Selenium Species and Their Distribution in Freshwater Fish from Argentina

The distribution and speciation of selenium (Se) in freshwater fish (muscle and liver tissue) from lakes in Argentina was investigated. Three introduced species, brown trout (Salmo trutta), rainbow trout (Oncorhynchus mykiss) and brook trout (Salvelinus fontinalis), and one native species, creole perch (Percichthys trucha), were investigated. Values for total selenium in muscle ranged from 0.66 to 1.61 μg/g, while in the liver, concentrations were much higher, from 4.46 to 73.71 μg/g on a dry matter basis. Separation of soluble Se species (SeCys₂, selenomethionine (SeMet), SeMeSeCys, selenite and selenate) was achieved by ion exchange chromatography and detection was performed by inductively coupled plasma–mass spectrometry. The results showed that in fish muscle, from 47 to 55 % of selenium was soluble and the only Se species identified was SeMet, which represented around 80 % of soluble Se, while in the liver, the amount of soluble Se ranged from 61 to 76 % and the percentage of species identified (SeMet and SeCys₂) was much lower and ranged from 8 to 17 % of soluble Se.     

Cyanogenic Glycosides from Four Latin American Species of Acacia

The cyanogenic glucosides of four Latin American species of Acacia (Fabceae: Mimosoideae) have been isolated and characterized. Acacia atramentaria (Argentina) contains proacacipetalin, A.aroma (Argentina) linamarin and lotaustralin, A. tortuosa (Venezuela) proacacipetalin and a second presently uncharacterized glycoside, and A. globulifera (Guatemala) epiproacacipetalin which has not previously been reported as naturally occurring.     

Detection of alginate oligosaccharides from mollusks

We attempted in this study to detect alginate oligosaccharides (AO) from mollusks. The samples used were digestive organs taken from turban shells and abalones which commonly ate brown algae. High-performance liquid chromatography (HPLC) and negative-ion electrospray ionization (ESI) quadrupole time-of-flight (Q-TOF) mass spectrometry (MS) analyses were used to confirm the presence of AO. Samples spiked with AO resulted in observable peaks where the HPLC area was increased. The highest content was estimated to be 401.8 mg/100 g of digestive organ. The product-ion data derived from AO molecular weight were detected at a constant interval by Q-TOF MS/MS analysis. These findings indicate that AO was present in the digestive organs of mollusks.     

Isolation of Ewingella americana from mollusks

Twenty-three of 2446 strains of Enterobacteriaceae isolated from mollusks were identified as Ewingella americana both biochemically and by DNA hybridization with strain S6/1111. The biochemical characteristics of the new strains showed few differences from previously reported strains obtained from human clinical specimens. These are the first strains of E. americana isolated from animals.     

Chromosome studies: Latin American Compositae

Chromosome observations reported here from 98 collections representing 91 species from 58 genera of Compositae provide taxonomically useful information. First counts for 52 species, including first counts for eight genera (Alepidocline [n = 8], Damnxanthodium [n = 12], Dyscritothamnus [n = 20 in both species], Idiopappus [n = ca. 31–33], Oblivia [n = 16], Oteiza [n = 17 + 0–3 f], Rensonia [n = 17], and Viguethia [n = 19]), may prove to be especially interesting in relation to generic alignments of the species and tribal or subtribal alignments of the genera.     

Dr. Hector Barra,An Outstanding Latin American Neurochemist

Neurochemical Research -