The primary and secondary spore cyst of Aphanomyces (Oomycetes, Saprolegniales)

The ultrastructural organization of the primary (1°) and secondary (2°) cysts of Aphanomyces astaci and A. laevis is extremely similar, and similar to that of the 1° and 2° cysts of A. eutekhes as presented earlier by Hoch and Mitchell. Synchronous populations of 2° cysts can be induced by mechanical shock and encystment appears to be essentially instantaneous. The cyst coat–wall appears to be formed extremely rapidly from material from the peripheral vesicles with flocculent content. After encystment the microtubule cytoskeleton found in the zoospore is maintained in the 1° and 2° cyst (i.e. the single microtubules which extend along the pyriform nucleus from the ki–netosomes–centrioles and the bundles of closely appressed microtubules are retained). The peripheral vesicles with granular content found in the zoospore are not seen in the 1° or 2° cyst. Multivesicular bodies and lomasomes are observed in the 1° and 2° cyst which are not found in the zoospore. The peripheral cisternae of the zoospore are lost upon encystment and may be formed from dictyosome–derived vesicles during excystment of the 1° and 2° cyst. The U–body of A. astaci has a paracrystalline content while the U–body of A laevis and A eutekhes has a tubular content. A microbody–lipid body complex (sensu Powell) is found in the 1° and 2° cysts of A laevis but not in A astaci or A eutekhes. The significance of the presence of a microbody–lipid body complex in a biflagellate zoospore is discussed.     

The secondary zoospore of Aphanomyces astaci and A. laevis (Oomycetes, Saprolegniales)

The ultrastructure of the secondary zoospores of Aphanomyces astaci and A. laevis was compared. The general appearance of the organelles and their compartmental–ization is the same, but some subtle differences were found. A. laevis has a less distinct distribution of fuzzy vesicles around the border of the water expulsion apparatus than A. astaci. The content of the U–body of the A. astaci zoospore is paracrystalline but the A. laevis U–body has a tubular content. In the peripheral cytoplasm of both species are seen vesicles with a granular content. Flattened cisternae are found in a narrow zone just below the plasmalemma. These two structures are confined to the zoospore stage of the fungi. The lipid–microbody complex of A. laevis cysts is not present in the zoospore. The ultrastructural organization of uniflagellate and bi–flagellate zoospores is compared.     

A new species of Brevilegnia (Saprolegniales, Straminipila) from Buenos Aires Province, Argentina

Brevilegnia ensenadensis sp. nov. is described from litter (floating twigs, leaves, and roots) in a man-made, polluted channel near a petroleum refinery, in Buenos Aires Province, Argentina. The species is illustrated and compared with other species of the genus; it can be identified by the preponderance of smooth or papillate oogonia, with a distinctive irregular inner wall, borne in bent or coiled oogonial stalks, which are terminal, lateral or of the intercalary position. The oogonia often are irregular in shape, and the oospheres mostly are immature. The single oospore is eccentric inside the great oogonia, and the species develops mainly diclinous antheridial branches and has fewer monoclinous and androgynous ones.     

A. robusta sp. nov., a new species of Achlya (Saprolegniales,Straminipila) from a polluted Argentine channel

Achlya robusta sp. nov. was found on litter (floating twigs, leaves, and roots) in an artificial polluted channel, near a petroleum refinery, in Buenos Aires province, Argentina. The species is described, illustrated and compared with other species of the genus. A. robusta produces mainly smooth and papillate, tuberculate or bullate oogonia and monoclinous antheridial branches. It develops spherical and subglobose oogonia, with the oogonial wall yellowish and containing mainly immature oospheres. The oospores are eccentric and ranging from (1) 4-17 (30) per oogonium.     

An ultrastructural study of the invasion of Culex quinquefasciatus larvae by Leptolegnia chapmanii (Oomycetes: Saprolegniales)

Transmission electron microscopy of the invasion of Culex quinquefasciatus by Leptolegnia chapmanii confirmed that it is a primary pathogen and revealed several differences between penetration via the gut and penetration via the integument. The latter often involved aggregations of zoospores, appressoria-like swellings of the invasive hyphae, and lateral growth of hyphae between the epicutical and endocuticle. These features were not detected in the case of gut invasion, but hyphal septa at the point of entry were apparently peculiar to this route. There was no evident tissue specificity, and death presumably resulted from generalized destruction of tissues.     

Evaluation of histological techniques for the detection of fungal infections caused byLeptolegnia chapmanii (Oomycetes: Saprolegniales) inAedes aegypti (Diptera: Culicidae) larvae

We evaluated which of the fixatives and stains most frequently used for observation of insect tissues were the most appropriate for histopathological visualization of entomopathogenic fungal infections with Leptolegnia chapmanii in larvae of Aedes aegypti. The best contrast between the host tissues and the fungal structures was obtained when using a combination of Camoy fixative with Grocott staining contrasted with light green. Masson trichromic stain combined with 10% formaldehyde-phosphate buffer also provided satisfactory results--a good contrast and clearly distinguishable host tissues and fungal structures.     

The occurrence of Cavia tschudi (Rodentia,Caviidae) in the Southwest of Salta Province,Argentina

The first record of Cavia tschudi Fitzinger, 1857 for the subandean area of Salta Province, Argentina, is herein presented.

This species presently inhabits the subandean area of the provinces of Tucumán and Jujuy. The materials are composed of two mandibles coming from an archaeological site, which had been occupied ca. 1480 AD, at 2300 m a.s.l.     

Note on genus Achlya Billberg, 1820 from China (Lepidoptera,Thyatiridae)

The genus Achlya Billberg, 1820 is reported for the first time from China as A. jezoensis (Matsumura, 1927), which is a species collected from Maorshan, Heilongjiang Province. The adult and genitalia characters of the species are briefly redescribed and illustrated, distribution data is provided.     

The occurrence of Microsporon gypseum (Bodin,Guiart & Grigorakis) in soil nematodes

Summary The author gives a brief survey on the prevailing statements of today's soil biology on the occurrence of nematodes in soils, further on their conditions of living and on those of the rapacious fungi as well. On the basis of his own investigations carried out mainly in garden soils of the Hungarian Plain being dressed and undressed with manure, he comes to the conclusion that the occurrence ofM. gypseum cultured by means of the To-Ka-Va method, and on the presence of the nematodes in the soil admit the assumption that the frequent infection of persons engaged in gardening which is generally caused byM. gypseum, is likely to be in correlation with the abundance of nematodes in these soils.     

The Scoliolegnia asterophora aggregate, formerly Saprolegnia asterophora de Bary (Oomycetes)

The taxonomy of isolates referred to Saprolegnia asterophora de Bary has been investigated. Two new species are described and Saprolegnia asterophora has been re-defined. These three species are regarded as segregate species within an aggregate and are placed in a new genus of the Saprolegniaceae, Scoliolegnia Dick.     

Pinguisane-type sesquiterpenes from the South American liverwort Porella recurva (Taylor) Kuhnemann

The chemical composition of a dichloromethane extract of the South American liverwort Porella recurva has been examined. Two new pinguisane-type norsesquiterpenoid natural products were isolated: 6,11-epoxy-15-nor-3,4-dioxo-5,10-pinguisadien-12-acetate and 6,11-epoxy-15-nor-4-oxo-5,10-pinguisadien-12-acetate. In addition two known pinguisane-type sesquiterpenes were also isolated: norpinguisone and norpinguisone methyl ester. All structures were elucidated by means of NMR spectroscopic techniques and mass spectrometry.     

Cadmium removal capacities of filamentous soil fungi isolated from industrially polluted sediments,in La Plata (Argentina)

Aspergillus terreus, Cladosporium cladosporioides, Fusarium oxysporum, Gliocladium roseum, Penicillium spp., Talaromyces helicus and Trichoderma koningii were isolated from heavily polluted streams near an industrial area in La Plata, Argentina. The fungi were obtained from sediments with 0.25–0.50 mg Cd/l and they were isolated in cadmium-basal medium. They were then cultivated to evaluate their Cd detoxification abilities. The biomass developed in static assays represented 5–53% of the yield of stirred cultures, for the different fungal species, although the cadmium absorption were similar in both cases. These soil fungi represented 50% of the total isolates and their mycelial growth was conspicuous in these polluted sediments. Although bacteria have been mentioned as active microorganisms against heavy metals, the mycelial fungi were able to develop a significantly higher mass to sequestrate more metals. Thus, they could be used in remediation biotechnology to improve the Cd detoxification of chronically contaminated habitats.     

Seasonal fluctuation of the Oomycetes in a polluted environment: Santigo River and affluents (Buenos Aires, Argentina).

Oomycetes are ubiquitous filamentous water molds. They occur as saprotrophs on bits of substrata of both plant and animal origin, principally in fresh water. This paper results from an integral research on the Oomycetous flora of Santiago River and several associated shallow streams (Buenos Aires, Argentina). Information is provided concerning this polluted habitat and seasonal distribution of the zoosporic fungi. The principal physico-chemical characteristics of the aquatic environmental samples are described: temperature, pH, dissolved oxygen, nitrate concentration, sulphate concentration, phosphate concentration and heavy metals.     

The Stenopodainae (Hemiptera,Heteroptera) of Argentina

In Argentina, 10 genera and 33 species of Stenopodainae (Hemiptera: Reduviidae) have been recorded. Diagnoses of the genera, subgenera and species are given, and an illustrated key to genera is provided. Six species are new records for Argentina and an additional seven species represent new records for provinces.     

The occurrence of Calanidae species in waters off Argentina

As food of planktivorous fish and likely good predictors of natural perturbations, members of the family Calanidae are recognised to be key species in ecosystems worldwide. The distribution and seasonal relative abundance of the Calanidae species occurring in the Argentine Sea were reviewed from published and unpublished data collected over the last three decades. Species are also figured in order to elucidate any possible taxonomic uncertainty. Calanoides cf. carinatus, Calanus australis and Calanus simillimus are the most abundant calanids in the region. The former two species typically inhabit inner and middle shelf waters decreasing offshore, while Calanus simillimus is distributed in the middle and outer shelf, its abundance increasing towards the shelf-break. The southern limit of the distribution of Calanoides cf. carinatus appears to be 46° S. Calanus australis is the most common large copepod in coastal and inner shelf waters off southern Patagonia. Neocalanus tonsus and Calanoides patagoniensis are a much rarer species. The latter is recorded in the southwestern Atlantic, for the first time, immediately east of Magallanes Strait and the Beagle Channel. The taxonomic status and worldwide biogeographic distribution of the region's calanids are briefly described and the patterns identified off Argentina are discussed in relation to the major hydrographic characteristics.     

Mycoflora and mycotoxins natural occurrence in corn from entre rios province, Argentina

Corn samples were collected in 1999 from three departments of Entre Réos province, Argentina, and were surveyed for mould contamination and natural occurrence ofFusarium mycotoxins, ochratoxin A and aflatoxins.Fusarium verticillioides was the most prevalent fungal species recorded at all departments. Zearalenone, deoxynivalenol and ochratoxin A were not found in any samples. Only one of the 52 corn samples analysed was contaminated with aflatoxin B₁ (17 μg/kg). Fumonisin B₁ was found in 58 % of samples (range of positive samples: 47– 3,347 μg/kg), fumonisin B₂ in 33.0 % (range of positive samples: 23–537 μg/kg) and fumonisin B₃ in 25.0 % (range of positive samples: 24–287 μg/kg) of them. This is the first report on the natural occurrence of mycotoxins in corn from Entre Ríos province, Argentina. Levels of fumonisins were lower than detected in other Argentinian provinces.     

The karyotype of Adenomera diptyx (Boettger 1885) (Anura, Leptodactylidae) from northeastern Argentina

In this work we analyzed the karyotype of five populations of Adenomera diptyx from Argentina after conventional staining, Ag-NOR and C-banding. All specimens presented 2n = 26 and FN = 34. The karyotype was formed by three submetacentric, one metacentric and nine telocentric pairs. Silver staining revealed that the NOR was located on a secondary constriction in pair 7. C- banding evidenced constitutive heterochromatin at the pericentromeric region of all chromosomes. The karyotype of A. diptyx was similar to that of A. hylaedactyla (2n = 26, FN = 34) and different from that of A. andreae (2n = 26, FN = 40) in the fundamental number and secondary constriction position. It also differed from the karyotypes of A. marmorata (2n = 24, FN = 34 and 36) and of A. aff. bokermanni (2n = 23, FN = 34) in diploid number. Until a comprehensive cytogenetic analysis of all the species of the genus is performed, their chromosome evolution will remain poorly understood.