Protoplasts of Cosmarium as a Potential Protein Source

Cosmarium turpinii, a fast-growing desmid alga, transforms into protoplasts in 4 h when incubated in a mineral medium + 0.4 M mannitol + 0.5% Cellulysin.     

Polymorphism in the desmid Cosmarium taxichondrum Lundell

Polymorphism in a population of C. taxichondrum Lundell var. taxichondrum has been studied. Cell outline does not vary greatly but variability in the morphology of the basal angles shows that var. bidentulum Lagerheim must be reduced to synonymy with var. taxichondrum. The subapical set of granules, usually 5 or 6, may be reduced to three or be completely lacking. The central set of granules exhibits great variability (3–7) and may even occasionally be lacking. Large isthmus granules are usually present, but their usefulness in separating C. taxichondrum and C. pseudotaxichondrum Nordst. is questioned.     

Biological decolorization of dye solution containing Malachite Green by microalgae Cosmarium sp

The potential of Cosmarium species, belonging to green algae, was investigated as a viable biomaterial for biological treatment of triphenylmethane dye, Malachite Green (MG). The results obtained from the batch experiments revealed the ability of algal species in removing dye. The effects of operational parameters (temperature, pH, dye concentration and algal concentration) on decolorization were examined. Optimal initial pH was determined 9. The stability and efficiency of the algae in long-term repetitive operations were also examined. Michaelis-Menten kinetics was used to describe the apparent correlation between the decolorization rate and the dye concentration. The optimal kinetic parameters, nu(max) and K(m) are 7.63 mg dye g cell(-1)h(-1) and 164.57 ppm, respectively. All assays were conducted in triplicates.     

In search of monophyletic taxa in the family Desmidiaceae (Zygnematophyceae, Viridiplantae): the genus Cosmarium

Nuclear-encoded small subunit (SSU) rDNA, 1506 group I introns, and chloroplast rbcL genes were sequenced from 97 strains representing the largest desmid genus Cosmarium (45 spp.), its putative relatives Actinotaenium (5 spp.), Xanthidium (4 spp.), Euastrum (9 spp.), Staurodesmus (13 spp.), and other Desmidiaceae (Zygnematophyceae, Streptophyta) and used to assess phylogenetic relationships in the family. Analyses of single genes and of a concatenated data set (3260 nt) established 10 well-supported clades in the family with Cosmarium species distributed in six clades and one nonsupported assemblage. Most of the clades contained representatives of at least two genera highlighting the polyphyletic nature of the genera Cosmarium, Euastrum, Staurodesmus, and Actinotaenium. To enhance resolution between clades, we extended the data set by sequencing the slowly evolving chloroplast-encoded large subunit (LSU) rRNA gene from 40 taxa. Phylogenetic analyses of a concatenated data set (5509 nt) suggested a sister relationship between two clades that consisted mainly of Cosmarium species and included C. undulatum, the type species of the genus. We describe molecular signatures in the SSU rRNA for two clades and conclude that more studies involving new isolates, additional molecular markers, and reanalyses of morphological traits are necessary before the taxonomic revision of the genus Cosmarium can be attempted.     

Periphytic desmids in Corumbá Reservoir, Goiás, Brazil: genus Cosmarium Corda.

With the objective of investigating the taxa of Cosmarium, four collection stations along the Corumbá Reservoir were set up. This resulted in the first work done on the genus in the State of Goiás. The collections of the material, of the epilithon type, were carried out in July 1996 and in the period between December 1996 and July 1997. The samples were preserved with 0.5% acetic lugol. The qualitative analysis was done by optical microscopic on non-permanent slides. Twenty-one taxa of the Cosmarium were described, each one illustrated by means of a camera lucida attachment.     

Nutrition of Threonine

By administering 2 mg/day of cortisone acetate to adrenalectomized rats, the hepatic threonine dehydratase activity of these rats increased 5 times as much as that of the control. By administering 5 IU/day of ACTH to hypophysectomized rats, both the hepatic threonine dehydratase activity and the adrenal glucose-6-phosphate dehydrogenase activity increased 3 times and 7 times as much as that of the control group, respectively. The effects of excess feeding of lysine or threonine on the increase of the dehydratase activity by the adminitration of cortisone to the adrenalectomized rats and the administration of ACTH to the hypophysetomized rats were negative. When the intact rats were fed on lysine and/or threonine excess diet, the amount of glucocorticoid secretion as measured by the adrenal glucose-6-phosphate dehydrogenase activity increased and the hepatic threonine dehydratase activity increased accordingly. A linear relationship was found between these two activities and no significant deviation from the relationship due to the difference in diet composition was observed. A mechanism was proposed, based on these results, explaining the fact that the hepatic threonine dehydratase activity increased when rats were fed on lysine or threonine excess diet.     

Nutrition of Threonine

Among the threonine dehydratase activities in liver of rat fed on basal diet (B-group), lysine added diet (L-group) and threonine added diet (T-group), a following relationship was found: A_B?A_LT, where A_B, A_L and A_T were the activities of B-, L-and T-group, respectively. The types of the activity increase in L- or T-group were investigated by examining the possibility of the cause—the existence of activators in L- or T-group (I), the existence of inhibitors in B-group (II), the activation of the latent enzyme in L- or T-group (III), and the induction of the dehydratase by biosynthesis in L- or T-group (IV). Addition of various amounts of liver homogenate of L- or T-group to a given amount of that of B-group gave a result as would be obtained in cases where neither activators nor inhibitors existed in the liver (I and II). No correlationship was found between the activity and the preincubation time, which denied the presence of the latent enzyme which would easily change into the active form by preincubation (III). Actinomycin D administered to rats inhibited the increase of the dehydratase activity of L- or T-group by about 50% (IV). On the other hand, preliminary experiments using hypophysectomized or adrenal-ectomizecl rats showed the results of A_в?A_L?A_т. Both results may suggest the possibility that the increase of the dehydratase activity is ascribed to the induction of this enzyme through biosynthesis, and perhaps through endocrine systems.     

Nutrition of lead

At the levels to which human beings are exposed in the workplace as well as in the general environment, lead has been shown to be a toxic element in most of its chemical forms, whether it is inhaled or ingested in water or food. The four main sources of contamination of food are soil, industrial pollution, agricultural technology and food processing. Reasonable quantities of the metal can be stored by humans in a relatively inert form in bone; lead has an affinity for bone and acts by replacing calcium. Gastrointestinal lead absorption and retention, the major pathway of lead intake, has been shown to vary widely depending on the chemical environment of the gastrointestinal lumen, age and iron stores (nutritional status of the subject). Studies in animals have shown that certain substances bind lead and increase its solubility, thus enhancing its absorption. These dietary components consist of sodium citrate, ascorbate, amino acids, vitamin D, protein and fat, and lactose. Data suggest a three-compartmental pool for lead metabolism: (1) blood; (2) soft tissue (hair, nails, sweat, salivary, gastric, pancreatic and biliary secretions); and (3) skeleton. Lead absorption occurs primarily in the duodenum where lead enters the epithelial mucosal cells. The total bodily amount of lead does not affect lead absorption; lead does not have a feedback mechanism which limits absorption. In the adult rat, lead absorption from the intestinal lumen appears to proceed by both active transport and passive diffusion. Bile is an important route of excretion in the gut.(ABSTRACT TRUNCATED AT 250 WORDS)