Immunofluorescence location using monoclonal antibodies of prolactin receptors in mammary epithelial cells of lactating rabbits

Immunofluorescent staining of PRL receptors on frozen sections of lactating rabbit mammary gland with a monoclonal antibody (IgG1 M110) shows that receptors are localized in the cytoplasm of epithelial cells and on short portions of plasma membrane. In vivo treatment by bromocriptine or in vitro treatment of mammary tissue slices by monensin modifies localization of receptors.     

Endocytic prolactin routes to the secretory pathway in lactating mammary epithelial cells

Plasma-borne prolactin is carried from blood to milk by transcytosis across the mammary epithelial cell through the endocytic and secretory pathways. To determine the precise route of prolactin endocytosis, intracellular transport of biotinylated prolactin was monitored, in parallel with endocytosis of fluorescein isothiocyanate-conjugated dextran and IgG, by using pulse-chase experiments in lactating mammary fragments and in enzymatically dissociated acini. Biotinylated prolactin was sorted to vesiculo-tubular organelles whereas dextran was very rapidly carried to the lumen and IgG remained accumulated in the basal region of cells. To determine whether prolactin uses routes into and across the Golgi and trans-Golgi network, localisation of biotinylated prolactin was combined with the immunofluorescence detection of caseins and, respectively, p58 and TGN38. Biotinylated prolactin strongly colocalised with caseins during a chase but not all or only very little with p58 and TGN38. To characterise the organelles involved in transcytosis, gold-labelled prolactin, experimentally accumulated in late endosomes and which recovered a normal transport, was localised by electron microscopy. In mammary fragments incubated at low temperature, and in mammary fragments from rats fed with a lipid-deprived diet, transport of gold-labelled prolactin was restored by increasing the temperature and by adding arachidonic acid, respectively. These data demonstrate that a sorting occurs very rapidly between prolactin, dextran and IgG. They suggest that prolactin may reach the biosynthetic pathway after direct fusion between multivesicular bodies and secretory vesicles.     

Improvement of both lipid and biomass productivities of Qatar Chlorocystis isolate for biodiesel production and food security

Microalgae are considered a very promising alternative for biofuel production. Several strategies were developed to modulate and improve algae metabolites production to meet the requirements for biodiesel production. Most previous research evidenced that the increase of the lipid content is accompanied by a decrease of the biomass production, which increases the cost of the downstream processing. Hence, the challenge is to find special culture conditions that increase the lipid and the biomass productivities simultaneously. In the present work, we developed a strategy for the improvement of biomass and lipid productivities in a novel local microalga isolate, Chlorocystis sp. QUCCCM14, which was not previously known as a promising strain. Indeed, culturing QUCCCM14 using f/2 medium with 10× NaH₂PO₄ (0.15 g L^?1 NaNO₃ and 5.6 mg L^?1 NaH₂PO₄) resulted in an improvement of 3.178 folds the lipid productivity reaching 56.121 mg L^?1 day^?1 and enhanced the biomass productivity reaching 141.363 mg L^?1 day^?1, simultaneously. Comparative analyses of the FAME profiles demonstrated that fed‐batch culture with phosphate or nitrate separately leads to a high production of the omega 3 fatty acids (Linolenic acid), whereas fed‐batch culture with phosphate and nitrate simultaneously increased the production of fatty acids suitable for biodiesel production.     

Infection of CD127+ (interleukin-7 receptor+) CD4+ cells and overexpression of CTLA-4 are linked to loss of antigen-specific CD4 T cells during primary human immunodeficiency virus type 1 infection

We recently found that human immunodeficiency virus (HIV)-specific CD4+ T cells express coreceptor CCR5 and activation antigen CD38 during early primary HIV-1 infection (PHI) but then rapidly disappear from the circulation. This cell loss may be due to susceptibility to infection with HIV-1 but could also be due to inappropriate apoptosis, an expansion of T regulatory cells, trafficking out of the circulation, or dysfunction. We purified CD38+++CD4+ T cells from peripheral blood mononuclear cells, measured their level of HIV-1 DNA by PCR, and found that about 10% of this population was infected. However, a small subset of HIV-specific CD4+) T cells also expressed CD127, a marker of long-term memory cells. Purified CD127+CD4+ lymphocytes contained fivefold more copies of HIV-1 DNA per cell than did CD127-negative CD4+ cells, suggesting preferential infection of long-term memory cells. We observed no apoptosis of antigen-specific CD4+ T cells in vitro and only a small increase in CD45RO+CD25+CD127dimCD4+ T regulatory cells during PHI. However, 40% of CCR5+CD38+++ CD4+ T cells expressed gut-homing integrins, suggesting trafficking through gut-associated lymphoid tissue (GALT). Furthermore, 80% of HIV-specific CD4+ T cells expressed high levels of the negative regulator CTLA-4 in response to antigen stimulation in vitro, which was probably contributing to their inability to produce interleukin-2 and proliferate. Taken together, the loss of HIV-specific CD4+ T cells is associated with a combination of an infection of CCR5+ CD127+ memory CD4+ T cells, possibly in GALT, and a high expression of the inhibitory receptor CTLA-4.     

Le passage Cénomanien–Turonien dans le Nord-Ouest algérien (coupe de Douar Menkouchi,Ouarsenis) : biostratigraphie des radiolaires

The Ouarsenis Massif belongs to the Algerian Tell domain which is considered as the eastern part of the Maghrebian Tethys former margin. The Cenomanian-Turonian Douar Menkouchi section outcropping in the eastern side of the Ouarsenis massif is composed of marls and laminated limestone alternations, including massive limestone and a biosiliceous bed toward the upper part of the succession. It reveals the presence of well-preserved and diversified radiolarians. In this study, we have identified for the first time in the Algerian domain, age-diagnostic radiolarian assemblages characterizing the Cenomanian-Turonian transition (C/T). The organic-rich laminated beds (black shales) confined to Silvae Zone, Cenomanian in age and underlying a biosiliceous interval, have provided radiolarian assemblages dominated by Pseudodictyomitrae. The successions overlying the biosiliceous interval have provided diversified radiolarian assemblages including Hagiastridae (i,e. Crucella cachensis, Alievium cf. superbum) and abundant Dictymitrae taxa (i,e. Dictyomitra cf. napaensis and Dictyomitra undata) indicating early Turonian age. These marl-limestone alternations are assigned to the Alievium superbum Zone. Considering taphonomic and diagenetic implications on assemblages content, we conclude that organic-rich beds and biosiliceous interval outline the latest Cenomanian. The radiolarian assemblage composition exhibits similarities to microfauna recovered from Bonarelli Horizon in Central Italy. Morphological similarities are also deduced from assemblages containing Pseudodictyomitrae tiara morphotypes (synonym of P. nakasekoi) which resemble those recovered from ophiolitic intervals in Cyprus and Oman areas.     

Cryopreservation of microalgae from desert environments of Qatar

The Qatar University Culture Collection of Cyanobacteria and Microalgae (QUCCCM) is a unique resource containing a diverse collection of microalgae and cyanobacteria, isolated from the Qatar desert environment. In order to ensure maximum preservation of this resource, a number of cryopreservation techniques were applied to various strains, and the preservation effectiveness (cell viability and lipid productivity) was determined. The conditions tested were direct, passive, and freeze-cooling cryopreservation (technique), dimethyl sulfate and methanol (cryoprotectant), and 5 and 10 % cryoprotectant concentrations over storage durations of up to 1 year. It was shown that the cryopreservation regime is strain dependent, and strains belonging to the same genera can have different requirements. On the other hand, neutral lipid estimation, via Nile red fluorescence determination of pre- and post-cryopreserved microalgae isolates, confirmed that the lipid production is affected by the applied cryopreservation method.     

Calreticulin, a potential cell surface receptor involved in cell penetration of anti-DNA antibodies

A 50-kDa protein was purified as a potential receptor, using an affinity matrix containing biotinylated F14.6 or H9.3 anti-DNA mAbs derived from autoimmune (New Zealand Black x New Zealand White)F(1) mouse and membrane extracts from cells. This protein was identified as calreticulin (CRT) by microsequencing. Confocal microscopy and FACS analysis showed that CRT was present on the surface of various cells. CRT protein was recognized by a panel of anti-DNA mAbs in ELISA. The binding of F14.6 to lymphocytes and Chinese hamster ovary cells was inhibited by soluble CRT or SPA-600. Thus, the anti-DNA mAbs used in this study bound to CRT, suggesting that CRT may mediate their penetration into the cells and play an important role in lupus pathogenesis.     

Multilocus allozyme differentiation of populations of the mussel Mytilus galloprovincialis Lmk. from Moroccan coasts

Along the Moroccan coasts, the systematic status of Mytilus populations have been for a long time uncertain and confused, due to the use of unreliable morphometric criteria. In the present study, allozyme markers reveal the exclusive existence of M. galloprovincialis on Mediterranean and Atlantic coasts. Nei's genetic distances are low and reflect a high gene flow between Atlantic and Mediterranean populations. However, a significant multilocus discontinuity revealed by F-statistics separate southern Atlantic populations from Mediterranean and north Atlantic ones and could be explained by a gene flow breaking because of a larval dispersal decrease, due to a sea surface current direction change from Cap Ghir towards the Canaries archipelago, and probably by differential selection effects in these two geographic areas.