Sex reversal in Nile tilapia (Oreochromis niloticus) using a nonsteroidal aromatase inhibitor

Several studies have demonstrated that steroid hormones can influence sex differentiation in nonmammalian vertebrates and it has been hypothesized that male and female sex differentiation are driven by androgen and estrogen hormones, respectively. Estrogen biosynthesis is mediated by the steroidogenic enzyme cytochrome P450 aromatase, which converts androgens to estrogens. In the present study we examined the efficacy of a potent nonsteroidal aromatase inhibitor incorporated into the food, on sex reversal of Nile tilapia (Oreochromis niloticus) larvae. Nile tilapia larvae were divided in seven groups, which were fed with diets containing different amounts of the aromatase inhibitor Fadrozole (0, 50, 75 and 100 mg/kg) during 15 and 30 days, starting 9 days after hatching. Independent of the period, the proportion of males was significantly higher in the treated groups. Treatment with the highest doses (75 and 100 mg/kg) for 30 days produced 100% males. Histological examination revealed no differences in gonadal tissues between control males and treated fish. Furthermore, one intersex fish was identified in the group treated with 50 mg Fadrozole/kg for 30 days. This study reports that a 100% Nile tilapia male population can be obtained by suppressing aromatase activity and suggests that besides steroid hormones, nonsteroidal compounds, such as aromatase inhibitors, have potential for production of monosex population in tilapia. J. Exp. Zool. 290:177-181, 2001.     

The thermal stability of a castor bean seed acid phosphatase

The effect of temperature on the activity and structural stability of an acid phosphatase (EC 3.1.3.2.) purified from castor bean (Ricinus communis L.) seeds have been examined. The enzyme showed high activity at 45 degrees C using p-nitrophenylphosphate (p-NPP) as substrate. The activation energy for the catalyzed reaction was 55.2 kJ mol(-1) and the enzyme maintained 50% of its activity even after 30 min at 55 degrees C. Thermal inactivation studies showed an influence of pH in the loss of enzymatic activity at 60 degrees C. A noticeable protective effect from thermal inactivation was observed when the enzyme was preincubated, at 60 degrees C, with the reaction products inorganic phosphate-P (10 mM) and p-nitrophenol-p-NP(10 mM). Denaturation studies showed a relatively high transition temperature (Tm) value of 75 degrees C and an influence of the combination of Pi (10 mM) and p-NP (10 mM) was observed on the conformational behaviour of the macromolecule.     

Enantiomeric resolution of kielcorin derivatives by HPLC on polysaccharide stationary phases using multimodal elution

Analytical HPLC methods using carbamate chiral stationary phases of polysaccharide derivatives were developed for the enantiomeric resolution of five racemic mixtures of xanthonolignoids: rac-trans-kielcorin C, rac-cis-kielcorin C, rac-trans-kielcorin D, rac-trans-isokielcorin D, and rac-trans-kielcorin E. The separations were evaluated with the stationary phases cellulose tris-3,5-dimethylphenylcarbamate, amylose tris-3,5-dimethylphenylcarbamate, amylose tris-(S)-1-phenylethylcarbamate, and amylose tris-3,5-dimethoxyphenylcarbamate under normal, reversed-phase, and polar organic elution conditions. Chiral recognition of those chiral stationary phases, the influence of mobile phases on the enantiomers separation, and the effects of structural features of the solutes on the chiral discrimination observed are discussed. The best performance was achieved on an amylose tris-3,5-dimethylphenylcarbamate phase. Polar organic conditions gave shorter retention factors and better resolutions and were a valuable alternative to the alcohol-hexane or reversed-phase conditions.     

Modulation of the activity of sea bass (Dicentrarchus labrax) head-kidney macrophages by macrophage activating factor(s) and lipopolysaccharide

The aim of this study was to establish the requirements for macrophage activating factor (MAF) production by sea bass head-kidney leucocytes and the kinetics of macrophage activation when exposed to MAF-containing supernatants and/or lipopolysaccharide (LPS), a known macrophage stimulant. MAF activity was found in culture supernatants of total head-kidney leucocytes pulsed with 5 microg ml(-1)Con A, 5 or 10 ng ml(-1)PMA and 100 ng ml(-1)calcium ionophore, or 10 microg ml(-1)Con A alone, as assessed by the capacity to prime macrophages for enhanced production of reactive oxygen intermediates (ROI). Mixed leucocyte cultures from two or eight fish showed higher MAF activity after stimulation, indicating that a mixed leucocyte reaction was also important for MAF production. MAF-induced activation of macrophage cultures was highest at 18 h of exposure and was lost by 72 h except for MAF induced by Con A-stimulation alone. LPS primed macrophages for increased ROI production at early incubation times and down-regulated ROI production after 24 h. LPS had no effect in further stimulating the MAF-induced priming effect on production of ROI and down-regulated the MAF-priming by 48 h. Sea bass head-kidney macrophages did not show increased nitrite production when exposed to MAF and/or LPS, which may be related to their differentiation status.     

Sex-Specific Mediating Role of Insulin Resistance and Inflammation in the Effect of Adiposity on Blood Pressure of Prepubertal Children

Objective

To evaluate the association between obesity indices and blood pressure (BP) at 4 years of age, in each sex, and to quantify to which extent this association is mediated by inflammation and insulin resistance (IR).

Materials and Methods

We studied 1250 4-year-old children selected from the population-based birth cohort Generation XXI. Associations between body mass index (BMI) z-score and waist-to-height ratio (WHtR), office BP, inflammation (high sensitivity C-reactive protein) and IR (HOMA-IR index) were assessed. Path Analysis, a modified multivariate regression approach, was applied to test causal models and quantify direct and indirect effects of predictors of systolic (SBP) and diastolic BP (DBP).

Results

SBP and DBP increased significantly with BMI and WHtR in both sexes. There was a strong direct association (explaining 74.1-93.2% of the total association) of both measures of adiposity with SBP, in both sexes. This association was additionally indirectly mediated by IR, particularly regarding WHtR (20.5% in girls and 9.4% in boys). Mediation by inflammation did not reach statistical significance in either sex. Regarding DBP, the direct effect of adiposity was strong (>95% for BMI and WHtR in boys) and the mediation by IR was much smaller in boys than in girls.

Discussion

The direct association between adiposity and BP in healthy 4-year-old children is strong and IR plays an important mediating role. The strength of effects of IR and inflammation suggests sex differences in the complex interplay between BP, adiposity and inflammation.     

Rotavirus and adenovirus in Rondônia

Acute gastroenteritis is one of the most common diseases in humans worldwide. Viral gastroenteritis is a global problem in infants and young children. In this study the incidence of diarrhea was assessed in 877 hospitalized children under five years old, over a period of 24 months and distributed in 470 cases of diarrhea and 407 age-matched group with other pathologies, as control group. Two antigen detection techniques based on enzyme immunoassay (EIA) and latex particles were used for detection of rotavirus and adenovirus. Rotavirus A was a major cause of gastroenteritis with 23.6% of cases, being 90% of these cases in young children. Adenovirus infections was detected by EIA with frequency of 6.4%. Rotavirus and adenovirus were detected in 10.1 and 1.7% of stools from control group, respectively. Interestingly, the frequency of the youngest children in the control group excreting Rotavirus A was comparable to that detected in stools from diarrheic children. We cannot rule out the existence of other enteric viruses because the etiology of 171 cases of diarrhea was not determined and active search for astrovirus and calicivirus was not done. This is the first study that shows the presence of enteric viruses in the infantile population from Western Brazilian Amazonia and it was important to help physicians in the treatment of viral gastroenteritis.     

Human blood-brain barrier disruption by retroviral-infected lymphocytes: role of myosin light chain kinase in endothelial tight-junction disorganization

The blood-brain barrier (BBB), which constitutes the interface between blood and cerebral parenchyma, has been shown to be disrupted during retroviral associated neuromyelopathies. Human T cell leukemia virus (HTLV-1)-associated myelopathy/tropical spastic paraparesis is a slowly progressive neurodegenerative disease, in which evidence of BBB breakdown has been demonstrated by the presence of lymphocytic infiltrates in the CNS and plasma protein leakage through cerebral endothelium. Using an in vitro human BBB model, we investigated the cellular and molecular mechanisms involved in endothelial changes induced by HTLV-1-infected lymphocytes. We demonstrate that coculture with infected lymphocytes induces an increase in paracellular endothelial permeability and transcellular migration, via IL-1alpha and TNF-alpha secretion. This disruption is associated with tight junction disorganization between endothelial cells, and alterations in the expression pattern of tight junction proteins such as zonula occludens 1. These changes could be prevented by inhibition of the NF-kappaB pathway or of myosin light chain kinase activity. Such disorganization was confirmed in histological sections of spinal cord from an HTLV-1-associated myelopathy/tropical spastic paraparesis patient. Based on this BBB model, the present data indicate that HTLV-1-infected lymphocytes can induce BBB breakdown and may be responsible for the CNS infiltration that occurs in the early steps of retroviral-associated neuromyelopathies.     

Sheeppox virus kelch-like gene SPPV-019 affects virus virulence

Sheeppox virus (SPPV), a member of the Capripoxvirus genus of the Poxviridae, is the etiologic agent of a significant disease of sheep in the developing world. Genomic analysis of pathogenic and vaccine capripoxviruses identified genes with potential roles in virulence and host range, including three genes with similarity to kelch-like genes of other poxviruses and eukaryotes. Here, a mutant SPPV with a deletion in the SPPV-019 kelch-like gene, DeltaKLP, was derived from the pathogenic strain SPPV-SA. DeltaKLP exhibited in vitro growth characteristics similar to those of SPPV-SA and revertant virus (RvKLP). DeltaKLP-infected cells exhibited a reduction in Ca(2+)-independent cell adhesion, suggesting that SPPV-019 may modulate cellular adhesion. When inoculated in sheep by the intranasal or intradermal routes, DeltaKLP was markedly attenuated, since all DeltaKLP-infected lambs survived infection. In contrast, SPPV-SA and RvKLP induced mortality approaching 100%. Lambs inoculated with DeltaKLP exhibited marked reduction or delay in fever response, gross lesions, viremia, and virus shedding compared to parental and revertant viruses. Together, these findings indicate that SPPV-019 is a significant SPPV virulence determinant in sheep.