Effect of enzymatic treatment on calcium absorption by small intestine: a comparative study between rat and rabbit transport mechanisms

Calcium absorption by the small intestine of rat and rabbit reached steady state after 60 min of incubation with intracellular to extracellular ratio of 2.0. Trypsin and neuraminidase significantly inhibited (P less than 0.05) calcium accumulation in rat small intestine. These enzymes showed no significant effect (P greater than 0.05) on calcium transport across rabbit small intestine. The inhibitory action of trypsin and neuraminidase on calcium accumulation by the rat small intestine does not involve the influx of calcium into the intestinal cells.     

Effect of 2,4-Dinitrophenol on Auxin-induced Ethylene Production and Auxin Conjugation by Mung Bean Tissue

Auxin-induced ethylene production by mung bean (Phaseolus mungo L.) hypocotyl segments was markedly inhibited by 2,4-dinitrophenol regardless of whether or not kinetin was present. Uptake of indoleacetic acid-2-¹⁴C was also inhibited in the presence of 2,4-dinitrophenol. Segments treated only with indoleacetic acid rapidly converted indoleacetic acid into indole-3-acetylaspartic acid with time whereas kinetin suppressed indoleacetic acid conjugation. Formation of indole-3-acetylaspartic acid was significantly reduced when 2,4-dinitrophenol was present. The suppression of indoleacetic acid conjugation by kinetin and 2,4-dinitrophenol appeared to be additive, and the free indoleacetic acid level in segments treated with 2,4-dinitrophenol in the presence of indoleacetic acid or indoleacetic acid plus kinetin was remarkably higher than in corresponding segments which received no 2,4-dinitrophenol.     

Ins oberste Lechthal!

Ohne Zusammenfassung     

Anabolic steroids abuse and male infertility

For several decades, testosterone and its synthetic derivatives have been used with anabolic and androgenic purposes. These substances were first restricted to professional bodybuilders, but become more and more popular among recreational athletes. Up to date, 3,000,000 anabolic-androgenic steroids (AAS) users have been reported in the United States with an increasing prevalence, making AAS consumption a major public health growing concern. Infertility is defined by the WHO as the failure to achieve a clinical pregnancy after 12 months or more of regular unprotected sexual intercourse and a male factor is present in up to 50 % of all infertile couples. Several conditions may be related to male infertility.Substance abuse, including AAS, is commonly associated to transient or persistent impairment on male reproductive function, through different pathways. Herein, a brief overview on AAS is offered. Steroids biochemistry, patterns of use, physiological and clinical issues are enlightened. A further review about fertility outcomes among male AAS abusers is also presented, including the classic reports on transient anabolic steroid-induced hypogonadism (ASIH), and the more recent experimental reports on structural and genetic sperm damage.     

The interaction between HIV-1 Gag and human lysyl-tRNA synthetase during viral assembly

Human lysyl-tRNA synthetase (LysRS) is a tRNA-binding protein that is selectively packaged into HIV-1 along with its cognate tRNALys isoacceptors. Evidence exists that Gag alone is sufficient for the incorporation of LysRS into virions. Herein, using both in vitro and in vivo methods, we begin to map regions in Gag and LysRS that are required for this interaction. In vitro reactions between wild-type and truncated HIV-1 Gag and human LysRS were monitored using GST-tagged molecules and glutathione-agarose chromatography. Gag/LysRS interaction in vivo was detected in 293FT cells cotransfected with plasmids coding for wild-type or mutant HIV-1 Gag and LysRS, either by monitoring Gag.LysRS complexes immunoprecipitated from cell lysate with anti-LysRS or by measuring the ability of LysRS to be packaged into budded Gag viral-like particles. Based on these studies, we conclude that the Gag/LysRS interaction depends upon Gag sequences within the C-terminal domain of capsid (the last 54 amino acids) and amino acids 208-259 of LysRS. The latter domain includes the class II aminoacyl-tRNA synthetase consensus sequence known as motif 1. Both regions have been implicated in homodimerization of capsid and LysRS, respectively. Sequences falling outside these amino acid stretches can be deleted from either molecule without affecting the Gag/LysRS interaction, further supporting the observation that LysRS is incorporated into Gag viral-like particles independent of its ability to bind tRNALys.     

Wichtigere neue Funde von Phanerogamen in Nordtirol

Ohne Zusammenfassung     

Effect of age on high-fat diet-induced hypertension

Aging and obesity both have a significant impact on central blood pressure (BP) regulation, and previous studies indicated that changes in central redox signaling with age may affect high-fat (HF) diet-induced cardiovascular responses. Therefore, we investigated the effects of 60% HF feeding on BP regulation in young adult (5 mo) and old (26 mo) Fischer-344 × Brown-Norway rats. Radiotelemetric transmitters were implanted to measure BP, heart rate (HR), locomotor activity, and spontaneous baroreflex sensitivity. Expression and activity of NADPH oxidase and ANG II type 1 receptor were assessed in the hypothalamus and in the nucleus tractus solitarii. Old animals gained more weight on HF diet compared with young, whereas central NADPH oxidase expression and activity elevated similarly in the two age groups. After an initial hypotensive and tachycardic response during the first week of HF feeding, BP in young animals increased and became significantly elevated after 6 wk of HF feeding. In contrast, BP in old animals remained depressed. Nighttime HR and locomotor activity decreased in both young and old rats fed with HF diet, but these changes were more significant in young rats. As a result, amplitudes of circadian variation of BP, HR, and activity that were originally higher in young rats declined significantly and became similar in the two age groups. In conclusion, our experiments led to the surprising finding that HF diet has a more serious impact on cardiovascular regulation in young animals compared with old.     

An octakis-intercalating molecule

Herein we report the synthesis and characterization of a polyintercalator with eight potential intercalating l,4,5,8-naphthalenetetracarboxylic diimide (NDI) units linked in a head-to-tail arrangement via a peptide linker. UV spectroscopy and viscometry measurements indicated the molecule binds to double-stranded DNA with all eight NDI units intercalated simultaneously. Competition dialysis and DNAse 1 footprinting studies revealed a preference for GC-rich regions of DNA, and circular dichroism studies revealed significant distortion of B-form DNA upon binding. Our so-called "octamer" represents, to the best of our knowledge, the first intercalator that binds as an octakis-intercalator, capable of spanning at least 16 base pairs of DNA.