The distribution and interaction of haemoglobin variants and the β thalassaemia gene in Liberia

In a population survey in Liberia, West Africa, 12 major tribes were examined for the prevalence of Hb S, Hb C, and the beta thalassaemia (beta Thal) gene. Hb C is rare; Hb S and beta Thal occur in polymorphic frequencies. The distribution of both genes shows an inverse correlation. The beta Thal trait was diagnosed by quantitation of Hb A2 on DE 52-microchromatography. This method proved to be reliable and useful for mass screening.     

Fatigue and contraction of slow and fast muscles in hypokinetic/hypodynamic rats

This investigation examined the effects of hypokinesia/hypodynamia (H/H) on fatigability and contractile properties of rat soleus (S) and gastrocnemius (G) muscles. Whole-body suspension for 1 wk was used to eliminate hindlimb load-bearing functions and simultaneously permit voluntary isotonic contractions. Train stimulations (45/min, 16 min) resulted in significantly (P less than 0.05) faster rates of fatigue to lower asymptotes in G from H/H rats. Fatigue in the S was minimal at this stimulation frequency and differences between H/H and control animals were not significant. Contractile properties (twitch and tetanic) were measured before and after train stimulations. H/H suspension resulted in an increased twitch tension in G. However, H/H did not change train or tetanic tensions per gram or other G contractile properties. Peak twitch, train, and tetanic tensions, time to peak tension, one-half relaxation time, and twitch and tetanic peak rates of tension development and decline were unchanged by H/H in S muscles. These results indicate that 1 wk of H/H-induced muscle atrophy significantly increases fatigability in G but does not effect contractile properties of fast-twitch (G) or slow-twitch (S) muscles.     

Kinetics of the interaction of alpha-chymotrypsin with trypsin kallikrein inhibitor (Kunitz) in which the reactive-site peptide bond Lys-15--Ala-16 is split.

Modified trypsin kallikrein inhibitor (I*), with the reactive-site peptide bond Lys-15--Ala-16 split, reacts with alpha-chymotrypsin (E) via an intermediate X to the stable tetrahedral complex C:E + I in equilibrium X leads to C. Formation X constitutes a fast pre-equilibrium (equilibrium constant Kx = 7 X 10(-5) M, association rate constant kx = 4 X 10(3)M-1s-1) to the slow reaction X leads to C (rate constant kc = 2 X 10(-3) s-1), all values at pH 7.5. No intermediate X is observed when alpha-chymotrypsin reacts with I*-OMe in which the carboxyl group of Lys-15 is esterified by methanol. This observation as well as the different pH dependence of the overall association rate constants in the case of I* and I*-OMe indicate tha formation of X precedes formation of the acyl enzyme in the catalytic pathway. The data are compared to the similar results obtained with beta-trypsin and I* or I*-OMe.     

Ontogeny of glycerolipid biosynthetic enzymes in swine liver and adipose tissue.

Enzymes associated with glycerolipid biosynthesis were examined in microsomal fractions of liver and adipose tissue obtained from swine of various ages. Generally, liver glycerophosphate acyltransferase, phosphatidate phosphohydrolase, diglyceride acyltransferase, and choline phosphotransferase activities were substantial at birth but increased 2- to 3-fold by day 14 postpartum, decreased at day 25, then increased at the oldest ages studied (up to 155 days postpartum). In adipose tissue, enzyme activities were low at birth and developed through day 25 in a pattern generally similar to that observed in liver. In contrast to liver, the adipose enzymes were depressed immediately postweaning (day 32) with subsequent recovery. The observed decline in adipose tissue enzyme activities expressed on a tissue basis at older ages was primarily the result of increased adipocyte size, since the activities expressed on a cell basis did not decline as rapidly. In both liver and adipose tissue, phosphatidate was the major glycerolipid synthesized by the microsomal glycerophosphate acyltransferase enzymes at all ages (generally greater than 75%). The ratio of neutral lipids to phospholipids produced by acylation of glycerophosphate was increased when a microsomal--cytosolic preparation was used as a source of enzyme in contrast to a microsomal preparation.     

The importance and future of biochemical engineering

Today's Biochemical Engineer may contribute to advances in a wide range of technical areas. The recent Biochemical and Molecular Engineering XXI conference focused on “The Next Generation of Biochemical and Molecular Engineering: The role of emerging technologies in tomorrow's products and processes”. On the basis of topical discussions at this conference, this perspective synthesizes one vision on where investment in research areas is needed for biotechnology to continue contributing to some of the world's grand challenges.     

Sequence composition versus sequence order in the cryoprotective function of an intrinsically disordered stress‐response protein

Intrinsically disordered stress proteins have been shown to act as chaperones, protecting proteins from damage caused by stresses such as freezing and thawing. Dehydration proteins (dehydrins) are intrinsically disordered stress proteins that are found in almost all land plants. They consist of a variable number of the short, semi‐conserved, Y‐, S‐, and K‐segments, with longer stretches of poorly conserved sequences in between. Previous studies have provided conflicting views on the details of the dehydrin cryoprotective mechanism of enzymes. Experiments with polyethylene glycol (PEG) have shown that PEG cryoprotective efficiency is the same as dehydrins of the same hydrodynamic radius, suggesting that the protein's disordered and polar nature is important, rather than the specific order of the residues. To further elucidate the mechanism, we created scrambled variants of the wild grape dehydrins K₂ and YSK₂ and tested their ability to protect lactate dehydrogenase and yeast frataxin homolog‐1 from freeze/thaw damage. The results show that for preventing aggregation, it is the sequence composition and the size of the dehydrin that is the most important factor in protection, while for freeze/thaw damage causing loss of secondary structure, it is the sequence composition that is most significant.     

Specific humoral immune response to the Thomsen-Friedenreich tumor antigen (CD176) in mice after vaccination with the commensal bacterium Bacteroides ovatus D-6

The tumor-specific Thomsen-Friedenreich antigen (TFα, CD176) is an attractive target for a cancer vaccine, especially as TF-directed antibodies play an important role in cancer immunosurveillance. However, synthetic TF vaccines have not overcome the low intrinsic immunogenicity of TF. Since natural TF-directed antibodies present in human sera are generated in response to microbes found in the gastrointestinal tract, microbial TF structures are obviously more immunogenic than synthetic TF. We recently isolated a new strain (D-6) of the human gut bacterium Bacteroides ovatus, which carries the true TFα antigen. Here, we present experimental data on the immunogenicity of this strain. Mice immunized with B. ovatus D-6 in the absence of adjuvants developed specific anti-TFα IgM and IgG antibodies which also bound to human cancer cells carrying TFα. Our data suggest that B. ovatus D-6 presents a unique TFα-specific immunogenicity based on a combination of several inherent properties including: expression of the true TFα antigen, clustering and accessible presentation of TFα as repetitive side chains on a capsular polysaccharide, and intrinsic adjuvant properties. Therefore, B. ovatus strain D-6 is an almost perfect candidate for the development of the first adjuvant-free TFα-specific anti-tumor vaccine.     

Structural basis for VIPP1 oligomerization and maintenance of thylakoid membrane integrity

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Immunolocalization of serotonin in Onychophora argues against segmental ganglia being an ancestral feature of arthropods

Background  

Onychophora (velvet worms) represent the most basal arthropod group and play a pivotal role in the current discussion on the evolution of nervous systems and segmentation in arthropods. Although there is a wealth of information on the immunolocalization of serotonin (5-hydroxytryptamine, 5-HT) in various euarthropods, as yet no comparable localization data are available for Onychophora. In order to understand how the onychophoran nervous system compares to that of other arthropods, we studied the distribution of serotonin-like immunoreactive neurons and histological characteristics of ventral nerve cords in Metaperipatus blainvillei (Onychophora, Peripatopsidae) and Epiperipatus biolleyi (Onychophora, Peripatidae).