EFFECTS OF CELL DENSITY,TEMPERATURE, AND LIGHT INTENSITY ON GROWTH AND STALK PRODUCTION IN THE BIOFOULING DIATOM ACHNANTHES LONGIPES (BACILLARIOPHYCEAE)1

Achnanthes longipes Ag. is a marine stalk‐forming diatom that grows in dense biofilms. The effects of cell density, temperature, and light on growth and stalk production were examined in the laboratory to determine how they affected the ability of this diatom to form a biofilm. Stalk production abruptly increased when A. longipes was cultured at a density of 5.4 × 10³ cells·mL ^{? 1} 1 Received 23 February 2002. Accepted 22 July 2002.
, with a lag before stalk production occurring in cultures initiated at lower densities. Growth occurred at all temperatures from 8 to 32° C, with maximum growth at 26° C. Growth rate was light saturated at 60 μmol photons·m ^{? 2}·s ^{? 1} 1 Received 23 February 2002. Accepted 22 July 2002.
. Stalk production was determined as the proportion of cells producing stalks and stalk length in response to various temperatures and light intensities at high (5000 cells·mL ^{? 1} 1 Received 23 February 2002. Accepted 22 July 2002.
) and low (500 cells·mL ^{? 1} 1 Received 23 February 2002. Accepted 22 July 2002.
) densities. More cells formed stalks at high density, with no difference in stalk length. The proportion of cells producing stalks was maximal at 20° C, with little change at 17–32° C. Stalk length was at a maximum between 14 and 26° C. Stalk production showed little change in response to varying light intensity. The results of an earlier investigation on the effects of bromide concentration on stalk formation were expressed as the proportion of cells forming stalks and the lengths of the stalks. Both measures of stalk production varied with bromide concentration, with maximum values at 30 mM bromide. The increased stalk production at higher densities may be a means of elevating cells above the substrate to avoid competition in the dense biofilm.     

Effects of converting enzyme inhibitors on renal P-450 metabolism of arachidonic acid

The effects of blockade of the renin-angiotensin system on the renal metabolism of arachidonic acid (AA) were examined. Male Sprague-Dawley rats were treated with vehicle, captopril (25 mg x kg(-1) x day(-1)), enalapril (10 mg x kg(-1) x day(-1)), or candesartan (1 mg x kg(-1) x day(-1)) for 1 wk. The production of 20-hydroxyeicosatetraenoic acid (20-HETE) and epoxyeicosatrienoic acids (EETs) by renal cortical microsomes increased in rats treated with captopril by 59 and 24% and by 90 and 58% in rats treated with enalapril. Captopril and enalapril increased 20-HETE production in the outer medulla by 100 and 143%, respectively. In contrast, blockade of ANG II type 1 receptors with candesartan had no effect on the renal metabolism of AA. Captopril and enalapril increased cytochrome P-450 (CYP450) reductase protein levels in the renal cortex and outer medulla and the expression of CYP450 4A protein in the outer medulla. The effects of captopril on the renal metabolism of AA were prevented by the bradykinin-receptor antagonist, HOE-140, or the nitric oxide (NO) synthase inhibitor, N(G)-nitro-L-arginine methyl ester. These results suggest that angiotensin-converting enzyme inhibitors may increase the formation of 20-HETE and EETs secondary to increases in the intrarenal levels of kinins and NO.     

Induction of infection in Sesbania exaltata by Colletotrichum gloeosporioides f. sp. aeschynomene formulated in an invert emulsion

World Journal of Microbiology and Biotechnology - In greenhouse experiments, an invert emulsion (MSG 8.25) was tested with spores of the mycoherbicidal fungus Colletotrichum gloeosporioides f. sp....     

Molekulare Karyotypisierung in der klinischen Diagnostik

The term “molecular karyotyping” refers to the genome-wide analysis of copy number variations using arrays that cover the genome with genomic markers with varying density. Currently the main application is the investigation of patients with otherwise unexplained mental retardation and multiple congenital anomalies. Studies of such patients who remained without etiological diagnosis after conventional karyotyping, subtelomeric screening, and targeted molecular–cytogenetic studies for well-known microdeletion syndromes revealed chromosomal microaberrations in about 10% of cases and allowed the delineation of several new microdeletion and microduplication syndromes. Nevertheless, because of the large number of copy number polymorphisms, interpretation of unique findings needs thorough consideration.     

Nichtinvasive molekulargenetische Methoden in der pränatalen Diagnostik

Work on the development of noninvasive prenatal tests to avoid risk to the fetus in traditional amniocentesis or chorion villus biopsy has been ongoing for many years. Until recently, most approaches were extremely expensive and limited only to selected applications, thus they failed to develop beyond a “proof-of-principle” status. This has changed radically as a result of the introduction of new sequencing methods, since initial studies have shown that fetal aneuploidies from maternal plasma DNA can be identified correctly. In addition, these techniques make it possible to establish even the mutation status of the fetus. While on the one hand this offers completely new options in prenatal diagnosis, progress of this kind is associated with significant ethical challenges on the other. This overview article presents the development of these new methods.