Triplex gene dosage effect for β-glucronidase and possible assignment to band q22 in a partial duplication 7q

Summary A 2-year-old girl had a de novo duplication in the long arm of one chromosome 7 and an increased level of the enzyme -glucuronidase in cultured fibroblasts. The phenotype of the girl partly overlaps those of two presumptive syndromes due to secondary partial trisomies 7q. The ratio of the enzyme activity was 1.43 to the controls, and 1.37 to her parent's values. We could not define the abnormality but suggest two alternatives: either the patient is trisomic for region q112 to q22 or for the region q22 to q34. If the second alternative is correct the locus for -glucuronidase is possibly assigned to band 7q22.     

Correlative immunocytochemical and electron microscopic studies: Identification of (Entero)glucagon-somatostatin- and pancreatic polypeptide-like-containing cells in the human colon

Summary Correlative immunocytochemical and electron microscopic studies, using the semi thin-thin technic, were performed to identify the (entero) glucagon, somatostatin and pancreatic polypeptide-like immunoreactive cells of the human colonic mucosa. Mean granule diameter for each cell type was estimated according to two methods and histograms showing the granule size distribution were constructed. A total of 139 immunostained cells identified at the ultrastructural level were analyzed. Mean granule diameter for (entero)glucagon-containing cells was 318±11 nm but a reduction of granule size with age was noteworthy: granules were larger in the fetus (mean diameter 350±15) than in adults (mean diameter 310±10 nm). Somatostatin-containing cells, very rare in adults, were present in the fetal distal colon. Their general mean granule diameter was 354±18 nm but many cells had a mean granule diameter of more than 400 nm. A pancreatic polypeptidelike immunoreactivity was found only in (entero)glucagon-containing cells, pointing out the possible occurrence of both peptides (or of similar sequences) in the same cells. Previous ultrastructural studies dealing with a tentative classification of the human colonic endocrine cells were compared with the present data.This work was supported by the Institut National de la Santé et de la Recherche Médicale (INSERM).     

Enhanced erythroid burst formation in mice after testosterone treatment

A single administration of testosterone propionate (TP) in ex-hypoxic polycythemic mice induces, at 24 hr after androgen, an amplification of the erythroid burst-forming unit (BFU-E or B) pool in marrow. This phenomenon is not associated with an amplification of the erythroid colony-forming unit (CFU-E or E) compartment and is followed by its depletion. In the other hand, the 36–49 hr rise of erythropoietin (Ep) levels in serum is followed by a 60-hr amplification of the E pool. It is suggested that the latter phenomenon is mediated by enhanced Ep production, whereas the early amplification of the B compartment may derive from a direct influence of TP at the stem cell level.     

Developmental analysis of the cell recognition mechanism in the ciliate Euplotes raikovi

Euplotes raikovi, like other ciliates, passes through a postconjugal immaturity, operatively identified by an apparent cell inability to form mating pairs under experimental conditions that are the same as those used for inducing mating at maturity. In cells homozygous for the gene mat-2, which controls the pheromone Er-2, Er-2 mRNA synthesis and mature Er-2 secretion were shown to start from the very beginning of the life cycle and continue throughout immaturity, although to extents estimated to be 5- to 10-fold lower than at maturity. In addition, experiments of ¹²⁵ I-Er-2 binding and crosslinking provided evidence that autocrine pheromone-binding sites, showing values of the dissociation constant of the order of 10^?9 M, are on the surface of immature cells. The number of these sites per cell was estimated to increase from less than 10⁶ per cell of 5–7 fissions of age, to about 16 × 10⁶ at maturity. These results were taken to suggest that a pheromone-receptor production is stimulated during immaturity by autocrine pheromone binding to cells and that this production might be essential for the development of a pheromone-receptor density high enough to transform the cell from “immature” to “adult,” that is competent to respond as well to pheromones of conspecific, genetically different cells. © 1992 Wiley-Liss, Inc.     

Enzyme polymorphism in a population of Calomys musculinus (Rodentia,Cricetidae)

NAD-linked lactate, malate, glycerophosphate, alcohol and nonspecific dehydrogenases, aspartate aminotransferases, and soluble esterases from extracts of tissues of individuals from a wild population of Calomys musculinus (Rodentia, Cricetidae) have been analyzed by means of starch gel electrophoresis and specific staining. Allelic frequencies and heterozygosity have been determined. Mendelian inheritance of some of the variants detected was confirmed by breeding experiments. Ten out of fifteen (66.6%) of the genetic loci investigated presented polymorphism. Mean heterozygosity per locus was very high (H=0.2014, se 0.046).This work has been supported, in part, by grants from the Secretaria de Ciencia y Tecnología de la Nación (National Program for Endemic Diseases) and from the Fundación Emilio Ocampo. C. N. G. is a Fellow and A. B. a Career Investigator of the Consejo Nacional de Investigaciones Científicas y Técnicas of Argentina.     

Review of the Neotropical Isertieae (Rubiaceae)

All neotropical genera previously included in the tribe Isertieae A. Rich. ex DC. are considered. The tribe Isertieae is here delimited by the following characters: absence of rhaphides, valvate aestivation of the corolla, cordiform or discoid placenta, fleshy indehiscent fruit, and seed coat cells with pitted walls. As so delimited, the tribe definitely includes the neotropical generaIsertia Schreb.,Gonzalagunia Ruiz & Pav.,Amphidasya Standl.,Raritebe Wernh.,Sabicea Aubl., andMussaenda L. as well as some paleotropical genera not here considered. The following neotropical genera are excluded from tribe Isertieae:Hippotis Ruiz & Pav.,Pentagonia Benth.,Sommera Schlecht.,Tammsia Karst.,Coccocypselum P. Browne,Schradera Vahl,Didymochlamys Hook, f., andXerococcus Oerst. The position of four genera,Striolaria Ducke,Patima Aubl.,Habroneuron Standl., andNeosabicea Wernh., remains uncertain due to a lack of material.     

Chromosome polymorphism in populations of the grasshopper Trimerotropis pallidipennis from southern Argentina

Three populations of the grasshopper Trimerotropis pallidipennis from southern Argentina have been studied cytologically. A very characteristic B-chromosome was found in all three. They also showed geographical variability in respect of the presence of pericentric inversions, and the inversion system was found to influence chiasma frequency. The Laguna Blanca population, which is on the hypothetical pathway the species is believed to have followed during its migration from northern to southern latitudes, has the same karyotype composition as the N. American form, with fixed inversions in the 3 largest autosomes and the X-chromosome. Its members have a high total chiasma frequency and a great number of interstitial chiasmata. The Sierra de la Ventana population, situated at the absolute eastern border of the species distribution is highly polymorphic with respect to the presence of inversions in the medium chromosomes. Its members have the lowest total chiasma frequency and a greatly reduced number of interstitial chiasmata. Situated geographically between the other two, the Choele-Choel population has the highest frequency of inversions and many of them are homozygous. Its members have a higher total chiasma frequency than that observed in specimens from Sierra de la Ventana, and a greatly reduced number of interstitial chiasmata, similar to that observed in individuals from the latter population.     

Oncogenic KRAS G12C: Kinetic and redox characterization of covalent inhibition

The recent development of mutant-selective inhibitors for the oncogenic KRAS^G12C allele has generated considerable excitement. These inhibitors covalently engage the mutant C12 thiol located within the phosphoryl binding loop of RAS, locking the KRAS^G12C protein in an inactive state. While clinical trials of these inhibitors have been promising, mechanistic questions regarding the reactivity of this thiol remain. Here, we show by NMR and an independent biochemical assay that the pK_a of the C12 thiol is depressed (pK_a ∼7.6), consistent with susceptibility to chemical ligation. Using a validated fluorescent KRAS^Y137W variant amenable to stopped-flow spectroscopy, we characterized the kinetics of KRAS^G12C fluorescence changes upon addition of ARS-853 or AMG 510, noting that at low temperatures, ARS-853 addition elicited both a rapid first phase of fluorescence change (attributed to binding, K_d = 36.0 ± 0.7 μM) and a second, slower pH-dependent phase, taken to represent covalent ligation. Consistent with the lower pK_a of the C12 thiol, we found that reversible and irreversible oxidation of KRAS^G12C occurred readily both in vitro and in the cellular environment, preventing the covalent binding of ARS-853. Moreover, we found that oxidation of the KRAS^G12C Cys12 to a sulfinate altered RAS conformation and dynamics to be more similar to KRAS^G12D in comparison to the unmodified protein, as assessed by molecular dynamics simulations. Taken together, these findings provide insight for future KRAS^G12C drug discovery efforts, and identify the occurrence of G12C oxidation with currently unknown biological ramifications.     

MicroRNA 320a and Membrane Antigens as Tools to Evaluate the Pathophysiology of Platelets Stored in Blood Banks

Our research group, through the analysis of miRNomes in platelet concentrates (PCs) stored in blood banks, identified and validated the miR-127 and miR-320a miRNAs as biomarkers of platelet storage lesions (PSLs) in PCs. In order to validate the miRNAs 127 and 320a methodologically, as PSL biomarkers in a large number of PC bags, we also evaluated important immunological markers involved in the platelet activation/aggregation process—the CD62P receptor (P-selectin), the surface glycoproteins (GP) IIb/IIIa, and the purinergic P2Y12 receptor—via flow cytometry. The miRNAs miR-127 and miR-320a were quantified by real-time quantitative PCR (RT-qPCR). To carry out this study, 500 collection tubes were used at the upper edge of the PC bags containing platelets. Each tube was divided into seven equal parts (totaling 3500 samples) for platelet analysis from 7 different storage days, where the 1st day represents the high-quality control, and the 7th day corresponds to the low-quality control of the platelets. After analyzing all parameters during storage days, it was concluded that the relative quantification of miR-320a below 0.50 and the CD62P receptor below 27.92% are reliable indicators of the absence of storage lesions in blood banks. We believe that the values found in the expression of the CD62P receptor legitimize the use of the miR-320a and miR-127 miRNAs to build a kit capable of accurately measuring whether the stored platelets are suitable for transfusion.