First report of inventory and role of macroinvertebrates and fish in Cautín river (38° S, Araucania region Chile) / Primeiro relato do inventário e papel dos macroinvertebrados e peixes no rio Cautín (39° S, região de Araucania Chile)

Abstract The Cautin river is located in the 137 years old Araucania region, Chile (38°S), and is characterized by alterations through human interference due agriculture and towns in its surrounding basin, the presence of salmonids, and by its mixed regime, originated from snow melting in summer and rains in winter. The aim of the present study was to make a review of the inventory and ecological role of the benthic inland water macroinvertebrates of the River Cautin, in order to understand their importance in the ecosystem of the river. The fauna of this river includes a fauna composed of endemic and introduced fish, which has, however, been only poorly studied until now. The literature revealed the presence of abundant populations of Diptera, Trichoptera and Ephemeroptera larval stages, and few crustaceans specifically amphipods and freshwater crabs along the river's course. Many of these macroinvertebrates are prey for both introduced salmonids and native fishes. Similar results have been reported for other southern Argentinean and Chilean Patagonian rivers.

Resumo O rio Cautin está localizado na região de Araucania, no Chile (38°S), é caracterizado por alterações através da interferência humana devido à agricultura e as cidades da bacia circundante, a presença de salmonídeos e pelo seu regime misto, originado pela queda de neve verão e chuvas no inverno. O objetivo do presente estudo foi fazer uma revisão do papel ecológico dos macroinvertebrados bentônicos das águas interiores do rio Cautin, para entender sua importância no ecossistema do rio. A fauna deste rio inclui uma fauna composta de espécies de peixes endêmicos e introduzidos, que, no entanto, tem sido mal estudada até agora. A literatura revelou a presença de abundantes populações de estádios de larvas Diptera, Trichoptera e Ephemeroptera, e poucos crustáceos especificamente anfípodes e caranguejos de água doce ao longo do curso do rio. Muitos desses macroinvertebrados são presas tanto para salmonídeos introduzidos quanto para peixes nativos. Resultados semelhantes foram relatados para outros rios sul da Patagônia Chilena e Argentina.

First report of inventory and role of macroinvertebrates and fish in Cautín river (38° S, Araucania region Chile).

The Cautin river is located in the 137 years old Araucania region, Chile (38°S), and is characterized by alterations through human interference due agriculture and towns in its surrounding basin, the presence of salmonids, and by its mixed regime, originated from snow melting in summer and rains in winter. The aim of the present study was to make a review of the inventory and ecological role of the benthic inland water macroinvertebrates of the River Cautin, in order to understand their importance in the ecosystem of the river. The fauna of this river includes a fauna composed of endemic and introduced fish, which has, however, been only poorly studied until now. The literature revealed the presence of abundant populations of Diptera, Trichoptera and Ephemeroptera larval stages, and few crustaceans specifically amphipods and freshwater crabs along the river's course. Many of these macroinvertebrates are prey for both introduced salmonids and native fishes. Similar results have been reported for other southern Argentinean and Chilean Patagonian rivers.

Low-Molecular-Weight Thiols and Thioredoxins Are Important Players in Hg(II) Resistance in Thermus thermophilus HB27.

Mercury (Hg), one of the most toxic and widely distributed heavy metals, has a high affinity for thiol groups. Thiol groups reduce and sequester Hg. Therefore, low-molecular-weight (LMW) and protein thiols may be important cell components used in Hg resistance. To date, the role of low-molecular-weight thiols in Hg detoxification remains understudied. The mercury resistance (mer) operon of Thermus thermophilus suggests an evolutionary link between Hg(II) resistance and low-molecular-weight thiol metabolism. The mer operon encodes an enzyme involved in methionine biosynthesis, Oah. Challenge with Hg(II) resulted in increased expression of genes involved in the biosynthesis of multiple low-molecular-weight thiols (cysteine, homocysteine, and bacillithiol), as well as the thioredoxin system. Phenotypic analysis of gene replacement mutants indicated that Oah contributes to Hg resistance under sulfur-limiting conditions, and strains lacking bacillithiol and/or thioredoxins are more sensitive to Hg(II) than the wild type. Growth in the presence of either a thiol-oxidizing agent or a thiol-alkylating agent increased sensitivity to Hg(II). Furthermore, exposure to 3 µM Hg(II) consumed all intracellular reduced bacillithiol and cysteine. Database searches indicate that oah2 is present in all Thermus sp. mer operons. The presence of a thiol-related gene was also detected in some alphaproteobacterial mer operons, in which a glutathione reductase gene was present, supporting the role of thiols in Hg(II) detoxification. These results have led to a working model in which LMW thiols act as Hg(II)-buffering agents while Hg is reduced by MerA.IMPORTANCE The survival of microorganisms in the presence of toxic metals is central to life's sustainability. The affinity of thiol groups for toxic heavy metals drives microbe-metal interactions and modulates metal toxicity. Mercury detoxification (mer) genes likely originated early in microbial evolution in geothermal environments. Little is known about how mer systems interact with cellular thiol systems. Thermus spp. possess a simple mer operon in which a low-molecular-weight thiol biosynthesis gene is present, along with merR and merA In this study, we present experimental evidence for the role of thiol systems in mercury resistance. Our data suggest that, in T. thermophilus, thiolated compounds may function side by side with mer genes to detoxify mercury. Thus, thiol systems function in consort with mer-mediated resistance to mercury, suggesting exciting new questions for future research.

First report of inventory and role of macroinvertebrates and fish in Cautín river (38° S, Araucania region Chile)

Abstract The Cautin river is located in the 137 years old Araucania region, Chile (38°S), and is characterized by alterations through human interference due agriculture and towns in its surrounding basin, the presence of salmonids, and by its mixed regime, originated from snow melting in summer and rains in winter. The aim of the present study was to make a review of the inventory and ecological role of the benthic inland water macroinvertebrates of the River Cautin, in order to understand their importance in the ecosystem of the river. The fauna of this river includes a fauna composed of endemic and introduced fish, which has, however, been only poorly studied until now. The literature revealed the presence of abundant populations of Diptera, Trichoptera and Ephemeroptera larval stages, and few crustaceans specifically amphipods and freshwater crabs along the rivers course. Many of these macroinvertebrates are prey for both introduced salmonids and native fishes. Similar results have been reported for other southern Argentinean and Chilean Patagonian rivers.

Resumo O rio Cautin está localizado na região de Araucania, no Chile (38°S), é caracterizado por alterações através da interferência humana devido à agricultura e as cidades da bacia circundante, a presença de salmonídeos e pelo seu regime misto, originado pela queda de neve verão e chuvas no inverno. O objetivo do presente estudo foi fazer uma revisão do papel ecológico dos macroinvertebrados bentônicos das águas interiores do rio Cautin, para entender sua importância no ecossistema do rio. A fauna deste rio inclui uma fauna composta de espécies de peixes endêmicos e introduzidos, que, no entanto, tem sido mal estudada até agora. A literatura revelou a presença de abundantes populações de estádios de larvas Diptera, Trichoptera e Ephemeroptera, e poucos crustáceos especificamente anfípodes e caranguejos de água doce ao longo do curso do rio. Muitos desses macroinvertebrados são presas tanto para salmonídeos introduzidos quanto para peixes nativos. Resultados semelhantes foram relatados para outros rios sul da Patagônia Chilena e Argentina.

Decidual changes in the endometrium and morphological adaptation of the associated supplying arteries in the normal and diabetic pseudopregnant rat.

After an electrically induced pseudopregnancy in rats in which deciduomas were produced by an intraluminal oil injection, the decidual tissue was studied morphologically on days 7, 10 and 13. A constant and dynamic wave of mitotic figures was found, which started on day 7 in the antimesometrial decidua, moving to the mesometrial decidua on day 10 and finally to the mesometrial triangle area on day 13 of pseudopregnancy. This and other morphological changes were compared with those found in pseudopregnant rats with streptozotocin-induced diabetes. On days 7 and 10 the incidence and distribution of mitotic figures were practically identical in both groups and statistically no significant difference was found in the uterine weight between the two groups on these two days. On day 13, two statistically significant differences were observed in the diabetic group: a fall in the uterine weight and a fall in the incidence of mitotic figures in the mesometrial triangle decidual cells. Associated with decidualization, a series of histological changes were studied in the arteries of the mesometrial triangle. Although the difference was not statistically significant, changes seemed to occur to a lesser degree in the diabetic group. It is concluded that the diabetic state has no influence in the early decidualization period, but it does have influence late in pseudopregnancy: a fall in the mitotic activity in the decidual tissue, a fall in the uterine weight and a less marked change in the spiral arteries which during pregnancy would supply the developing placenta with maternal blood.