Conformational dynamics of the tetrameric hemoglobin molecule as revealed by hydrogen exchange: 2. Effect of intersubunit contact cleavage

IR spectroscopy was used to study the rate of hydrogen-deuterium (H-D) exchange of peptide NH atoms in isolated α and β subunits of human hemoglobin (Hb) at pH 5.5–9.0 and 20°C. The H-D exchange occurs by the EX2 mechanism. The retardation factor of subunit exchange rate (P) is in a range of approximately 10²–10⁷. Compared to tetrameric Hb, the probability of local fluctuations (1/P) increases to a slightly greater extent in monomeric α subunits than in tetrameric β subunits. Unlike in the whole Hb molecule, oxygenation of its subunits has no effect on the probability of local fluctuations, and the subunits show no pH-dependent changes in 1/P values (observed for liganded Hb). Probable mechanisms accounting for overall intensification of local fluctuations upon the cleavage of contacts between subunits of the tetrameric Hb molecule are discussed with regard to structural crystallographic data.     

Escherichia coli K-12 mutants with an increased efficiency of plasmid transformation

Escherichia coli K-12 mutants with an enhanced efficiency of plasmid transformation were obtained. In all the mutants, the efficiency of transfection with lambda vir phage DNA was changed, in comparison to the parent strain. However, these changes did not always correlate strictly with plasmid transformation alterations. For instance, two mutants with an increased plasmid transformation efficiency demonstrated 50-fold decrease in the level of transfection with lambda phage DNA. Polyacrylamide gel electrophoresis points to both quantitative and qualitative differences in protein composition of the mutant cell envelopes, as compared with the parent strain.     

Identified taste bud cell proliferation in the perihatching chick [published erratum appears in Chem Senses 1998 Aug;23(4):459]

Developing taste buds in the anterior mandibular floor of perihatching chicks were studied by high voltage electron microscopic autoradiography in order to identify proliferating gemmal cell types. Montaged profiles of 29 taste buds in five cases euthanized between embryonic day 21 and posthatching day 2 were analyzed after a single [3H]thymidine injection administered on embryonic day 16, 17 or 18. Results showed that dark cells comprised 55% of identified (n = 900 cells) and 62% of labeled (n = 568 cells) gemmal cells as compared with light, intermediate, basal or perigemmal bud cells. Dark cells had both a greater (P < 0.05) number of labeled cells and a greater amount of label (grains/nucleus) than the other four bud cell types, irrespective of injection day. The nuclear area (micron 2) of dark cells was not significantly larger (P > 0.05) than that of the other gemmal cell types and therefore cannot account for the greater amount for label in the dark cells. Interestingly, only dark cells showed a positive correlation (P < 0.003) between amount of label and nuclear area. Results suggest that, during the perihatching period of robust cell proliferation, dividing dark cells may give rise primarily, but not exclusively, to dark cell progeny.      

The ecological integrity of the Lower Olifants River,Limpopo province,South Africa: 2009–2015 – Part A: Olifants River main stem

The major rivers of the South African ‘Lowveld’ (low-latitude savanna) suffer numerous impacts from upstream economic activities. Whereas monitoring these rivers is required to detect biodiversity losses, record pollution events and devise mitigation strategies, current monitoring programmes are inadequate. In 2009, the South African Earth Observation Network initiated an intensive long-term research programme on the Lowveld reaches of the Olifants River. Physico-chemical parameters, aquatic macroinvertebrates and fish abundances were recorded at four Lowveld sites in the Olifants River. We review six years of this programme. The results suggest deterioration in the ecological condition of the Olifants River with no discernible improvement through protected areas. Trends could not be detected. The parameters measured, sampling methods and/or sampling frequency might be responsible for the limited trends observed, or alternatively the results simply reflect stable conditions despite on-going pollution. Real time monitoring and an expansion in the parameters monitored would add value to the monitoring programme.     

Primary structure of abnormal E-like hemoglobin]

An E-like abnormal hemoglobin was detected in a hematological patient and one of the members of her family. The composition of blood hemolyzates was characterized using acetate cellulose electrophoresis. The abnormal beta-chain was isolated by ion-exchange chromatography of total globin on CM-cellulose. Using peptide mapping of the abnormal beta-chain trypsin hydrolysates, it was shown that the amino acid substitution occurs in peptide beta T3. The amino acid analysis and determination of the abnormal fragment C-terminal amino acid allowed to establish the locus and type of this substitution. The first case of hemoglobin E(alpha 2 beta 2 26Glu leads to Lys) identification on the territory of the USSR is reported.     

Correlation of the differentiation of the epithelium of provisory and definitive kidneys in vertebrates]

Opisthonephros-the primary kidney of the frog-has features similar in its development to both primary and secondary kidneys of the rabbit, and at the same time they greatly differ from the frog's pronephros in the course of its development. It is in the development of the frog's pronephros where the regularity of shortened and accelerated differentiation of tissue of provisory organs as compared with definitive ones formulated by P.P. Ivanov has distinct manifestation. It is in agreement with the fact that the pronephros of lower vertebrates is considerably more primitive in its anatomical and physiological features than the primary and secondary kidneys of higher vertebrates which are in general similar with each other though functioning in different developmental periods.     

The sensitivity of mesenchymal stromal cells subpopulations with different adhesion properties and derived from hemopoietic organs to growth factors EGF,bFGF, and PDGF

The action of three growth factors (EGF, bFGF, and PDGF) on mesenchymal stromal cell (MSC) subpopulations from rat adult bone marrow (BM) and embryo liver (EL) was investigated. These cells are plastic-adhesive and have different rates of adhesion (AS1–AS4 subpopulations). The efficiency of colony-formation, the size of colonies, and the number of early osteogenic progenitors with alkaline phosphatase activity in colonies and induced osteogenesis were analyzed. It was shown that EGF increased the number of bone marrow (BM) MSC colonies, but it had no influence on osteogenic differentiation. bFGF suppressed colony formation, but it stimulated both early and late stages of osteogenesis. PDGF increased the size and the number of colonies in AS2 and AS3 subpopulations, but it stimulated only the terminal stage of ostegenesis. The distinction between MSC subpopulations from two organs was found: MSC from EL had small osteogenic capacities and low sensitivity to grow factors; MSC from BM had no such characteristics. MSC subpopulations with different adhesion properties and from different tissues had compatible sensitivity to growth factors.     

The immunotropism of sunflower oil and starch in peroral administration to mice]

It has been shown that per os introduction of sunflower oil and starch to adult thymectomized mice resulted in reconstitution of the number of Thy-I+ spleen cells similar of the glutamic acid effect. Glutamic acid restored the immune response to sheep red blood cells (SRBC), however, sunflower oil and starch were not effective. The influence of these compounds on the immune response to SRBC in normal and sham-thymectomized mice was different: glutamic acid stimulated it, starch had no influence on the immune response, sunflower oil suppressed it.     

Dynamic structural characteristics of the m. triceps surae in human subjects of various physiques

At examination of 305 boys and girls Russian, Kazakh in Alma-Ata strength of the m. triceps surae (strength of the foot flexion) has been estimated, anatomical diameter of this muscle and strength per 1 sm2 of the anatomical diameter (specific strength) has been calculated. Somatotyping after V. N. Shevkunenko has been performed. At dolichomorphy the specific strength is higher than at brachymorphy. In 24 corpses of 18-38-year-old men typical peculiarities of construction and structure of the m. triceps surae is studied. Correlation of the m. triceps surae parts and degree of its pinnateness do not reveal any definite differences in connection with the complexion. As demonstrate the data of light microscopy and mathematical treatment of the results by means of mixtures method statistically reliable predominance of the connective tissue component in the m. triceps surae and more often occurrence of thick muscle fibers in the m. soleus at dolichomorphy is stated. According to the electron microscopy data, better development of the connective tissue carcass of the m. triceps surae is proved in persons of dolichomorphic complexion.