Proliferative and Differentiation Potential of Individual Clones Derived from Bone Marrow Stromal Precursor Cells

We present the results of a study on the proliferative and differentiation potential of individual clones of stromal fibroblasts growing in monolayer cultures of bone marrow cells. Each precursor cell yielding a large colony in primary culture is capable of up to 34 doublings in vitro. The transplantation of clones or monoclonal strains of stromal fibroblasts into the open system results in the formation of microenvironment consisting of the bone and reticular tissue and is suitable for the differentiation of all three lines of hemopoiesis. Evidence has been obtained that, in a closed system, individual clones are capable of differentiation into the bone, cartilaginous, and reticular tissues. In other words, the adult organism has a common cell precursor for these tissues.     

Localized reversible frameshift mutation in an adhesin gene confers a phase-variable adherence phenotype in mycoplasma

The variable adherence-associated (Vaa) antigen of Mycoplasma hominis is an abundant surface lipoprotein adhesin that may mediate important interactions of this wall-less prokaryotic pathogen with the human host. Extensive mutational variation of Vaa size, as well as sequence and antigenic divergence, has been described previously. Using a series of clonal isolates representing an isogenic lineage of variants oscillating in Vaa expression, Vaa is further shown in this study to undergo high-frequency phase variation in expression, which correlated precisely with the ability of M . hominis to adhere to cultured human cells. Although no DNA rearrangements or sequence differences in the 5' regions flanking vaa alleles were detected between Vaa⁺ and Vaa⁻ variants, intragenic vaa sequences from this lineage revealed an oscillating mutation involving a single nucleotide deletion/insertion in a short tract of adenine residues near the 5' end of the mature Vaa coding sequence, which created a translational frameshift resulting in either a complete Vaa ORF or an in-frame UAG stop codon immediately downstream of the poly-A tract. Evidence for the occurrence of this high-frequency frameshift mutation in vivo was obtained from analysis of PCR-generated vaa sequences amplified from the joint synovial fluid of a patient with M . hominis -associated arthritis, which indicated that Vaa phase variation occurs during M . hominis infection in the natural host. These results identify a distinctive frameshift mutator element in the vaa gene that governs M . hominis adherence and highlight the importance of mutational alteration of primary gene products on the mycoplasma surface as a means of generating and maintaining functional diversity in the host.     

Structure of vegetation of steppe hills in the Altai piedmont

The phytocenotic diversity of the Altai steppe piedmont is described. Plant communities were ordinated along the moisture gradient. The results were used to analyze the structure of vegetation of steppe hill massifs. Distribution of steppe vegetation over an ideal hill was simulated, and the main patterns of distribution were typified.     

Oculomotor activities in monkeys with N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced syndrome of parkinsonism

In twoMacaca rhesus monkeys that received repeated N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) injections (single dose 0.2 mg/kg, i.m.; cumulative dose 11.2–13.3 mg), changes in characteristics of spontaneous saccadic eye movements and vestibulo-ocular reflex (VOR) were evaluated. With the development of severe behavioral disturbances, amplitude of spontaneous saccadic eye movements gradually decreased. Pronounced changes in duration of saccadic eye movements, frequency of spontaneous saccades, and their pattern were observed. No changes in parameters of VOR slow component were recorded, but high total MPTP doses suppressed fast phase of the reflex.Neirofiziologiya/Neurophysiology, Vol. 25, No. 3, pp. 184–190, May–June, 1993.     

Association between misalignment of circadian rhythm and obesity in Korean men: Sixth Korea National Health and Nutrition Examination Survey

ABSTRACT

Background: The disruption of circadian rhythm has been found to associate with obesity in vivo and in vitro. Sleep duration, eating habits, total feeding time, and nightshift work can also affect circadian rhythms. This study investigated the association between misalignment of circadian rhythm and obesity in Korean men, using a cross-sectional database.

Methods: This study used data from the Korean National Health and Nutrition Examination Survey (KNHANES), whose study population was 3,658 men aged 18 to 60 years. General and abdominal obesity was defined as a body mass index (BMI) ≥ 25 kg/m² and waist circumference ≥ 90 cm, respectively. Circadian rhythm factors were determined with a self-report questionnaire and included breakfast frequency, sleep duration, and work time. Frequency of breakfast was divided into regular breakfast (five to seven times a week) and irregular breakfast (less than five times a week). Sleep duration was divided into less than 7 hours, 7–9 hours, and over 9 hours. Working time was defined as day/evening, night shift, and other type. The adjusted odds ratios (aORs) and 95% confidence intervals (CIs) for general and abdominal obesity were calculated using multivariable logistic regression according to the number of factors that disturb the circadian rhythm.

Results: Participants with 1 (aOR 1.34, 95% Cl 1.10–1.61) and ≥2 (aOR 1.62, 95% Cl 1.29–2.05) factors disturbing circadian rhythms were associated with elevated risk for general obesity. Similarly, those with 1 (aOR 1.33, 95% Cl 1.09–1.63) and ≥2 (aOR 1.70, 95% Cl 1.32–2.20) factors had elevated risk for abdominal obesity.

Conclusions: Factors disturbing the circadian rhythm were associated with general and abdominal obesity. Additional studies are needed, and associations with metabolic diseases should be investigated.     

The Drosophila tissue polarity gene starry night encodes a member of the protocadherin family.

The tissue polarity genes control the polarity of hairs, bristles and ommatidia in the adult epidermis of Drosophila. We report here the identification of a new tissue polarity gene named starry night (stan). Mutations in this essential gene alter the polarity of cuticular structures in all regions of the adult body. The detailed polarity phenotype of stan on the wing suggested that it is most likely a component of the frizzled (fz) pathway. Consistent with this hypothesis, stan appears to be downstream of and required for fz function. We molecularly cloned stan and found that it encodes a huge protocadherin containing nine cadherin motifs, four EGF-like motifs, two laminin G motifs, and seven transmembrane domains. This suggests that Stan functions in signal reception, perhaps together with Fz.     

Cartographic analysis of the population of amphibians,reptiles, and birds of the West Siberian plain and Altai

For the entire territory of West Siberia, including its plain and mountainous parts, two maps were constructed for populations of amphibians together with reptiles, and of birds. Communities of these classes of vertebrates differ from one another in their spatial differentiation. The differences are demonstrated for the plain and mountainous territories considered jointly and separately.