Kassir Yona 
Published: May 2005

AbstractPrevious studies have shown that the IME1 gene is required for sporulation and the expression of meiosis specific genes in Saccharomyces cerevisiae. However, sequence analysis has not revealed the precise functional role of the Ime1 protein. By engineering constructs which express various portions of the Ime1p fused to either the DNA binding or transcriptional activation domains of GAL4, we have conclusively demonstrated that IME1 is a transcription factor, apparently required for sporulation to activate the transcription of meiosis specific genes. The full Ime1p, when fused to the GAL4 DNA binding domain, can both activate GAL1‐IacZ expression, and complement Ime1‐0 (a null allele) for the ability to sporulate, and transcriptionally activate IME2, a meiosis specific gene. As successively larger portions of the encoded Ime1p N‐terminus are deleted from the GAL4(bd)‐IME1 construct, the encoded fusion proteins retain the ability to complement an ime1 null allele, despite a decreasing ability to activate GAL1‐lacZ transcription. However, a fusion construct which retains only the last 45 C‐terminal amino acids of IME1 provides neither transcriptional activation of GAL1‐lacZ nor complementation of ime1‐0. Fusion of a GAL4 activation domain to this portion of IME1, results in a construct with a restored ability to complement an ime1‐0 cllele. This restored ability is dependent upon galactose induction. We conclude, therefore, that IME1 functions in meiosis as a transcriptional activator. © 1994 Wiley‐Liss, Inc.
Isolation of silencer‐containing sequences causing a tissue‐specific position effect on alcohol dehydrogenase expression in Drosophila melanogaster
Authors: Kirkpatrick Robert B. , Parveen Zahida , Martin Presley F. 
Published: May 2005

AbstractA transient expression assay has been used to investigate the cause of a tissuespecific position effect on Adh expression from a transgene insertion in Drosophila. A 15.4‐kb genomic clone containing the 3.2‐kb Adh insert along with flanking regions of genomic DNA is expressed in this assay in a tissue‐specific pattern resembling the abnormal expression pattern of the position effect. The 3.2‐kb Adh insert is expressed normally without the flanking sequences. A silencer element is located upstream of the Adh gene within a 2‐kb fragment that acts in both orientations and at a distance of at least 6.5 kb from the larval Adh promoter to suppress ADH expression in a nontissue specific fashion. The DNA sequence of the 2‐kb fragment indicates that it is a noncoding region. A 17‐bp sequence is repeated within this region and may be associated with the silencer activity, since subclones from the 2‐kb fragment, each containing one of the repeated regions, both retain full silencer activity. This silencer fails to suppress expression from an α1‐tubulin promoter‐LacZ fusion construct or an hsp70 promoter‐Ach fusion construct. In addition to the silencer, another element is located downstream of the Adh gene that produces a higher level of anterior than posterior midgut expression. These results suggest that the 5′ silencer and the 3′ element act together to create the tissue specific pcsition effect characteristic of the GC‐1 line. © 1994 Wiley‐Liss, Inc.
Genetics of sex determination in flowering plants
Authors: Grant Sarah , Houben Andreas , Vyskot Boris , Siroky Jiri , Pan Wei‐Hua , Macas Jiri , Saedler Heinz 
Published: May 2005

AbstractMost flowering plant species are hermaphroditic, but a small number of species in most plant families are unisexual (i.e., an individ‐ual will produce only male or female gametes). Because species with unisexual flowers have evolved repeatedly from hermaphroditic progenitors, the mechanisms controlling sex determination in flowering plants are extremely diverse. Sex is most strongly determined by genotype in all species but the mechanisms range from a single controlling locus to sex chromosomes bearing several linked locirequired for sex determination. Plant hormones also influence sex expression with variable effects from species to species. Here, we review the genetic control of sex determination from a number of plant species to illustrate the variety of extant mechanisms. We emphasize species that are now used as models to investigate the molecular biology of sex determination. We also present our own investigations of the structure of plant sex chromosomes of white campion (Silene latifolia ‐ Melan‐drium album). The cytogenetic basis of sex determination in white campion is similar to mammals in that it has a male‐specific Y‐chromosome that carries dominant male determining genes. If one copy of this chromosome is in the genome, the plant is male. Otherwise it is female. Like mammalian Y‐chromosomes, the white campion Y‐chromosome is rich in repetitive DNA. We isolated repetitive sequences from microdissected Y‐chromosomes of white campion to study the distribution of homologous repeated sequences on the Y‐chromosome and the other chromosomes. We found the Y to be especially rich in repetitive sequences that were generally dispersed over all the white campion chromosomes. Despite its repetitive character, the Y‐chromosome is mainly euchromatic. This may be due to the relatively recent evolution of the white campion sex chromosomes compared to the sex chromosomes of animals. © 1994 Wiley‐Liss, Inc.
Function of the her‐1 gene is required for maintenance of male differentiation in adult tissues of C. elegans
Authors: Schedin Pepper , Jonas Petra , Wood William B. 
Published: May 2005

AbstractFunction of the sex‐determining gene her‐1 is required in XO embryos cf C. elegans to specify male development. Using a temperature‐sensitive mutant of her‐1, we show that when XO males reared at a permissive temperature are shifted as adults to a nonpermissive temperature, they initiate vitellogenin synthesis in the intestine and oocyte production in the germline. A similar shift has no effect on her‐1(+) males. We conclude that sexual differentiation of the intestine and germline is plastic, requiring her‐1 expression throughout adulthood for maintenance of the male state. © 1994 Wiley‐Liss, Inc.
Behavioral and neurobiological implications of sex‐determining factors inDrosophila
Authors: Taylor Barbara J. , Villella Adriana , Ryner Lisa C. , Baker Bruce S. , Hall Jeffrey C. 
Published: May 2005

AbstractThe function of the central nervous system as it controls sex‐specific behaviors inDrosophilahas been studied with renewed intensity, in the context of genetic factors that influence the development of sexually differentiated aspects of this insect. Three categories of genetic variations that cause anomalies in courtship and mating behaviors are discussed: (1) mutants isolated with regard to courtship defects, of which putatively courtship‐specific variants such as thefruitlessmutant are a subset; (2) general behavioral and neurological variants (including sensory and learning mutants), whose defects include subnormal reproductive performance; and (3) mutations of genes within the sex‐determination regulatory hierarchy ofDrosophila, the analysis of which has included studies of reproductive behavior. Recent studies of mutations in two of these categories have provided new insights into the control of neuronally based aspects of sex‐specific behavior. Thedoublesexgene, the final factor acting in the sex‐determination hierarchy, had been previously thought to regulate all aspects of sexual differentiation. Yet, it has been recently shown thatdoublesexdoes not control at least one neuronally‐determined feature of sex‐specific anatomy—a muscle in the male's abdomen, whose normal development is, however, dependent on the action offruitless.These considerations prompted us to examine further (and in some cases re‐examine) the influences exerted by sex‐determination hierarchy genes on behavior. Our results—notably those obtained from assessments ofdoublesexmutations' effects on general reproductive actions and on a particular component of the courtship sequence (male “singing” behavior)—lead to the suggestion that there is a previously unrecognized branch within the sexdetermination hierarchy, which controls the differentiation of the male‐ and female‐ specific phenotypes ofDrosophila.This new branch separates from thedoublesex‐related one immediately before the action of that gene (just afterfransformerandtransformer‐2) and appears to control as least some aspects of neuronally determined sexual differentiation of males. © 1994 Wiley‐Liss, Inc.