Diversity and biogeography of Ni‐hyperaccumulators of Alyssum section Odontarrhena (Brassicaceae) in the central western Mediterranean: evidence from karyology,morphology and DNA sequence data

The diversity of Alyssum section Odontarrhena in the central–western Mediterranean region was investigated to elucidate relationships and biogeography of Ni‐hyperaccumulators in the group. Karyological, morphometric and molecular phylogenetic analyses were performed on accessions of Ni‐hyperaccumulators from serpentine outcrops and non‐hyperaccumulators from calcareous–dolomitic soils in the region. Alpine and Apennine populations of A. argenteum, Sardinian A. tavolarae and some Tuscan A. bertolonii had a tetraploid chromosome complement and larger silicles, seeds and seed wings than diploid accessions. DNA sequences from the plastid rpoC1 locus corroborated the monophyly of section Odontarrhena but species relationships were poorly resolved. Bayesian analysis of combined ITS‐rpoC1 sequences retrieved three main lineages including hyperaccumulators and non‐hyperaccumulators of contrasting geographical origin. One lineage was mainly continental and included alpine and northern Apennine populations of A. argenteum, the Balkan complex of A. murale and the Iberian group of A. serpyllifolium, sister to Corsican A. robertianum as suggested by their similar diploid karyotype. In this clade no divergence was found between typical A. serpyllifolium and related Ni‐hyperaccumulator races from the Iberian peninsula, supporting their conspecific status. A second lineage was prevalently Mediterranean and included the sister species A. bertolonii and A. tavolarae, and other endemics from Sicily, the southern Balkans and Turkey from dolomite and serpentine habitats. The present data suggest new model systems consisting of hyperaccumulators and non‐hyperaccumulators of proven phylogenetic affinity for further research on the molecular mechanisms of Ni‐hyperaccumulation and serpentine tolerance at the diploid and tetraploid level. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2013, 173 , 269–289.     

Genetic affinities of the central Indian tribal populations

Background

The central Indian state Madhya Pradesh is often called as ‘heart of India’ and has always been an important region functioning as a trinexus belt for three major language families (Indo-European, Dravidian and Austroasiatic). There are less detailed genetic studies on the populations inhabited in this region. Therefore, this study is an attempt for extensive characterization of genetic ancestries of three tribal populations, namely; Bharia, Bhil and Sahariya, inhabiting this region using haploid and diploid DNA markers.

Methodology/Principal Findings

Mitochondrial DNA analysis showed high diversity, including some of the older sublineages of M haplogroup and prominent R lineages in all the three tribes. Y-chromosomal biallelic markers revealed high frequency of Austroasiatic-specific M95-O2a haplogroup in Bharia and Sahariya, M82-H1a in Bhil and M17-R1a in Bhil and Sahariya. The results obtained by haploid as well as diploid genetic markers revealed strong genetic affinity of Bharia (a Dravidian speaking tribe) with the Austroasiatic (Munda) group. The gene flow from Austroasiatic group is further confirmed by their Y-STRs haplotype sharing analysis, where we determined their founder haplotype from the North Munda speaking tribe, while, autosomal analysis was largely in concordant with the haploid DNA results.

Conclusions/Significance

Bhil exhibited largely Indo-European specific ancestry, while Sahariya and Bharia showed admixed genetic package of Indo-European and Austroasiatic populations. Hence, in a landscape like India, linguistic label doesn''t unequivocally follow the genetic footprints.     

Pubblicazioni pervenute in dono alla Società durante l'anno 1940

Abstract

Viola etrusca Erben, an endemic species of mountains of Southern Tuscany, belonging to the ser. Calcaratae Becker, is investigated under chorological and caryological aspects. On the basis of our data, the distribution area results larger than previously thought, extending to Monte Labbro and Monte Amiata. The known chromosome number is confirmed, and the caryotipic formula is reported.     

Trait variation in juvenile plants from the soil seed bank of temperate forests in relation to macro- and microclimate

Aim

The soil seed bank is a key component of the biodiversity of plant communities, but various aspects of its functioning in temperate forest ecosystems are still unknown. We here adopted a trait-based approach to investigate the effects of macro- and microclimatic gradients on the juvenile plant communities from the realized seed bank of two types of European temperate forest.

Location

Oak-dominated forests in Italy and Belgium.

Methods

We analysed the variation of key functional traits (plant height, leaf area, leaf dry weight, specific leaf area and leaf number) of juvenile plants from the realised soil seed bank in relation to elevation (from 0 to 800 m a.s.l.), forest type (thinned and unthinned forest) and distance to the forest edge. We translocated soil samples from the forest core to the edge (and vice versa) and from high- to low-elevation forests to test the effects of edge and warming respectively.

Results

Taller communities developed at the forest edge due to higher light availability and warmer temperatures. The translocation from the core to the edge did not significantly modify mean trait values. Instead, the shadier and cooler microclimate of the forest core reduced the mean leaf area, mean dry weight, height and leaf number in the communities realised from the edge soil. The translocation from high- to lowland forests led to increased values for all traits (except specific leaf area). Edge vs core trait variation was more driven by intraspecific variability, whereas the translocation from high- to low-elevation forests caused trait changes mostly due to species turnover.

Conclusions

Global warming might result in a functional shift of the understorey due to both an early filtering effect on the seedlings from soil seed banks and their adaptive trait adjustments to temperature increase. Furthermore, our study underpins the importance of edge vs core microclimate in driving the functional composition of the realised soil seed bank.     

Plasmodium falciparum hypoxanthine guanine phosphoribosyltransferase. Stability studies on the product-activated enzyme

Hypoxanthine guanine phosphoribosyltransferases (HGPRTs) catalyze the conversion of 6-oxopurine bases to their respective nucleotides, the phosphoribosyl group being derived from phosphoribosyl pyrophosphate. Recombinant Plasmodium falciparum HGPRT, on purification, has negligible activity, and previous reports have shown that high activities can be achieved upon incubation of recombinant enzyme with the substrates hypoxanthine and phosphoribosyl pyrophosphate [Keough DT, Ng AL, Winzor DJ, Emmerson BT & de Jersey J (1999) Mol Biochem Parasitol98, 29-41; Sujay Subbayya IN & Balaram H (2000) Biochem Biophys Res Commun279, 433-437]. In this report, we show that activation is effected by the product, Inosine monophosphate (IMP), and not by the substrates. Studies carried out on Plasmodium falciparum HGPRT and on a temperature-sensitive mutant, L44F, show that the enzymes are destabilized in the presence of the substrates and the product, IMP. These stability studies suggest that the active, product-bound form of the enzyme is less stable than the ligand-free, unactivated enzyme. Equilibrium isothermal-unfolding studies indicate that the active form is destabilized by 2-3 kcal x mol(-1) compared with the unactivated state. This presents a unique example of an enzyme that attains its active conformation of lower stability by product binding. This property of ligand-mediated activation is not seen with recombinant human HGPRT, which is highly active in the unliganded state. The reversibility between highly active and weakly active states suggests a novel mechanism for the regulation of enzyme activity in P. falciparum.     

Epitope mapping from real time kinetic studies — Role of cross-linked disulphides and incidental interacting regions in affinity measurements: Study with human chorionic gonadotropin and monoclonal antibodies

Real time kinetic studies were used to map conformational epitopes in human chorionic gonadotropin (hCG) for two monoclonal antibodies (MAbs). The epitopes were identified in the regions (α5-14 and α55-62). The association rate constant (k₊₁) was found to be altered by chemical modification of hCG, and the ionic strength of the reaction medium. Based on these changes, we propose the presence of additional interactions away from the epitope-paratope region in the hCG-MAb reaction. We have identified such incidental interacting regions (IIRs) in hCG to be the loop region α35-47 and α60-84. The IIRs contribute significantly towards theK _A of the interaction. Therefore, in a macromolecular interaction of hCG and its MAb,K _A is determined not only by epitopeparatope interaction but also by the interaction of the nonepitopic-nonparatopic IIRs. However, the specificity of the interaction resides exclusively with the epitope-paratope pair.     

The effect of L-NAME administrations after oral mucosal incision on wound NO level in rabbit

The aim of the current study was to comparatively investigate the effect of inhibition of nitric oxide (NO) production by N-nitro-L-arginine methyl ester (L-NAME), an isoform non-specific inhibitor of nitric oxide synthase (NOS), after oral mucosal incision on wound tissue NO levels. A standard incision was applied to the oral mucosa of rabbits. After oral mucosal incision, rabbits were divided into five groups as follows: (1) Untreated incisional group (control); (2) Titanium (Ti) implanted group; (3) Ti + Polyethylene glycol (PEG) 4000 implanted group; (4) Ti + PEG 4000 + L-NAME (2 × 10⁻⁴ M) implanted group and (5) i.p. L-NAME administrated group (10 mg/kg). At 5 days after oral incision operations, wound tissue strips and plasma were obtained from rabbits. Oral wound tissue and plasma nitric oxide, plasma thiobarbituric acid reactive substances (TBARS) and total sulfhydryl group (RSH) levels were investigated. Plasma TBARS and NOx levels decreased after i.p. L-NAME administration. Total RSH group levels were not changed in all groups (p>0.05). This means that L-NAME inhibits the deteriorating effects of free radicals without affecting healing. L-NAME in PEG and titanium also has no effect on tissue and plasma NOx levels. These findings indicate that NO generation will not be affected both Ti and local nitric oxide synthase (NOS) inhibitor. (Mol Cell Biochem 278: 65–69, 2005)     

Reversible acetylation of chromatin: Implication in regulation of gene expression,disease and therapeutics

The eukaryotic genome is a highly dynamic nucleoprotein complex that is comprised of DNA, histones, nonhistone proteins and RNA, and is termed as chromatin. The dynamicity of the chromatin is responsible for the regulation of all the DNA-templated phenomena in the cell. Several factors, including the nonhistone chromatin components, ATP-dependent remodeling factors and the chromatin-modifying enzymes, mediate the combinatorial post-translational modifications that control the chromatin fluidity and, thereby, the cellular functions. Among these modifications, reversible acetylation plays a central role in the highly orchestrated network. The enzymes responsible for the reversible acetylation, the histone acetyltransferases (HATs) and histone deacetylases (HDACs), not only act on histone substrates but also on nonhistone proteins. Dysfunction of the HATs/HDACs is associated with various diseases like cancer, diabetes, asthma, cardiac hypertrophy, retroviral pathogenesis and neurodegenerative disorders. Therefore, modulation of these enzymes is being considered as an important therapeutic strategy. Although substantial progress has been made in the area of HDAC inhibitors, we have focused this review on the HATs and their small-molecule modulators in the context of disease and therapeutics. Recent discoveries from different groups have established the involvement of HAT function in various diseases. Furthermore, several new classes of HAT modulators have been identified and their biological activities have also been reported. The scaffold of these small molecules can be used for the design and synthesis of better and efficient modulators with superior therapeutic efficacy.     

Xanthohumol Inhibits Notch Signaling and Induces Apoptosis in Hepatocellular Carcinoma

Despite improvement in therapeutic strategies, median survival in advanced hepatocellular carcinoma (HCC) remains less than one year. Therefore, molecularly targeted compounds with less toxic profiles are needed. Xanthohumol (XN), a prenylated chalcone has been shown to have anti-proliferative effects in various cancers types in vitro. XN treatment in healthy mice and humans yielded favorable pharmacokinetics and bioavailability. Therefore, we determined to study the effects of XN and understand the mechanism of its action in HCC. The effects of XN on a panel of HCC cell lines were assessed for cell viability, colony forming ability, and cellular proliferation. Cell lysates were analyzed for pro-apoptotic (c-PARP and cleaved caspase-3) and anti-apoptotic markers (survivin, cyclin D1, and Mcl-1). XN concentrations of 5μM and above significantly reduced the cell viability, colony forming ability and also confluency of all four HCC cell lines studied. Furthermore, growth suppression due to apoptosis was evidenced by increased expression of pro-apoptotic and reduced expression of anti-apoptotic proteins. Importantly, XN treatment inhibited the Notch signaling pathway as evidenced by the decrease in the expression of Notch1 and HES-1 proteins. Ectopic expression of Notch1 in HCC cells reverses the anti-proliferative effect of XN as evidenced by reduced growth suppression compared to control. Taken together these results suggested that XN mediated growth suppression is appeared to be mediated by the inhibition of the Notch signaling pathway. Therefore, our findings warrants further studies on XN as a potential agent for the treatment for HCC.