Effects of brain ischemia on intermediate filaments of rat hippocampus

Neurofilaments subunits (NF-H, NF-M, NF-L) and glial fibrillary acidic protein (GFAP) were investigated in the hippocampus of rats after distinct periods of reperfusion (1 to 15 days) following 20 min of transient global forebrain ischemia in the rat. In vitro [¹⁴Ca]leucine incorporation was not altered until 48 h after the ischemic insult, however concentration of intermediate filament subunits significantly decreased in this period. Three days after the insult, leucine incorporation significantly increased while the concentration NF-H, NF-M, and NF-L were still diminished after 15 days of reperfusion. In vitro incorporation of³²P into NF-M and NF-L suffered immediately after ischemia, but returned to control values after two days of reperfusion. GFAP levels decreased immediately after ischemia but quickly recovered and significantly peaked from 7 to 10 days after the insult. These results suggest that transient ischemia followed by reperfusion causes proteolysis of intermediate filaments in the hippocampus, and that proteolysis could be facilitated by diminished phosphorylation levels of NF-M and NF-L.     

Changes in extracellular levels of dopamine metabolites in somatosensory cortex after peripheral denervation

This study examined the effects of a nerve transection on monoamine release from primary somatosensory cortex. The technique of microdialysis was employed to sample extracellular levels of norepinephrine (NE), 3,4-dihydroxyphenylacetic acid (DOPAC), 5-hydroxyindole-3-acetic acid (5-HIAA) and homovanillic acid (HVA) in the barrel field of freely moving rats following the surgical transection of the contralateral infraorbital nerve. Microdialysates obtained 3, 4, and 5 days after deafferentation were analyzed using high-performance liquid chromatography with electrochemical detection. We found a significant increase in the release of the dopamine metabolites, DOPAC and HVA from the deafferented cortex. Three days after deafferentation the release of DOPAC was three-fold higher in the deafferented than in the control animals, and remained about 100% higher in the next two days in this group of animals. The release of HVA showed a gradual increase following the deafferentation procedure, since a 92% larger value on day 3 increased to a 338% difference on day 5. On the other hand, the release rate of NE and the levels of the serotonin metabolite 5-HIAA were not significantly affected by the deafferentation procedure. These results are discussed in the context of the possible participation of dopamine in the reorganization of the deafferented somatosensory cortex.     

Biflavonoid differentiation in sixBartramia species (Bartramiaceae,Musci)

The occurrence of eight biflavones belonging to the biluteolin series, the apigenin-luteolin series and the 2,3-dihydro-biluteolin series, and one monomeric flavone with an acid group, was investigated in six taxa ofBartramia with emphasis on sect.Ithyphyllae. The variation of biflavone profiles contributes to the characterization of theBartramia species studied; substitution patterns signalize relevance also on the sectional level. Based upon the flavonoid composition,Bartramia afro-ithyphylla is suggested to be transferred from sect.Ithyphyllae to sect.Bartramia of the genusBartramia.     

Changes in the lower premolar-size sequence during hominid evolution. Physlogenetic implications

The size relationship between the crown area of the lower canines (Cs), third (P3s) and fourth premolars (P4s), and first molars (M1s) in hominids is examined by means of the regression analysis. The lower P3 seem to be under the influence of those factors that control both the size of the anterior and posterior teeth, and the P4:P3 size ratio is related to the relative size of the anterior and posterior dentitions. So, the P4>P3 sequence is associated with the megadontia and hipermegadontia of the posterior teeth, whereas the expansion of the anterior teeth produces the P3>P4 sequence. We consider the P4:P3 size ratio as an excellent indicator of the taxonomic and philogenetic status of fossil hominids.     

Cineanthropometric Study in Spanish Judoists

Anthropometric characteristics of proportionality, body composition and somatotype have been determined in a group of 72 Spanish judoists. The sample includes the junior male and female National Team, and seniors competitors in the last Olimpic Games held in 1992, and participants in the National Championship of 1993. The methodology has been used according to Weiner and Lourie(1981)and MOGAP procedures described by Borms et al. (1979). The obtained results show a similar proportionality profile and mesoendomorphic mean somatotype in both male and female series. However, were found significant differences between sexes as well as depending of weight categories.     

Establishment of transformed root cultures of Perezia cuernavacana producing the sesquiterpene quinone perezone

Summary The sesquiterpene quinone currently known as perezone is abundantly produced by the roots of Perezia cuernavacana. This compound is of biotechnological interest since it may be used as a pigment and has several pharmacological properties. In this work we demonstrate that perezone is also produced in transformed root cultures of P. cuernavacana. Hairy roots were induced by inoculation of internodal segments of sterile plants of P. cuernavacana with Agrobacterium rhizogenes AR12 strain. The axenic liquid MS medium cultures of the hairy roots isolated from the internodes showed active growth in the absence of growth regulators. The transformed nature of the tissue was confirmed by genomic integration (PCR and slot blot hybridization) and expression (enzyme activity) of the marker gus-gene. The production of perezone by a transformed root culture was evidenced by IR spectroscopy. Our results offer an alternative for enhanced production of perezone and represent an advantage over its extraction from natural plant populations which present problems in their agronomic culture.     

Partial auxin deprivation affects endogenous cytokinins in an auxin-dependent,cytokinin-independent tobacco cell strain

The dynamics of individual endogenous cytokinins within the growth cycle (subculture interval) of an auxin-dependent and cytokinin-independent cell suspension culture ofNicotiana tabacum L. (strain VBI-0) were determined using high performance liquid chromatography and radioimmunoassay. In cells grown at an optimum auxin concentration the transient maxima of N⁶-(²-isopentenyl)adenine and N⁶-(²-isopentenyl)-adenosine correlated with the onset of cell division. Cultivation of the cells in a partially auxin-deprived medium resulted in ca. tenfold increase of all endogenous cytokinins. A very distinct maximum of N⁶-(²-sopentenyl) adenine appeared at the beginning of subculture. This indicates that a lack of auxin induced an accumulation of cytokinins predominantly in the form of the free bases, which are physiologically more active than the corresponding ribosides.Abbreviations iP N⁶-(²-isopentenyl)adenine - [9R]iP N⁶-(²-isopentenyl)adenosine - t-Z trans-zeatin - t-[9R]Z trans-zeatin riboside - IAA indole-3-acetic acid - NAA 1-naphthaleneacetic acid - 2,4-D 2,4-dichlorophenoxyacetic acid - f.w. fresh weight - SBI subculture interval - C complete medium - PAD partially auxin-deprived medium - RP-HPLC reverse phase high performance liquid chromatography - RIA radioimmunoassay - PAL L-phenylalanine ammonia lyase     

Construction of an Aspergillus nidulans multicopy transformant for the xlnB gene and its use in purifying the minor X24 xylanase

 Using recombinant DNA techniques, an Aspergillus nidulans multicopy transformant for the gene xlnB coding for the minor X₂₄ xylanase has been constructed. When grown on glucose as sole carbon source this transformant secretes 114 U of xylanase (mg protein)^-1. In this culture condition, X₂₄ is the only xylanase secreted and the predominant protein in the culture filtrate. This strategy has been used to purify the X₂₄ enzyme to homogeneity. The purified xylanase showed a single band on sodium dodecyl sulphate/ polyacrylamide gel electrophoresis with a molecular mass of 24 kDa and had an isoelectric point of approximately 3.5. The enzyme was a non-debranching endo-1,4-β-xylan xylanohydrolase highly specific for xylans and showed optimal activity at pH 5.5 and 52°C. The X₂₄ xylanase had a Michaelis constant, K _m, of 12.43 mg oat spelt xylan ml^-1 and a V _max of 1639 μmol min^-1 (mg protein)^-1. Received: 17 May 1995/Received last revision: 25 September 1995/Accepted: 29 September 1995     

Use of zeolite to control ammonium in Bacillus amyloliquefaciensα-amylase fermentations

 Both synthetic and natural ammonium-sorbing zeolite were used to control the NH⁺ ₄ level in Bacillus amyloliquefaciens cultures producing extracellular α-amylase. The addition of biochemically inert calcium aluminosilicates significantly increased the yield of the enzyme. A simple mathematical model explaining the mechanism has been formulated and its parameters estimated. Received: 1 August 1995/Received revision: 20 October 1995/Accepted: 24 October 1995     

Moniliformin production byFusarium species isolated from Argentinian corn

Forty-one isolates ofFusarium obtained from the main Argentinian corn production area were tested for their ability to produce moniliformin. One of 22 isolates ofF. moniliforme, 2/10 of F.proliferatum and 3/9 ofF. subglutinans, produced moniliformin in a range between 0,3 to 2,7 mg/g. These data represent the first report of the production of moniliformin byFusarium species from section Liseola in Argentina.