Zinc and Metallothionein in the Development and Progression of Dental Caries

Biological Trace Element Research - Chronic oxidative stress and reactive oxygen species (ROS) in oral cavity as well as acidic pH on dental enamel surface due to the metabolic activities of...     

Kappaphycus malesianus sp. nov.: a new species of Kappaphycus (Gigartinales,Rhodophyta) from Southeast Asia

A new species, Kappaphycus malesianus, is established as a new member of the genus Kappaphycus. Locally known as the “Aring-aring” variety by farmers in Malaysia and the Philippines, this variety has been commercially cultivated, often together with Kappaphycus alvarezii due to the similarities in morphology. Despite also producing kappa-carrageenan, the lower biomass of the K. malesianus when mixed with K. alvarezii ultimately affects the carrageenan yield. Morphological observations, on both wild and cultivated plants, coupled with molecular data have shown K. malesianus to be genetically distinct from its Kappaphycus congeners. The present study describes the morphology and anatomy of this new species as supported by DNA data, with additional morphological features for distinguishing between commercial Kappaphycus cultivars.     

Factors responsible for the curling and branching of clover root hairs by Rhizobium

Summary The branching of clover root hairs was due to a factor (or factors) readily extracted from cells of Rhizobium trifolii and found in seedling solution supporting clover roots inoculated with this organism. Part of the active material was retained within a dialysis sac but a smaller, escaping fraction evoked the same response. The branching fraction was stable at 100°C and, partly, to nuclease and periodate, but was unstable when left in contact with the cells and when treated with trypsin. The dried residue of active filtrate contained 2% nucleic acid, 20% protein and about 34% carbohydrate which included antigenic lipopolysaccharide (approximately 1.6%). The branching response could not be attributed to either of these polysaccharides or to indole acetic acid. The capacity to cause branching was absent from all non-invasive mutants, but was increased in ineffective invasive forms, compared with the effective parent strain.Moderate curling was quantitatively much less striking and was generally found in the same preparations as showed branching. Notable exceptions were the lack of significant moderate curling in the filtered inoculated seedling solution and retention of this capacity in avirulent mutants.Marked curling occurred only when viable virulent rhizobia were present. Avirulent mutants were incapable of causing marked curling but the response to ineffective variants was rather better than to their effective parent strains. A dialysis membrane separating bacteria and plant roots prevented marked curling. re]19750214     

Potential involvement of galanin in the regulation of fluid homeostasis in the rat

A physiological role for galanin, a 29-amino acid neuropeptide, has not been established. However, anatomical studies have demonstrated the presence of galanin in brain regions associated with the control of water balance in the rat, most notably in the paraventricular nucleus (PVN) of the hypothalamus and the neurointermediate lobe of the pituitary gland (NIL). In the PVN, galanin coexists with arginine vasopressin (AVP) in magnocellular neurons. The present study demonstrates that homozygous Brattleboro rats, which lack AVP, produce galanin. Galanin concentrations in the median eminence (ME) of the homozygous Brattleboro rat do not differ from the galanin concentrations in the ME of either heterozygous Brattleboro or Sprague-Dawley rats. However, galanin concentrations in the NIL of the homozygous Brattleboro rat were reduced by 75%. Similarly, dehydration induced by salt-loading reduced galanin concentrations in the NIL and produced transient changes in the ME. These data demonstrate that galanin concentrations are influenced by changes in fluid homeostasis and suggest that galanin may be an important component in the regulation of neurohypophyseal function and AVP secretion.     

Age-dependent deamidation of glutamine residues in human γS crystallin: deamidation and unstructured regions

Human aging is associated with the deterioration of long-lived proteins. Gradual cumulative modifications to the life-long proteins of the lens may ultimately be responsible for the pronounced alterations to the optical and physical properties that characterize lenses from older people. γS crystallin, a major human lens protein, is known to undergo several age-dependent changes. Using proteomic techniques, a site of deamidation involving glutamine 92 has been characterized and its time course established. The proportion of deamidation increased from birth to teen-age years and then plateaud. Deamidation at this site increased again in the eighth decade of life. There was no significant difference in the extent of deamidation between cataract and age-matched normal lenses. Gln92 is located in the linker region between the two domains, and the introduction of a negative charge at this site may alter the interaction between the two regions of the protein. Gln170, which is located in another unstructured part of γS crystallin, showed a similar deamidation profile to that of Gln92. As the other Gln residues in β-sheet regions of γS crystallin appear to remain as amides, modification of Gln92 and Gln170 thus conforms to a pattern whereby deamidation is localized to the unstructured regions of long-lived proteins.