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At least 181 records · Page 10Linked to original sources
PubMed1999

Characterization by enzyme electrophoresis of specimens of the genus Helicometra (Trematoda, Opecoelidae) from fish caught off the coast of northwest Spain.

Species within the genus Helicometra are difficult to distinguish on morphological grounds alone, and are best discriminated with the aid of biochemical techniques. In the work reported here, the electrophoretic mobility of malate dehydrogenase isoenzyme of the Mdh-1 locus was used to characterize 375 individuals of Helicometra obtained from various teleost species (Anguilla anguilla, Conger conger, Gobius niger or Ciliata mustela) caught off the coast of northwest Spain. The results suggest that all specimens belong to only one species, probably H. fasciata. Observed genotype frequencies did not differ from those expected under the assumptions of Hardy-Weinberg equilibrium, even when the genic frequencies differ considerably respecting a Mediterranean population.

Alleles↗
PubMed2004

Reduced fecundity in small populations of the rare plant Gentianopsis ciliate (Gentianaceae).

Habitat destruction is the main cause for the biodiversity crisis. Surviving populations are often fragmented, i.e., small and isolated from each other. Reproduction of plants in small populations is often reduced, and this has been attributed to inbreeding depression, reduced attractiveness for pollinators, and reduced habitat quality in small populations. Here we present data on the effects of fragmentation on the rare, self-compatible perennial herb Gentianopsis ciliata (Gentianaceae), a species with very small and presumably well-dispersed seeds. We studied the relationship between population size, plant size, and the number of flowers produced in 63 populations from 1996-1998. In one of the years, leaf and flower size and the number of seeds produced per fruit was studied in a subset of 25 populations. Plant size, flower size, and the number of seeds per fruit and per plant increased with population size, whereas leaf length and the number of flowers per plant did not. The effects of population size on reproduction and on flower size remained significant if the effects were adjusted for differences in plant size, indicating that they could not be explained by differences in habitat quality. The strongly reduced reproduction in small populations may be due to pollination limitation, while the reduced flower size could indicate genetic effects.

Biodiversity↗
PubMed1995

Isolation of the anthropogenic compound fluoranthene in a screening of Chinese medicinal plants for antiviral compounds.

Thirty-one species of medicinal plants used in the treatment of diseases of viral origin in Yunnan Province of China were assayed for inhibition of Sindbis and murine cytomegalovirus in mammalian cell cultures. Sixteen species displayed antiviral activity. A compound, which exhibited long wavelength UV-mediated antiviral activity, was isolated from leaves and twigs of Elsholtzia ciliata (Lamiaceae) using bioassay-guided fractionation and identified as the polycyclic aromatic hydrocarbon, fluoranthene. The discovery of an anthropogenic photosensitizer with antiviral activity in a plant has implications in studies of plants as sources of bioactive constituents.

Antiviral Agents↗
PubMed2001

"Electro-fishing" in the lab: a new method to detect acute effects of heavy metals and organic pollutants in invertebrate indicator organisms.

Acute toxicity of heavy metals and organic pollutants was examined using Rhabditis oxycerca (Nematoda) and Paramecium spec. (Protozoa, Ciliata) as indicator organisms. The substances tested were based on the composition found in the river Odra. They were used in graduated dilution series (1000-fold, 500-, 250-, 167-, 125-, 100-, and 83-fold of the Odra concentration). In a special apparatus with an electric field the animals were induced to migrate from the anode to the cathode. Their migration activity (distance) and the number of migrating animals were influenced by the substances tested. To assess the extent of damage, results were compared with controls (tap water) and reference substances (aldicarb and chloracetamide). The investigations showed that heavy metal concentrations > 100-fold of the Odra concentration led to behavioural changes of both test organisms. The organic pollutants, in contrast, did not cause detectable changes in ciliates and only led to slight reductions in the migration activity of nematodes, without concentration-dependent gradations.

Animals↗
PubMed1958

An electron microscope study of the contractile vacuole in Tokophrya infusionum.

Contractile vacuoles are organelles that collect fluid from the cytoplasm and expel it to the outside. After each discharge (systole), they appear again and expand (diastole). They are widely distributed among Protozoa, and have been found also in some fresh water algae, sponges, and recently in some blood cells of the frog, guinea pig, and man. In spite of the extensive work on the contractile vacuole, very little is known concerning its mode of operation. An electron microscope study of a suctorian Tokophrya infusionum provided an opportunity to study thin sections of contractile vacuoles, and in these some structures were found which could be part of a mechanism for the systolic and diastolic motions the organelle displays. In Tokophrya, as in Suctoria and Ciliata in general, the contractile vacuole has a permanent canal connecting it with the outside. The canal appears to have a very elaborate structure and is composed of three parts: (1) a pore; (2) a channel; and (3) a narrow tubule located in a papilla protruding into the cavity of the contractile vacuole. Whereas the pore and channel have fixed dimensions and are permanently widely open, the tubule has a changeable diameter. At diastole it is so narrow (about 25 to 30 mmicro in diameter) that it could be regarded as closed, while at systole it is widely open. It is assumed that the change in diameter is due to the contraction of numerous fine fibrils (about 180 A thick) which are radially disposed around the canal in form of a truncated cone, with its tip at the channel, and its base at the vacuolar membrane. It seems most probable that the broadening of the tubule results in discharge of the content of the contractile vacuole. In the vicinity of the very thin limiting vacuolar membrane, small vesicles and canaliculi of the endoplasmic reticulum, very small dense particles, and mitochondria may be found. In addition, rows of closely packed vesicles are present in this region, and in other parts of the cytoplasm. It is suggested that they might represent dictyosome-like bodies, responsible for withdrawing fluids from the cytoplasm and then conveying them to the contractile vacuole, contributing to its expansion at diastole.

Animals↗
PubMed2004

Soluble inorganic tissue phosphorus and calcicole-calcifuge behaviour of plants.

BACKGROUND AND AIMS: Natural and semi-natural, non-fertilized calcareous soils are consistently low in soluble and easily exchangeable phosphate. An over-utilization, or possibly an immobilization, of inorganic P in the tissues of calcifuge plants may take place, if such plants are forced to grow on a calcareous soil, though this has not been experimentally demonstrated. The objectives of this study are, therefore, to elucidate if calcifuge plants, when forced to develop on a calcareous soil, not only have lower total P (Ptot) concentrations in their leaves than calcicole plants grown on such soil, but also a lower proportion of Ptot as water-soluble, inorganic phosphate. Such differences may be of importance in understanding the calcicole-calcifuge behaviour of plants. MATERIALS AND METHODS: Plants of five calcicole and five calcifuge herbs and three calcicole and three calcifuge grasses were cultivated in a glasshouse on a moderately acid Cambisol and a calcareous Rendzic Leptosol using seeds of wild populations from southern Sweden. The calcifuges were: Corynephorus canescens, Deschampsia flexuosa, Holcus mollis, Digitalis purpurea, Lychnis viscaria, Rumex acetosella, Scleranthus annuus and Silene rupestris. The calcicoles were: Melica ciliata, Phleum phleoides, Sesleria caerulea, Arabis hirsuta, Sanguisorba minor, Scabiosa columbaria, Silene uniflora ssp. petraea and Veronica spicata. KEY RESULTS: At harvest, calcifuges had much lower leaf tissue concentrations of Ptot and Pi than calcicoles when grown on the calcareous soil, and biomass production of the calcifuges was poor on this soil. Moreover, the calcifuge herbs had, on average, a lower proportion of their Ptot as Pi than had the calcicole herbs. The calcifuge herbs were also unable to avoid excessive uptake of Ca from the calcareous soil. The calcifuge grasses maintained a similar proportion of Ptot as Pi as the calcicole grasses, but their growth was still poor on the calcareous soil. CONCLUSIONS: On calcareous soil, very little Pi in the tissues of calcifuge herbs is, at any time, available for use in various physiological functions. This is of importance to their photosynthesis, growth, competition and final survival on such soils.

Adaptation, Physiological↗
PubMed2002

COMPARATIVE SPERM ULTRASTRUCTURE OF BAIKALIAN ENDEMIC PROSOBRANCH GASTROPODS.

Mature euspermatozoan ultrastructure is described for seven species of the rissooidean family Baicaliidae (endemic to Lake Baikal, Russia)-Liobaicalia stiedae, Teratobaikalia ciliata, T. macrostoma, Baicalia carinata, Pseudobaikalia pulla, Maackia bythiniopsis, M. variesculpta, and M. herderiana. For comparison with these species and previously investigated Rissooidea, two species of the Lake Baikal endemic genus Benedictia (B. cf. fragilis and B. baicalensis; Hydrobiidae: Benedictiinae of some authors, Benedictiidae of other authors) in addition to Lithoglyphus naticoides (Hydrobiidae: Lithoglyphinae) and Bythinella austriaca (Hydrobiidae: Bythinellinae) were also investigated. Paraspermatozoa were not observed in any of the species examined, supporting the view that these cells are probably absent in the Rissooidea. In general, the euspermatozoa of all species examined resemble those of many other caenogastropods (basally invaginated acrosomal vesicle, mid-piece with 7-13 helical mitochondria, an annulus, glycogen piece with nine peri-axonemal tracts of granules). However, the presence of a completely flattened acrosomal vesicle and a specialized peri-axonemal membranous sheath (a scroll-like arrangement of 4-6 double membranes) at the termination of the mid-piece, clearly indicates a close relationship between the Baicaliidae and other rissooidean families possessing these features (Bithyniidae, Hydrobiidae, Pyrgulidae, and Stenothyridae). Euspermatozoa of Benedictia, Lithoglyphus, Bythinella, and Pyrgula all have a solid nucleus, which exhibits a short, posterior invagination (housing the centriolar complex and proximal portion of the axoneme). Among the Rissooidea, this form of nucleus is known to occur in the Bithyniidae, Hydrobiidae, Truncatellidae, Pyrgulidae, Iravadiidae, Pomatiopsidae, and Stenothyridae. In contrast, the euspermatozoa of the Baicaliidae all have a long, tubular nucleus, housing not only the centriolar derivative, but also a substantial portion of the axoneme. Among the Rissooidea, a tubular nuclear morphology has previously been seen in the Rissoidae, which could support the view, based on anatomical grounds, that the Baicaliidae may have arisen from a different ancestral source than the Hydrobiidae. However, the two styles of nuclear morphology (short, solid versus long, tubular) occur widely within the Caenogastropoda, and sometimes both within a single family, thereby reducing the phylogenetic importance of nuclear differences within the Rissooidea. More significantly, the occurrence of the highly unusual membranous sheath within the mid-piece region in the Baicaliidae appears to tie this family firmly to the Bithyniidae + Hydrobiidae + Stenothyridae + Pyrgulidae assemblage. Eusperm features of Benedictia spp. strongly resemble those of hydrobiids and bithyniids, and neither support recognition of a distinct family Benedictiidae (at best this is a subfamily of Hydrobiidae) nor any close connection with the hydrobiid subfamily Lithoglyphinae.

Journal Article↗
PubMed2003

Pollinator attraction in a sexually deceptive orchid by means of unconventional chemicals.

Ophrys flowers mimic virgin females of their pollinators, and thereby attract males for pollination. Stimulated by scent, the males attempt to copulate with flower labella and thereby ensure pollination. Here, we show for the first time, to our knowledge, that pollinator attraction in sexually deceptive orchids may be based on a few specific chemical compounds. Ophrys speculum flowers produce many volatiles, including trace amounts of (omega-1)-hydroxy and (omega-1)-oxo acids, especially 9-hydroxydecanoic acid. These compounds, which are novel in plants, prove to be the major components of the female sex pheromone in the scoliid wasp Campsoscolia ciliata, and stimulate male copulatory behaviour in this pollinator species. The specificity of the signal depends primarily on the structure and enantiomeric composition of the oxygenated acids, which is the same in wasps and in the orchids. The overall composition of the blend differs significantly between the orchid and its pollinator and is of secondary importance. 9-Hydroxydecanoic acid is a rarely occurring compound that until now has been identified only in honeybees. Contrary to the standard hypothesis that Ophrys flowers produce only 'second-class attractivity compounds' and are neglected once the pollinator females are present, we show that flowers are more attractive to the males than are their own females.

Animals↗
PubMed2005

Pseudomonas argentinensis sp. nov., a novel yellow pigment-producing bacterial species, isolated from rhizospheric soil in Cordoba, Argentina.

During a study in the Argentinian region of Chaco (Cordoba), some strains were isolated from the rhizosphere of grasses growing in semi-desertic arid soils. Two of these strains, one isolated from the rhizospheric soil of Chloris ciliata (strain CH01(T)) and the other from Pappophorum caespitosum (strain PA01), were Gram-negative, strictly aerobic rods, which formed yellow round colonies on nutrient agar. They produced a water-insoluble yellow pigment, and a fluorescent pigment was also detected. A polyphasic taxonomic approach was used to characterize the strains. Comparison of the 16S rRNA gene sequences showed a similarity of 99.3 % between them, and phylogenetic analysis revealed that the strains belong to the genus Pseudomonas, within the gamma-subclass of the Proteobacteria. The closest related species is Pseudomonas straminea IAM 1598(T) (similarity of 99.0 % to strain CH01(T) and 98.8 % to strain PA01), clustering in a separate branch with the various methods of tree building used. Strains CH01(T) and PA01 both had a single polar flagellum, like other yellow pigment-producing pseudomonads related to them. Both strains produced catalase and oxidase. Similar to P. straminea, they did not hydrolyse gelatin or casein. The G+C DNA contents determined were 57.5 mol% for CH01(T) and 58.0 mol% for PA01. DNA-DNA hybridization results showed 81 % relatedness between them, and only 40-44 % relatedness with respect to the type strain of P. straminea. These results, together with other phenotypic characteristics, support the conclusion that both isolates belong to the same species, and should be described as representing a novel species within the genus Pseudomonas, for which the name Pseudomonas argentinensis sp. nov. is proposed. The type strain is CH01(T) (=LMG 22563(T) = CECT 7010(T)).

Aerobiosis↗
PubMed1988

Primary and secondary structure of the 18S ribosomal RNA of the bird spider Eurypelma californica and evolutionary relationships among eukaryotic phyla.

The primary structure of the 18S rRNA of the bird spider Eurypelma californica has been determined in the framework of a study of metazoan phylogeny on the basis of ribosomal RNA structure. A secondary-structure model was derived by comparison of the sequence with that of 43 other eukaryotic small-ribosomal-subunit RNA sequences presently available. This comparison allows a rather detailed secondary-structure pattern to be postulated for a eukaryote-specific area of highly variable sequence and length for which no consensus model has hitherto been attained. A dendrogram, reflecting evolutionary relationships among the 40 eukaryotic species of known 18S rRNA structure, was constructed by a matrix method selecting the best-fitting tree on the basis of a least-squares criterion. The tree shows an early divergence of a microsporidium, an euglenoid, kinetoplastids and a slime mold. Among the remaining species, two main clusters are distinguishable, one comprising the Ciliata, the other comprising Metazoa, green plants, fungi and several protists. Among the Metazoa, the three phyla presently investigated, viz. Chordata, Arthropoda and Nemathelminthes, are distinguishable as three separate lines of descent.

Animals↗
PubMed2007

Reproductive limits of a late-flowering high-mountain Mediterranean plant along an elevational climate gradient.

Mountain plants are particularly sensitive to climate warming because snowmelt timing exerts a direct control on their reproduction. Current warming is leading to earlier snowmelt dates and longer snow-free periods. Our hypothesis is that high-mountain Mediterranean plants are not able to take advantage of a lengthened snow-free period because this leads to longer drought that truncates the growing season. However, reproductive timing may somewhat mitigate these negative effects through temporal shifts. We assessed the effects of flowering phenology on the reproductive success of Silene ciliata, a Mediterranean high-mountain plant, across an altitudinal gradient during two climatically contrasting years. The species showed a late-flowering pattern hampering the use of snowmelt water. Plant fitness was largely explained by the elapsed time from snowmelt to onset of flowering, suggesting a selective pressure towards early flowering caused by soil moisture depletion. The proportion of flowering plants decreased at the lowest population, especially in the drier year. Plants produced more flowers, fruits and seeds at the highest population and in the mild year. Our results indicate that water deficit in dry years could threaten the lowland populations of this mountainous species, while high-altitude environments are more stable over time.

Altitude↗
PubMedDate not supplied

Timing of life cycle morphogenesis in synchronous samples of Sterkiella histriomuscorum. II. The sexual pathway.

Isolates of Sterkiella (Oxytrichidae, Stichotrichia, Ciliata) are commonly used to study macronuclear development. These organisms respond to changes in food abundance variably by encystment-excystment, conjugation, cannibalism or rescaling cell size. An isolate of Sterkiella histriomuscorum (previously Oxytricha fallax and O. trifallax) is used because two complementary mating types are available. We provide observations on conjugation in cultures of this isolate. Using synchronous samples of conjugants, the timing of stages of nuclear divisions during conjugation was determined. Following ex-conjugant cultures over time, the onset of clonal aging and senescence is described. Cells become sexually mature after a brief period of "adolescence", during which time selfing is possible. Senescent cultures are less vigorous, unable to conjugate and encyst more readily. Excystment survival decreases with clonal age. These results can serve as reference for long-term cultures of this species and for analysing particular stages of developmental processes during conjugation.

Animals↗
PubMed1999

Photosynthetic bradyrhizobia from Aeschynomene spp. are specific to stem-nodulated species and form a separate 16S ribosomal DNA restriction fragment length polymorphism group.

We obtained nine bacterial isolates from root or collar nodules of the non-stem-nodulated Aeschynomene species A. elaphroxylon, A. uniflora, or A. schimperi and 69 root or stem nodule isolates from the stem-nodulated Aeschynomene species A. afraspera, A. ciliata, A. indica, A. nilotica, A. sensitiva, and A. tambacoundensis from various places in Senegal. These isolates, together with 45 previous isolates from various Aeschynomene species, were studied for host-specific nodulation within the genus Aeschynomene, also revisiting cross-inoculation groups described previously by D. Alazard (Appl. Environ. Microbiol. 50:732-734, 1985). The whole collection of Aeschynomene nodule isolates was screened for synthesis of photosynthetic pigments by spectrometry, high-pressure liquid chromatography, and thin-layer chromatography analyses. The presence of puf genes in photosynthetic Aeschynomene isolates was evidenced both by Southern hybridization with a Rhodobacter capsulatus photosynthetic gene probe and by DNA amplification with primers defined from photosynthetic genes. In addition, amplified 16S ribosomal DNA restriction analysis was performed on 45 Aeschynomene isolates, including strain BTAi1, and 19 reference strains from Bradyrhizobium japonicum, Bradyrhizobium elkanii, and other Bradyrhizobium sp. strains of uncertain taxonomic positions. The 16S rRNA gene sequence of the photosynthetic strain ORS278 (LMG 12187) was determined and compared to sequences from databases. Our main conclusion is that photosynthetic Aeschynomene nodule isolates share the ability to nodulate particular stem-nodulated species and form a separate subbranch on the Bradyrhizobium rRNA lineage, distinct from B. japonicum and B. elkanii.

Bradyrhizobium↗
PubMed1997

Evolution of taste and solitary chemoreceptor cell systems.

Vertebrates possess four distinct chemosensory systems distinguishable on the basis of structure, innervation and utilization: olfaction, taste, solitary chemoreceptor cells (SCC) and the common chemical sense (free nerve endings). Of these, taste and the SCC sense rely on secondary receptor cells situated in the epidermis and synapsing on sensory nerve fibers innervating them near their base. The SCC sense occurs in anamniote aquatic craniates, including hagfish, and may be used for feeding or predator avoidance. The sense of taste occurs only in vertebrates and is always utilized for feeding. The SCC system achieves a high degree of specialization in two teleosts: sea robins (Prionotus) and rocklings (Ciliata). In sea robins, SCCs are abundant on the three anterior fin rays of the pectoral fin which are free of fin webbing and are used in active exploration of the substrate. Behavioral and physiological studies show that this SCC system responds to feeding cues and drives feeding behavior. It is connected centrally like a somatosensory system. In contrast, the specialized SCC system of rocklings occurs on the anterior dorsal fin which actively samples the surrounding water. This system responds to mucus substances and may serve as a predator detector. The SCC system in rocklings is connected centrally like a gustatory system. Taste buds contain multiple receptor cell types, including a serotonergic Merkel-like cell. Taste receptor cells respond to nutritionally relevant substances. Due to similarities between SCCs and one type of taste receptor cell, the suggestion is made that taste buds may be compound sensory organs that include some cells related to SCCs and others related to cutaneous Merkel cells. The lack of taste buds in hagfish and their presence in all vertebrates may indicate that the phylogenetic development of taste buds coincided with the elaboration of head structures at the craniate-vertebrate transition.

Animals↗
PubMed1984

Comparative freeze-fracture study of perialgal and digestive vacuoles in Paramecium bursaria.

In the endosymbiotic unit of Paramecium bursaria (Ciliata) and Chlorella sp. (Chlorophyceae) algae are enclosed individually in perialgal vacuoles, which do not show acid phosphatase activity and thus differ from digestive vacuoles. Both types of vacuoles have been studied by freeze-fracture. Perialgal vacuoles are nearly spherical; their membrane always fits tightly to the algal surface. The vacuole size and shape do not vary much. During division of the algal cell into four autospores the vacuole diameter only doubles. After autospore formation the vacuole invaginates around the algal daughter cells and divides. Newly formed perialgal vacuoles remain in intimate contact and exhibit characteristic attachment zones before final separation. The two fracture faces of perialgal vacuole membranes are homogeneously covered with intramembranous particles (IMPs) but rarely show signs of vesicles pinching off or fusing with the membrane, except during vacuole division. The P-faces bear more IMPs (3164 +/- 625 IMP/micron 2) than the E-faces (654 +/- 208 IMP/micron 2). The range of IMP density on both faces is enormous, suggesting that the membrane is not static. Membrane changes are supposed to occur simultaneously with the enlargement of the vacuole and to be caused by fusion with cytoplasmic vesicles, as the fractured necks on vacuole membranes may indicate. Digestive vacuoles in P. bursaria show significant variations in size, shape, membrane topography and IMP density, as well as signs of endocytic activity. Different vacuole populations are present in P. bursaria according to different feeding conditions: ciliates fed for a long time have small vacuoles with few IMPs (322 +/- 198 IMP/micron 2 on the E-faces, 1438 +/- 458 IMP/micron 2 on the P-faces), which are probably condensed digestive vacuoles, whereas organisms fed for a short time have larger vacuoles with highly particulate faces (680 +/- 282 IMP/micron 2 on the E-faces, 2701 +/- 503 IMP/micron 2 on the P-faces) and thus are supposed to be older vacuoles. The digestive vacuole membrane changes continuously. Compared to digestive vacuoles perialgal vacuoles are characterized by small size combined with high IMP density on the two fracture faces. Their IMP densities resemble those of old digestive vacuole membranes. However, it would be premature to conclude that membranes of perialgal and old digestive vacuoles are identical. Membranes of old digestive vacuoles are mainly derived from lysosomal material, which presumably does not contribute to the formation of perialgal vacuole membranes as is indicated by the small vacuole diameter; fusion with lysosomes would considerably enlarge it.(ABSTRACT TRUNCATED AT 400 WORDS)

Chlorella↗
PubMedDate not supplied

[Various aspects of the ecology of mosquitoes (Diptera, Culicidae) from a plains area (Calabria Farms) in Jacarepagua, Rio de Janeiro. V. Breeding grounds].

Results are presented of observations on the breeding places of mosquitoes, carried out in a coastal lowland farm--Granjas Calábria, in Jacarepguá, city of Rio de Janeiro, Brazil. The majority of species preferred breeding places on the ground, chiefly the natural ones, but also developed in those originated from human activities. Cx. saltanensis and the species belonging to the Aedini tribe, such as Ae. scapularis, Ae. taeniorhynchus, Ps. ciliata, Ps. confinnis and Ps. pseudomelanota were more abundant in temporary breeding places, while Ma. titillans, Cx. amazonensis, Cx. chidesteri, Cx. bidens, Cx. declarator, Cx. nigripalpus and Cx. plectoporpe occurred usually in the permanent ones. Some species were collected in natural recipients: Cx. ocellatus, the Cx. (Microculex), Ph. davisi, Ph. deanei and Wy. forcipenis, in bromeliads; Ae. terrens, Cx. imitator and Cx. gairus, in tree-holes; and Wy. leucostigma, in the submerged Typha dominguensis leaf axils. Cx. gairus was found for the first time breeding in artificial containers, which were also preferred by Cx. corniger, Cx. quinquefasciatus and Li. durhami.

Animals↗
PubMedDate not supplied

Classification of immature stage habitats of Culicidae (Diptera) collected in Córdoba, Argentina.

In order to classify mosquito immature stage habitats, samples were taken in 42 localities of Córdoba Province, Argentina, representing the phytogeographic regions of Chaco, Espinal and Pampa. Immature stage habitats were described and classified according to the following criteria: natural or artificial; size; location related to light and neighboring houses; vegetation; water; permanence, movement, turbidity and pH. Four groups of species were associated based on the habitat similarity by means of cluster analysis: Aedes albifasciatus, Culex saltanensis, Cx. mollis, Cx. brethesi, Psorophora ciliata, Anopheles albitarsis, and Uranotaenia lowii (Group A); Cx. acharistus, Cx. quinquefasciatus, Cx. bidens, Cx. dolosus, Cx. maxi and Cx. apicinus (Group B); Cx. coronator, Cx. chidesteri, Mansonia titillans and Ps. ferox (Group C); Ae. fluviatilis and Ae. milleri (Group D). The principal component analysis (ordination method) pointed out that the different types of habitats, their nature (natural or artificial), plant species, water movement and depth are the main characters explaining the observed variation among the mosquito species. The distribution of mosquito species by phytogeographic region did not affect the species groups, since species belonging to different groups were collected in the same region.

Aedes↗
PubMed1986

Gastrointestinal helminths of the Mexican duck, Anas platyrhynchos diazi Ridgway, from north central Mexico and southwestern United States.

Twenty-five species of helminths, recovered from the gastrointestinal tracts of 129 Mexican ducks from Mexico and the United States, were all new host records. The species included: Echinoparyphium recurvatum, Echinostoma revolutum, Hypoderaeum conoideum, Notocotylus attenuatus, Prosthogonimus cuneatus, Zygocotyle lunata, Anomotaenia ciliata, Cloacotaenia megalops, Diorchis bulbodes, Diorchis sp., Drepanidotaenia lanceolata, Echinocotyle rosseteri, Fimbriaria fasciolaris, Fimbriarioides sp., Hymenolepis sp. 1, Hymenolepis sp. 2, Sobolevicanthus gracilis. Corynosoma constrictum, Polymorphus minutus, Amidostomum acutum, Echinuria sp., Epomidiostomum crami, Hystrichis varispinosus, Rusguniella arctica, and Tetrameres sp. Fimbriarioides sp. occurred predominantly in ducks from south-central Chihuahua, Mexico. The distributions for the other 24 species of the helminths were not significantly different among the four collecting areas. The helminth fauna for the 32 complete specimens and 97 intestinal tracts was distributed relatively evenly among the hosts with a calculated mean evenness of 0.77 +/- 0.15 and 0.89 +/- 0.03 respectively. The parasite fauna was more similar to those of the black duck Anas rubripes Brewster of eastern North America (53%), the mallard, Anas platyrhynchos (L.) (49%), and the mottled duck, Anas fulvigula Ridgway, from Florida (45%), than to the green-winged teal, Anas crecca (L.) (36%), the gadwall, Anas strepera (L.) (30%), and the American wigeon, Anas americana Gmelin (26%), collected in the Southwest.

Acanthocephala↗