Understanding biological conservation strategies: a molecular-genetic approach to the case of myrtle (<Emphasis Type="Italic">Myrtus communis</Emphasis> L.) in two Italian regions: Sardinia and Calabria

Myrtle (Myrtus communis L.), a shrub widespread in the Mediterranean area, is the only species belonging to the Myrtaceae family growing in Europe. The pharmacological and aromatic properties of myrtle have caused a growing interest in this plant. The use of myrtle as an aromatic plant is traditionally established in the Italian regions of Sardinia and Calabria, where it is subjected to an ecological stress due to the large biomass removal for liquor production and environmental damage. The reduction in size and number of wild populations is often related to a loss of genetic variation and reproductive potential. In this study fluorescent amplified fragment length polymorphisms (fAFLPs) were employed to assess the genetic variation within and among natural populations of myrtle from Sardinia and Calabria to gain new insights into their fitness and survival potential. AMOVA analysis indicated that genetic variation was greater within populations (51.86%) than among populations (16.99%), as previously reported for outcrossing species. A significant amount of variation (31.15%) was attributed to variation between Sardinia and Calabria population groups, suggesting a genotypic differentiation between the myrtle populations of these two regions. Intra-population genetic variation, assessed by estimating expected unbiased heterozygosity (H _E), ranged from 0.0595 to 0.2595. These values resulted correlated with population extension (r = 0.918; P < 0.01) and with two reproductive parameters: seed germinability (r = 0.793; P < 0.01) and number of seeds per fruit (r = 0.631; P < 0.05). A moderate gene flow among Sardinia myrtle populations and Calabria populations (1.2719 and 1.0478, respectively) counteracts the low level of genetic variation observed in some␣populations and avoids their differentiation and isolation.     

Hypothyroidism Leads to a Decreased Expression of Mitochondrial F0F1-ATP Synthase in Rat Liver

In liver mitochondria isolated from hypothyroid rats, the rate of ATP synthesis is lower than in mitochondria from normal rats. Oligomycin-sensitive ATP hydrolase activity and passive proton permeability were significantly lower in submitochondrial particles from hypothyroid rats compared to those isolated from normal rats. In mitochondria from hypothyroid rats, the changes in catalytic activities of F₀F₁-ATP synthase are accompanied by a decrease in the amount of immunodetected -F₁, F₀1-PVP, and OSCP subunits of the complex. Northern blot hybridization shows a decrease in the relative cytosolic content of mRNA for -F₁ subunit in liver of hypothyroid rats. Administration of 3,5,3-triodo-L-thyronine to the hypothyroid rats tends to remedy the functional and structural defects of F₀F₁-ATP synthase observed in the hypothyroid rats. The results obtained indicate that hypothyroidism leads to a decreased expression of F₀F₁-ATP synthase complex in liver mitochondria and this contributes to the decrease of the efficiency of oxidative phosphorylation.     

A preliminary investigation of allozyme genetic variation and population geographical structure in Aphanius fasciatus from Italian brackish-water habitats

A total of 150 individuals from Aphanius fasciatus from coastal brackish-water habitats was analysed by allozyme electrophoresis to collect data on its genetic variation. From 22 enzymes, 43 putative enzyme-coding loci were resolved, 12 of which were polymorphic at P_0·99 level. Only one of the 31 probability tests showed a significant departure from the Hardy-Weinberg equilibrium. Aphanius fasciatus showed low levels of genetic polymorphism, with expected heterozygosity values ranging from 0·027 (S.E.=0·013) to 0·064 ( s.e. =0·023). Nei's genetic distances between populations ranged from 0·002 to 0·042. Weir & Cockerham F -statistics showed high levels of genetic heterogeneity among populations (jackknifed θ=0·302, s.e. =0·045) and estimates of N _m were < 1, indicating restricted gene flow. Significant positive correlation between genetic distance and geographical distance matrices, detected by Mantel's test ( g =1·941; P 0·001), is consistent with the prediction that the species is genetically structured by isolation-by-distance.     

Photosynthesis of two poplar clones under long‐term exposure to ozone

The photosynthetic response was studied in two clones ( Populus deltoides × maximowiczii Eridano and Populus × euramericana I‐214), known for their differential response to ozone (O₃) in terms of visible symptoms, when exposed to O₃ (60 nl l⁻¹ 5 h day⁻¹, 7 and 15 days). The photosynthetic ability was tested using gas exchange and chlorophyll fluorescence analysis. O₃ caused a decrease in the CO₂ assimilation rate at light saturation level in mature leaves of both clones. Alterations of Chl fluorescence parameters, in particular the F_v/F_m ratio and non‐photochemical quenching were also observed. The effects were similar for both clones and it could not be concluded that differential effects on electron transport capacity were responsible for the observed reduction in photosynthesis. The reduction of photosynthetic rate in Eridano was due mainly to a reduced mesophyll activity, as evidenced by the increase in intercellular CO₂ concentration and the minimal changes in stomatal conductance. In contrast, in I‐214, stomatal effects were primarily responsible, although effects on the mesophyll cannot be excluded. Data obtained indicate that the effects observed at the mesophyll level may be attributed to indirect effects caused by membrane disorders.     

Temporal Genetic Variation in a Population of Aphanius fasciatus (Cyprinodontidae) from a Brackish-water Habitat at Elba Island (Italy)

Allozyme electrophoresis was used to assess temporal genetic variation in three successive generations of the Mediterranean killifish, Aphanius fasciatus. Samplings were carried out in 1995, 1996 and 1997 in a brackish-water habitat at Elba Island, Italy and a total of 212 specimens were collected. The five loci for which polymorphism has been detected in a previous study were assayed. Mean expected heterozygosity values [H=0.397 (SE 0.077), H=0.336 (SE 0.092) and H=0.313 (SE 0.092) in 1995, 1996 and 1997, respectively] were not significantly different by ANOVA test. Deviations from Hardy–Weinberg equilibrium were minimal, with only one out of the 15 probability tests showing a significant departure from the equilibrium; whereas genotypic linkage disequilibrium was not detected. Values of Nei's genetic distance were lower than 0.04. Temporal genetic variation in the A. fasciatus population at Elba Island was observed, with F-statistics indicating significant genetic divergence among samples (=0.035, SE 0.027, p<0.001). Genetic drift acting on two loci (GPD-1 ^* and LDH-3 ^*) is presumably the main force determining the temporal genetic heterogeneity observed; however, the occurrence of selection on individual loci and/or sampling error cannot be excluded. The observed allelic variation among generations in a single population of A. fasciatus is much less than levels observed among geographically discrete samples in previous studies.     

Human Serotonin Transporter Expression During Megakaryocytic Differentiation of MEG-01 Cells

The serotonin (5-HT) transporter (SERT) has been found altered in platelets of patients with genetically complex disorders, including mood-anxiety, pain and eating disorders. In this study, we used cell cultures of platelet precursors as models of investigation on mechanisms of SERT regulation: SERT expression was appraised during megakaryocytic differentiation of human megakaryoblastic MEG-01 cells. Cells were cultured for 8 days with 10^?7M 4-β-12-tetradecanoylphorbol-13-acetate (β-TPA) in the presence of 10% fetal bovine serum (FBS) and SERT was assessed by real time PCR, immunofluorescence microscopy, Western blot and [³H]5-HT re-uptake. Results revealed that SERT is present in control-untreated MEG-01 cells. β-TPA-differentiating MEG-01 cells showed a redistribution of SERT fluorescence, diffuse to cell bodies and blebs along with a 3-fold SERT mRNA increase and a moderate raise in SERT protein (1.5/1.4-fold) by immunoblot and re-uptake assays. In summary, we have shown herein that control megakaryoblasts express the SERT protein. SERT is modulated by differentiation events, implying that SERT density in platelets is under the control of megakaryocytopoiesis stages. Differentiation of MEG-01 cells can provide considerable insight into interactions between SERT genetics, transmitter-hormonal/homeostatic mechanisms and signaling pathways.     

Analysis of genetic variability in Aristaeomorpha foliacea (crustacea, aristeidae) using DNA-ISSR (Inter Simple Sequence Repeats) markers

This work reports the first genetic data of Aristaeomorpha foliacea, a marine decapod of high commercial value, from six Mediterranean localities and one new fishing ground in the Mozambique Channel. The use of five Inter Simple Sequence Repeat (ISSR) primers provided 150 polymorphic loci. Average estimates of genetic diversity did not significantly differ among sampled localities, with a mean value of heterozygosity H = 0.105 ± 0.015. Analysis of molecular variance (AMOVA) allocated > 98% of genetic variability to the within-sample component, displaying values higher than those previously reported in ISSR studies on marine invertebrates. Cluster analyses did not detect geographically or genetically distinct groups. The observed lack of large-scale genetic differentiation is discussed in relation to the high potential for larval dispersal of the species and to features of the marker employed.     

Mitochondrial DNA variability of the pipefish Syngnathus abaster

This study provides data on the genetic structuring of the pipefish Syngnathus abaster in the western Mediterranean and Adriatic Seas. A total of 109 specimens were collected in brackish‐water biotopes. The control region and three other regions of the mitochondrial genome were analysed. The most relevant result was the high genetic structuring found by Bayesian inference (BI), maximum likelihood (ML) and network analyses, which were consistent in showing three well‐separated clusters of S. abaster populations. Furthermore, BI and ML did not support the monophyly of the taxon S. abaster. These results suggest the occurrence of a species complex in the study area, whose differentiation may have occurred since the Pleistocene. The results also show a very high genetic variability at the inter‐population level, with no shared haplotypes among sites. Evolutionary forces due to the fragmented nature of the brackish‐water habitats may account for the high genetic divergence found among the groups and populations. Finally, although dispersal by rafting over long distances may occasionally occur, this study suggests linear stepping‐stone model of colonization to be most likely. The complexity of the results obtained suggests that further studies are needed to elucidate the phylogeny of S. abaster.     

A microsatellite marker based linkage map of tobacco

We report the first linkage map of tobacco (Nicotiana tabacum L.) generated through microsatellite markers. The microsatellite markers were predominantly derived from genomic sequences of the Tobacco Genome Initiative (TGI) through bioinformatics screening for microsatellite motives. A total of 684 primer pairs were screened for functionality in a panel of 16 tobacco lines. Of those, 637 primer pairs were functional. Potential parents for mapping populations were evaluated for their polymorphism level through genetic similarity analysis. The similarity analysis revealed that the known groups of tobacco varieties (Burley, Flue-cured, Oriental and Dark) form distinct clusters. A mapping population, based on a cross between varieties Hicks Broad Leaf and Red Russian, and consisting of 186 F2 individuals, was selected for mapping. A total of 282 functional microsatellite markers were polymorphic in this population and 293 loci could be mapped together with the morphological trait flower color. Twenty-four tentative linkage groups spanning 1,920 cM could be identified. This map will provide the basis for the genetic mapping of traits in tobacco and for further analyses of the tobacco genome. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.