DNA sequences 3' of the Ig H chain cluster rearrange in mouse B cell lines

A mouse myeloma cell line MPC11 (IgG2b, kappa) and variants derived from it have been used to study DNA rearrangements that occur at the Ig H chain locus. One variant, F5.5, has acquired both VH gene and C epsilon gene rearrangements. Through genomic Southern blot analysis initially directed to mapping the C epsilon gene rearrangement, we observed that the VH region rearrangement was linked, through an inversion event, to sequences that originate 3' of the CH cluster, i.e., 3' of the C alpha gene. Subsequent studies have shown that DNA rearrangements within the region 3' of the C alpha gene are detected in several other mouse myeloma and hybridoma cell lines and are not associated with the expression of specific isotypes.     

Steroid modulation of oxytocin/vasopressin receptors in the uterus

Oxytocin (OT) and V1 vasopressin (VP) receptors are present simultaneously in several tissues, including the uterus. In myometrium these receptors mediate contractility, while in endometrium they mediate the release of other uterotonic substances as endothelin (ET). In rabbit myometrium, estrogens increase, while progesterone blunts neurohypophysial hormone receptors. However, the action of sex steroids on OT and V1 VP receptors differs in terms of the ED₅₀ and maximal effect. Therefore, at parturition, only OT receptors show a dramatic rise, while V1 VP receptors do not change, suggesting a major role for OT in labor. ET is a potent stimulator of uterine activity acting through specific receptors present on myometrial cells. These receptors as well as the endometrial localization of ET are modulated by sex steroids, indicating that ET might represent a paracrine regulator of uterine activity. In humans, OT but not V1 VP receptors increase as pregnancy progresses, confirming the primary relevance of OT in timing delivery.     

Optimization of accessible catalase activity in polyacrylamide gel-immobilized Saccharomyces cerevisiae

The permeabilization of Saccharomyces cerevisiae (baker's yeast), either before or after immobilization in polyacrylamide gel (PAG), has been examined as a means to increase the catalase activity of PAG-immobilized yeast cells. Prior permeabilization of the cells resulted in large losses of catalase activity during immobilization, but permeabilization after immobilization produced increases in the catalase activity of yeast/PAG particles. A dependence of the accessible catalase activity on the concentration of polyacrylamide in permeabilized yeast/PAG particles, and on the method of permeabilization of the immobilized cells, was observed. Optimal levels of stable catalase activity (1000-2000 IU/g PAG particles; ca. 5%-10% of total available activity) were obtained by immobilizing yeast cells (0.5 g wet cells/mL gel) in 10% (w/v) PAG, followed by permeabilization of the entrapped cells with either cetyltrimethylammonium bromide, Triton X-100 and one freeze-thaw, or five freeze-thaw cycles. (c) 1992 John Wiley & Sons, Inc.     

Aldosterone biosynthesis induced by ACTH and angiotensin II in newborn rat adrenocortical cells transfected by c-EJ-Ha-ras oncogene.

Adrenocortical cells were obtained by fractionated trypsination of newborn rat adrenal glands and transfected with a plasmid containing the EJ/T24-Ha-ras oncogene. Isolation of adhesive cells led to a proliferative cell line with an overexpression of 21 kDa ras protein. These cells incubated with corticosterone or deoxycorticosterone as the precursor produced a high level of 18-hydroxycorticosterone and aldosterone as identified by gas chromatography- mass spectrometry. ACTH and angiotensin II increased the basal production of aldosterone nineteen-fold and six-fold respectively. Under ACTH stimulation the ratio between aldosterone and 18-hydroxycorticosterone production was 1:3. The transformation of corticosterone under angiotensin II stimulation yielded up to 41% of 18-hydroxycorticosterone (4.7 micrograms/mg of cell protein per 24h) and 4.4% of aldosterone (0.5 microgram/mg of cell protein per 24h) in a low potassium concentration medium (6 mmol/l). To our knowledge this is the first report of continuous proliferative adrenocortical cells producing aldosterone.     

An inducible n-alkane hydroxylase system containing cytochrome “O” from Candida lipolytica

Summary In this work the terminal oxidase system of C. lipolytica grown on n-alkanes was identified, and partially purified. Spectral characteristics typical of cytochrome O are obtained, inhibition and photodissociation of CO are reported.     

Bacillus subtilis as a host for mosquitocidal toxins production

Aedes albopictus transmits several arboviral infections. In the absence of vaccines, control of mosquito populations is the only strategy to prevent vector-borne diseases. As part of the search for novel, biological and environmentally friendly strategies for vector control, the isolation of new bacterial species with mosquitocidal activity represents a promising approach. However, new bacterial isolates may be difficult to grow and genetically manipulate. To overcome these limits, here we set up a system allowing the expression of mosquitocidal bacterial toxins in the well-known genetic background of Bacillus subtilis. As a proof of this concept, the ability of B. subtilis to express individual or combinations of toxins of Bacillus thuringiensis israelensis (Bti) was studied. Different expression systems in which toxin gene expression was driven by IPTG-inducible, auto-inducible or toxin gene-specific promoters were developed. The larvicidal activity of the resulting B. subtilis strains against second-instar Ae. albopictus larvae allowed studying the activity of individual toxins or the synergistic interaction among Cry and Cyt toxins. The expression systems here presented lay the foundation for a better improved system to be used in the future to characterize the larvicidal activity of toxin genes from new environmental isolates.     

Ecomorphology of the African felid ensemble: The role of the skull and postcranium in determining species segregation and assembling history

Morphology of extant felids is regarded as highly conservative. Most previous studies have focussed on skull morphology, so a vacuum exists about morphofunctional variation in postcranium and its role in structuring ensembles of felids in different continents. The African felid ensemble is particularly rich in ecologically specialized felids. We studied the ecomorphology of this ensemble using 31 cranial and 93 postcranial morphometric variables measured in 49 specimens of all 10 African species. We took a multivariate approach controlling for phylogeny, with and without body size correction. Postcranial and skull + postcranial analyses (but not skull‐only analyses) allowed for a complete segregation of species in morphospace. Morphofunctional factors segregating species included body size, bite force, zeugopodial lengths and osteological features related to parasagittal leg movement. A general gradient of bodily proportions was recovered: lightly built, long‐legged felids with small heads and weak bite forces vs. the opposite. Three loose groups were recognized: small terrestrial felids, mid‐to‐large sized scansorial felids and specialized Acinonyx jubatus and Leptailurus serval. As predicted from a previous study, the assembling of the African felid ensemble during the Plio‐Pleistocene occurred by the arrival of distinct felid lineages that occupied then vacant areas of morphospace, later diversifying in the continent.     

Risposte Fotomorfogeniche Indotte Dalla Radiazione UV-B in Brassica Oleracea var. Capitata

Abstract

Photomorphogenic responses induced by UV-B radiation in Brassica oleracea var. capitata.—Ultraviolet radiation can induce a plethora of “damaging” and “non damaging” effects in higher plants. We analyzed two possible photomorphogenic responses to UV-B radiation, the anthocyanin accumulation and the inhibition of hypocotyl elongation by modifying the UV spectral range with specific cut-off filters, under two levels of photon fluence rate. Experimental results suggest that detrimental effects are due to shorter wavelenghts of UV-B region (less than 305 nm); in contrast some adaptative responses may be induced by longer wavelenghts of UV-B region (between 305 and 320 nm). We attempted to determine the involvment of endogenous anthocyanin content in the UV-B photoprotection. Our experiments suggest a secondary role of anthocyanin accumulation in UV-B plant adaptation.     

Changes of nitric oxide,carbon monoxide and oxidative stress in term infants at birth

The higher risk of respiratory problem in infants delivered by elective caesarean section in comparison with vaginally born infants may be favoured by lower level of nitric oxide (NO) and carbon monoxide (CO) and higher oxidative stress in infants born by caesarean section. We studied healthy term infants born by vaginal delivery or by elective caesarean section. Nitric oxide, CO, guanosine 3–5 cyclic monophosphate, total hydroperoxide and advanced oxidation protein products (AOPP) were measured at birth and 48–72 h of life. Nitric oxide, CO and cGMP were lower at birth and at 48–72 h of life in infants born by elective caesarean delivery. Total hydroperoxide and AOPP levels were similar in the two groups and increased from birth to 48–72 h of life. In conclusion, nitric oxide and CO concentrations were higher in term infants vaginally born than in infants born by elective caesarean section and decreased from birth to 48–72 h of life. The mode of delivery did not affect the oxidative stress which increases from birth to 48–72 h of life.     

DNA barcoding as a complementary tool for conservation and valorisation of forest resources

Since the pre-historic era, humans have been using forests as a food, drugs and handcraft reservoir. Today, the use of botanical raw material to produce pharmaceuticals, herbal remedies, teas, spirits, cosmetics, sweets, dietary supplements, special industrial compounds and crude materials constitute an important global resource in terms of healthcare and economy. In recent years, DNA barcoding has been suggested as a useful molecular technique to complement traditional taxonomic expertise for fast species identification and biodiversity inventories. In this study, in situ application of DNA barcodes was tested on a selected group of forest tree species with the aim of contributing to the identification, conservation and trade control of these valuable plant resources.The “core barcode” for land plants (rbcL, matK, and trnH-psbA) was tested on 68 tree specimens (24 taxa). Universality of the method, ease of data retrieval and correct species assignment using sequence character states, presence of DNA barcoding gaps and GenBank discrimination assessment were evaluated. The markers showed different prospects of reliable applicability. RbcL and trnH-psbA displayed 100% amplification and sequencing success, while matK did not amplify in some plant groups. The majority of species had a single haplotype. The trnH-psbA region showed the highest genetic variability, but in most cases the high intraspecific sequence divergence revealed the absence of a clear DNA barcoding gap. We also faced an important limitation because the taxonomic coverage of the public reference database is incomplete. Overall, species identification success was 66.7%.This work illustrates current limitations in the applicability of DNA barcoding to taxonomic forest surveys. These difficulties urge for an improvement of technical protocols and an increase of the number of sequences and taxa in public databases.