The rat strain transgenic for the murine Ren-2 renin gene (TGR) is defined as a monogenic model of angiotensin II-dependent hypertension with endogenous activation of the renin-angiotensin system. Homozygous males TGR develop malignant hypertension with a strong salt-sensitive component. These animals show severe hypertension, proteinuria and high mortality. Morphological changes of renal parenchyma correspond to chronic ischemic glomerular changes. Heterozygous TGR develop only mild hypertension and thus provide a more suitable model of hypertension regarding to clinic al studies. Within the renal parenchyma, secondary focal segmental glomerulosclerosis (FSGS) predominates. High-salt diet in heterozygous animals induces transition from benign to malignant phase of hypertension. In this case, ischemic glomerular changes are superimposed on preexisting secondary FSGS. In the regression model of hypertension (late-onset treatment) the effect of salt intake is attenuated. In homozygous TGR, early selective ET A receptor blockade decreased blood pressure and ameliorated end-organ damage. Late selective ET A receptor blockade reduced podocyte injury despite final severe hypertension. Survival rate was markedly improved in both regimens with ETA selective blockade, while there was only partial improvement with early non-selective blockade. Both bosentan and atrasentan decreased ET-1 levels in both regimens. In heterozygous TGR, early and late ETA treatment substantially while ETA/ETB treatment partially improved survival rate. Significant effect on BP was found with early and late ETA blockade, while ETA/ETB blockade had no effect. Bosentan and at rasentan similarly decreased ET-1 levels on both regimens. In conclusion, selective ETA receptor blockade is superior to nonselective ETA/ETB receptor blockade in attenuating hypertension and end-organ damage. Its effect is more pronounced when applied early in the life., Z. Vernerová ... [et al.]., and Obsahuje seznam literatury
The age and growth of weatherfish (Misgurnus fossilis), an endangered and protected freshwater fish with a poorly known life history, was studied in two watercourses (the River Ner and the Nowy Rów canal, Poland). The weight, length and sagittal otoliths of 166 specimens collected in April 2015 were measured for weight-length relationships, ageing and back-calculation of length at age. At both sites sex ratio did not differ from 1:1. Weatherfish otoliths were small, elliptic (1.85 mm longer axes of the largest otolith) and the annuli were clearly visible. Female lifespan was six years but the oldest males were four and five years. In both sites populations were dominated by 2+ (the River Ner) and 3+ (the Nowy Rów canal) specimens. In general, weatherfish grows isometrically (b = 3) and the intercept of the weight-length relationship differ between study sites but not between sexes. Its total length (TL) was predicted by an interaction between sex and age, as well as capture site and age. Back-calculated estimates of TL fitted a von Bertalanffy growth function, though Taylor’s criterion showed that the asymptotic length were overestimated. Multiple comparisons of the von Bertalanffy growth function parameter revealed difference between sexes and sites.
There are 20 endemic genera of mosses and three of liverworts in North America, north of Mexico. All are monotypic except Thelia, with three species. General ecology, reproduction, distribution and nomenclature are discussed for each genus. Distribution maps are provided. The Mexican as well as Neotropical genera of bryophytes are also noted without detailed discussion.
Vřetenovka opavská (Cochlodina cerata opaviensis) je jedním z mála našich endemitů mezi měkkýši. Izolovaná populace na Moravě, v povodí řeky Moravice a okolí, pochází z období klimatického optima holocénu. Nynější průzkumy ukázaly na silný ústup z jejího moravského areálu, z 18 historických lokalit byla nalezena pouze na čtyřech. Hlavním důvodem jejího úbytku je bezesporu ničení jejích přirozených stanovišť – suťových lesů. Otázkou však zůstává mizení také z některých málo dotčených lokalit, kde byla ještě v 60. letech minulého století hojná. and Cochlodina cerata opaviensis is one of the few endemics among Czech molluscs. An isolated population in Moravia, in the catchments of the Moravice River and surroundings, was established during the Holocene climatic optimum. Recent research has shown a rapid decline in most sites; its occurrence was confirmed in only four out of 18 historical sites. Human-made degradations of talus forests are certainly the main threat of the species. The question is why the species also disappeared from several almost untouched sites.
Prvotní příčinou podivuhodného složení hadcové flóry jsou zvláštní chemické a fyzikální vlastnosti samotného hadce, které se však projevují v různé míře v závislosti na místních klimatických a geomorfologických podmínkách. Extrémní podmínky substrátu a izolovanost hadcových oblastí, které jsou u nás roztroušeny po celé republice, mohly vést až k evoluci hadcových (sub)endemitů. and The primary reason for the special composition of serpentine flora are the special chemical and physical features of the serpentine itself, whose expression differs according to local climatic and geomorphological conditions. The extreme condition of the substrate and the isolation of serpentine areas, dispersed across the whole country in the Czech Republic, can subsequently lead to the evolution of serpentine (sub)endemic species.
Článek je zaměřen na systematiku, evoluci, ekologii a možné příčiny ohrožení čtyř hadcových subendemitů ČR. Zatímco chrastavec rolní hadcový (Knautia arvensis subsp. serpentinicola) a mochna Crantzova hadcová (Potentilla crantzii subsp. serpentini) jsou poměrně dobře definované poddruhy, hvozdík kartouzek hadcový (Dianthus carthusianorum subsp. capillifrons) a trávnička obecná hadcová (Armeria vulgaris subsp. serpentini) jsou možná taxonomicky heterogenní jednotky, které spojuje pouze výskyt na hadcovém substrátu. Přesto však hadcové populace těchto druhů představují významný ekologický a fytogeografický prvek středoevropské flóry. and The article describes the possible reasons why four of the Czech serpentine subendemic species are endangered, as well as their systematics, evolution and ecology. While Knautia arvensis subsp. serpentinicola and Potentilla crantzii subsp. serpentini are relatively well defined subspecies, Dianthus carthusianorum subsp. capillifrons and Armeria vulgaris subsp. serpentini might be heterogeneous units having only the distribution on a serpentine substrate in common. Nevertheless, serpentine populations of these species are an important ecological and phytogeographical phenomenon among Central European flora.
Oba taxony s podobnou evoluční historií jsou dlouhodobě uznávanými endemity českých hadcových substrátů a nejsou doprovázeny dalšími blízkými či velmi podobnými druhy v okolí. Vzhledem k tomu, že oba jsou zařazeny mezi kriticky ohrožené taxony a jsou pod ochranou evropského projektu Natura 2000, zaslouží si naši prvořadou pozornost. and Both taxa (Cerastium alsinifolium and Minuartia Smejkalii) with similar evolutionary history have for years been included among the endemic species of the Czech serpentine substrate, not accompanied by other near or similar species in given localities and their neighbourhood. Both species are critically endangered and protected under the European Natura 2000 project and therefore deserve special attention.
Small mammals are just as likely to become extinct as larger species, although the latter receive disproportionate attention with respect to conservation activity and research. We focused on rarity, vulnerability to extinction and conservation status for small terrestrial mammals from the orders Soricomorpha and Rodentia occurring in the Balkans and Anatolia. Although these two regions have fewer mammalian species than Central Europe in very small biota areas (surface areas 4 km2), they accumulate species at a much faster rate with increases in surface area. The distribution ranges of fifteen species from a total of 88 (= 17%) are confined to this studied area, with eight species being endemic to Anatolia and six to the Balkans. High endemism is indicative of small ranges, i.e. of one form of rarity of Rabinowitz’s ‘seven forms of rarity’ model. The ranges of at least three species (Talpa davidiana, Myomimus roachi and Dinaromys bogdanovi) have declined since the Last Glacial Maximum. Although numbers of extinctions correlates strongly with the number of endemics, and species displaying both restricted distribution and low density are those most at risk of extinction, very little conservation activity and research is focused on small-range endemics.