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1.
Opa proteins are major proteins involved in meningococcal colonization of the nasopharynx and immune interactions. Opa proteins undergo phase variation (PV) due to the presence of the 5′-CTCTT-3′ coding repeat (CR) sequence. The dynamics of PV of meningococcal Opa proteins is unknown. Opa PV, including the effect of transformation on PV, was assessed using a panel of Opa-deficient strains of Neisseria meningitidis. Analysis of Opa expression from UK disease-causing isolates was undertaken. Different opa genes demonstrated variable rates of PV, between 6.4 ×10–4 and 6.9 ×10–3 per cell per generation. opa genes with a longer CR tract had a higher rate of PV (r 2=0.77, p=0.1212). Bacterial transformation resulted in a 180-fold increase in PV rate. The majority of opa genes in UK disease isolates (315/463, 68.0%) were in the ‘on’ phase, suggesting the importance of Opa proteins during invasive disease. These data provide valuable information for the first time regarding meningococcal Opa PV. The presence of Opa PV in meningococcal populations and high expression of Opa among invasive strains likely indicates the importance of this protein in bacterial colonization in the human nasopharynx. These findings have potential implications for development of vaccines derived from meningococcal outer membranes.  相似文献   

2.
Intercontinental introductions are widespread in the genus Spartina, with important ecological and evolutionary consequences. The native or introduced status of Spartina species is then critical with regard to biodiversity assessment, especially for vulnerable Mediterranean coastline ecosystems. Spartina versicolor was first recorded in southern France in 1849, then successively in various places on the European and North-African Mediterranean and Atlantic coasts. This species is considered to be either a European native or an invasive species introduced from North America which has a high morphological similarity to the Atlantic American species Spartina patens. We performed extensive sampling of S. versicolor in Europe and North Africa (from natural populations and herbarium collections) and compared these samples to other European and American Spartina species (including S. patens). Chromosome counts were reported for the first time and revealed that S. versicolor is tetraploid (2n = 4x = 40). Phylogenetic analyses based on chloroplast and nuclear ribosomal DNA sequences did not reveal any molecular variation within S. versicolor. In this species, a single haplotype, that is identical to one haplotype of S. patens, was found in the four chloroplast and the nuclear ribosomal ITS regions investigated. In addition, simple sequence repeat markers were used and revealed a low level of genetic diversity within S. versicolor, suggesting that the introduction of S. versicolor occurred from a narrow genetic pool of S. patens from North America.  相似文献   

3.
Caries and chronic periodontitis are common oral diseases where a higher Candida colonization is reported. Antifungal agents could be adjuvant drugs for the therapy of both clinical conditions. The aim of the current study has been to evaluate the in vitro activities of conventional and new antifungal drugs against oral Candida isolates from patients suffering from caries and/or chronic periodontitis. In vitro activities of amphotericin B, fluconazole, itraconazole, miconazole, nystatin, posaconazole and voriconazole against 126 oral Candida isolates (75 Candida albicans, 18 Candida parapsilosis, 11 Candida dubliniensis, six Candida guilliermondii, five Candida lipolytica, five Candida glabrata, four Candida tropicalis and two Candida krusei) from 61 patients were tested by the CLSI M27-A3 method. Most antifungal drugs were highly active, and resistance was observed in less than 5% of tested isolates. Miconazole was the most active antifungal drug, being more than 98% of isolates susceptible. Fluconazole, itraconazole, and the new triazoles, posaconazole and voriconazole, were also very active. Miconazole, fluconazole and voriconazole have excellent in vitro activities against all Candida isolates and could represent suitable treatment for a hypothetically adjunctive therapy of caries and chronic periodontitis.  相似文献   

4.
Many of the plants found in serpentine areas are endemics and they may accumulate Ni at high concentration. High accumulation of Cr is rare, or in some views, never properly demonstrated. Generally, a very small proportion of any serpentine flora shows high accumulation of Ni, in some serpentine areas Ni accumulators are completely absent. There are approximately 570 hyperaccumulator plant species found on earth, 450 of them are Ni hyperaccumulators. A few of the Ni accumulators have potential for phytoremediation or phytomining. In the present study, 19 different Brassicaceae members growing in serpentine habitats in the district of Yahyal?, Kayseri province, Turkey viz., members of genera Aethionema, Alyssum, Arabis, Heldreichia, Hesperis, Iberis, Isatis, Microthlaspi, Odontarrhena, Pseudosempervivum and Thlaspi were investigated. Nickel concentrations in the soil and underground and aboveground parts of plants were determined by using ICP-OES. It was observed that Ni concentrations of seven taxa (Odontarrhena muralis, O. oxycarpa, Isatis cappadocica subsp. cappadocica, Microthlaspi perfoliatum, Pseudosempervivum sempervivum, Thlaspi triangulare, Thlaspi rosulare) reach the threshold criterion of 1,000 mg kg?1 for Ni hyperaccumulation. In this study Ni concentrations in aboveground tissues of I. cappadocica subsp. cappadocica are determined as 5,587 mg kg?1 (in dry weight). Accordingly, it is suggested that this taxon be added to the list of Ni hyperaccumulator plants.  相似文献   

5.
Sarcophagidae (Diptera) are potential vectors of several pathogens. They are also very important in forensic entomology, providing basic information on the circumstances of death. The objective of this study was to determine the synanthropic index of adult Sarcophagidae collected in Rio Claro, state of São Paulo, southeastern Brazil. Sampling occurred between September 2009 and August 2010. Traps baited with sardines, beef liver, or minced meat were set for five consecutive days per month in three distinct ecological areas representing urban, rural, and forest environments. A total of 440 specimens of sarcophagids were collected. The most abundant species was Peckia (Sarcodexia) lambens (Wiedemann), followed by Oxysarcodexia thornax (Walker), Peckia (Euboettcheria) collusor (Curran & Walley), Peckia (Euboettcheria) sp., and Peckia (Pattonella) intermutans (Walker). The only species with positive synanthropic index values were O. thornax and P. (S.) lambens, which demonstrated a greater preference for inhabited areas. Peckia (Euboettcheria) florencioi (Prado & Fonseca), P. (P.) intermutans, and Peckia (Euboettcheria) australis (Townsend) were only found in the forested area, which demonstrates their importance in forensic entomology because of their preference for a particular type of environment. The greatest number of sarcophagids was found in the forest environment; however, only the forest and rural areas were significantly different in Sarcophagidae abundance.  相似文献   

6.
The Cerrado Biome is the second largest in Brazil covering roughly 2 million km2, with varying features throughout its area. The Biome is endangered but it is also source of animal species for rural, green urban and degraded rainforest areas. Ticks are among Cerrado species that establish at anthropogenic sites and although information about them is steadily increasing, several features are unknown. We herein report tick species, abundance and some ecological relationships within natural areas of the Cerrado at higher altitudes (800–1500 m) within and around Serra da Canastra National Park, in Minas Gerais State Brazil. In total of 1196 ticks were collected in the environment along 10 campaigns held in 3 years (2007–2009). Amblyomma sculptum was the most numerous species followed by Amblyomma dubitatum and Amblyomma brasiliense. Distribution of these species was very uneven and an established population of A. brasiliense in the Cerrado is reported for the first time. Other tick species (Amblyomma ovale, Amblyomma nodosum, Amblyomma parvum, Ixodes schulzei and Haemaphysalis leporispalustris) were found in lesser numbers. Domestic animals displayed tick infestations of both rural and urban origin as well as from natural areas (Rhipicephalus sanguineus sensu lato, Rhipicephalus microplus, Dermacentor nitens, A. sculptum, A. ovale, Amblyomma tigrinum, Argas miniatus). Amblyomma sculptum had the widest domestic host spectrum among all tick species. DNA of only one Rickettsia species, R. bellii, was found in an A. dubitatum tick. Several biological and ecological features of ticks of the studied areas are discussed.  相似文献   

7.
The following paper describes the foraminiferal fauna and associated faunal assemblages of the bedded and reef carbonates of the Upper Triassic (most probably Rhaetian) Nayband Formation, which are exposed in a section south of the small town of Bagher-Abad, northeast of Esfahan. Foraminifers are extremely rare in sponge- or coral-dominated bioconstructions and in the bedded carbonates of the Nayband Formation in central Iran. Some carbonate beds are composed of bioclastic wackstone/packstone. These are exposed in the solenoporacean horizon at the uppermost part of the section. Here, the aulotortid- and trocholinid-type foraminifers are relatively abundant. The following foraminiferal taxa with different abundances were found within the carbonates of the investigated section: Trocholina umbo Frentzen, T. turris Frentzen, T. gracilis Blau, Aulotortus tumidus (Kristan-Tollmann), Aulotortus tenuis (Kristan), Aulotortus friedli (Kristan-Tollmann), Coronipora etrusca (Pirini), Semiinvoluta clari Kristan, Turrispirillina? licia variabilis Blau, Galeanella? laticarinata Al-Shaibani, Carter and Zaninetti, Ophthalmidium sp., Agathammina sp., “Sigmoilinaschaeferae Zaninetti, Planiinvoluta carinata Leischner, Planiinvoluta sp., Nubecularia sp., Endothyra sp., Paeolituonella sp. and some sessile agglutinated and nodosariid types. All mentioned taxa are very rare, except the involutinid and trocholinid types. The following species are described as new: Trocholina blaui nov. sp., Spirilina? iranica nov. sp., and Coronipora serraforma nov. sp. Trocholina blaui is usually attached to solenoporacean thalli. Four foraminiferal associations, which are named after the occurrence of the abundant species, were distinguished as Aulotortus tumidus association, Aulotortus friedli association, Trocholina umbo association, and Trocholina blaui association. Aulotortid types and Trocholina umbo were found within the bioclastic wackstone/packstone carbonates. Trocholina blaui is abundant in solenoporacean framestones. The foraminiferal association of investigated carbonates contains a mixed fauna, known from Upper Triassic–Liassic in the Tethyan realm. Carbonates of the whole investigated section are dated—due to occurrence of the genus Aulotortus, with species A. tumidus (Kristan-Tollmann), A. tenuis (Kristan), and A. friedli (Kristan-Tollmann)—as Upper Triassic (most probably Rhaetian). The “typical” foraminifers occurring in the reef biotopes in the northwestern Tethys are either missing or extremely rare in the Iranian bioconstructions.  相似文献   

8.
Mucormycosis is an invasive infection caused by opportunistic fungi. Rhizopus, Lichtheimia, Mucor and Rhizomucor are the most common isolated genera. Primary cutaneous mucormycosis is usually related to traumatic injuries, but immunocompromised cases are associated with underlying conditions such as diabetes mellitus and malignancies. The treatment of choice is surgical debridement and liposomal amphotericin B. We present a 40-year-old male with fever and a painful necrotic lesion on the middle back and history of poorly controlled diabetes mellitus. Rhizopus oryzae was isolated and identified using an internal transcribed spacer regions ITS1 and ITS2. An initial good response to treatment was observed; however, 7 days later a diabetic ketoacidosis due to poor adherence to treatment caused a lethal outcome.  相似文献   

9.
10.
Investigations were carried out in June–August 2012 and 2013 in broadleaf forests and planted stands of the northern red oak Quercus rubra in Kiev. The ant visitation rates of 3–6 most abundant plant species within each vegetation layer were analyzed. In all, 16 species of ants were found in the broadleaf forest (Quercus robur + Acer spp. + Carpinus betulus), with the dominance of three species: Formica rufa, Lasius fuliginosus, and L. emarginatus. Eight ant species occurred in Q. rubra stands with the undergrowth of Acer campestre and A. platanoides; the dominant species were Lasius fuliginosus and L. emarginatus. The northern red oak stands with conspecific undergrowth had only four ant species with no dominants among them. Plants with the highest ant visitation rates in the herbage layer of the broadleaf forest were the invasive Impatiens parviflora and the native Aegopodium podagraria. Ants were rare or absent on the remaining herbs: Impatiens noli-tangere, Carex sylvatica, Stellaria holostea, and Galium odoratum. The herbage layer was mostly visited by influents, the dominants being represented only by Lasius emarginatus. Within the shrub layer, ants most frequently visited the undergrowth of the maple Acer platanoides, often harboring colonies of the aphid Periphyllus lyropictus; the highest visitation rates were recorded in the dominants L. emarginatus and L. fuliginosus. The arboreal layer had the highest visitation rate and was most often visited by the dominants Lasius fuliginosus, L. emarginatus, and F. rufa. The common oak Q. robur was the most visited tree in broadleaf forests. In addition to providing ants with food (colonies of the aphids Lachnus roboris and Stomaphis quercus, and also phytophagous insects and other invertebrates), these trees were used for nesting by the dominants L. fuliginosus and L. emarginatus. The presence of aphid colonies was also typical of ripe trees and undergrowth of the maple A. platanoides, the second-visited tree in broadleaf forests. The common hornbeam Carpinus betulus was the least frequently visited, though some ant species, usually L. emarginatus, nested in the trunks and branches of old trees. The vertical distribution of ants in broadleaf forests and red oak stands formed two clusters: the influents occupied the lower (herbage and shrub) vegetation layers, while the subdominants and dominants occupied the upper (shrub and arboreal) ones. The smallest number of ant species (1 or 2) in all the vegetation layers was recorded in the areas with F. rufa; areas with L. fuliginosus had twice as many species; the greatest numbers of ant species were found in the areas with L. emarginatus and in those without dominants. This pattern may result from different territoriality of the dominants: the strongest in F. rufa (defending the whole territory) and the weaker in the other two species (defending only a part of the territory). Plants of all the vegetation layers varied in their attractiveness to ants. As a result, the layers had a mosaic structure in their vertical (between-layer) and horizontal (between different plant species within one layer) arrangement. From 60 to 100% of plants of certain species were visited by ants while plants of other species were not visited at all. The main reason for visiting plants by ants was the presence of aphid colonies.  相似文献   

11.
The cultured aerobic copiotrophic bacteria and fungi from food-free digestive tracts of Aporrectodea caliginosa, Lumbricus terrestris, and Eisenia fetida earthworms, soil (compost), and fresh earthworm excrements were investigated. The microorganisms were isolated on nutrient media and identified by sequencing the fragments of bacterial 16S rRNA and fungal 28S rRNA (D1/D2 domain) gene sequences with subsequent phylogenetic analysis. Bacteria isolated from the digestive tracts of earthworms belonged to the families Aeromonadaceae, Comamonadaceae, Enterobacteriaceae, Flavobacteriaceae, Moraxellaceae, Pseudomonadaceae, and Sphingobacteriaceae (Bacteroidetes), as well as Actinobacteria. For five strains, namely Ochrobactrum sp. 341-2 (α-Proteobacteria), Massilia sp. 557-1 (β-Proteobacteria), Sphingobacterium sp. 611-2 (Bacteroidetes), Leifsonia sp. 555-1, and a bacterium from the family Microbacteriaceae, isolate 521-1 (Actinobacteria), the similarity to known 16S rRNA sequences was 93–97%; they therefore, probably belong to new species and genera. Bacterial groups isolated from the digestive tracts of earthworms were significantly different from those isolated from soil and excrements. Some bacterial taxa occurred in different sections of A. caliginosa intestine and in intestines of different earthworm species; however, the overall composition of bacterial communities in these objects is different. Existence of bacterial groupings symbiotically associated with intestines is proposed. Among the fungi, Bjerkandera adusta and Syspastospora parasitica were isolated from the cleaned digestive tracts as light-colored, sterile mycelium, as well as Geotrichum candidum, Acremonium murorum (A. murorum var. felina), Alternaria alternata, Aspergillus candidus, A. versicolor, Cladosporium cladosporioides, Rhizomucor racemosus, Mucor hiemalis, Fusarium (F. oxysporum, Fusarium sp.), and Penicillium spp. These fungi survive for a long time in the earthworm’s digestive environment. Investigation of the functional characteristics and role in the host organism is required to confirm the symbiotic status of the microorganisms associated with the earthworm digestive tract.  相似文献   

12.
Pseudomonas aeruginosa, a Gram-negative, rod-shaped bacterium causes widespread diseases in humans. This bacterium is frequently related to nosocomial infections such as pneumonia, urinary tract infections (UTIs) and bacteriaemia especially in immunocompromised patients. The current review focuses on the recent perspectives on biofilms formation by these bacteria. Biofilms are communities of microorganisms in which cells stick to each other and often adhere to a surface. These adherent cells are usually embedded within a self-produced matrix of extracellular polymeric substance (EPS). Pel, psl and alg operons present in P. aeruginosa are responsible for the biosynthesis of extracellular polysaccharide which plays an important role in cell surface interactions during biofilm formation. Recent studies suggested that cAMP signalling pathway, quorum-sensing pathway, Gac/Rsm pathway and c-di-GMP signalling pathway are the main mechanism that leads to the biofilm formation. Understanding the bacterial virulence depends on a number of cell-associated and extracellular factors and is very essential for the development of potential drug targets. Thus, the review focuses on the major genes involved in the biofilm formation, the state of art update on the biofilm treatment and the dispersal approaches such as targeting adhesion and maturation, targeting virulence factors and other strategies such as small molecule-based inhibitors, phytochemicals, bacteriophage therapy, photodynamic therapy, antimicrobial peptides and natural therapies and vaccines to curtail the biofilm formation by P. aeruginosa.  相似文献   

13.
Ambrosia beetles subsist on fungal symbionts that they carry to, and cultivate in, their natal galleries. These symbionts are usually saprobes, but some are phytopathogens. Very few ambrosial symbioses have been studied closely, and little is known about roles that phytopathogenic symbionts play in the life cycles of these beetles. One of the latter symbionts, Raffaelea lauricola, causes laurel wilt of avocado, Persea americana, but its original ambrosia beetle partner, Xyleborus glabratus, plays an uncertain role in this pathosystem. We examined the response of a putative, alternative vector of R. lauricola, Xyleborus bispinatus, to artificial diets of R. lauricola and other ambrosia fungi. Newly eclosed, unfertilized females of X. bispinatus were reared in no-choice assays on one of five different symbionts or no symbiont. Xyleborus bispinatus developed successfully on R. lauricola, R. arxii, R. subalba and R. subfusca, all of which had been previously recovered from field-collected females of X. bispinatus. However, no development was observed in the absence of a symbiont or on another symbiont, Ambrosiella roeperi, recovered from another ambrosia beetle, Xylosandrus crassiusculus. In the no-choice assays, mycangia of foundress females of X. bispinatus harbored significant colony-forming units of, and natal galleries that they produced were colonized with, the respective Raffaelea symbionts; with each of these fungi, reproduction, fecundity and survival of the beetle were positively impacted. However, no fungus was recovered from, and reproduction did not occur on, the A. roeperi and no symbiont diets. These results highlight the flexible nature of the ambrosial symbiosis, which for X. bispinatus includes a fungus with which it has no evolutionary history. Although the “primary” symbiont of the neotropical X. bispinatus is unclear, it is not the Asian R. lauricola.  相似文献   

14.
Brain-derived neurotrophic factor (BDNF) plays a key role in neural development and physiology, as well as in pathological states. Post-mortem studies demonstrate that BDNF is reduced in the brains of patients affected by neurodegenerative diseases. Iron accumulation has also been associated to the pathogenesis of neurodegenerative diseases. In rats, iron overload induces persistent memory deficits, increases oxidative stress and apoptotic markers, and decreases the expression of the synaptic marker, synaptophysin. Deferiprone (DFP) is an oral iron chelator used for the treatment of systemic iron overload disorders, and has recently been tested for Parkinson’s disease. Here, we investigated the effects of iron overload on BDNF levels and on mRNA expression of genes encoding TrkB, p75NTR, catalase (CAT) and NQO1. We also aimed at investigating the effects of DFP on iron-induced impairments. Rats received iron or vehicle at postnatal days 12–14 and when adults, received chronic DFP or water (vehicle). Recognition memory was tested 19 days after the beginning of chelation therapy. BDNF measurements and expression analyses in the hippocampus were performed 24 h after the last day of DFP treatment. DFP restored memory and increased hippocampal BDNF levels, ameliorating iron-induced effects. Iron overload in the neonatal period reduced, while treatment with DFP was able to rescue, the expression of antioxidant enzymes CAT and NQO1.  相似文献   

15.
A taxonomic review of the Dendrochirus brachypterus complex resulted in the recognition of five species, including Dendrochirus barberi (Steindachner 1900), Dendrochirus bellus (Jordan and Hubbs 1925), Dendrochirus brachypterus (Cuvier in Cuvier and Valenciennes 1829), Dendrochirus hemprichi sp. nov. and Dendrochirus tuamotuensis Matsunuma and Motomura 2013. The complex is defined as having usually 9 dorsal-fin soft rays, usually 5 anal-fin soft rays, 17–20 (rarely 20) pectoral-fin rays, no ocellated spots on the soft-rayed portion of the dorsal fin and usually 2 (sometimes none) barbels on the snout tip. Dendrochirus barberi, known from the Hawaiian Islands and Johnston Atoll, is characterized by usually 18 pectoral-fin rays, a relatively high number of scale rows in the longitudinal series (modally 51 vs. 39–49 in other species) and mottled markings on the pectoral fin in large specimens. Dendrochirus bellus, restricted to the northwestern Pacific Ocean from the South China Sea north to southern Japan, is characterized by usually 17 pectoral-fin rays, a relatively low number of scale rows in the longitudinal series (modally 38 vs. 44–51 in other species), and the absence of skin flaps on the orbit surface and uppermost preopercular spine base. Dendrochirus tuamotuensis, recorded only from the Tuamotu Archipelago, is characterized by 19 pectoral-fin rays, the posterior margin of the pectoral fin strongly notched, and a relatively shallow and narrow head and body. Dendrochirus hemprichi sp. nov. is distributed in the western Indian Ocean, including the Red Sea. Although previously confused with a closely related congener (D. brachypterus, known from the northern and eastern Indian Ocean and western Pacific), D. hemprichi can be distinguished from the former by having fewer scale rows between the last dorsal-fin spine base and lateral line, and between the sixth dorsal-fin spine base and lateral line [4–7 (5) in D. hemprichi vs. 5–7 (6) in D. brachypterus, in both cases], a slightly greater interorbital width at the mid-orbit [5.5–10.7 (mean 7.8) % SL vs. 4.5–8.9 (6.8) % of SL] and at preocular spine base [4.4–9.1 (6.6) % SL vs. 3.5–7.8 (5.7) % of SL], and slightly shorter posteriormost (usually 13th) dorsal-fin spine length [11.8–19.9 (15.3) % SL vs. 13.3–21.3 (17.2) % of SL]. Moreover, D. hemprichi tends to have relatively more spinous points on the head spines and ridges, compared with D. brachypterus. Notwithstanding the morphological similarity between the two species, an obvious genetic difference was observed between D. hemprichi and D. brachypterus. Dendrochirus chloreus Jenkins 1903 and Dendrochirus hudsoni Jordan and Evermann 1903 were synonymized under Pterois barberi, as in some previous studies. Scorpaena koenigii Bloch 1789 was regarded as conspecific with D. brachypterus, which it predated. However, the former name should be suppressed under Reversal of Precedence.  相似文献   

16.
Economically feasible systems for heterologous production of complex secondary metabolites originating from difficult to cultivate species are in demand since Escherichia coli and Saccharomyces cerevisiae are not always suitable for expression of plant and animal genes. An emerging oilseed crop, Camelina sativa, has recently been engineered to produce novel oil profiles, jet fuel precursors, and small molecules of industrial interest. To establish C. sativa as a system for the production of medicinally relevant compounds, we introduced four genes from Veratrum californicum involved in steroid alkaloid biosynthesis. Together, these four genes produce verazine, the hypothesized precursor to cyclopamine, a medicinally relevant steroid alkaloid whose analogs are currently being tested for cancer therapy in clinical trials. The future supply of this potential cancer treatment is uncertain as V. californicum is slow-growing and not amendable to cultivation. Moreover, the complex stereochemistry of cyclopamine results in low-yield syntheses. Herein, we successfully engineered C. sativa to synthesize verazine, as well as other V. californicum secondary metabolites, in seed. In addition, we have clarified the stereochemistry of verazine and related V. californicum metabolites.  相似文献   

17.
Satellite DNA repeats (or satDNA) are fast-evolving sequences usually associated with condensed heterochromatin. To test whether the chromosomal organisation of centromeric and non-centromeric satDNA differs in species with holocentric chromosomes, we identified and characterised the major satDNA families in the holocentric Cyperaceae species Rhynchospora ciliata (2n = 10), R. globosa (2n = 50) and R. tenuis (2n = 2x = 4 and 2n = 4x = 8). While conserved centromeric repeats (present in R. ciliata and R. tenuis) revealed linear signals at both chromatids, non-centromeric, species-specific satDNAs formed distinct clusters along the chromosomes. Colocalisation of both repeat types resulted in a ladder-like hybridisation pattern at mitotic chromosomes. In interphase, the centromeric satDNA was dispersed while non-centromeric satDNA clustered and partly colocalised to chromocentres. Despite the banding-like hybridisation patterns of the clustered satDNA, the identification of chromosome pairs was impaired due to the irregular hybridisation patterns of the homologues in R. tenuis and R. ciliata. These differences are probably caused by restricted or impaired meiotic recombination as reported for R. tenuis, or alternatively by complex chromosome rearrangements or unequal condensation of homologous metaphase chromosomes. Thus, holocentricity influences the chromosomal organisation leading to differences in the distribution patterns and condensation dynamics of centromeric and non-centromeric satDNA.  相似文献   

18.
From 2005 to 2009, 147 ticks found on 32 wild animals from or referred to two zoobotanical parks (Parque Zoobotânico Arruda Câmara and Parque Estadual Dois Irmãos) located in northeastern Brazil were identified. Ticks found on two veterinarians working in one of the parks (i.e., Parque Estadual Dois Irmãos), after return from forested areas within the park’s territory, were also identified. The following tick-host associations were recorded: Amblyomma fuscum Neumann on Boa constrictor L.; Amblyomma longirostre Koch on Ramphastos vitellinus ariel Vigors and Coendou prehensilis (L.); Amblyomma varium Koch on Bradypus variegates Schinz; Amblyomma rotundatum Koch on Chelonoidis carbonaria (Spix), Chelonoidis denticulata (L.), Micrurus ibiboboca (Merrem), Python molurus bivittatus Kuhl, Iguana iguana (L.) and B. variegatus; Amblyomma nodosum Neumann on Myrmecophaga tridactyla L. and Tamandua tetradactyla (L.); and Rhipicephalus sanguineus (Latreille) on Nasua nasua (L.). The ticks found on the veterinarians were identified as nine Amblyomma larvae. The presence of Am. nodosum in Pernambuco and Am. rotundatum and Am. varium in Paraíba is recorded for the first time and the occurrence of Am. longirostre in Pernambuco is confirmed. Ramphastos vitellinus ariel is a new host record for Am. longirostre whereas M. ibiboboca and B. variegatus are new host records for Am. rotundatum. Finally, the human parasitism by Amblyomma ticks is reported for the first time in Pernambuco, highlighting the potential of tick-borne pathogen transmission in this state.  相似文献   

19.
Convergence is observed in groups, which are phylogenetically remote. A flat test is typical for some representatives of the order Cassiduloida, such as Jurassic and Early Cretaceous species of the genera Pygurus and Clypeus, and also many Cenozoic «sand dollars,» i.e., echinoids of the order Clypeasteroida. Both usually inhabit coarse sandy grounds of shallow areas. The superorder Spatangacea includes the so-called Echinocorys life form, which is characterized by an oval test with superficial nonpetaloid or subpetaloid ambulacra, marginal or inframarginal periproct, and absence of fascioles. These are the following genera: Early Cretaceous Corthya (family Collyritidae), Late CretaceousLate Paleocene Echinocorys (family Holas-teridae), Paleocene Isaster, Recent Isopatagus (family Isasteridae), Recent Scrippsechinus (family Palaeotro-pidae), and Recent Urechinus (family Urechinidae). In contrast to the majority of spatangaceans with the burrowing mode of life, these genera dwell on the substrate surface. In the Cenozoic, the monobasal apical system appears in some genera of the order Spatangoida, most genera of the order Cassiduloida, all groups of the orders Clypeasteroida and Oligopygoida, and in the genus Echinoneus (order Holectypoida). The paral-lelism is revealed in groups connected by remote relationships. At the end of the Middle Jurassic (Callovian) and, especially, Late Jurassic, the so-called disasterid echinoids (superorder Spatangacea) show a distinct trend to the loss of contact between ocular plates I and V and apices of the posterior ambulacra with the periproct, which are shifted to the anterior part of the apical system (genera Collyrites, Collyropsis, Cyclolam-pas). At the same time, the peristome of some genera was displaced to the anterior margin of the test, which became bilaterally symmetrical in outline. However, in the Jurassic, all spatangaceans remained disasterid echinoids, i.e., had a disjunct apical system, which can be interpreted as a somewhat “abnormal” state. This trend disappeared only at the beginning of the Cretaceous, when “normal” forms with a joint apical system appeared, that is, the families Holasteridae (genera Eoholaster and Holaster, order Holasteroida) and Toxas-teridae (genus Toxaster, order Spatangoida). Interesting examples of synchronous parallelism are provided by the appearance of meridosternous (diasternal) plastron in two collyritid genera (Tetraromania and Corthya) in the Barremian, whereas in the holasterid genus Holaster, this type of plastron apparently appeared in the Valanginian (heterochronous parallelism). The ethmolitic type of the apical system appeared at the end of the Cretaceous and Paleocene at least in five families: Schizasteridae, Paleopneustidae, Brissidae, Spatangidae, and Loveniidae.  相似文献   

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