Postnatal development of cholesterol ester hydrolase activity in the rat adrenal

In certain circumstances the activity of cholesterol ester hydrolase (CEH) activity is believed to be rate-limiting for corticosterone production by the adrenal. The principal aim of the current study was to determine whether the activity of CEH displays a developmental increase in the infant rat which could, in part, account for the marked increase in serum corticosterone which begins at the end of the second postnatal week. The data show that the specific activity of CEH (units/mg cytosolic protein) during development is actually a mirror image of the pattern seen for serum corticosterone, i.e. CEH activities are high when serum corticosterone concentrations are low and then fall when serum corticosterone is rising. Even when total activities of CEH in the adrenal were calculated, there was no increase in parallel with the initial rise of serum corticosterone. At each age studied, stressed pups displayed significant increases of serum corticosterone; however, their CEH activities were no different from those in the non-stressed littermates. It is concluded that the activity of CEH is not the rate-determining factor for the developmental surge of basal concentrations of serum corticosterone nor for stress-induced elevation of corticosterone during the developmental period. A second aim of the current study was to address the more general question of whether steroidogenesis in the developing adrenal is limited by substrate supply. Measurement of the cholesterol content of adrenal mitochondria showed no ontogenic increase, suggesting that substrate supply, from any source, is not rate-limiting for steroidogenesis at these ages.     

Brain ascorbic acid and block of the catecholamine synthesis induced by alpha-methyl-tyrosine

In brain medial-basal areas (midbrain, hypothalamus, striatum) ascorbic acid (AA) content is lower than in the rest of the brain. It has been hypothesized that AA may be involved in brain catecholamine metabolism. To test this hypothesis AA content in medial-basal areas and in the remaining brain areas was measured in rats pretreated with alpha-methyl-paratyrosine (alpha-MpT), a tyrosine hydroxylase inhibitor. The AA content, in brain medial-basal areas, had slightly decreased, without statistically significant differences, in rats treated with alpha-MpT in comparison with untreated animals. Therefore the role of AA in brain metabolism is not clear to.     

Effects of habitat conditions at hatching time on growth history of offspring European anchovy, <Emphasis Type="Italic">Engraulis encrasicolus</Emphasis>, in the Central Mediterranean Sea

Species distributions are structured by regional and local determinants, which operate at multiple spatial and temporal scales. The purpose of our work was to distinguish the relative roles of local variables, climate, geographical location and post glaciation condition (i.e., delineation between supra- and subaquatic lakes during the post-glacial Ancylus Lake) in explaining variation in macrophyte community composition of all taxa, helophytes and hydrophytes. In addition, we investigated how these four explanatory variable groups affected macrophyte strategy groups based on Grime’s classification. Using partial linear regression and variation partitioning, we found that macrophyte communities are primarily filtered by local determinants together with regional characteristics at the studied spatial scale. We further evidenced that post glaciation condition indirectly influenced on local water quality variables, which in turn directly contributed to the macrophyte communities. We thus suggest that regional determinants interact with local-scale abiotic factors in explaining macrophyte community patterns and examining only regional or local factors is not sufficient for understanding how aquatic macrophyte communities are structured locally and regionally.     

In situ rheology of yeast biofilms

The aim of the present work was to investigate the in situ rheological behavior of yeast biofilms growing on stainless steel under static and turbulent flow. The species used (Rhodototula mucilaginosa, Candida krusei, Candida kefyr and Candida tropicalis) were isolated from a clarified apple juice industry. The flow conditions impacted biofilm composition over time, with a predominance of C. krusei under static and turbulent flow. Likewise, structural variations occurred, with a tighter appearance under dynamic flow. Under turbulent flow there was an increase of 112 μm in biofilm thickness at 11 weeks (p < 0.001) and cell morphology was governed by hyphal structures and rounded cells. Using the in situ growth method introduced here, yeast biofilms were determined to be viscoelastic materials with a predominantly solid-like behavior, and neither this nor the G’₀ values were significantly affected by the flow conditions or the growth time, and at large deformations their weak structure collapsed beyond a critical strain of about 1.5–5%. The present work could represent a starting point for developing in situ measurements of yeast rheology and contribute to a thin body of knowledge about fungal biofilm formation.     

Neurochemical investigation of an endogenous model of the "hyperkinetic syndrome" in a hybrid dog.

A telomian-beagle hybrid has been recently proposed as a possible model for the hyperkinetic syndrome. They resemble hyperkinetic children in their poor ability to respond with the appropriate behavior in an inhibitory training test. Two groups of hybrids could be differentiated, the behavior of one of which improved with amphetamine (“Responders”) and of the other did not (“Non responders”). In the present study, the levels of HVA, 5-HIAA, MOPEG-SO were measured in CSF and the levels of NA, DA, HVA, DOPAC⁴, 5-HIAA were assayed in brain tissues from different regions, taken under basal conditions from beagles and telomian-beagle hybrids. Responder hybrids had lower levels of NA, DA, HVA in brain and low HVA in CSF. Therefore, they can be distinguished biochemically as well as behaviorally from non-responder hybrids and beagles and may prove to be useful as models for study of the mechanism and the therapy of this syndrome.