Proteolytic activity in enzymatic extracts from Carica papaya L. cv. Maradol harvest by-products

Proteolytic activity and the cysteine protease profile were determined for enzymatic extracts (EE) from Carica papaya L. cv. Maradol harvest by-products (stems, unripe fruit, petioles and leaves). The proportion of each by-product type in the sampled plantation was calculated. Polypeptide bands were identified by SDS–PAGE for each EE and molecular weight calculated for the cysteine proteases. Leaf and fruit tissue had the highest protein contents of the by-products. Leaf tissue also produced the highest total EE yield. All the SDS–PAGE gels for the EE’s exhibited an approximately 23 kDa band probably corresponding to papain. The zymography profiles of the EE’s were similar, with bands at approximately >202.8, 76.8, 55.4 and 46.5 kDa. The fruit EE had the highest specific proteolytic activity and the leaf EE the lowest. Fruit and stem by-products are the most promising for proteolytic enzyme extraction.     

Numb proteins specify asymmetric cell fates via an endocytosis- and proteasome-independent pathway

Numb proteins are evolutionarily conserved signaling molecules that make the daughter cells different after asymmetric divisions by segregating to only one daughter. They contain distinct binding motifs for alpha-adaptin (alpha-Ada) and proteins with Eps15 homology (EH) domains, which regulate endocytosis, and for E3 ubiquitin ligases, which target proteins for proteasome-mediated degradation. In Drosophila melanogaster, Numb acts by inhibiting Notch activity to cause a bias in Notch-mediated cell-cell communication. These findings have led to the hypothesis that Numb modulates Notch signaling by using endocytosis and proteasomes to directly reduce Notch protein levels at the cell surface. Here we show that two Drosophila EH proteins, Eps15 homologue 1 (EH1) and the dynamin-associated 160-kDa protein (Dap160), negatively regulate Notch signaling. However, neither elimination of the binding motifs for endocytic proteins nor simultaneous reduction of proteasome activity affects the activity of Numb proteins. Our findings indicate that an endocytosis- and proteasome-independent pathway may mediate Numb signaling in asymmetric cell fate specification.     

Serologic evidence of human metapneumovirus circulation in Uruguay

First identified in 2001, the human metapneumovirus (hMPV), is a respiratory tract pathogen that affects young children, elderly, and immunocompromised patients. The present work represents the first serologic study carried out in Uruguay. It was performed with the purpose of obtaining serological evidence of hMPV circulation in Uruguay and to contribute to the few serologic reports described until now. Sixty nine serum samples collected between 1998 and 2001 by vein puncture from patients without respiratory symptoms or underlying pathology aged 6 days to 60 years were examined using an indirect immunofluorescence assay (IFA). The global seropositivity rate of the samples was 80% (55/69). Rates of 60% (15/25) and 91% (40/44) were observed for the pediatric and adult cohorts, respectively. Results obtained from a longitudinal analysis of 6 children aged 6 days to 18 months are discussed. These results are a clear evidence of hMPV circulation in Uruguay, at least since 1998, and reinforce the previous data on worldwide circulation of this virus.     

Simian immunodeficiency virus infection in free-ranging sooty mangabeys (Cercocebus atys atys) from the Taï Forest, Côte d'Ivoire: implications for the origin of epidemic human immunodeficiency virus type 2

Simian immunodeficiency virus of sooty mangabeys (SIVsmm) is recognized as the progenitor of human immunodeficiency virus type 2 (HIV-2) and has been transmitted to humans on multiple occasions, yet the epidemiology and genetic diversity of SIVsmm infection in wild-living populations remain largely unknown. Here, we report the first molecular epidemiological survey of SIVsmm in a community of approximately 120 free-ranging sooty mangabeys in the Ta? Forest, C?te d'Ivoire. Fecal samples (n = 39) were collected from 35 habituated animals (27 females and 8 males) and tested for SIVsmm virion RNA (vRNA). Viral gag (800 bp) and/or env (490 bp) sequences were amplified from 11 different individuals (eight females and three males). Based on the sensitivity of fecal vRNA detection and the numbers of samples analyzed, the prevalence of SIVsmm infection was estimated to be 59% (95% confidence interval, 0.35 to 0.88). Behavioral data collected from this community indicated that SIVsmm infection occurred preferentially in high-ranking females. Phylogenetic analysis of gag and env sequences revealed an extraordinary degree of genetic diversity, including evidence for frequent recombination events in both the recent and distant past. Some sooty mangabeys harbored near-identical viruses (<2% interstrain distance), indicating epidemiologically linked infections. These transmissions were identified by microsatellite analyses to involve both related (mother/daughter) and unrelated individuals, thus providing evidence for vertical and horizontal transmission in the wild. Finally, evolutionary tree analyses revealed significant clustering of the Ta? SIVsmm strains with five of the eight recognized groups of HIV-2, including the epidemic groups A and B, thus pointing to a likely geographic origin of these human infections in the eastern part of the sooty mangabey range.     

PI3Kgamma inhibition blocks glomerulonephritis and extends lifespan in a mouse model of systemic lupus

Systemic lupus erythematosus (SLE) is a chronic inflammatory disease generated by deregulation of T cell-mediated B-cell activation, which results in glomerulonephritis and renal failure. Disease is treated with immunosuppressants and cytostatic agents that have numerous side effects. Here we examine the use of inhibitors of phosphoinositide 3-kinase (PI3K) gamma, a lipid kinase that regulates inflammation, in the MRL-lpr mouse model of SLE. Treatment reduced glomerulonephritis and prolonged lifespan, suggesting that P13Kgamma may be a useful target in the treatment of chronic inflammation.     

Papillomaviruses: different genes have different histories

Papillomaviruses (PVs) infect stratified squamous epithelia in vertebrates. Some PVs are associated with different types of cancer and with certain benign lesions. It has been assumed that PVs coevolved with their hosts. However, recently it has been shown that different regions of the genome have different evolutionary histories. The PV genome has a modular nature and appeared after the addition of pre-existent blocks. This order of appearance in the PV genome is evident today in the different evolutionary rates of the different genes, with new genes--E5, E6 and E7--diverging faster than old genes--E1, E2, L2 and L1. Here, we propose an evolutionary framework aiming to integrate genome evolution, PV biology and epidemiology of PV infections.     

HCV core protein localizes in the nuclei of nonparenchymal liver cells from chronically HCV-infected patients

Understanding the mechanism of hepatitis C virus (HCV) pathogenesis is an important part of HCV research. Recent experimental evidence suggests that the HCV core protein (HCcAg) has numerous functional activities. These properties suggest that HCcAg, in concert with cellular factors, may contribute to pathogenesis during persistent HCV infection. HCV is capable of infecting cells other than hepatocytes. Although the extrahepatic cellular tropism of HCV may play a role in the pathophysiology of this infection, the precise biological significance of the presence of HCV components in different liver cell types presently remains to be established. In this study, HCcAg was detected in nonparenchymal liver cells of six patients out of eight positive for serum HCV RNA. Immunostaining with anti-HCcAg mAbs revealed the presence of this protein in different liver cell types such as lymphocytes, Kupffer, polymorphonuclear, pit, endothelial, stellate, and fibroblast-like cells. Interestingly, HCcAg was immunolabeled not only in the cytoplasm but also in the nucleus of these cells. Remarkably, HCcAg co-localized with large lipid droplets present in stellate cells and with collagen fibers in the extracellular matrix. Moreover, HCcAg was immunolabeled in bile canaliculus suggesting the involvement of the biliary system in the pathobiology of HCV. Data suggest that nonparenchymal liver cells may constitute a reservoir for HCV replication. Besides, HCcAg may contribute to modulate immune function and fibrosis in the liver as well as steatosis.