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At least 757 records · Page 42Linked to original sources
PubMed1995

Analysis of the paramyosin/miniparamyosin gene. Miniparamyosin is an independently transcribed, distinct paramyosin isoform, widely distributed in invertebrates.

Miniparamyosin, a distinct Drosophila melanogaster paramyosin isoform of 60 kDa, is shown here to be encoded by the same gene as paramyosin. The gene, located at 66D14, spans over 12.8 kilobases (kb) and is organized into 10 exons, 9 of which code for the paramyosin transcripts. An exon, located between exons 7 and 8, codes for the 5'-end of the miniparamyosin, and the two proteins share the two last exons of the gene. Mapping of the 5'-ends of these transcripts indicates that the paramyosin and miniparamyosin mRNAs arise from two overlapping transcriptional units; the miniparamyosin transcription initiation site is located inside a paramyosin intron, 8 kb downstream of the one used for paramyosin transcription. The existence of two different promoters and the conserved and nonconserved features of their sequences suggest a very complex regulation of these two muscle proteins. In fact, while paramyosin is expressed at two distinct stages of development as most other Drosophila muscle proteins, miniparamyosin appears late in development, being present only in the adult musculature. The absence of exon 1B, the specific exon of miniparamyosin, in the nematode Caenorhabditis elegans, as well as additional lines of evidence support the lack of miniparamyosin in this particular organism. However, it is present in most invertebrate species examined, including different arthropod, annelid, mollusc, and echinoderm species.

Animals↗
PubMed2002

Nitric oxide limits parasite development in vectors and in invertebrate intermediate hosts.

Nitric oxide (NO) possesses antiparasitic effects on both Protozoa and Metazoa in vertebrate definitive and intermediate hosts. Inducible NO limits parasite development also in Rhodnius prolixus and Anopheles stephensi, the natural vectors of human trypanosomiasis and malaria respectively, and in the snail Biomphalaria glabrata, a natural invertebrate intermediate host of human schistosomiasis. Therefore, NO limits Trypanosoma, Plasmodium, and Schistosoma development at all stages of the parasite life cycle.

Animals↗
PubMed1961

Applications of freeze-substitution to electron microscope studies of invertebrate oocytes.

A modified freeze-substitution process is described which gives a low percentage (less than 5 per cent) of preparations of invertebrate eggs which appear to be ice crystal-free at the resolution of the electron microscope. The mitochondria show no membranes in these preparations but can be recognized by internal spaces with the size and the distribution of the cristae. The Golgi bodies resemble those seen with diffusion fixatives, but the limiting membranes are here double; that is, they appear to be a triple-layered sandwich with two outer dark approximately 25A layers and an inner light layer of the same thickness. The endoplasmic reticulum is clearly present and resembles that seen with diffusion fixatives. Here again, the limiting membranes are double with the same dimensions as those in the Golgi bodies. The membranes of the Golgi bodies and ER are seen after permanganate but not lead hydroxide staining. The hyaloplasm (or "cell sap") is crowded with 150 to 200A particles and these are also seen lining the ER membranes. In general, the structures as seen with the present technique show considerable similarity to those seen with diffusion fixatives.

Animals↗
PubMed1997

A key for freshwater invertebrates using fuzzy logic.

MOTIVATION: This paper summarizes a biological key using a fuzzy logic expert system. This approach allows the user to make some errors, be uncertain about some answers and not answer questions if unsure, but have an opportunity to identify unknown specimens correctly. This approach was adopted in order to develop a 'forgiving' key for users with little or no prior knowledge of identification. The system was implemented using a multi-media expert system builder, 'Matcher', operating in a Microsoft Windows environment. RESULTS: The paper reports the design issues for a key to identify freshwater invertebrates to family level and describes the types of questions used within the key, the fuzzy inference engine, the structure of the system and the methodology adopted for testing it. Following this, an empirical test is reported of the hypothesis that a fuzzy logic expert system can improve identification accuracy for a sample of intended users. Finally, the discussion considers the practicalities of using such a system as an aid to organism identification.

Algorithms↗
PubMed1997

Invertebrate retroviruses: ZAM a new candidate in D.melanogaster.

ZAM, a new retroelement of Drosophila melanogaster, was identified as a mutational insertion at the white locus. It displays all the structural features of a vertebrate retrovirus. Its three open reading frames encode predicted products resembling the products of the gag, pol and env genes of retroviruses. Its transcription gives rise to an 8.6 kb full-length RNA and a 1.7 kb spliced message for the env gene. The latter encodes an envelope protein that is typical of elements having an extracellular phase of the life cycle. The identification of a ZAM envelope retrogene provides evidence that ZAM is mobilized through a reverse trancriptional process in the germ line of flies. We report that ZAM is distributed differently among D.melanogaster strains. Two stocks out of >15 tested display a ZAM high copy number, with numerous copies distributed on chromosomal arms. This high copy number is associated with a high transcriptional rate of ZAM. The existence of these two categories of strains offers a new genetic system in which the properties of a potential invertebrate retrovirus can be tested.

Amino Acid Sequence↗
PubMed2001

Invertebrate connectin spans as much as 3.5 microm in the giant sarcomeres of crayfish claw muscle.

In crayfish claw closer muscle, the giant sarcomeres are 8.3 microm long at rest, four times longer than vertebrate striated muscle sarcomeres, and they are extensible up to 13 microm upon stretch. Invertebrate connectin (I-connectin) is an elastic protein which holds the A band at the center of the sarcomere. The entire sequence of crayfish I-connectin was predicted from cDNA sequences of 53 424 bp (17 352 residues; 1960 kDa). Crayfish I-connectin contains two novel 68- and 71-residue repeats, and also two PEVK domains and one kettin region. Kettin is a small isoform of I-connectin. Immunoblot tests using antibody to the 68-residue repeats revealed the presence of I-connectin also in long sarcomeres of insect leg muscle and barnacle ventral muscle. Immunofluorescence microscopy demonstrated that the two repeats, the long spacer and the two PEVK domains contribute to sarcomere extension. These regions rich in charged amino acids, occupying 63% of the crayfish I-connectin molecule, may allow a span of a 3.5 microm distance as a new class of composite spring.

Amino Acid Sequence↗
PubMed2004

Fucosyltransferase substrate specificity and the order of fucosylation in invertebrates.

Core alpha1,6-fucosylation is a conserved feature of animal N-linked oligosaccharides being present in both invertebrates and vertebrates. To prove that the enzymatic basis for this modification is also evolutionarily conserved, cDNAs encoding the catalytic regions of the predicted Caenorhabditis elegans and Drosophila melanogaster homologs of vertebrate alpha1,6-fucosyltransferases (E.C. 2.4.1.68) were engineered for expression in the yeast Pichia pastoris. Recombinant forms of both enzymes were found to display core fucosyltransferase activity as shown by a variety of methods. Unsubstituted nonreducing terminal GlcNAc residues appeared to be an obligatory feature of the substrate for the recombinant Caenorhabditis and Drosophila alpha1,6-fucosyltransferases, as well as for native Caenorhabditis and Schistosoma mansoni core alpha1,6-fucosyltransferases. On the other hand, these alpha1,6-fucosyltransferases could not act on N-glycopeptides already carrying core alpha1,3-fucose residues, whereas recombinant Drosophila and native Schistosoma core alpha1,3-fucosyltransferases were able to use core alpha1,6-fucosylated glycans as substrates. Lewis-type fucosylation was observed with native Schistosoma extracts and could take place after core alpha1,3-fucosylation, whereas prior Lewis-type fucosylation precluded the action of the Schistosoma core alpha1,3-fucosyltransferase. Overall, we conclude that the strict order of fucosylation events, previously determined for fucosyltransferases in crude extracts from insect cell lines (core alpha1,6 before core alpha1,3), also applies for recombinant Drosophila core alpha1,3- and alpha1,6-fucosyltransferases as well as for core fucosyltransferases in schistosomal egg extracts.

Amino Acid Sequence↗
PubMed2026

Di-, tri-, and tetranucleotide frequencies covary with lifespan and genome size across protostome invertebrates.

Animal lifespans span orders of magnitude, yet how genome sequence covaries with lifespan remains poorly characterized outside vertebrates. Although promoter CpG density has been linked to vertebrate longevity due to its gene-regulatory function through DNA methylation, it is unclear whether such patterns are promoter- and CpG-specific, or if they reflect broader sequence evolution. We curated maximum lifespan estimates for 466 protostome species spanning eight phyla with available genome assemblies and quantified mono-, di-, tri-, and tetranucleotide composition across whole genomes, intergenic regions, and six gene-associated regions (two upstream regions, exons, introns, and two downstream regions) defined using Benchmarking Universal Single-Copy Orthologs. Dinucleotide observed/expected ratios showed significant associations with lifespan and genome size in different ways. Lifespan-associated motifs were most pronounced in gene-associated non-coding regions, especially in introns and downstream regions, whereas genome-size effects were strongest in whole-genome and intergenic sequence. Tri- and tetranucleotide observed/expected ratios broadly recapitulated this regional organization. In contrast, GC content was not associated with lifespan across regions, indicating that the observed signals are not explained by mononucleotide composition but instead by how those nucleotides are arranged into short sequence motifs. These results suggest that lifespan and genome size show distinct but overlapping associations with regional sequence composition across invertebrate species and that lifespan-associated motif evolution extends beyond vertebrate promoter methylation architectures.

CpG density↗
PubMed2006

Insights into early extracellular matrix evolution: spongin short chain collagen-related proteins are homologous to basement membrane type IV collagens and form a novel family widely distributed in invertebrates.

Collagens are thought to represent one of the most important molecular innovations in the metazoan line. Basement membrane type IV collagen is present in all Eumetazoa and was found in Homoscleromorpha, a sponge group with a well-organized epithelium, which may represent the first stage of tissue differentiation during animal evolution. In contrast, spongin seems to be a demosponge-specific collagenous protein, which can totally substitute an inorganic skeleton, such as in the well-known bath sponge. In the freshwater sponge Ephydatia mülleri, we previously characterized a family of short-chain collagens that are likely to be main components of spongins. Using a combination of sequence- and structure-based methods, we present evidence of remote homology between the carboxyl-terminal noncollagenous NC1 domain of spongin short-chain collagens and type IV collagen. Unexpectedly, spongin short-chain collagen-related proteins were retrieved in nonsponge animals, suggesting that a family related to spongin constitutes an evolutionary sister to the type IV collagen family. Formation of the ancestral NC1 domain and divergence of the spongin short-chain collagen-related and type IV collagen families may have occurred before the parazoan-eumetazoan split, the earliest divergence among extant animal phyla. Molecular phylogenetics based on NC1 domain sequences suggest distinct evolutionary histories for spongin short-chain collagen-related and type IV collagen families that include spongin short-chain collagen-related gene loss in the ancestors of Ecdyzosoa and of vertebrates. The fact that a majority of invertebrates encodes spongin short-chain collagen-related proteins raises the important question to the possible function of its members. Considering the importance of collagens for animal structure and substratum attachment, both families may have played crucial roles in animal diversification.

Amino Acid Sequence↗
PubMed1999

Invertebrate compounds acting on the hemostatic mechanism.

Physiological secretions from some invertebrates have toxic effects on mammalian blood coagulation and fibrinolytic systems. Some of these effects occur because the substances contained in the secretions resemble the components of the hemostatic system. Some of the substances have been characterized, and have been found to have similar molecular weights or sequences, which may indicate a common ancestry. The components can be divided into five groups: antithrombic agents (group I); inhibitors and activators of the prothrombinase complex (group II); substances that affect platelet function (group III); substances that affect the fibrinolytic mechanism (group IV); and a group of miscellaneous agents whose activities are difficult to group together (group V). In group I special mention of the antithrombin agents in Hirudo medicinalis should be made. In group II, the agents affecting the prothrombinase complex are antistasin from Haementeria officinalis, ghilanten from Haementeria Ghiliani and the tick anticoagulant protein from Ornithodoros moubata, a factor V activator/inhibitor from Lonomia achelous and factor II and factor X activators from L. achelous and Lonomia obliqua. Examples of factors which affect platelet function (group III) are glossina from the black fly Glossina morsitans, calin from H. medicinalis, decorsin (a desintegrin) from Macrobdella decorsa, and FAGA from Stichopus japonicus selenka. The first three of these are inhibitors of platelet aggregation, and the last is an inducer. The plasminogen activators (group IV) from the L. achelous caterpillar and Eutriatoma maculata trigger the fibrinolytic system, whereas hementin from H. officinalis and hementerin from Haementeria depressa are directly fibrinolytic. The last group of substances (group V) include those with factor-XIIa-like activity from D. farinae, kallikrein-like activity and a factor XIII degrading enzyme from L. achelous, destabilase from H. medicinalis and prolixin S (nitroforin 2, or anti-factor-IXa) from Rhodnius prolixus. Some of these components have been well characterized, cloned and prepared in recombinant form, and seem to be very promising from the therapeutic point of view.

Animals↗
PubMed1994

Brooding and the evolution of parthenogenesis: strategy models and evidence from aquatic invertebrates.

Developmental defects are expected to be common and severe in the early evolution of parthenogenesis, and they could help to explain the predominance of sexual forms of reproduction. It is difficult, however, to see how such defects might explain the ecological and phylogenetic correlates of sex. Here we suggest that internally fertilized animals that brood their young may be more susceptible to invasion by parthenogenetic mutants. The reason is that brooders could establish 'selective arenas' in which developmentally defective embryos are competitively displaced. Brooders could also selectively abort defective embryos, and replace them with minimal cost. Consistent with these ideas, we found a striking association between brooding and parthenogenesis in aquatic invertebrates. For example, in the Cnidaria and Mollusca, parthenogenesis is significantly more common in lineages that retain their young through the early stages of development. Hence brooding and ecological factors (such as escape from parasites) might combine to explain the initial spread, long-term persistence, and phylogenetic distribution of parthenogenetic reproduction.

Animals↗
PubMed2003

Invertebrates and vegetation of field margins adjacent to crops subject to contrasting herbicide regimes in the Farm Scale Evaluations of genetically modified herbicide-tolerant crops.

The effects of management of genetically modified herbicide-tolerant (GMHT) crops on adjacent field margins were assessed for 59 maize, 66 beet and 67 spring oilseed rape sites. Fields were split into halves, one being sown with a GMHT crop and the other with the equivalent conventional non-GMHT crop. Margin vegetation was recorded in three components of the field margins. Most differences were in the tilled area, with fewer smaller effects mirroring them in the verge and boundary. In spring oilseed rape fields, the cover, flowering and seeding of plants were 25%, 44% and 39% lower, respectively, in the GMHT uncropped tilled margins. Similarly, for beet, flowering and seeding were 34% and 39% lower, respectively, in the GMHT margins. For maize, the effect was reversed, with plant cover and flowering 28% and 67% greater, respectively, in the GMHT half. Effects on butterflies mirrored these vegetation effects, with 24% fewer butterflies in margins of GMHT spring oilseed rape. The likely cause is the lower nectar supply in GMHT tilled margins and crop edges. Few large treatment differences were found for bees, gastropods or other invertebrates. Scorching of vegetation by herbicide-spray drift was on average 1.6% on verges beside conventional crops and 3.7% beside GMHT crops, the difference being significant for all three crops.

Agriculture↗
PubMed2003

Responses of plants and invertebrate trophic groups to contrasting herbicide regimes in the Farm Scale Evaluations of genetically modified herbicide-tolerant crops.

Effects of genetically modified herbicide-tolerant (GMHT) and conventional crop management on invertebrate trophic groups (herbivores, detritivores, pollinators, predators and parasitoids) were compared in beet, maize and spring oilseed rape sites throughout the UK. These trophic groups were influenced by season, crop species and GMHT management. Many groups increased twofold to fivefold in abundance between early and late summer, and differed up to 10-fold between crop species. GMHT management superimposed relatively small (less than twofold), but consistent, shifts in plant and insect abundance, the extent and direction of these effects being dependent on the relative efficacies of comparable conventional herbicide regimes. In general, the biomass of weeds was reduced under GMHT management in beet and spring oilseed rape and increased in maize compared with conventional treatments. This change in resource availability had knock-on effects on higher trophic levels except in spring oilseed rape where herbivore resource was greatest. Herbivores, pollinators and natural enemies changed in abundance in the same directions as their resources, and detritivores increased in abundance under GMHT management across all crops. The result of the later herbicide application in GMHT treatments was a shift in resource from the herbivore food web to the detritivore food web. The Farm Scale Evaluations have demonstrated over 3 years and throughout the UK that herbivores, detritivores and many of their predators and parasitoids in arable systems are sensitive to the changes in weed communities that result from the introduction of new herbicide regimes.

Agriculture↗
PubMed2002

Metamorphosis of benthic invertebrate larvae: a sensitive indicator for detection of changes in marine environmental quality.

Many marine coastal ecosystems are threatened by increasing waste discharge, and bioassays are needed because chemical and physical tests alone are not sufficient to assess potential effects on aquatic biota. In light of the fact that larval metamorphosis of benthic invertebrates is usually very sensitive to environmental changes, this paper reviews sensitivity comparisons of larval metamorphosis with other common bioassays in different species and those in different developmental stages of the same species, and it discusses the potential use of larval metamorphosis as an indicator of marine environmental quality.

Animals↗
PubMed2001

Bridging the "beech-gap": New Zealand invertebrate phylogeography implicates Pleistocene glaciation and Pliocene isolation.

The existence of areas of lower endemism and disjunction of New Zealand biota is typified by Nothofagus beech trees (hence "beech-gap") and have been attributed to a variety of causes ranging from ancient fault-mediated displacement (20-25 million years ago) to Pleistocene glacial extirpation (< 1.8 million years ago). We used cytochrome oxidase I and 12S mtDNA sequence data from a suite of endemic invertebrates to explore phylogeographic depth and patterns in South Island, New Zealand, where the "beech-gap" occurs. Phylogeographic structure and genetic distance data are not consistent with ancient vicariant processes as a source of observed pattern. However, we also find that phylogeographic patterns are not entirely congruent and appear to reflect disparate responses to fragmentation, which we term "gap," "colonization," and "regional." Radiations among congenerics, and in at least one instance within a species, probably took place in the Pliocene (2-7 million years ago), possibly under the influence of the onset of mountain building. This orogenic phase may have had a considerable impact on the development of the biota generally. Some of the taxa that we studied do not appear to have suffered range reduction during Pleistocene glaciation, consistent with their survival throughout that epoch in alpine habitats to which they are adapted. Other taxa have colonized the beech-gap recently (i.e., after glaciation), whereas few among our sample retain evidence of extirpation in the most heavily glaciated zone.

Animals↗
PubMed2004

The prophenoloxidase-activating system in invertebrates.

A major innate defense system in invertebrates is the melanization of pathogens and damaged tissues. This important process is controlled by the enzyme phenoloxidase (PO) that in turn is regulated in a highly elaborate manner for avoiding unnecessary production of highly toxic and reactive compounds. Recent progress, especially in arthropods, in the elucidation of mechanisms controlling the activation of zymogenic proPO into active PO by a cascade of serine proteinases and other factors is reviewed. The proPO-activating system (proPO system) is triggered by the presence of minute amounts of compounds of microbial origins, such as beta-1,3-glucans, lipopolysaccharides, and peptidoglycans, which ensures that the system will become active in the presence of potential pathogens. The presence of specific proteinase inhibitors prevents superfluous activation. Concomitant with proPO activation, many other immune reactions will be produced, such as the generation of factors with anti-microbial, cytotoxic, opsonic, or encapsulation-promoting activities.

Animals↗
PubMed2004

Anti-microbial peptides: from invertebrates to vertebrates.

Gene-encoded anti-microbial peptides (AMPs) are widespread in nature, as they are synthesized by microorganisms as well as by multicellular organisms from both the vegetal and the animal kingdoms. These naturally occurring AMPs form a first line of host defense against pathogens and are involved in innate immunity. Depending on their tissue distribution, AMPs ensure either a systemic or a local protection of the organism against environmental pathogens. They are classified into three major groups: (i) peptides with an alpha-helical conformation (insect cecropins, magainins, etc.), (ii) cyclic and open-ended cyclic peptides with pairs of cysteine residues (defensins, protegrin, etc.), and (iii) peptides with an over-representation of some amino acids (proline rich, histidine rich, etc.). Most AMPs display hydrophobic and cationic properties, have a molecular mass below 25-30 kDa, and adopt an amphipathic structure (alpha-helix, beta-hairpin-like beta-sheet, beta-sheet, or alpha-helix/beta-sheet mixed structures) that is believed to be essential to their anti-microbial action. Interestingly, in recent years, a series of novel AMPs have been discovered as processed forms of large proteins. Despite the extreme diversity in their primary and secondary structures, all natural AMPs have the in vitro particularity to affect a large number of microorganisms (bacteria, fungi, yeast, virus, etc.) with identical or complementary activity spectra. This review focuses on AMPs forming alpha-helices, beta-hairpin-like beta-sheets, beta-sheets, or alpha-helix/beta-sheet mixed structures from invertebrate and vertebrate origins. These molecules show some promise for therapeutic use.

Amino Acid Sequence↗
PubMed2006

A truce with neutral theory: local deterministic factors, species traits and dispersal limitation together determine patterns of diversity in stream invertebrates.

1. Studies seeking to explain local patterns of diversity have typically relied on niche explanations, reflected in correlations with local environmental conditions, or neutral theory, invoking dispersal processes and speciation. 2. We used macroinvertebrate community data from 10 streams that varied independently in local ecological conditions and spatial proximity. Neutral theory predicts that similarity in communities will be negatively associated with distance between sites, while niche theory suggests that community similarity will be positively associated with similarity in local ecological conditions. 3. Similarity in total invertebrate, grazer and predator assemblages showed negative relationships with distance and, for grazers and predators, positive relationships with local ecological conditions. However, the best model predicting community similarity in all three cases included aspects of both local ecological conditions and distance between sites. 4. When assemblages were analysed according to dispersal ability, high-dispersal species were shown to be freely accessing all sites and community similarity was not well predicted by either local ecology or spatial separation. Assemblages of species with low and moderate dispersal ability were best predicted by combined models, including distance between sites and local ecological factors. 5. The results suggest that the perceived dichotomy between neutral and local environmental processes in determining local patterns of diversity may not be useful. Neutral and niche processes structured these communities differentially depending on trophic level and species traits. 6. We emphasize the potential for both dispersal processes and local environmental conditions to explain local patterns of diversity.

Animals↗