Isolation and functional characterization of rat pancreatic acini.

The Authors describe an optimized procedure for the isolation of rat pancreatic acini and the preliminary results concerning the functional characterization of the cells. Isolation is carried out by two sequential digestive steps in a KREBS modified medium containing collagenase, separated by an intermediate step in which acini separation is fostered by incubation in a Ca++ free medium containing the Ca++ chelator EDTA. Final separation is obtained through the application of mechanical forces by aspirating the suspension in plastic pipettes. The choice of the collagenase, the duration and the entity of the mechanical dissociation strength are the main modifications to the classic procedure and allow to obtain a very high yield of cells maintaining their ability to secrete enzymes for a long period (6-7 hours). Functional characterization is completed mainly by the determination of the amylase release stimulated by increasing doses of cholecystokinin.     

Atmospheric input of inorganic nitrogen to the Western Mediterranean

Bulk inorganic nitrogen deposition was monitored over a period of 3 years at the Bavella Pass (Corsica, France). Annual fluxes range between 126 and 150mol.m^–2.d-^–1, increasing slightly with annual rainfall. Natural background average concentrations of rain water and associated fluxes were estimated from a classification of rain events into natural (Oceanic and Saharan), polluted and composite. Long range transport of incoming polluted air masses increases the atmospheric wet nitrogen input by at least a factor of 1.6 in this Mediterranean area. Extrapolation of atmospheric dissolved inorganic nitrogen input to the Western Mediterranean leads to fluxes of 80 to l00mol.m^–2.d-^–1. This atmospheric input is in the same order of magnitude as the inorganic nitrogen riverine input. As a consequence, the nitrogen budget for the Mediterranean has had to be reassessed. Atmospheric wet inorganic nitrogen input is of noticeable importance to marine Mediterranean ecosystems, representing on average 10 to 25% of new production in the Western Basin, with values of up to 60% in oligotrophic zones.     

Classification of European Mtdnas from an Analysis of Three European Populations

Mitochondrial DNA (mtDNA) sequence variation was examined in Finns, Swedes and Tuscans by PCR amplification and restriction analysis. About 99% of the mtDNAs were subsumed within 10 mtDNA haplogroups (H, I, J, K, M, T, U, V, W, and X) suggesting that the identified haplogroups could encompass virtually all European mtDNAs. Because both hypervariable segments of the mtDNA control region were previously sequenced in the Tuscan samples, the mtDNA haplogroups and control region sequences could be compared. Using a combination of haplogroup-specific restriction site changes and control region nucleotide substitutions, the distribution of the haplogroups was surveyed through the published restriction site polymorphism and control region sequence data of Caucasoids. This supported the conclusion that most haplogroups observed in Europe are Caucasoid-specific, and that at least some of them occur at varying frequencies in different Caucasoid populations. The classification of almost all European mtDNA variation in a number of well defined haplogroups could provide additional insights about the origin and relationships of Caucasoid populations and the process of human colonization of Europe, and is valuable for the definition of the role played by mtDNA backgrounds in the expression of pathological mtDNA mutations     

Light induction of the clock-controlled geneccg-1 is not transduced through the circadian clock inNeurospora crassa

Ambient light and the circadian clock have been shown to be capable of acting either independently or in an interrelated fashion to regulate the expression of conidiation in the ascomycete fungusNeurospora crassa. Recently several molecular correlates of the circadian clock have been identified in the form of the morning-specific clock-controlled genesccg-1 andccg-2. In this paper we report studies on the regulation ofccg-1, an abundantly expressed gene displaying complex regulation. Consistent with an emerging consensus for clock-controlled genes and conidiation genes inNeurospora, we report thatccg-1 expression is induced by light, and show that this induction is independent of the direct effects of light on the circadian clock. Although circadian regulation of the gene is lost in strains lacking a functional clock, expression ofccg-1 is still not constitutive, but rather fluctuates in concert with changes in developmental potential seen in such strains. Light induction ofccg-1 requires the products of theNeurospora wc-1 andwc-2 genes, but surprisingly the requirement forwc-2 is suppressed in conditional mutants ofcot-1, a gene that encodes a cAMP-dependent protein kinase. These data provide insight into a complex regulatory web, involving at least circadian clock control, light control, metabolic control, and very probably developmental regulation, that governs the expression ofccg-1.     

Biphasic Stimulation of Translational Activity Correlates with Induction of Translation Elongation Factor 1 Subunit [alpha] upon Wounding in Potato Tubers

Potato (Solanum tuberosum) tubers exhibit an increase in translational activity in response to mechanical wounding. The response is biphasic, with an initial stimulation apparent within the first 2 h after wounding and a second increase occurring 12 to 24 h after wounding. Increased activity is apparent by measurement of protein synthesis both in vivo and in vitro using a cell-free extract. Accumulation of the translational elongation factor 1 subunit [alpha] (EF-1[alpha]) parallels translational activity. Changes in the steady-state level of EF-1[alpha] mRNA, and expression of a chimeric EF-1[alpha] promoter/[beta]-glucuronidase construct in transgenic potato tubers, indicate that the gene encoding EF-1[alpha] is transcribed during both periods of translational stimulation. These results indicate that stimulation of translational activity is coordinated with increased expression and accumulation of translation factors.     

Modulation of drug-induced cytotoxicity by a bispecific monoclonal antibody that recognizes the epidermal growth factor receptor and doxorubicin

A hybrid hybridoma secreting a bispecific hybrid mAb (bsmAb), which recognizes both the epidermal growth factor receptor (EGF-R) and the drug doxorubicin, was produced by somatic hybridization of two hybridomas. The bsmAb obtained was able to retarget doxorubicin cytotoxicity in vitro specifically on EGF-R-positive cells exerting at the same time an antidotal effect on cells that did not overexpress the EGF-R. Distribution studies in mice indicate that the bsmAb selectively delivers the drug to tumour cells and modifies doxorubicin biodistribution with a statistically significant decrease of drug concentration in the intestine, which is the main target of early anthracycline toxicity. In keeping with this finding is the remarkable antidotal activity exerted by bsmAb in mice treated with doxorubiein, which is proved by retardation in loss of body weight and mortality. The effectiveness on tumour growth of the mAb followed by the administration of doxorubicin appears to be equal to that of the drug alone; however, the bsmAb exerts a remarkable antidotal activity.     

Observaciones de campo sobre la biologia deMetriona elatior (Col.: Chrysomelidae) enSolanum elaeagnifolium (Solanaceae) del uruguay

Field observations on the biology ofMetriona elatior (Col.: Chrysomelidae) onSolanum elaeagnifolium (Solanaceae) from Uruguay. Specimens ofMetriona elatior were found feeding on leaves of the silverleaf nightshade,Solanum elaeagnifolium, from the eastern of Uruguay since 1984. According to a field study the young leaves were skeletonized since spring to early autumn by larvae and adults. Oothecae and pupae were found mainly on old leaves. The egg mean volume was of 0.614 mm³. Young plants of the weed were always killed after massive natural infections ofM. elatior. Therefore, this tortoise leaf-beetle may be studied as a potential biocontrol agent on populations ofS. elaeagnifolium.

     

Design of metal ion binding peptides

Two cyclic and branched peptides (PLA and AZU) were synthesized with the aim of reproducing the active site of the blue copper proteins plastocyanin and azurin. Both peptides, designed on the basis of the x-ray structures of Poplar plastocyanin and Alcaligenes denitrificans azurin. contain the same coordinating residues of the parent native proteins. The visible spectra of PLA in the presence of equimolar amount of Cu(II) strongly support the interaction between the peptide and copper(II) ion. The CD titration of AZU with the Hg(II) ion indicates for the formation of two species. [A ZUHg]⁺ and [A ZUHg₂]³⁺ having binding constants (K_eq) of 3.10⁶ and 2–10⁴M^?1, respectively. © 1994 John Wiley & Sons, Inc.     

A monoclonal antibody extends the half-life of an anti-HIV oligodeoxynucleotide and targets it to CD4+ cells.

An approach was sought to increase the half-life and target cell specificity of antisense oligodeoxynucleotides (oligos). A monoclonal antibody (MAb) was derived from mice immunised with an oligo complementary to a region (1-20) of the HIV genome. This MAb exerts a protective effect on the oligo from the degradation induced by plasma exonucleases in vitro and in vivo. Moreover the anti-oligo MAb dissociates from the oligo in the presence of its complementary sequence to allow hybridization of the two complementary strands. To direct the oligo to CD4+ cells the anti-oligo MAb was cross-linked to an anti-CD4 MAb. The heteroaggregate determines a 5-fold increase in the cellular membrane binding of the oligo to CD4+ lymphocytes. These findings suggest a new approach to enhancing the therapeutic action and the target specificity of antisense oligodeoxynucleotides useful for the selective inhibition of HIV replication in vivo.     

G6PD Cagliari: A new low activity glucose 6-phosphate dehydrogenase variant characterized by enhanced intracellular lability

Summary A new variant of human erythrocyte glucose 6-phosphate dehydrogenase (G6PD), designated G6PD Cagliari, has been characterized. It is associated with severe enzyme deficiency and can be placed in Class 2 of the usual tabulation of G6PD variants. The specific activity of this variant is near normal, while its decay within the circulating erythrocytes is very rapid compared with normals. Genetic analysis of the family of the propositus indicated that the two available females are heterozygotes characterized by extremely unbalanced mosaic phenotypes.