Submarine Hydrothermal Vents of the Aeolian Islands: Relationship Between Microbial Communities and Thermal Fluids

The relationship between fluid geochemistry and microbial communities was investigated for shallow (< 25 m) submarine hydrothermal vents in the Aeolian Islands (Southern Italy). Thermal waters, gases, and deposits of white filamentous material were collected from 11 sites. The geochemical analyses showed a magmatic component was present in all sampled fluids. The total microbial abundances, evaluated as direct counts of picoplanktonic cells (ranging from 0.2 to 2 mu m in diameter), were between 1.55 107 and 4.18 108 cells per liter. Picophytoplankton (total autofluorescent cells) ranged from 9.6 105 to 7.88 106 cells per liter. Yellow-orange autofluorescent prokaryotes belonging to the cyanobacteria were more abundant than red autofluorescent eukaryotic cells. Chemolithoautotrophic, sulfur-oxidizing, rod-shaped Bacteria were isolated from venting water samples and identified as Thiobacillus -like. Microscopic examination of the white mat deposits showed the presence of filamentous microorganisms.     

Differential expression of PARK2 splice isoforms in an in vitro model of dopaminergic‐like neurons exposed to toxic insults mimicking Parkinson's disease

Mutations in PARK2 (or parkin) are responsible for 50% of cases of autosomal‐recessive juvenile‐onset Parkinson's disease (PD). To date, 21 alternative splice variants of the human gene have been cloned. Yet most studies have focused on the full‐length protein, whereas the spectrum of the parkin isoforms expressed in PD has never been investigated. In this study, the role of parkin proteins in PD neurodegeneration was explored for the first time by analyzing their expression profile in an in vitro model of PD. To do so, undifferentiated and all‐trans‐retinoic‐acid (RA)‐differentiated SH‐SY5Y cells (which thereby acquire a PD‐like phenotype) were exposed to PD‐mimicking neurotoxins: 1‐methyl‐4‐phenylpyridinium (MPP⁺) and 6‐hydroxydopamine (6‐OHDA) are widely used in PD models, whereas carbonyl cyanide m‐chlorophenyl hydrazone (CCCP) and carbobenzoxy‐Leu‐Leu‐leucinal (MG132) interfere, respectively, with mitochondrial mitophagy and proteasomal degradation. Following treatment with each neurotoxin H1, the first parkin isoform to be cloned, was down‐regulated compared to the respective controls both in undifferentiated and RA‐differentiated cells. In contrast, the expression pattern of the minor splice isoforms varied as a function of the compound used: it was largely unchanged in both cell cultures (eg, H21‐H6, H12, XP isoform) or it showed virtually opposite alterations in undifferentiated and RA‐differentiated cells (eg, H20 and H3 isoform). This complex picture suggests that up‐ or down‐regulation may be a direct effect of toxin exposure, and that the different isoforms may exert different actions in neurodegeneration via modulation of different molecular pathways.     

The geographic apportionment of mitochondrial genetic diversity in east African chimpanzees, Pan troglodytes schweinfurthii

This study is a geographically systematic genetic survey of the easternmost subspecies of chimpanzee, Pan troglodytes schweinfurthii. DNA was noninvasively collected in the form of shed hair from chimpanzees of known origin in Uganda, Rwanda, Tanzania, and Zaire. Two hundred sixty-two DNA sequences from hypervariable region 1 of which of the mitochondrial control region were generated. Eastern chimpanzees display levels of mitochondrial genetic variation which are low and which are similar to levels observed in humans (Homo sapiens). Also like humans, between 80% and 90% of the genetic variability within the eastern chimpanzees is apportioned within populations. Spatial autocorrelation analysis shows that genetic similarity between eastern chimpanzees decreases clinically with distance, in a pattern remarkably similar to one seen for humans separated by equivalent geographic distances. Eastern chimpanzee mismatch distributions (frequency distributions of pairwise genetic differences between individuals) are similar in shape to those for humans, implying similar population histories of recent demographic expansion. The overall pattern of genetic variability in eastern chimpanzees is consistent with the hypothesis that the subject has responded demographically to paleoclimatically driven changes in the distribution of eastern African forests during the recent Pleistocene.      

NAP modulates hyperglycemic–inflammatory event of diabetic retina by counteracting outer blood retinal barrier damage

Diabetic retinopathy (DR) is a common microvascular complication of diabetes. Prolonged hyperglycemia stimulates inflammatory pathway characterized by the release of some cytokines leading to the impairment of blood retinal barrier (BRB). NAP exerts a protective effect in various eye diseases, including DR. So far, the role of NAP in the modulation of inflammatory event during early phase of this pathology has not been investigated yet. In the current study, we have studied the retinal protective effect of NAP, injected into the eye, in diabetic rats. NAP treatment exerts a dual effect downregulating interleukin (IL)-1β and its related receptors and upregulating IL-1Ra expression. We have also tested the role of this peptide in human retinal epithelial cells (ARPE19) cultured on a semipermeable support and exposed to hyperglycemic–inflammatory insult, representing a in vitro model of diabetic macular edema, a clinical manifestation of DR. The results have shown that NAP prevents outer BRB impairment by upregulating the tight junctions. In conclusion, deepened characterization of NAP action mechanism on hyperglycemic–inflammatory damage may be useful to develop a new strategy to prevent retinal damage during DR.     

Cyclic 3', 5'-AMP relay dictyostelium discoideum. V. Adaptation of the cAMP signaling response during cAMP stimulation

In dictyostelium discoideum, extracellular cAMP activates adenylate cyclase, which leads to an increase in intracellular cAMP and the rate of cAMP secretion. The signaling response to a constant cAMP stimulus is terminated after several minutes by an adaptation mechanism. The time- course of adaptation stimuli of 10(-6) or 10(-7) M cAMP was assessed. We used a perfusion technique to deliver defined cAMP stimuli to [(3)H]adenosine-labeled amoebae and monitored their secretion of [(3)H]cAMP. Amoebae were pretreated with 10(-6) or 10(-7) M cAMP to periods of 0.33-12 minutes, and then immediately given test stimuli of 10(-8) M to 2.5 x 10(-7) M cAMP. The response to a given test stimulus was progressively attenuated and finally extinguished as the duration of the pretreatment stimulus increased. During concentration of the test stimulus. The responses to test stimuli of 10(-8), 5 x 10(-8), 10(-7), or 2.5 x 10(-7) M cAMP were extinguished after approximately 1, 2.25,2.5, and 10 min, respectively. 1.5 min of stimulation with 10(-7) M cAMP was necessary to extinguish the response of a test stimulus of 10(-8) M cAMP. Our data suggest that adaptation begins within 20 s of stimulation, rises rapidly for approximately 2.5 min, and reaches a plateau after approximately 10 min. The absolute rate of rise was faster during pretreatment with 10(-6) than with 10(-7) M cAMP. These results support a working hypothesis in which the occupancy of surface cAMP receptors leads to changes in two opposing cellular processes, excitation and adaptation, that control the activity of D. discoideum adenylate cyclase.     

In vitro synthesis of oligosaccharides by acceptor reaction of dextransucrase from Leuconostoc mesenteroides

Glucose was used as acceptor to obtain small chain oligossaccharides from sucrose using dextransucrase from Leuconostoc mesenteroides NRRL B-512F. Better conditions for the synthesis of the oligosaccharides were obtained using experimental design and response surface methodology. Yield of oligosaccharides was increased from 5% to 45% following an increase in both sucrose and glucose/sucrose concentrations, from 58 g/l to 142 g/l and from 0.02 to 0.18, respectively. Molecular weight increased from 2800 to 4500 daltons with a temperature shifting from 10°C to 30°C. © Rapid Science Ltd. 1998     

The self-incompatibility phenotype in brassica is altered by the transformation of a mutant S locus receptor kinase

The self-incompatible (SI) Brassica napus line W1, which carries the 910 S allele, was transformed with an inactive copy of the 910 S locus receptor kinase (SRK) gene. Two transformed lines were analyzed based on their heritable ability to set self-seed. The first line was virtually completely self-compatible (SC), and reciprocal pollinations with the original W1 line demonstrated that only the stigma side of the SI phenotype was altered. An analysis of the expression of endogenous SRK-910 demonstrated that the mechanism of transgene action is via gene suppression. Furthermore, the expression of the S locus glycoprotein gene present in the 910 allele (SLG-910), SLG-A10, which is derived from a nonfunctional S allele, and an S locus-related gene were also suppressed. When the transgene was crossed into another SI line carrying the A14 S allele, it was also capable of suppressing the expression of the endogenous genes and of making this line SC. The second transgenic line studied was only partly SC. In this case as well, only the stigma phenotype was affected, although no gene suppression was detected for endogenous SRK-910 or SLG-910. In this line, the expression of the transgene most likely was causing the change in phenotype, and no effect was observed when this transgene was crossed into the other SI line. Therefore, this work reinforces the hypothesis that the SRK gene is required, but only for the stigma side of the SI phenotype, and that a single transgene can alter the SI phenotype of more than one S allele.