A study of the hydration and thermodynamics of warm-water and cold-water fish collagens.

The hydrated volumes, Vh, of collagens extracted from various fish species were calculated by using the Simha-Einstein equation, and it was found that the hydration of warm-water fish collagen is greater than that of cold-water fish collagen (halibut). Although the intrinsic viscosities of warm-water fish (bigeye-tuna, carp and catfish) collagens are almost the same, the hydrated volume of bigeye-tuna collagen is approx. 1.5 and 3 times those of carp and catfish collagens respectively. The extent of hydration at 20 degrees C is in the following order: bigeye tuna greater than carp greater than catfish greater than halibut. The various thermodynamic activation parameters (delta G*, delta H* and delta S*) were calculated and it was found that they are useful for determining the exact denaturation temperature. It was calculated that the denaturation temperatures of halibut, bigeye-tuna, carp and catfish collagens are 17, 31, 32 and 26-30 degrees C respectively. The variations of hydration, intrinsic viscosity, denaturation temperature and the thermodynamic parameters with the variation of concentration of catfish collagen were also thoroughly examined. The change of thermodynamic parameters from coiled-coil to random-coil conformation upon denaturation of collagen were calculated from the amount of proline and hydroxyproline residues and compared with viscometric results.     

Effect of methionine-sulfoximine on nitrate uptake and photosynthesis in the cyanobacteriumAnabaena doliolum Bharadwaja

l-Methionine-dl-sulfoximine (MSX) stimulated nitrate uptake but inhibited¹⁴CO₂ fixation and O₂ evolution inAnabaena doliolum. Nitrate uptake was inhibited by ammonium (NH ₄ ⁺ ) in the absence of MSX, but not in the presence of MSX. Glutamine or a derivative of it appears to be the actual negative effector of nitrate utilization. In presence of nitrate, MSX-treated cells ofA. doliolum evolve more O₂ than do untreated cells. Our results suggest a close relation between photoassimilation of carbon and utilization of nitrogen.     

Analysis of the Escherichia coli glycogen gene cluster suggests that catabolic enzymes are encoded among the biosynthetic genes

The nucleotide sequences of the Escherichia coli genome between the glycogen biosynthetic genes glgB and glgC, and 1170 bp of DNA which follows glgA have been determined. The region between glgB and glgC contains an open reading frame (ORF) of 1521 bp which we call glgX. This ORF is capable of coding for an M_r 56 684 protein. The deduced amino acid (aa) sequence for the putative product shows significant similarity to the E. coli glycogen branching enzyme, and to several different glucan hydrolases and transferases. The regions of sequence similarity include residues which have been reported to be involved in substrate binding and catalysis by taka-amylase. This suggests that the proposed product may catalyze hydrolysis or glycosyltransferase reactions. The cloned region which follows glgA contains an incomplete ORF (1149 bp), glgY, which appears to encode 383 aa of the N terminus of glycogen phosphorylase, based upon sequence similarity with the enzyme from rabbit muscle (47% identical aa residues) and with maltodextrin phosphorylase from E. coli (37% identical aa residues). Results suggest that neither ORF is required for glycogen biosynthesis. The localization of glycogen biosynthetic and degradative genes together in a cluster may facilitate the regulation of these systems in vivo.     

Simultaneous saccharification and protein enrichment fermentation of sugar beet pulp

Summary A product with 40 % protein content was obtained from sugar beet pulp (1.25–2.0 mm) in 48 h one stage (simultaneous) saccharification/fermentation process under optimized conditions using a specific enzyme mixture andCandida tropicalis strain, also saving about 40 % enzymes in comparison to a 2-stage process.     

The dynamics of quadrupedal locomotion

This paper presents a dynamical analysis of quadrupedal locomotion, with specific reference to an adult Nubian goat. Measurements of ground reaction forces and limb motion are used to assess variations in intersegmental forces, joint moments, and instantaneous power for three discernible gaits: walking, running, and jumping. In each case, inertial effects of the torso are shown to dominate to the extent that lower-extremity contributions may be considered negligible. Footforces generated by the forelimbs exceed those exerted by the hindlimbs; and, in general, ground reactions increase with speed. The shoulder and hip dominate mechanical energy production during walking, while the knee plays a more significant role in running. In both cases, however, the elbow absorbs energy, and by so doing functions primarily as a damping (control) element. As opposed to either walking or running, jumping requires total horizontal retardation of the body's center of mass. In this instance, generating the necessary vertical thrust amounts to energy absorption at all joints of the lower extremities.     

Protection of photosynthetic O2 evolution against heat inactivation: the role of chloride,pH and coupling status

Heat inactivation of photosynthetic O₂ evolution was studied in isolated thylakoids from spinach (Spinacia oleracea) and mangrove (Avicennia marina) leaves. Different temperatures, salt, pH and uncoupler effects were investigated. From these results and others in the literature it was concluced that chloride loss from the membrane and, more specifically, the oxygen-evolving complex of photosystem II, may be the cause of inhibition of oxygen evolution during heat inactivation.Abbreviations Hepes 4-(2-hydroxyethyl)-1-piperazinethanesulfonic acid - Tris 2-amino-2-(hydroxymethyl)-1,3-propanediol - Tricine N-2-hydroxy-1, 1-bis (hydroxymethyl) ethyl glycine - EDTA ethylenediaminetetraacetic acid - FeCN K-ferricyanide     

Micropropagation of Plumbago rosea Linn.

Multiple shoot formation from the medicinal plant Plumbago rosea Linn. was induced on callus from stem segments on Murashige & Skoog media containing auxin and cytokinin. 2,4-D (2.5 mg l^-1) and kinetin (1.5 mg l^-1) added to the media gave best callus production, while BAP (2 mg l^-1) plus NAA (1.0 mg l^-1) induced shoot formation from that callus. Numerous shoots with roots could be produced by transferring shoots to media containing IBA (1.5 mg l^-1). Regenerated plantlets were transferred to pots and 60% survived.     

Effect of Maternal Alcohol Consumption on the Lipid Composition of CNS in the Offspring

Maternal alcohol consumption at a level that does not affect calorie intake increases cholesterol concentration and content as well as incorporation of labeled glucose into cholesterol in the brain and spinal cord of newborn rat pups. Continued consumption of alcohol during lactation also affects the galactolipid concentration in the brain and spinal cord of pups at 21 days of age, and this increase seems mainly to be due to an increase in content of myelin lipids. Analysis of myelin shows that the concentration of phospholipids also increases in this fraction. The increase in incorporation of labeled glucose into these membrane lipids suggests an increase in the synthesis of these lipids, which prevents fluidization of the membrane by alcohol. That in the brainstem the increase in levels of cholesterol and galactolipids is higher than in other regions and that there is also an increase in content of sphingomyelin, phosphatidylcholine, and phosphatidylethanolamine suggest that the brainstem needs better protection against fluidization.