Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Crustacea”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 433 records · Page 24Linked to original sources
PubMed1983

Diseases of farmed fish: non-salmonids including eels and crustacea.

All cultured fish are subject to very similar parasitic and bacterial conditions. These disease outbreaks are often stress mediated due to adverse environmental factors. The non-salmonid fishes are affected by a number of specific viral diseases which may vary from mild skin infections to systemic conditions resulting in high mortality. Nutritional diseases may be associated with dietary deficiencies or inclusion of toxic products in artificial feeds.

Animal Husbandry↗
PubMed2006

Molecular characterization of ribosomal intergenic spacer in the tadpole shrimp Triops cancriformis (Crustacea, Branchiopoda, Notostraca).

Nuclear ribosomal DNA constitutes a multigene family, with tandemly arranged units linked by an intergenic spacer (IGS), which contains initiation/termination transcription signals and usually tandemly arranged subrepeats. The structure and variability of the IGS region are analyzed here in hermaphroditic and parthenogenetic populations of the "living fossil" Triops cancriformis (Branchiopoda, Notostraca). The results indicate the presence of concerted evolution at the population level for this G+C-rich IGS region as a whole, with the major amount of genetic variability found outside the subrepeat region. The subrepeats region is composed of 3 complete repeats (a, c, d) intermingled with 3 repeat fragments (b, e, f) and unrelated sequences. The most striking datum is the absolute identity of subrepeats (except type d) occupying the same position in different individuals/populations. A putative promoter sequence is present upstream of the 18S rRNA gene, but not in subrepeats, which is at variance with other arthropod IGSs. The absence of a promoter sequence in the subrepeats and subrepeat sequence conservation suggests that this region acts as an enhancer simply by its repetitive nature, as observed in some vertebrates. The putative external transcribed spacer (840 bp) shows hairpin structures, as in yeasts, protozoans, Drosophila, and vertebrates.

Animals↗
PubMed1975

[Karyotypes, supernumerary chromosomes, rudimentary parthenogenesis and polyploidy in 2 species of the genus Phronima (Crustacea, Amphipoda)].

The diploid number of Phronima sedentaria and P. atlantica is 30, all the chromosomes are metacentric or submetacentric; the caryotypes of these two species are compared with those of other Amphipods. Some individuals of each species have a supernumerary chromosome. This element, found in both sexes, remains as an univalent at meiosis and goes earlier to one pole. In some cases nonfertilized ova undergo segmentation; this rudimentary parthenogenesis stops quickly and is partly related to polyploidization.

Aneuploidy↗
PubMed1997

Immunocytochemical localization of Na+,K(+)-ATPase in the calcium-transporting sternal epithelium of the terrestrial isopod Porcellio scaber L. (Crustacea).

Terrestrial isopods store large amounts of calcium carbonate between the epithelium and the old cuticle of the first four anterior sternites before molt. During the formation of these sternal CaCO3 deposits, large amounts of calcium are transported across the anterior sternal epithelium from the base to the apical side of the integument, and in the reverse direction during resorption of the deposit. A monoclonal antibody against the avian alpha-subunit of Na+,K(+)-ATPase was used to localize Na+,K(+)-ATPase in the anterior and the posterior sternal epithelium of Porcellio scaber. Semithin cryosections 0.5 micron thick were used for immunofluorescence microscopy and ultrathin cryosections for immunogold electron microscopy. The Na+,K(+)-ATPase was localized in the basolateral plasma membrane of the posterior and anterior sternal epithelium. The apical plasma membrane, including cytoplasmic extensions into the newly secreted cuticle, was virtually devoid of the enzyme. This pattern of immunolocalization was not affected by the direction of transepithelial calcium transport associated with the deposition and resorption phases of the molt cycle.

Animals↗
PubMed2006

The complete mitochondrial genome of the common sea slater, Ligia oceanica (Crustacea, Isopoda) bears a novel gene order and unusual control region features.

BACKGROUND: Sequence data and other characters from mitochondrial genomes (gene translocations, secondary structure of RNA molecules) are useful in phylogenetic studies among metazoan animals from population to phylum level. Moreover, the comparison of complete mitochondrial sequences gives valuable information about the evolution of small genomes, e.g. about different mechanisms of gene translocation, gene duplication and gene loss, or concerning nucleotide frequency biases. The Peracarida (gammarids, isopods, etc.) comprise about 21,000 species of crustaceans, living in many environments from deep sea floor to arid terrestrial habitats. Ligia oceanica is a terrestrial isopod living at rocky seashores of the european North Sea and Atlantic coastlines. RESULTS: The study reveals the first complete mitochondrial DNA sequence from a peracarid crustacean. The mitochondrial genome of Ligia oceanica is a circular double-stranded DNA molecule, with a size of 15,289 bp. It shows several changes in mitochondrial gene order compared to other crustacean species. An overview about mitochondrial gene order of all crustacean taxa yet sequenced is also presented. The largest non-coding part (the putative mitochondrial control region) of the mitochondrial genome of Ligia oceanica is unexpectedly not AT-rich compared to the remainder of the genome. It bears two repeat regions (4x 10 bp and 3x 64 bp), and a GC-rich hairpin-like secondary structure. Some of the transfer RNAs show secondary structures which derive from the usual cloverleaf pattern. While some tRNA genes are putative targets for RNA editing, trnR could not be localized at all. CONCLUSION: Gene order is not conserved among Peracarida, not even among isopods. The two isopod species Ligia oceanica and Idotea baltica show a similarly derived gene order, compared to the arthropod ground pattern and to the amphipod Parhyale hawaiiensis, suggesting that most of the translocation events were already present the last common ancestor of these isopods. Beyond that, the positions of three tRNA genes differ in the two isopod species. Strand bias in nucleotide frequency is reversed in both isopod species compared to other Malacostraca. This is probably due to a reversal of the replication origin, which is further supported by the fact that the hairpin structure typically found in the control region shows a reversed orientation in the isopod species, compared to other crustaceans.

Animals↗
PubMed2001

Diurnal changes in retinula cell sensitivities and receptive fields (two-dimensional angular sensitivity functions) in the apposition eyes of Ligia exotica (Crustacea, Isopoda).

The structural organization of the retinula cells in the eye of Ligia exotica changes diurnally. At night, the microvilli elongate, losing the regular and parallel alignment characteristic of the day condition. Crystalline cones and distal rhabdom tips are not pushed into each other during the day, but at night the rhabdoms protrude into the crystalline cones by up to 5 microm. Screening pigment granules in the retinula cells disperse during the night, but migrate radially towards the vicinity of the rhabdom during the day. No such displacements of the pigment granules of either distal or proximal screening pigment cells were observed. The sensitivity of the eye, monitored by electroretinogram (ERG) recordings, changes diurnally: values at midnight are, on average, 10 times those occurring during the day. However, intracellular recordings from single retinula cells (50 during the day and 50 at night) indicate that the difference between night and day sensitivities is only 2.5-fold. Two-dimensional angular sensitivity curves, indicative of a single unit's spatial sensitivity, had considerably less regular outlines at night than during the day. If based on the 50 % sensitivity level, day and night eyes possessed receptive fields of almost identical width (approximately 2 degrees), but if sensitivities below the 50 % limit were included, then receptive fields at night were significantly more extensive. We suggest that the morphological adaptations and diurnal changes in chromophore content seen in the apposition eye of L. exotica allow this animal to improve its photon capture at night while preserving at least some of the spatial resolving power characteristic of the light-adapted state. This would explain why this animal is capable of performing complex escape behaviours in the presence of predators both in bright and in very dim light.

Animals↗
PubMed2001

Control of cardiovascular function and its evolution in Crustacea.

Work in the last decade has shown that crustacean open circulatory systems are highly efficient and controlled in a complex manner. Control occurs at several levels. Myocardial contraction is initiated in the cardiac ganglion but constantly modulated by the central nervous system, both directly via the cardioregulatory nerves and indirectly via the neurohormonal system. Heart rate and stroke volume can be controlled independently and measurements of both are needed to assess cardiac output accurately. Haemolymph outflow from many arthropod hearts is via a complex multiarterial distribution system, and the regional distribution of cardiac output is tightly controlled via cardioarterial valves at the base of each artery. These valves contain innervated muscle, and differential contraction serves to regulate the efflux of oxygenated haemolymph into a particular system. The major influence on both the evolution and control of arthropod open blood vascular systems is efficiency of oxygen uptake and delivery. This influence is illustrated by reference to a variety of crustacean and other arthropod types.

Animals↗
PubMed2000

A new species, Gnathia nkulu sp. n. (Crustacea: Isopoda: Gnathiidae) from southern Africa.

A new species, Gnathia nkulu sp. n. is described from material collected off the South African coast at 80-200m depth. It differs from the intertidal species Gnathia africana Barnard, 1914 in that the mediofrontal process is not deeply divided into two lobes, article 2 of the pylopod is rounded and small wart-like tubercles and long simple setae are present on both the cephalosome and pereon.

Animals↗
PubMed2002

Redescription of the female of Gnathia africana (Crustacea: Isopoda: Gnathiidae) from southern Africa.

A redescription of the female of the temporary fish parasite, Gnathia africana Barnard, 1914 is provided from specimens reared from final-stage G. africana praniza larvae collected from their intertidal fish hosts along the south coast of southern Africa. It differs from other known gnathiid females in the shape of the frontal border and the number and basic form of pylopod articles. This redescription aims to establish a format for future descriptions and redescriptions of gnathiid females.

Animals↗