A near-infrared method for studying hydration changes in aqueous solution: Illustration with protease reactions and protein denaturation

Proteins undergoing protease reactions, heat denaturation, or interactions with sodium dodecyl sulfate (SDS) were used to demonstrate the effectiveness of a near-infrared method for the quantitative study of changes in hydration or water binding during such processes. The spectra of different proteins showed that the liberation of $\text{COO}{}^{\mathrm{?}}\text{and NH}{}_3{}^{\mathrm{+}}$ groups during a protease reaction is associated with a large increase in hydration and excluded volume. On the basis of experiments with model compounds, other spectral changes, including development of continuum absorbance between 1.55 and 1.85 μm and a band with a peak near 2.1 μm, were also attributed to the liberation of these groups. After heat denaturation or in the presence of SDS, the rate of proteolytic hydrolysis was markedly increased, consistent with the view that some preliminary denaturation is necessary for protease activity. The validity of the hydration changes calculated for protease reactions was supported by model studies with l-lysine, and with poly-l-lysine before and after hydrolysis. The near-infrared spectrum of the protein substrate with no added protease was largely unaffected by heat treatment alone, indicating that the hydration as such was not changed to a large extent by the structural modifications of denaturation. In contrast to the protease reaction, the interactions between SDS and the proteins resulted in a decrease in hydration. Results of this paper are compared with those obtained from other methods. Some unique advantages of the near-infrared method for the study of hydration changes during reactions in aqueous solution are described.     

Gut Microbiome Fermentation Determines the Efficacy of Exercise for Diabetes Prevention

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Uncoupling of mitochondrial oxidative phosphorylation by thallium.

The mechanism of integration of λ$\text{bio}$ll, which is deleted of all the known λ recombination genes, was studied using $\text{bio}$ deleted hosts as recipients. The presence of $\text{rec}$BC DNase and $\text{exo}$I in the recipient cells affected the fate of λ$\text{bio}$ll DNA. In nine of ten $\text{imm}\text{λ}{}^{\mathrm{+}}$ transductants, insertion of the λ$\text{bio}$ll genome took place somewhere between J and N and the remaining one had abnormally permuted prophage λ. In this lysogen (#42), the sequence of prophage genes was similar to that of vegetative phage λ. The properties of lysogen #42 were compared with those of other lysogens.     

Genetic studies on seedling vigour in sesame

Genetic studies were carried out on seedling and agronomic characters amongst 50 sesame genotypes to estimate the genetic variation, determine the relationships amongst the characters and identify rapidly growing genotypes with vigorous seedling growth. The contribution of genetic variance was highest for the two mature characters, days to first flower (95.6%) and number of nodes to first flower (95.2%), and was medium/high (50–75%) for most of the seedling characters. Strong positive genetic correlations were obtained between various cotyledon and early leaf characteristics measured at 20 days after sowing. Based on these results several genotypes were identified as having rapid seedling growth and these could form an initial gene pool to provide material for screening for tolerance to sesame flea beetle.     

Don C. Ohadike: The Man, his Intellectual Legacy and African Historiography

It is difficult to completely understand the life history of an intellectual excluding an understanding of his family upbringing and formative years. Family upbringing and childhood environment, often the less known part of a life history, play crucial roles in shaping the ideas and values individuals espouse in their adult life. Notwithstanding, this paper is not concerned with Don C. Ohadike’s childhood. It rather focuses on the professional career of our able historian – that is the part of his life as revealed by his most outstanding published writings. Ohadike’s published works contain a wellspring of idioms that tell much about his values, quality of mind, and his mission as an African historian. Ohadike was a humanist, an African patriot, and a nationalist crusader. His entire philosophy centered on safeguarding his African identity in an emergent world of cultural imperialism. The funds for this research were provided by a NEH-funded fellowship at the Schomburg Center, New York in the Spring of 2007. I owe a lot of gratitude to Professor John McLeod and Dean Blaine Hudson for granting me the extra incentives to pursue my research in New York. While all errors and misinterpretations are mine, I wish to thank the editors and anonymous reviewers for Journal of Dialectical Anthropology for their perspective comments and suggestions on earlier drafts of this paper.     

Latency of Botrytis cinerea Pers.: Fr. and Biochemical Studies During Growth and Ripening of Two Grape Berry Cultivars, Respectively Susceptible and Resistant to Grey Mould

Latency and development of Botrytis cinerea were assessed under field conditions and after artificial inoculation of two grape varieties, Gamay (susceptible) and Gamaret (resistant). When the percentage of latent Botrytis was the same for both varieties, severity of visible grey mould remained very low in Gamaret berries, while Gamay clusters were destroyed by the disease to a high percentage. Some biochemical parameters were measured in berries, such as constitutive and induced anti‐fungal compounds, polymeric proanthocyanidins and lipid peroxidation products as markers of senescence. Differences were observed in polymeric proanthocyanidins (PPRA) of Gamaret compared with those of Gamay. Concentration and mean degree of polymerization (mDP) of PPRA were always higher in the berries of the resistant variety. The inhibitory effect of Gamaret PPRA on enzyme activity remained until harvest whereas Gamay PPRA lost their inhibitory activity at the beginning of véraison. Based on these results, resistance to B. cinerea seems to be linked to the maintainance of the fungus in its latent form in berries, mainly due to the ability of Gamaret PPRA to inhibit macerating fungal enzyme activities.     

Neutral mutations and repetitive DNA

We have previously shown that computer simulations of processes that generate selectively advantageous changes together with random duplications and deletions give rise to genomes with many different genes embedded in a large amount of dispensable DNA sequence. We now explore the consequences of neutral changes on the evolution of genomes. We follow the consequences of sequence divergences that are neutral when they occur in dispensable sequences or extra copies of genes present in multigene families. We find that when divergence occurs at about the same frequency as duplication/deletion events, genomes carry repetitive sequences in proportion to their size. Inspection of the genomes as they evolved showed that multigene families were generated by relatively recent duplications of single genes and so would be expected to be highly homogeneous.