VIP (Vasoactive Intestinal Polypeptide)-immunoreactive neurons in the retina of the rat

Summary Immunoreactive vasoactive intestinal polypeptide (VIP) was detected in a population of amacrine cells in the retina of the rat. Processes of these cells reach both the inner and outer half of the inner plexiform layer where they form sublayers. The VIP neurons are different from previously known amacrine cell types.     

Dendritic cells are less susceptible to human immunodeficiency virus type 2 (HIV-2) infection than to HIV-1 infection

Human immunodeficiency virus type 1 (HIV-1) infection of dendritic cells (DCs) has been documented in vivo and may be an important contributor to HIV-1 transmission and pathogenesis. HIV-1-specific CD4⁺ T cells respond to HIV antigens presented by HIV-1-infected DCs and in this process become infected, thereby providing a mechanism through which HIV-1-specific CD4⁺ T cells could become preferentially infected in vivo. HIV-2 disease is attenuated with respect to HIV-1 disease, and host immune responses are thought to be contributory. Here we investigated the susceptibility of primary myeloid DCs (mDCs) and plasmacytoid DCs (pDCs) to infection by HIV-2. We found that neither CCR5-tropic primary HIV-2 isolates nor a lab-adapted CXCR4-tropic HIV-2 strain could efficiently infect mDCs or pDCs, though these viruses could infect primary CD4⁺ T cells in vitro. HIV-2-exposed mDCs were also incapable of transferring virus to autologous CD4⁺ T cells. Despite this, we found that HIV-2-specific CD4⁺ T cells contained more viral DNA than memory CD4⁺ T cells of other specificities in vivo. These data suggest that either infection of DCs is not an important contributor to infection of HIV-2-specific CD4⁺ T cells in vivo or that infection of DCs by HIV-2 occurs at a level that is undetectable in vitro. The frequent carriage of HIV-2 DNA within HIV-2-specific CD4⁺ T cells, however, does not appear to be incompatible with preserved numbers and functionality of HIV-2-specific CD4⁺ T cells in vivo, suggesting that additional mechanisms contribute to maintenance of HIV-2-specific CD4⁺ T-cell help in vivo.     

Likely future extirpation of another Asian river dolphin: The critically endangered population of the Irrawaddy dolphin in the Mekong River is small and declining

The population of Irrawaddy dolphins that occupies the Mekong River in southern Lao People's Democratic Republic and Cambodia is classified as Critically Endangered by the IUCN. Based on capture‐recapture of photo‐identified individuals, we estimated that the total population numbered 93 ±  SE 3.90 individuals (95% CI 86–101), as of April 2007. The combined photo‐identification and carcass recovery program undertaken from 2001 to 2007 established that the Irrawaddy dolphin population inhabiting the Mekong River has reached a critical point with regards to its continued survival, where immediate research and management actions are required to greatly reduce adult mortality, and establish the cause of newborn mortality. In addition, community consultation is required to initiate, and evaluate, urgently required conservation measures. An ongoing well‐designed combined program of abundance estimation (i.e., photo‐identification) and carcass recovery is required to monitor total population size and mortality rates, to inform and evaluate management initiatives. The conclusions of this paper are likely generic to river dolphin populations, particularly where photo‐identification is possible.     

Comparative Effect of the I3.1 Probiotic Formula in Two Animal Models of Colitis

Use of probiotic therapy is an active area of investigation to treat intestinal disorders. The clinical benefits of the I3.1 probiotic formula (Lactobacillus plantarum (CECT7484, CECT7485) and P. acidilactici (CECT7483)) were demonstrated in irritable bowel syndrome (IBS) patients in a randomized, double-blind, placebo-controlled clinical trial. The aim of this study was to evaluate the therapeutic effects of I3.1 in two experimental models of colitis, a dextran sulfate sodium (DSS)-induced colitis model and an interleukin (IL)-10-deficient mice model. Colitis was induced in 32 8-week-old Balb/c mice by administering 3% (w/v) DSS in drinking water for 5 days. Probiotics were administered orally (I3.1 or VSL#3, 1 × 10⁹ CFU daily) for 10 days before the administration of DSS. Also, probiotics (I3.1 or VSL#3, 1 × 10⁹ CFU daily) were administered orally to 36 6-week-old C57B6J IL-10(?/?) mice for 10 weeks. Body weight was recorded daily. Colon samples were harvested for histological examination and cytokine measurements. Body weight after DSS administration did not change in the I3.1 group, whereas the VSL#3 group had weight loss. Also, I3.1 normalized IL-6 to levels similar to that of healthy controls and significantly increased the reparative histologic score. In the IL-10-deficient model, both VSL#3 and I3.1 reduced the severity of colitis compared to untreated controls, and I3.1 significantly reduced the levels of IFN-γ compared to the other two groups. In conclusion, I3.1 displays a protective effect on two murine models of experimental colitis. Results suggest that the mechanism of action could be different from VSL#3.     

Isolation from urine of two Serratia marcescens strains excreting a diffusible yellow pigment

Two bacterial strains excreting a yellow pigment were isolated from human urine and identified as Serratia marcescens. The pigment was produced in the late exponential and early stationary phases of growth. Minimal media supplemented with tyrosine, phenylalanine, 3,4-dihydroxyphenylacetate or tryptophan, as well as complex media, induced pigment production. UV-visible spectra of the extracted pigment had peaks characteristic of 2-hydroxy-5-carboxymethylmuconate semialdehyde, produced from meta-cleavage of 3,4-dihydroxyphenylacetate by the enzyme 3,4-dihydroxyphenylacetate 2,3-dioxygenase (EC 1.13.11.15). This enzyme was active when the bacteria were grown under conditions promoting pigment production. The kinetics and factors affecting pigment production are also reported.     

Display of whole proteins on inner and outer surfaces of grapevine fanleaf virus‐like particles

Virus‐like particles (VLPs) derived from nonenveloped viruses result from the self‐assembly of capsid proteins (CPs). They generally show similar structural features to viral particles but are noninfectious and their inner cavity and outer surface can potentially be adapted to serve as nanocarriers of great biotechnological interest. While a VLP outer surface is generally amenable to chemical or genetic modifications, encaging a cargo within particles can be more complex and is often limited to small molecules or peptides. Examples where both inner cavity and outer surface have been used to simultaneously encapsulate and expose entire proteins remain scarce. Here, we describe the production of spherical VLPs exposing fluorescent proteins at either their outer surface or inner cavity as a result of the self‐assembly of a single genetically modified viral structural protein, the CP of grapevine fanleaf virus (GFLV). We found that the N‐ and C‐terminal ends of the GFLV CP allow the genetic fusion of proteins as large as 27 kDa and the plant‐based production of nucleic acid‐free VLPs. Remarkably, expression of N‐ or C‐terminal CP fusions resulted in the production of VLPs with recombinant proteins exposed to either the inner cavity or the outer surface, respectively, while coexpression of both fusion proteins led to the formation hybrid VLP, although rather inefficiently. Such properties are rather unique for a single viral structural protein and open new potential avenues for the design of safe and versatile nanocarriers, particularly for the targeted delivery of bioactive molecules.     

Decreased Bone Formation Explains Osteoporosis in a Genetic Mouse Model of Hemochromatosiss

Osteoporosis may complicate iron overload diseases such as genetic hemochromatosis. However, molecular mechanisms involved in the iron-related osteoporosis remains poorly understood. Recent in vitro studies support a role of osteoblast impairment in iron-related osteoporosis. Our aim was to analyse the impact of excess iron in Hfe^-/- mice on osteoblast activity and on bone microarchitecture. We studied the bone formation rate, a dynamic parameter reflecting osteoblast activity, and the bone phenotype of Hfe^−/− male mice, a mouse model of human hemochromatosis, by using histomorphometry. Hfe^−/− animals were sacrificed at 6 months and compared to controls. We found that bone contains excess iron associated with increased hepatic iron concentration in Hfe^−/− mice. We have shown that animals with iron overload have decreased bone formation rate, suggesting a direct impact of iron excess on active osteoblasts number. For bone mass parameters, we showed that iron deposition was associated with bone loss by producing microarchitectural impairment with a decreased tendency in bone trabecular volume and trabecular number. A disorganization of trabecular network was found with marrow spaces increased, which was confirmed by enhanced trabecular separation and star volume of marrow spaces. These microarchitectural changes led to a loss of connectivity and complexity in the trabecular network, which was confirmed by decreased interconnectivity index and increased Minkowski’s fractal dimension. Our results suggest for the first time in a genetic hemochromatosis mouse model, that iron overload decreases bone formation and leads to alterations in bone mass and microarchitecture. These observations support a negative effect of iron on osteoblast recruitment and/or function, which may contribute to iron-related osteoporosis.     

Rapid extracellular acidification induced by glucose metabolism in non-proliferating cells of Serratia marcescens.

The addition of glucose or other sugars to resting cells of Serratia maurcescens induced rapid acidification of the extracellular medium. This acidification was due to the catabolism of sugars. The rate of acidification depended on the carbon source and its concentration. HPLC analysis of the supernatants demonstrated that the progressive fall in pH resulted from the rapid production of lactic, acetic, pyruvic and citric acids. Other microorganisms were tested for their ability to produce this rapid acidification of the medium. This study may provide a rapid and simple method for metabolism studies.