Predicted bacteriorhodopsin from Exiguobacterium sibiricum is a functional proton pump.

The predicted Exigobacterium sibiricum bacterirhodopsin gene was amplified from an ancient Siberian permafrost sample. The protein bacteriorhodopsin from Exiguobacterium sibiricum (ESR) encoded by this gene was expressed in Escherichia coli membrane. ESR bound all-trans-retinal and displayed an absorbance maximum at 534nm without dark adaptation. The ESR photocycle is characterized by fast formation of an M intermediate and the presence of a significant amount of an O intermediate. Proteoliposomes with ESR incorporated transport protons in an outward direction leading to medium acidification. Proton uptake at the cytoplasmic surface of these organelles precedes proton release and coincides with M decay/O rise of the ESR.

Microbial populations in Antarctic permafrost: biodiversity, state, age, and implication for astrobiology.

Antarctic permafrost soils have not received as much geocryological and biological study as has been devoted to the ice sheet, though the permafrost is more stable and older and inhabited by more microbes. This makes these soils potentially more informative and a more significant microbial repository than ice sheets. Due to the stability of the subsurface physicochemical regime, Antarctic permafrost is not an extreme environment but a balanced natural one. Up to 10(4) viable cells/g, whose age presumably corresponds to the longevity of the permanently frozen state of the sediments, have been isolated from Antarctic permafrost. Along with the microbes, metabolic by-products are preserved. This presumed natural cryopreservation makes it possible to observe what may be the oldest microbial communities on Earth. Here, we describe the Antarctic permafrost habitat and biodiversity and provide a model for martian ecosystems.

[Spectral properties of the green alga Trebouxia--a phycobiont of cryptoendolithic lichens in the high-latitude polar regions of Antarctica]. / Issledovanie spektral'nykh kharakteristik zelenoi vodorosli Trebouxia--fikobionta kriptoéndoliticheskikh lishainikovykh soobshchestv vysokopoliarnykh regionov Antarktidy.

An algologically pure culture of the green alga Trebouxia, a phycobiont of cryptoendolithic lichens, was isolated from the sandstone samples collected in the high-altitude polar regions of Antarctica. The absorption and the second-derivative absorption spectra of the acetone extract of the Antarctic phycobiont cells were studied in comparison with those of the Trebouxia phycobiont isolated recently from the Parmeliaceae lichen in the Mid-European climatic zone. The cells of the Antarctic phycobiont were characterized by a lower content of chlorophyll a and a higher ratio of chlorophyll b and carotenoids to chlorophyll a as compared to the Mid-European phycobiont. Furthermore, the carotenoids of the Antarctic phycobiont were more diverse. The low-temperature fluorescence spectra of the Antarctic phycobiont were characterized by an increased intensity of the short-wavelength fluorescence peak of chlorophyll a and a diminished intensity of fluorescence in the long-wavelength spectral region.

[The absorption and fluorescence spectra of the cyanobacterial phycobilins of cryptoendolithic lichens in the high-polar region of Antarctica]. / Issledovanie spektrov pogloshcheniia i fluorestsentsii tsianobakterii-fikobiontov kriptoéndoliticheskikh lishainikovykh soobshchestv vysokopoliarnykh regionov Antarktidy.

The algologically pure cultures of the green-brown cyanobacterium Chroococcidiopsis sp. and three cyanobacteria of the genus Gloeocapsa, the blue-green Gloeocapsa sp.1, the brown Gloeocapsa sp.2, and the red-orange Gloeocapsa sp.3, were isolated from sandstones and rock fissures in the high-polar regions of Antarctica. These cyanobacteria are the most widespread phycobionts of cryptoendolithic lichens in these regions. The comparative analysis of the absorption and the second-derivative absorption spectra of the cyanobacteria revealed considerable differences in the content of chlorophyll a and in the content and composition of carotenoids and phycobiliproteins. In addition to phycocyanin, allophycocyanin, and allophycocyanin B, which were present in all of the cyanobacteria studied, Gloeocapsa sp.2 also contained phycoerythrocyanin and Gloeocapsa sp.3 phycoerythrocyanin and C-phycoerythrin (the latter pigment is typical of nitrogen-fixing cyanobacteria). The fluorescence spectra of Gloeocapsa sp.2 and Gloeocapsa sp.3 considerably differed from the fluorescence spectra of the other cyanobacteria as well. The data obtained suggest that various zones of the lichens may be dominated either by photoheterotrophic or photoautotrophic cyanobacterial phycobionts, which differ in the content and composition of photosynthetic pigments.

[Myasthenia onset in elderly patients]. / Debiut miastenii u lits starcheskogo vozrasta.

Possibility of myasthenia debut at old age is shown. 5 cases of 73-87 year-olds with the diagnosis-generalized form of myasthenia are reported. Peculiarities of clinical manifestations in this age group are described. Polymorbidity in the individuals of old age is noted. It is recommended to include vasoactive preparations in the scheme of therapy.

[The computer diagnosis and prognosis of emergency states in neurology]. / Vychislitel'naia diagnostika i prognozirovanie neotlozhnykh sostoianii v nevrologii.

The authors provide the analysis of long-term experience gained in the field of devising and introduction of diagnostic algorithms adjusted for various mathematical approaches and aimed for resolving of clinical tasks in vascular and somatogenic impairments of the nervous system. Basic requirements have been formulated for effective use of the diagnostic tables. The authors suggest to compare on the training sample diverse mathematical methods in order to define most effective of them in each case. The application of artificial file of observations is important to determine maximum accuracy of the diagnostic system. An advantage of multivariate statistical methods is demonstrated in clinical decisions on the treatment of somatogenic nervous diseases.

Long-term preservation of microbial ecosystems in permafrost.

It has been established that significant numbers (up to 10 million cells per gram of sample) of living microorganisms of various ecological and morphological groups have been preserved under permafrost conditions, at temperatures ranging from -9 to -13 degrees C and depths of up to 100 m, for thousands and sometimes millions of years. Preserved since the formation of permafrost in sand-clay sediments of the Pliocene-Quaternary period and in paleosols and peats buried among them, these cells art the only living organisms that have survived for a geologically significant period of time. The complexity of the microbial community preserved varies with the age of the permafrost. Eukaryotes are found only in Holocene sediments; while prokaryotes are found to greater ages, i.e., Pliocene and Pleistocene. The diversity of microorganisms decreases with increasing age of sediments, and as a result cocci and corynebacteria are predominant. Enzyme activity (catalase and hydrolytic enzymes) and photosynthetic pigments (chlorophyll and pheophytin have also been detected in permafrost sediments. These results permit us to outline some approaches to the search for traces of life in the permafrost of Martian sediments by borehole core sampling. It is in the deep horizons (and not on the planet surface), isolated by permafrost from the external conditions, that results similar to those obtained on Earth can be expected.

[Global amnesia syndrome among the initial clinical manifestations of brain tumors]. / Sindrome global'noi amnezii v nachal'nykh klinicheskikh proiavle- niiakh opukholei golovnogo mozga.

Global amnesia is observable in different lesions of the nervous system, including glial tumors of the brain. It is emphasized that global amnesia may turn out to be the first clinical manifestation of brain tumors. In such a case severe mnemonic disorders are likely to regress under the influence of vasoactive and dehydration therapy, which does not exclude, however, their tumorous genesis. These data should be taken into consideration during analysis of mnemonic disorders in neurological patients. All the patients with the above syndrome should be subjected to a long follow-up even in cases where the syndrome completely regresses under the therapeutic influence.

[Elaboration and use of the methods of computer-assisted diagnosis of cerebrovascular pathology]. / O razrabotke i ispol'zovanii metodov vychislitel'noi diagnostiki pri sosudistoi patologii golovnogo mozga.

The purpose of the work was to analyze the experience with the trial of diagnostic algorithms to specify possibilities of differential diagnosis and forecasting the course or outcome of cerebrovascular diseases. Detailed study of 922 clinico-anatomic cases (547 with hemorrhagic brain stroke, 157 with ischemic, 218 with pseudostroke) enabled revealing differential-diagnostic criteria for the pathological patterns under study bearing in mind disease pathomorphism. Analysis was made of the tabular diagnosis of cerebrovascular pathology and of the experience gained with the trail of diverse diagnostic algorithms for staged diagnosis of brain stroke and pseudostroke, different varieties of cerebral hemorrhages (10 varieties). The results of the use of four algorithms for forecasting hemorrhagic brain stroke were studied and compared. The accuracy of the diagnosis and forecasting amounts from 55 to 82.3% depending on the problem to be solved and the algorithm used. The data show the necessity of the careful providing of the algorithm choice as dependent on the problem raised.