Comparison of clastogenic effects of inorganic selenium salts in mice in vivo as related to concentrations and duration of exposure

Inorganic selenium compounds in the diet have been known to protect against cancer in laboratory animals, but were harmful in high concentrations. In the present work, the relative effects of two salts, sodium selenite and sodium selenate, administered to mice in vivo, in different concentrations and durations of exposure, were compared. Aqueous solutions of each salt (7, 14, 21 and 28 mg Kg^–1 bw) were fed by gavaging to mice matched in age and sex. The animals were sacrificed at intervals of 6, 12, 18 and 24 h and chromosome preparations were made following the usual schedule of colchicine-hypotonic-fixative-airdrying-Giemsa staining. The endpoints screened were chromosomal aberrations (CA) and damaged cells (DC). Both salts affected chromosome structure and spindle formation, sodium selenite being more cytotoxic than sodium selenate. The frequencies of aberrations induced were directly proportional to the concentrations used and duration of exposure.     

Interaction between two group IV metals-lead and zirconium-in bone marrow cells ofMus musculus in vivo

The interaction between two group IV metals, the highly toxic lead and the relatively inactive and low toxic zirconium, was studied in the bone marrow chromosomes ofMus musculus in vivo. Low and high doses of zirconium oxychloride were fed orally to the experimental mice (i) 2 h before, (ii) 2 h after or (iii) together with different doses of lead nitrate. Protection against lead-induced clastogenicity was observed only when the lower dose of zirconium was administered prior to lead. All other combinations gave an additive or synergistic effect as was seen by significant increases in the frequencies of chromosomal aberrations.     

Zirconium

Summary The action of Zirconium (Zr) on biological systems presents an enigma. It is ubiquitous, being present in nature in amounts higher than most trace elements. It is taken up by plants from soil and water and accumulated in certain tissues. The entry into animal systems in vivo is related to the mode of exposure and the concentration in the surrounding environment. Retention is initially in soft tissues and then slowly in the bone. The metal is able to cross the blood brain-barrier and is deposited in the brain and the placental barrier to enter milk. The daily human uptake has been known to be as high as 125 mg. The level of toxicity has been found to be moderately low, both in histological and cytological studies. The toxic effects induced by very high concentrations are nonspecific in nature. Despite the presence and retention in relatively high quantities in biological systems, Zr has not yet been associated with any specific metabolic function. Very little information is available about its interaction with the compounds of the genetical systems, such as nucleic acids. Apparently, the metal is neither an essential nor toxic element in the conventional sense. However, the increasing exposure to this element through its increasing use in new materials and following radioactive fallout, has increased the importance of the study of its effects on living organisms. The tetravalent nature of the ionic state and the high stability of the compounds formed are important factors that need to be considered, as also the accumulation of this element in the brain, reminiscent of the relationship between Al³⁺ and Alzheimer's disease.     

The Yeast INO80 Complex Operates as a Tunable DNA Length-Sensitive Switch to Regulate Nucleosome Sliding

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Reproductive development and nuclear DNA content in angiosperms

Correlates of nuclear DNA content in angiosperms have been noted previously for a range of features, cellular to geographic. A new hypothesis, the correlation between nuclear DNA content and reproductive developmental features (after Cavalier-Smith, Journal of Cell Science 34, 247–268, 1978) is posed and tested here. Of three features tested (megasporogenesis, microsporogenesis, and endosperm development), megasporogenesis alone was shown to be correlated with nuclear DNA amount. The hypothesis was examined in 107 families of angiosperms using nonparametric statistics, and in 53 families of monocotyledons and outgroups using a phylogenetic test of association. A correlation was found between large genomes and successive microsporogenesis for all angiosperms, but not for monocots and dicots analyzed separately, thus underlining the importance of taking into account phylogenetic relationships in such studies. A correlation between cellular endosperm and large genomes in dicotyledons needs to be confirmed in a phylogenetic context. A tendency for deviations from monosporic megasporogenesis to occur in taxa that have a nuclear DNA content of over 9.0 pg/C was demonstrated using both phylogenetic and nonphylogenetic tests. It is hypothesized that cytoskeleton dynamics are affected in reproductive cells, enabling decoupling between nuclear and cytoplasmic cell cycles and leading to variation in reproductive development.     

In vitro screening procedure for osmotic tolerance in Prunus

Significant growth differences (p<0.01) were observed for two micropropagated Prunus accessions after 14 days in culture when 685 mM mannitol was included in Quoirin and Lepoivre nutrient medium. While there was an 11% growth increase in fresh weight during the 28-day culture period for accession K537-067, explants from New Jersey Plumcot No. 3 increased fresh weight an average of 123%. Similar tests were conducted to determine the repeatability of this short term in vitro screening procedure. Explants of Mananna 2624 were subjected to two levels of mannitol, 275 mM and 550 mM, included in the Quoirin and Lepoivre nutrient medium. Three successive 28-day tests were conducted. Explants were examined at both 14 and 28 days after the onset of the experiment for net growth changes. Addition of mannitol to the nutrient medium at concentrations of 275 mM and 550 mM decreased explant fresh weights of Marianna 2624 to 36% and 28% of controls, respectively, at 28 days past initial culture. Initial fresh weight and fresh weight changes at day 14 were significantly different (p 0.05) between tests. No significant differences existed between tests with regard to weight changes at 28 days past initial culture. This information may aid Prunus breeders in the choice of procedures for inducing drought stress and screening large numbers of plant accessions.Abbreviations K5 K537-067 - M2624 Marianna 2624 - NJPC3 New Jersey Plumcot No. 3 - Q & L Quoirin and Lepoivre     

An expeditious synthesis of blood-group antigens,ABO histo-blood group type II antigens and xenoantigen oligosaccharides with amino type spacer−arms

Blood group oligosaccharides are one of the most clinically important antigen families and they may also act as secondary ligands for bacterial toxins from Escherichia coli and Vibrio cholerae. Herein we report the synthesis of spacered (sp = CH₂CH₂CH₂NH₂) glycosides of A antigen {α-D-GalNAc-(l→3)-[α-L-Fuc-(l→2)]-β-D-Gal-}, B antigen{α-D-Gal-(l→3)-[α-L-Fuc-(l→2)]-β-D-Gal-}, LewisX{α-D-Gal-(l→4)-[α-L-Fuc-(l→3)]-β-D-GlcNAc-}, A type-II {α-D-GalNAc-(l→3)-[α-L-Fuc-(l→2)]-β-D-Gal-(1→4)-β-D-GlcNAc-}, B type-II {α-D-Gal-(l→3)-[α-L-Fuc-(l→2)]-β-D-Gal-(1→4)-β-D-GlcNAc-}, H type-II{α-L-Fuc-(l→2)-β-D-Gal-(1→4)-β-D-GlcNAc-}, xenoantigen {α-D-Gal-(l→3)-β-D-Gal-(1→4)-[α-L-Fuc-(l→2)]-β-D-GlcNAc-} and Linear B Type II {α-D-Gal-(l→3)-β-D-Gal-(1→4)-β-D-GlcNAc-} useful for a range of biochemical investigations. This linker was chosen so as to facilitate the future conjugation of the antigens to proteins or other molecules. We also measured the affinities of some synthesized oligosaccharides against El Tor CTB strain from V. cholera.     

Transstadial transmission of Theileria annulata through common ixodid ticks infesting Indian cattle.

Transstadial transmission of Theileria annulata with Hyalomma anatolicum anatolicum, H. dromedarii and H. marginatum isaaci, and Haemaphysalis bispinosa, Rhipicephalus haemaphysaloides haemaphysaloides and Boophilus microplus was determined. It was found that the infection was successfully transmitted by H. a. anatolicum from larva to nymph and nymph to adult in all attempts. When larvae were fed on an infected calf the succeeding adults transmitted the infection when the intervening nymphs fed on a rabbit (non-susceptible host) but not when fed on a calf (susceptible host). Infective adult ticks transmitted the parasite during the first 24 h of feeding on a calf. When the feeding was interrupted after 24 h, and the tick transferred to another calf, the infection was transmitted to the latter as well. H. dromedarii successfully transmitted the infection from larva to nymph and from nymph to adult. Larvae of H. marginatum isaaci did not feed on calves but the infection was successfully transmitted from nymph to adult. Haemaphysalis bispinosa, Rhipicephalus h. haemaphysaloides and Boophilus microplus did not transmit Th. annulata from larva to nymph to adult.     

Cytotoxicity of zinc chloride in mice in vivo

Intraperitoneal administration of zinc chloride (ZnCl2) to Swiss albino mice in vivo induced a significant (p less than or equal to 0.05) increase in the frequencies of chromosomal aberrations of the bone-marrow cells at all concentrations used following acute (7.5, 10, 15 mg/kg body weight) and chronic (2.0, 3.0 mg/kg body wt) treatment. The degree of clastogenicity was directly proportional to the concentrations (p less than or equal to 0.05, trend test) and indirectly to the period of treatment (p less than or equal to 0.05, ANOVA test). It induced a dose-dependent, statistically significant increase (Mann-Whitney U statistics, Student's t-test) in sperm-head abnormalities. The data designate ZnCl2 as a potent clastogen and as a toxic chemical at the concentrations used.