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At least 919 records · Page 51Linked to original sources
PubMed1988

Plasmodium falciparum gene encoding a protein similar to the 78-kDa rat glucose-regulated stress protein.

Genes homologous to heat shock protein 70 have been described in parasitic protozoa. It has been proposed that they may be important to the parasite as it moves from the vertebrate host at 37 degrees C to the insect. We now describe a genomic DNA clone isolated from Plasmodium falciparum that encodes a protein similar in sequence to a mammalian heat shock-related protein, the 78-kDa glucose-regulated protein of rat and hamster. The gene is expressed during the erythrocytic stage in both asexual and sexual parasites (RNA blot analysis) and a 72-kDa protein is immunoprecipitated from erythrocytic stage parasites. Importantly, the sequence of the clone is similar to the canonical sequence at the carboxyl termini of glucose-regulated proteins of mammals that determines their localization within endoplasmic reticulum. Since the parasite sequence has only three (Asp-Glu-Leu) of the four carboxyl-terminal amino acids, its location and its function within the parasite remain to be determined.

Amino Acid Sequence↗
PubMed2006

Five rules for the evolution of cooperation.

Cooperation is needed for evolution to construct new levels of organization. Genomes, cells, multicellular organisms, social insects, and human society are all based on cooperation. Cooperation means that selfish replicators forgo some of their reproductive potential to help one another. But natural selection implies competition and therefore opposes cooperation unless a specific mechanism is at work. Here I discuss five mechanisms for the evolution of cooperation: kin selection, direct reciprocity, indirect reciprocity, network reciprocity, and group selection. For each mechanism, a simple rule is derived that specifies whether natural selection can lead to cooperation.

Biological Evolution↗
PubMed1981

Synthesis of Black Beetle Virus Proteins in Cultured Drosophila Cells: Differential Expression of RNAs 1 and 2.

Black beetle virus is an insect virus with a split genome consisting of two single-stranded, messenger-active RNA molecules with molecular weights of 1.0 x 10(6) (RNA 1) and 0.5 x 10(6) (RNA 2), respectively. Virions contained two proteins, beta with a molecular weight of 43,000 (43K) and gamma (5K), and traces of a third protein, alpha (47K). When translated in cell-free extracts of rabbit reticulocytes, RNA 1 directed the synthesis of protein A (104K), whereas RNA 2 synthesized protein alpha. The in vitro translation efficiency of the two RNAs was roughly equal. Infection of cultured Drosophila cells induced the synthesis of five new proteins: A, alpha, beta, gamma, and B (10K), detected by autoradiography of polyacrylamide gels after electrophoresis of extracts from [(35)S]methionine-labeled cultures. All but protein gamma could also be detected by staining with Coomassie brilliant blue, indicating vigorous synthesis of viral proteins. Pulse-chase experiments in infected cells revealed the disappearance of protein alpha and the coordinate appearance of proteins beta and gamma, supporting an earlier proposal that coat protein of mature virions is made by cleavage of precursor alpha. Proteins A and B were stable in such pulse-chase experiments. The three classes of virus-induced proteins, represented by A, B, and alpha, were synthesized in markedly different amounts and with different kinetics. Synthesis of proteins A and B peaked early in infection and then declined, whereas synthesis of coat protein precursor alpha peaked much later. These results suggest that RNA 1 controls early replication functions via protein A (and also possibly protein B), whereas RNA 2 controls synthesis of coat protein required later for virion assembly.

Journal Article↗
PubMed2006

Long-term maintenance of in vitro cultured honeybee (Apis mellifera) embryonic cells.

BACKGROUND: In vitro cultivation of cells allows novel investigation of in vivo- mechanisms and is a helpful tool in developmental biology, biochemistry and functional genomics. Numerous cell lines of insect species, e.g., silkworm and mosquito, have been reported. However, this is not the case for successful long-term cultivation of cells in honeybees. RESULTS: Methods for cultivation of honeybee embryonic cells are discussed here. Pre-gastrula stage embryos were used to initiate cultures, and cells were reared on 96-wells microplates with Grace insect medium, supplemented with Fetal Bovine Serum. Cells proliferated in clusters, and maintained viable and mitotic for more than three months. CONCLUSION: We report here, for the first time, long-term cultivation of honeybee cells. Results represent a highly useful in vitro-system for studying a model organism of increasing importance in areas such as aging, sociality and neurobiology.

Animals↗
PubMed2002

[Transferring of multiple insect-resisting genes into two-line genetic male sterile rice Pei'ai 64S by particle bombardment].

Transformation of two-line genetic male sterile indica rice variety Pei'ai 64S was conducted by particle bombardment. Three insect-resisting genes ligased into plasmid vector pKC-3 was introduced into calli derived from mature embryo and a total of 33 transgenic plants had been obtained. The PCR and Southern blot analysis of each different gene in R0 plants and also PCR analysis of each different gene in R1 plants showed the integration of three insect-resisting genes into the genome of transgenic plants which could stably pass down.

Animals↗
PubMedDate not supplied

[Expression of hepatitis A virus procapsids in the insect cells infected by recombinant baculovirus].

The recombinant baculocvirus containing genome P1-2A-P3 of hepatitis A virus (HAV) was constructed and used for infecting the Sf9 insect cells. It was demonstrated that the deletion of 2BC from HAV polyprotein and the insertion of a new 3C protease cleavage site between P1-2A and P3 did not interfere with the processing of polyprotein or with forming the 70S-procapsids. The identity of the protein contents as well as of morphological and antigen characteristics, obtained in Sf9-cells, to HAV empty capsids, which take shape in the infected mammal cells, proves that it is possible to use them in making the vaccine and diagnostic preparations.

Animals↗
PubMed2005

Pulsed-field gel electrophoresis to study the diversity of whole-genome organization in the genus Ochrobactrum.

The alpha-proteobacterial genus Ochrobactrum groups together organisms that display varied life-styles, such as free-living bacteria, members of rhizosphere and soil, nitrogen-fixing bacteria in plant nodules, xenobiotic-degrading bacteria, colonizers of nematodes and insects, and opportunistic human pathogens. The genomes of nine strains of Ochrobactrum anthropi and eight strains of Ochrobactrum intermedium were analyzed by pulsed-field gel electrophoresis of the whole genome and of I-CeuI digestion fragments. All isolates and type strains of O. anthropi and O. intermedium possessed two high-molecular-weight circular replicons identified as two independent chromosomes on the basis of 16S rDNA hybridization. The genome of the type strain of Ochrobactrum tritici, Ochrobactrum grignonense, and Ochrobactrum gallinifaecis also contained two circular chromosomes. The megaplasmid content was highly variable even among strains in the same species, leading to whole-genome sizes that ranged from 5.060 to 8.300 Mbp and from 4.690 to 7.680 Mbp for O. anthropi and O. intermedium, respectively. This exceptional level of genomic diversity could be related to the adaptability of Ochrobactrum spp. to various ecological niches.

Chromosomes, Bacterial↗
PubMed2003

A preliminary linkage map of the hard tick, Ixodes scapularis.

A linkage map of the Ixodes scapularis genome was constructed, based upon segregation amongst 127 loci. These included 84 random amplified polymorphic DNA (RAPD) markers, 32 Sequence-Tagged RAPD (STAR) markers, 5 cDNAs, and 5 microsatellites in 232 F1 intercross progeny from a single, field-collected P1 female. A preliminary linkage map of 616 cM was generated across 14 linkage groups with one marker every 10.8 cM. Assuming a genome size of approximately 109 bp, the relationship of physical to genetic distance was found to be approximately 300 kb/cM in the I. scapularis genome.

Animals↗
PubMed2006

Molecular cloning and chromosomal localization of the Bombyx Sex-lethal gene.

We cloned Bm-Sxl, an orthologue of the Drosophila melanogaster Sex-lethal (Sxl) gene from embryos of Bombyx mori. The full-length cDNAs were of 2 sizes, 1528 and 1339 bp, and were named Bm-Sxl-L and Bm-Sxl-S, respectively. Bm-Sxl-L consists of 8 exons and spans more than 20 kb of genomic DNA. The open reading frame (ORF) codes for a protein 336 amino acids in length. Bm-Sxl-S is a splice variant that lacks the second exon. This creates a new translation start 138 nucleotides downstream and an ORF that codes for 46 amino acids fewer at the N-terminus. Linkage analysis using an F2 panel mapped Bm-Sxl to linkage group 16 at 69.8 cM. We isolated 2 BACs that include the Bm-Sxl gene. With BAC-FISH we located Bm-Sxl cytogenetically on the chromosome corresponding to linkage group 16 (LG16) at position >68.8 cM.

Alternative Splicing↗
PubMed2005

Genome-wide gene expression in response to parasitoid attack in Drosophila.

BACKGROUND: Parasitoids are insect parasites whose larvae develop in the bodies of other insects. The main immune defense against parasitoids is encapsulation of the foreign body by blood cells, which subsequently often melanize. The capsule sequesters and kills the parasite. The molecular processes involved are still poorly understood, especially compared with insect humoral immunity. RESULTS: We explored the transcriptional response to parasitoid attack in Drosophila larvae at nine time points following parasitism, hybridizing five biologic replicates per time point to whole-genome microarrays for both parasitized and control larvae. We found significantly different expression profiles for 159 probe sets (representing genes), and we classified them into 16 clusters based on patterns of co-expression. A series of functional annotations were nonrandomly associated with different clusters, including several involving immunity and related functions. We also identified nonrandom associations of transcription factor binding sites for three main regulators of innate immune responses (GATA/srp-like, NF-kappaB/Rel-like and Stat), as well as a novel putative binding site for an unknown transcription factor. The appearance or absence of candidate genes previously associated with insect immunity in our differentially expressed gene set was surveyed. CONCLUSION: Most genes that exhibited altered expression following parasitoid attack differed from those induced during antimicrobial immune responses, and had not previously been associated with defense. Applying bioinformatic techniques contributed toward a description of the encapsulation response as an integrated system, identifying putative regulators of co-expressed and functionally related genes. Genome-wide studies such as ours are a powerful first approach to investigating novel genes involved in invertebrate immunity.

Animals↗
PubMed2001

Expression pattern of Drosophila ret suggests a common ancestral origin between the metamorphosis precursors in insect endoderm and the vertebrate enteric neurons.

The RET gene, encoding a receptor tyrosine kinase, is unusual among human protooncogenes in that its mutant alleles are implicated in a developmental defect involving enteric neurons as well as in tumorigenesis. The cells affected in both types of disorders are derived from the neural crest. Targeted disruption of mouse ret has revealed an additional role in kidney development. Here we report the analysis of a ret homolog in Drosophila melanogaster, an arthropod with no neural crest. Drosophila ret (D-ret) encodes a protein of 1,235 amino acids that has all of the domains identified in the vertebrate ret, including a cadherin motif. During embryogenesis, D-ret mRNA is first detected in the yolk sac at the late gastrula stage. In the postgastrula, D-ret is expressed in the foregut neurons, excretory system, peripheral ganglia, and the central nervous system. Thus, despite the wide divergence of early embryonic fate maps between vertebrates and invertebrates, D-ret is expressed in cells that are presumed to be the functional equivalents of the ret-expressing cells in vertebrates. Unexpectedly, D-ret is also expressed in the imaginal islands of the endodermal gut. These cells are proliferation-competent precursors for adult midgut that are diffusely embedded in the growth-arrested juvenile gut. These ret-expressing nonneuronal cells are strikingly analogous to vertebrate enteric neurons in their topography, but not in their cell fate. Our finding suggests a previously unrecognized phylogenetic relationship between the ret-expressing cells in vertebrates and the precursor reserves of metamorphosing insects.

Amino Acid Sequence↗
PubMed1999

Isolation and characterization of human DNA from mosquitoes (Culicidae).

Human DNA was prepared from mosquitoes (Culicidae) which were collected in a room shared by four human individuals. Several insects did not contain human blood and DNA preparation from them was not successful. However, high molecular weight human genomic DNA could be isolated from four insects. HLA-DQalpha and D1S80 analysis showed that the blood from one insect was a mixture from two persons, whereas the others contained blood from single individuals. Human DNA isolated 26 h after ingestion was still suitable for typing. These results showed that DNA isolated from mosquitoes is qualitatively and quantitatively sufficient for DNA typing and could be helpful to identify individuals involved in certain cases of body violence or captivity.

Alleles↗
PubMed2006

Differential gene expression and phenotypic plasticity in behavioural castes of the primitively eusocial wasp, Polistes canadensis.

Understanding how a single genome can produce a variety of different phenotypes is of fundamental importance in evolutionary and developmental biology. One of the most striking examples of phenotypic plasticity is the female caste system found in eusocial insects, where variation in reproductive (queens) and non-reproductive (workers) phenotypes results in a broad spectrum of caste types, ranging from behavioural through to morphological castes. Recent advances in genomic techniques allow novel comparisons on the nature of caste phenotypes to be made at the level of the genes in organisms for which there is little genome information, facilitating new approaches in studying social evolution and behaviour. Using the paper wasp Polistes canadensis as a model system, we investigated for the first time how behavioural castes in primitively eusocial insect societies are associated with differential expression of shared genes. We found that queens and newly emerged females express gene expression patterns that are distinct from each other whilst workers generally expressed intermediate patterns, as predicted by Polistes biology. We compared caste-associated genes in P. canadensis with those expressed in adult queens and workers of more advanced eusocial societies, which represent four independent origins of eusociality. Nine genes were conserved across the four taxa, although their patterns of expression and putative functions varied. Thus, we identify several genes that are putatively of evolutionary importance in the molecular biology that underlies a number of caste systems of independent evolutionary origin.

Adaptation, Physiological↗
PubMed2002

Mutations in Drosophila myb lead to centrosome amplification and genomic instability.

We have previously established that the single myb gene in Drosophila melanogaster, Dm myb, which is related to the proto-oncogene Myb, is required for the G2/M transition of the cell cycle and for suppression of endoreduplication in pupal wing cells. We now report that studies of the abdominal phenotype in loss-of-function Dm myb mutants reveal additional roles for Dm myb in the cell cycle, specifically in mitosis. Abdominal epidermal cells that are mutant for Dm myb proliferate more slowly than wild-type controls throughout pupation, with particularly sluggish progression through the early stages of mitosis. Abnormal mitoses associated with multiple functional centrosomes, unequal chromosome segregation, formation of micronuclei, and/or failure to complete cell division are common in the later cell cycles of mutant cells. Resulting nuclei are often aneuploid and/or polyploid. Similar defects have also been observed in loss-of-function mutations of the tumor suppressor genes p53, Brca1 and Brca2. These data demonstrate that in abdominal epidermal cells, Dm myb is required to sustain the appropriate rate of proliferation, to suppress formation of supernumerary centrosomes, and to maintain genomic integrity.

Abdomen↗
PubMed2025

De Novo Whole Genome Assemblies of Unusual Case-Making Caddisflies (Trichoptera) Highlight Genomic Convergence in the Composition of the Major Silk Gene (h-fibroin).

Trichoptera (caddisflies) is one of the most species-rich orders of aquatic insects. Species of caddisflies cover a broad ecological diversity as exemplified by various uses of underwater silk secretions. Diversity of silk use generally aligns with the evolution of major caddisfly lineages, specifically at the subordinal level: Annulipalpia (retreat makers) and Integripalpia (cocoon and tube-case makers). However, silk use within suborders differs for a few exceptional species in these clades. In this study, we provide the first whole genome assemblies and annotations for two unusual Integripalpia species: Limnocentropus insolitus, whose hard tube-case is anchored to boulders by a rigid, elongated silken stalk, and Phryganopsyche brunnea which builds a "floppy" cylindrical case that lacks the typical robustness of tube-cases. Its texture rather resembles that of the flexible retreats built by Annulipalpia. Using the two high-quality genome assemblies, we identified and annotated the major silk gene, h-fibroin, and compared its amino acid composition across various groups, including retreat, cocoon, and tube-case makers. Our phylogenetic analysis confirmed the phylogenetic position of the two species in the tube-case-making clade. The major silk gene of L. insolitus shows a similar amino acid composition to other tube-case-making species. In contrast, the amino acid composition of P. brunnea resembles that of retreat-making species, in particular with regard to the high content of proline. This is consistent with the hypothesis that proline could be linked to enhanced extensibility of silk fibers. Taken together, our results underscore the role of silk genes in shaping the evolutionary ecology of retreat- and tube-case-making in caddisflies.

Animals↗
PubMed1993

Opa-like repeats in the genome of the Medfly Ceratitis capitata.

The sequence determination of several genomic clones isolated from the Mediterranean fruitfly Ceratitis capitata identified the existence of opa-like repeats, often more than one being clustered in small chromosomal segments. These repeats have previously been shown to consist of stretches of tandemly reiterated glutamine-encoding residues, and they are found in multiple genes of several organisms. Most of the repeats described here are flanked or interrupted by stop codons in all reading frames and, thus, could not possibly be part of protein-coding sequences. Furthermore, these repeats, of which there are several hundred in the genome of the Medfly, can be used effectively for the determination of sequence polymorphisms, providing a convenient approach to obtain additional landmarks for the construction of genomic maps of this economically important insect.

Amino Acid Sequence↗
PubMed2006

Behavioral genomics of honeybee foraging and nest defense.

The honeybee has been the most important insect species for study of social behavior. The recently released draft genomic sequence for the bee will accelerate honeybee behavioral genetics. Although we lack sufficient tools to manipulate this genome easily, quantitative trait loci (QTLs) that influence natural variation in behavior have been identified and tested for their effects on correlated behavioral traits. We review what is known about the genetics and physiology of two behavioral traits in honeybees, foraging specialization (pollen versus nectar), and defensive behavior, and present evidence that map-based cloning of genes is more feasible in the bee than in other metazoans. We also present bioinformatic analyses of candidate genes within QTL confidence intervals (CIs). The high recombination rate of the bee made it possible to narrow the search to regions containing only 17-61 predicted peptides for each QTL, although CIs covered large genetic distances. Knowledge of correlated behavioral traits, comparative bioinformatics, and expression assays facilitated evaluation of candidate genes. An overrepresentation of genes involved in ovarian development and insulin-like signaling components within pollen foraging QTL regions suggests that an ancestral reproductive gene network was co-opted during the evolution of foraging specialization. The major QTL influencing defensive/aggressive behavior contains orthologs of genes involved in central nervous system activity and neurogenesis. Candidates at the other two defensive-behavior QTLs include modulators of sensory signaling (Am5HT(7) serotonin receptor, AmArr4 arrestin, and GABA-B-R1 receptor). These studies are the first step in linking natural variation in honeybee social behavior to the identification of underlying genes.

Animals↗