Two gap genes mediate maternal terminal pattern information in Drosophila

In Drosophila three maternal pattern organizing activities, the anterior, the posterior, and the terminal, establish the anterior-posterior body pattern of the embryo by initiating the spatially restricted activities of the gap class of zygotic segmentation genes. The activities of tailless (tll) and the newly identified gap gene huckebein (hkb) are specifically involved in mediating the maternal terminal information at the posterior end of the blastoderm embryo.     

Expression of beta-nerve growth factor receptor mRNA in Sertoli cells downregulated by testosterone

Nerve growth factor (NGF) is synthesized in male germ cells. The NGF receptor (NGFR) mRNA was found in the Sertoli cells of rat testis. Hypophysectomy increased both NGFR mRNA in testis and the number of NGFR hybridizing cells in seminiferous tubules. This was suppressed by treatment with chorionic gonadotropin or testosterone, but not with follicle-stimulating hormone. The NGFR mRNA also increased after destruction of Leydig cells or blocking of the androgen receptor. This suggests that NGF produced by male germ cells regulates testicular function in an androgen-modulated fashion by mediating an interaction germ and Sertoli cells.     

Signal-driven computations in speech processing

Learning a language requires both statistical computations to identify words in speech and algebraic-like computations to discover higher level (grammatical) structure. Here we show that these computations can be influenced by subtle cues in the speech signal. After a short familiarization to a continuous speech stream, adult listeners are able to segment it using powerful statistics, but they fail to extract the structural regularities included in the stream even when the familiarization is greatly extended. With the introduction of subliminal segmentation cues, however, these regularities can be rapidly captured.     

Product differentiation via corporate social responsibility: consumer priorities and the mediating role of food labels

This article examines quantitatively the determinants of purchase decisions based on corporate social responsibility (CSR), adopting a hierarchical conceptual model of decision making where the key factors are personal concern, information availability and financial considerations. We use best–worst methods to assess consumer priorities (personal concern) for CSR activities in milk production; and elicit consumer interpretation of four labels (organic, Validus, Colorado Proud and rBST free) in terms of CSR and other outcomes (information availability). We then elicit willingness to pay (WTP) for the labels (financial considerations), and estimate regression models to determine how predictive each label perceptual profile is of WTP for milk. Animal welfare and sustainable agricultural practices are the most important activities, and milk labels do convey CSR-related messages. With the exception of the pair animal welfare-Validus, the link between CSR messages and WTP is tenuous. The discussion emphasizes the central role of each label’s perceptual profile in triggering product differentiation among consumers.     

Bypass of DNA lesions generated during anticancer treatment with cisplatin by DNA polymerase eta

DNA polymerase eta (Pol eta) is a eukaryotic lesion bypass polymerase that helps organisms to survive exposure to ultraviolet (UV) radiation, and tumor cells to gain resistance against cisplatin-based chemotherapy. It allows cells to replicate across cross-link lesions such as 1,2-d(GpG) cisplatin adducts (Pt-GG) and UV-induced cis-syn thymine dimers. We present structural and biochemical analysis of how Pol eta copies Pt-GG-containing DNA. The damaged DNA is bound in an open DNA binding rim. Nucleotidyl transfer requires the DNA to rotate into an active conformation, driven by hydrogen bonding of the templating base to the dNTP. For the 3'dG of the Pt-GG, this step is accomplished by a Watson-Crick base pair to dCTP and is biochemically efficient and accurate. In contrast, bypass of the 5'dG of the Pt-GG is less efficient and promiscuous for dCTP and dATP as a result of the presence of the rigid Pt cross-link. Our analysis reveals the set of structural features that enable Pol eta to replicate across strongly distorting DNA lesions.     

Understanding agri-food networks as social relations

Actor network theory and supply chainmanagement theory provide suggestive researchdirections for understanding regional agri-foodnetworks. These theories claim that relationshipsbased upon trust and cooperation are critical to thestrength and vitality of the network. This means thatexploring and detailing these relationships among thesuppliers, producers, workers, processors, brokers,wholesalers, and retailers within specific regionalgeographies of these networks are critical forfurthering cooperation and trust. Key areas ofcooperation include resource sharing andapprenticeship programs. Employing food networks as akey unit of contextual analysis will deepen ourunderstanding of how to enhance their resiliency andvibrancy. Important questions can be raised about thedifference gender makes for farmers, brokers,entrepreneurs, and workers in local food networks.     

Activation-driven programmed cell death and T cell receptor zeta eta expression

Activation of spontaneously dividing T cell hybridomas induces interleukin-2 (IL-2) production, a cell cycle block, and programmed cell death. T cell hybridomas that express the T cell antigen receptor (TCR) zeta homodimer (zeta 2), but not the TCR zeta eta heterodimer, were studied. The zeta eta- cells produced little or no inositol phosphates (IP) when stimulated with antigen. In most cases the hydrolysis of phosphoinositides was also impaired after stimulation with antibody to CD3, although one zeta eta- cell produced normal concentrations of IP. The zeta eta- cells slowed their growth and secreted IL-2 in response to both stimuli. However, the zeta eta- cells did not die after activation with antigen. Since activated thymocytes also undergo programmed cell death, these results may have important implications for the role of the zeta eta.TCR in negative selection.     

Evolutionary and somatic selection of the antibody repertoire in the mouse

The repertoire of antibody variable (V) regions has been subject to evolutionary selection, affecting both the diversity of V region genes in the germline and their expression in the B lymphocyte population and its subsets. In ontogeny, contact with an antigen leads to the expansion of B cells expressing antibodies complementary to it. In a defined phase of B cell differentiation, new sets of V regions are generated from the existing repertoire through somatic hypermutation. Cells carrying advantageous antibody mutants are selected into the memory compartment and produce a stable secondary response upon reexposure to the antigen.     

Brain tryptophan hydroxylation: dependence on arterial oxygen tension

The accumulation of cerebral 5-hydroxytryptophan after decarboxylase inhibition was decreased in rats maintained at arterial O(2) tensions below 60 mm-Hg. In contrast, brain lactate was stable above 40 mm-Hg and brain adenosine triphosphate, adenosine diphosphate, and adenosine monophosphate were unchanged above 30 mm-Hg. There was a linear correlation of brain 5-hydroxytryptophan accumulation to cerebral venous O(2) tension. Cerebral tryptophan hydroxylase appears to have a poor affinity for oxygen and to be affected by slight hypoxia. The resultant decreases in monoamine neurotransmitter metabolism may explain the behavioral changes of mild oxygen deprivation.