A comparison of responses and stimuli as time markers

A rat's behavior, as well as a stimulus, may be a time marker. But do they lead to similar performance? Eight rats were trained on a 20-s DRL procedure in which head-entry responses were time markers, i.e., each head-entry response indicated that food would not be delivered for 20 s. Concurrently, eight rats were trained on a control procedure in which light stimuli, yoked to the responses of a rat in the DRL procedure, were time markers, i.e., each light stimulus indicated that food would not be delivered for 20 s. A comparison of performance between the two groups showed a lower response rate in the DRL procedure than in the yoked control procedure. However, similar response patterns between the two groups were observed, suggesting that rats anticipated the food similarly with a stimulus or a response as the time marker.     

Dynamics of heparin-binding proteins on boar sperm

The presence, topology and dynamics of heparin-binding proteins (HBP) on boar sperm were evaluated. HBP distribution was analyzed by subcellular parting, using biotinylated heparin followed by colorimetric detection. HBP were detected as peripherical and integral periacrosomal membrane proteins. Indirect fluorescence microscopy of sperm incubated with biotinylated heparin was used to evidence heparin binding on sperm at different physiological stages. Two different fluorescent patterns (A and B) were found, which probably correspond to non-capacitated and capacitated sperm as assessed by the ability to undergo acrosome reaction with calcium ionophore A23187 and by the increase of p32 phosphorylated protein. In A pattern, corresponding to untreated sperm, fluorescence located mostly on the post-acrosomal region; in B pattern, corresponding to incubated sperm, on the acrosomal region. Upon incubation under capacitating conditions (TALP), sperm having the B pattern was augmented compared with non-incubated sperm (p < 0.001). Differences in the HBP patterns (p < 0.0001) were observed in sperm incubated under non-capacitating conditions in relation to sperm incubated in TALP, indicating that the modification of HBP patterns is probably related to capacitation. No difference was observed when untreated sperm were permeabilized prior to staining, suggesting that HBP are present on the sperm surface. The effect of heparin on capacitation dependent protein tyrosine phosphorylation was also analyzed, finding a decrease in p32 phosphorylation in the presence of heparin. This suggests that the capacitation enhancement mediated by this glycosaminoglycan involves an alternative intracellular pathway. The finding that heparin binds to sperm differently according to its physiological state, is a new evidence of the remodelling of sperm membrane surface upon capacitation and may provide a useful and relatively simple method to evaluate in vitro modification of boar sperm physiological state.     

The embryonic development of Schistosoma mansoni eggs: proposal for a new staging system

Schistosomiasis is a water-borne parasitic illness caused by neoophoran trematodes of the genus Schistosoma. Using classical histological techniques and whole-mount preparations, the present work describes the embryonic development of Schistosoma mansoni eggs in the murine host and compares it with eggs maintained under in vitro conditions. Two pre-embryonic stages occur inside the female worm: the prezygotic stage is characterized by the release of mature oocytes from the female ovary until its fertilization. The zygotic stage encompasses the migration of the zygote through the ootype, where the eggshell is formed, to the uterus. Fully formed eggs are laid still undeveloped, without having suffered any cleavage. In the outside environment, eight embryonic stages can be defined: stage 1 refers to early cleavages and the beginning of yolk fusion. Stage 2 represents late cleavage, with the formation of a stereoblastula and the onset of outer envelope differentiation. Stage 3 is defined by the elongation of the embryonic primordium and the onset of inner envelope formation. At stage 4, the first organ primordia arise. During stages 5 to 7, tissue and organ differentiation occurs (neural mass, epidermis, terebratorium, musculature, and miracidial glands). Stage 7 is characterized by the nuclear condensation of neurons of the central neural mass. Stage 8 refers to the fully formed larva, presenting muscular contraction, cilia, and flame-cell beating. This staging system was compared to a previous classification and could underlie further studies on egg histoproteomics (morphological localizome). The differentiation of embryonic structures and their probable roles in granulomatogenesis are discussed herein. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Treatment by acidification followed by solid–liquid separation affects slurry and slurry fractions composition and their potential of N mineralization

The aim of the present work was to assess the effect of treatments by acidification, solid–liquid separation or acidification followed by solid–liquid separation on the physical and chemical composition of pig slurry (S) and pig slurry fractions (non acidified and acidified solid (SF and ASF) and liquid (LF and ALF) fractions), as well as on the potential of N mineralization of these pig slurry derived materials. Acidification strongly decrease the inorganic carbon content of S, SF and LF and it also affects the distribution of P, Ca and Mg between the solid and liquid fraction leading to an ALF more equilibrated than LF in terms of nutrients. Acidification increases the potential of organic N mineralization in SF and decreases the potential of N immobilization in S and LF. It can be concluded that the proposed treatment generates valuable slurry fractions with distinct characteristics and potential of N mineralization that may be incorporated to soil at different periods after sowing to comply with plant nutrient requirements.     

Human Immunodeficiency Virus Type 1 (HIV-1) Induces the Cytoplasmic Retention of Heterogeneous Nuclear Ribonucleoprotein A1 by Disrupting Nuclear Import: IMPLICATIONS FOR HIV-1 GENE EXPRESSION*

Human immunodeficiency virus type 1 (HIV-1) co-opts host proteins and cellular machineries to its advantage at every step of the replication cycle. Here we show that HIV-1 enhances heterogeneous nuclear ribonucleoprotein (hnRNP) A1 expression and promotes the relocalization of hnRNP A1 to the cytoplasm. The latter was dependent on the nuclear export of the unspliced viral genomic RNA (vRNA) and to alterations in the abundance and localization of the FG-repeat nuclear pore glycoprotein p62. hnRNP A1 and vRNA remain colocalized in the cytoplasm supporting a post-nuclear function during the late stages of HIV-1 replication. Consistently, we show that hnRNP A1 acts as an internal ribosomal entry site trans-acting factor up-regulating internal ribosome entry site-mediated translation initiation of the HIV-1 vRNA. The up-regulation and cytoplasmic retention of hnRNP A1 by HIV-1 would ensure abundant expression of viral structural proteins in cells infected with HIV-1.     

Relationship Among Phenolic Contents,Seed Predation,and Physical Seed Traits in <Emphasis Type="Italic">Mimosa bimucronata</Emphasis> Plants

Phenolic contents were compared between Mimosa bimucronata seeds from infested and non-infested fruits to assess induced defense response. By measuring leg length of the bruchid beetle Acanthoscelides schrankiae, we verified whether phenolic contents affected bruchid body size. In addition, the relationship between physical seed traits and phenolic contents was examined. Results showed that seeds from infested fruits had significantly greater phenolic contents than seeds from non-infested fruits, which suggested induced defense. Body size variation in A. schrankiae was marginally nonsignificant according to phenolic contents among plants (negative trend), indicating that phenols may interfere directly with bruchid performance. Seeds that were more irregularly shaped had significantly greater phenolic contents than those that were more uniform. Therefore, the most perfectly spherical seeds may be more vulnerable to seed predation, and our results suggest that the production of phenolic compounds was increased in infested fruits, which in turn may affect A. schrankiae development.     

Hallmarks for senescence in carcinogenesis: novel signaling players

Cellular senescence is a potent anti-cancer mechanism controlled by tumor suppressor genes, particularly p53 and pRb, which is characterized by the irreversible loss of proliferation. Senescence induced by DNA damage, oncogenic stimulation, or excessive mitogenic input, serves as a barrier that counteracts cancer progression. Emerging evidence in cellular and in in vivo models revealed the involvement of additional signaling players in senescence, including PML, CK2, Bcl-2, PI3K effectors such as Rheb, Rho small GTPases, and cytokines. Recent studies have also implicated protein kinase C (PKC) isozymes as modulators of senescence phenotypes and showed that phorbol esters, widely used PKC activators, can induce senescence in a number of cancer cells. These novel findings suggest a complex array of cross-talks between senescence pathways and may have significant implications in cancer therapy.