Tree-ring wood anatomy and stable isotopes show structural and functional adjustments in olive trees under different water availability

Background and Aims

Olive tree (Olea europaea L.) is a drought-tolerant tree species cultivated in Mediterranean-type environments. Although it is tolerant to drought, dry conditions decrease its productivity. A thorough analysis of the hydraulic architecture and wood anatomical plasticity, as well as of their physiological significance, is needed to understand how olive trees will adapt to the predicted increase in frequency and severity of drought in the Mediterranean region.

Methods

Dendrochronological, stable isotopic (δ¹³C, δ¹⁸O) and wood anatomical analyses were applied to understand how different water availability can affect wood stem structure and function, in rainfed and irrigated at 100 % of crop evapotranspiration (ETc) olive trees in an experimental orchard close to Benevento (Italy) from 1992 to 2009.

Results

Dendrochronological data indicate that cross-dating and synchronization of ring-width time series in olive tree is possible. After the start of irrigation, significantly more negative δ¹³C and lower δ¹⁸O values were recorded in irrigated trees indicating higher stomatal conductance and transpiration rates. Increased water balance induced the formation of a higher number of vessels with higher diameter.

Conclusions

Water balance variations affected wood anatomy and isotopic composition. Anatomical analyses detected structural and functional adjustments in rainfed trees that produced more vessels with lower diameter to prevent cavitation. Isotopic analyses confirmed that irrigated trees continuously showed enhanced transpiration rates.     

Modeling the synergy between HSV-2 and HIV and potential impact of HSV-2 therapy

Mounting evidence indicates that genital HSV-2 infection may increase susceptibility to HIV infection and that co-infection may increase infectiousness. Accordingly, antiviral treatment of people with HSV-2 may mitigate the incidence of HIV in populations where both pathogens occur. To better understand the epidemiological synergy between HIV and HSV-2, we formulate a deterministic compartmental model that describes the transmission dynamics of these pathogens. Unlike earlier models, ours incorporates gender and heterogeneous mixing between activity groups. We derive explicit expressions for the reproduction numbers of HSV-2 and HIV, as well as the invasion reproduction numbers via next generation matrices. A qualitative analysis of the system includes the local and global behavior of the model. Simulations reinforce these analytical results and demonstrate epidemiological synergy between HSV-2 and HIV. In particular, numerical results show that HSV-2 favors the invasion of HIV, may dramatically increase the peak as well as reducing the time-to-peak of HIV prevalence, and almost certainly has exacerbated HIV epidemics. The potential population-level impact of HSV-2 on HIV is demonstrated by calculating the fraction of HIV infections attributable to HSV-2 and the difference between HIV prevalence in the presence and absence of HSV-2. The potential impact of treating people with HSV-2 on HIV control is demonstrated by comparing HIV prevalence with and without HSV-2 therapy. Most importantly, we illustrate that the aforementioned aspects of the population dynamics can be significantly influenced by the sexual structure of the population.     

Biochemical and physiological changes produced by Azotobacter chroococcum (INIFAT5 strain) on pineapple in vitro-plantlets during acclimatization

This study highlights some of the effects of the application of Azotobacter chroococcum (INIFAT5 strain) on in vitro-pineapple plantlets during acclimatization. The bacteria were sprayed immediately after transplanting to the ex vitro environment; the plants were then sprayed every 4 week. Subsequently (4 months) the evaluated variables included plantlet fresh and dry weights, leaf and root lengths, and composition of minerals, amino-acids, carbohydrates and proteins. Photosynthesis indicators were also evaluated. Significant effects of the application of Azotobacter over pineapple plantlets during acclimatization were observed in the mineral, amino-acid, carbohydrate and protein levels, as well as, in the photosynthesis indicators. Contrastingly, plant growth parameters showed modest increases caused by the bacteria, although they were statistically significant. Looking into specific minerals, the following significant effects of Azotobacter should be highlighted: increased levels of nitrogen, phosphorous, potassium, magnesium, copper and zinc. Moreover, contents of all amino-acids recorded showed significant increases in their levels in sprayed plantlets. Carbohydrates were also increased in leaves of plantlets bio-fertilized with the bacteria, mainly sucrose and fructose. Chlorophyll b levels were also significantly increased by Azotobacter. The biofertilizer did not modify levels of calcium, iron or manganese.     

Human talus bones from the Middle Pleistocene site of Sima de los Huesos (Sierra de Atapuerca,Burgos, Spain)

Here we present and describe comparatively 25 talus bones from the Middle Pleistocene site of the Sima de los Huesos (SH) (Sierra de Atapuerca, Burgos, Spain). These tali belong to 14 individuals (11 adult and three immature). Although variation among Middle and Late Pleistocene tali tends to be subtle, this study has identified unique morphological characteristics of the SH tali. They are vertically shorter than those of Late Pleistocene Homo sapiens, and show a shorter head and a broader lateral malleolar facet than all of the samples. Moreover, a few shared characters with Neanderthals are consistent with the hypothesis that the SH population and Neanderthals are sister groups. These shared characters are a broad lateral malleolar facet, a trochlear height intermediate between modern humans and Late Pleistocene H. sapiens, and a short middle calcaneal facet. It has been possible to propose sex assignment for the SH tali based on their size. Stature estimates based on these fossils give a mean stature of 174.4 cm for males and 161.9 cm for females, similar to that obtained based on the long bones from this same site.     

A class of pyrrole derivatives endowed with analgesic/anti-inflammatory activity

We report the synthesis and bio-pharmacological evaluation of a class of pyrrole derivatives featuring a small appendage fragment (carbaldehyde, oxime, nitrile) on the central core. Compound 1c proved to be extremely effective in vivo, showing an interesting anti-nociceptic profile that is comparable to reference compounds already marketed, hence representing a great stimulus for a further improvement of this class of molecules.     

Common and divergent functions of Beclin 1 and Beclin 2

In a recent paper published in Cell, He and colleagues reported the identification and functional characterization of Beclin 2, a mammal-specific homolog of the evolutionarily conserved autophagy-regulatory and oncosuppressive factor Beclin 1. In spite of a non-negligible degree of sequence identity, Beclin 1 and Beclin 2 differ from each other in multiple aspects, including their functional profile as well as the genomic organization of the respective loci.Originally identified as a BCL-2-interacting partner capable of protecting mice from viral encephalitis¹, Beclin 1 — the mammalian ortholog of yeast Atg6 — is nowadays well known as a core component of the class III phosphoinosite-3-kinase (PI3K) enzymatic complex that initiates the formation of autophagosomes in the course of macroautophagy (hereafter referred to as autophagy)². Presumably owing to the critical function of autophagy in embryonic development, mice lacking both copies of the Beclin 1-coding gene (Becn1) die early during embryogenesis. Moreover, Becn1^+/− mice suffer from a high incidence of spontaneous tumors, indicating that Beclin 1 acts as a haploinsufficient tumor suppressor³. At least in part, this reflects the central role that autophagy plays in the maintenance of intracellular homeostasis. Indeed, baseline levels of autophagy mediate the removal of various cytoplasmic entities that might favor oncogenesis, including damaged mitochondria and protein aggregates⁴. Conversely, established neoplasms often harness the cytoprotective functions of autophagy to their own benefit². The pathophysiological relevance of autophagy is not limited to cancer, but extends to a large panel of human diseases, including neurodegenerative, cardiovascular and infectious conditions⁵. Thus, during the last decade autophagy-regulatory signaling pathways have been intensively investigated.Until now, Beclin 1 was considered as the only Beclin encoded by the mammalian genome, sharing some degree of structural homology with so-called “BH3-only” proteins, pro-apoptotic members of the BCL-2 family that are involved in the activation of cell death in response to stress⁶. In a recent paper published in Cell, the research group led by Beth Levine⁷ identified a human and a mouse protein sharing 57% and 44% sequence identity with human and mouse Beclin 1, respectively, de facto unveiling the existence of an additional, mammal-specific ortholog of Atg6, Beclin 2. The mouse Beclin 2 mRNA was detected in multiple organs including the brain, skeletal muscle, placenta, thymus and uterus, as was the human protein in both fetal and adult brain tissues. These data demonstrate that the current classification of mouse and human Beclin 2-encoding genes (i.e., {"type":"entrez-nucleotide","attrs":{"text":"NG_022940","term_id":"298676453","term_text":"NG_022940"}}NG_022940 and {"type":"entrez-nucleotide","attrs":{"text":"NG_028451","term_id":"331028236","term_text":"NG_028451"}}NG_028451) as pseudogenes is incorrect.The knockdown of Beclin 2 reduced several manifestations of basal or starvation-induced autophagy in cultured mammalian cells, including the degradation of the autophagic substrate p62, the aggregation of a fluorescent form of LC3 into cytoplasmic dots and the lipidation of endogenous LC3. All such effects, which were not due to an increased autophagosomal turnover (as verified in the presence of the lysosomal inhibitor bafilomycin A1), could be rescued upon the transgene-driven expression of a non-interferable Beclin 2 variant. Thus, similar to Beclin 1, Beclin 2 regulates autophagy⁷. In fact, Beclin 2 turned out to physically interact with several (but not all) components of the class III PI3K complex organized around Beclin 1, including the catalytic subunit VPS34 as well as the regulatory factors ATG14, AMBRA1 and UVRAG, but not RUBICON (Figure 1A). Beclin 2 also appeared to share with Beclin 1 the ability to bind BCL-2, although only the latter gets dissociated from such an interaction in the course of stress-induced autophagy^7,8. As the greatest divergence between mammalian Beclins involves their N terminus, He and colleagues employed the N-terminal domain of Beclin 2 as a bait in a yeast two-hybrid screen, and identified G protein-coupled receptor (GPCR)-associated sorting protein 1 (GASP1) as a Beclin 2-specific interactor. Thus, similar to GASP1 (but not to Beclin 1), Beclin 2 was required for the agonist-induced lysosomal degradation of a subset of GPCRs including opioid receptor δ1 (DOR) and cannabinoid receptor 1 (CB1R). Importantly, such an activity, but not the capacity of Beclin 2 to regulate autophagic responses, appears to rely on the physical interaction between Beclin 2 and GASP1.Open in a separate windowFigure 1Common and divergent functions of mammalian Beclins. Specificity of the main interactors (A) and functions (B) ascribed to mammalian Beclin 1 and Beclin 2 to date. GPCR, G protein-coupled receptor; RTK, receptor tyrosine kinase.To obtain insights into the physiological functions of Beclin 2, He and colleagues attempted to generate Becn2^−/− mice, finding that these animals survived embryonic and early post-natal development at sub-Mendelian rates (approximately 4%). Not only Becn2^+/− and Becn2^−/− mouse embryonic fibroblasts, but also the brain of Becn2^+/− animals exhibited significant autophagic defects, corroborating the role of Beclin 2 in the regulation of autophagy in vivo. Moreover, these genotypes were associated with increased basal levels of multiple GPCRs, including CB1R and dopamine receptor D2 (DRD2)⁷. In line with the notion that increased CB1R signaling accrues food intake and hence favors obesity and insulin resistance, while pharmacological or genetic CB1R inhibition has opposite effects⁹, Becn2^+/− mice accumulated more weight than their wild-type littermates in response to a standard (as well as to a high-fat) diet. At odds with their Becn1^+/− counterparts, Becn2^+/− mice also exhibited impaired glucose tolerance and decreased insulin sensitivity, two effects that could be reverted by a chemical CB1R antagonist⁷. Taken together, these data demonstrate that besides regulating autophagy, Beclin 2 plays a unique role in glucose metabolism.Beclin 1 is known to regulate various processes other than autophagy, including vacuolar protein sorting and the degradation of specific growth factor receptors¹⁰. Thus, in spite of 44% - 57% sequence identity, the two mammalian Beclins described to date are relatively different from each other, exhibiting functional profiles that overlap to a limited degree (Figure 1B). Interestingly, He and colleagues have previously shown that defects in stimulus-induced autophagy (including those introduced by the Becn1^+/− genotype) are coupled to decreased endurance and altered glucose metabolism during acute exercise, as well as with an impaired capacity of training to protect mice against diet-induced glucose intolerance⁸. Part of these phenomena were shown to reflect defects in the AMP-activated protein kinase (AMPK)-dependent exposure of glucose transporters on the plasma membrane of skeletal muscle cells. It is therefore tempting to speculate that the metabolic phenotype of Becn2^+/− may in part originate from peripheral defects in glucose handling linked to autophagy. Thus, although the force driving the divergence of mammalian Beclins remains to be elucidated, it may reflect the need for an integrated regulation of central and peripheral mechanisms of metabolic homeostasis. Further studies are required to address this hypothesis.     

Aloin enhances cisplatin antineoplastic activity in B16-F10 melanoma cells by transglutaminase-induced differentiation

Aloin, a natural anthracycline from aloe plant, is a hydroxyanthraquinone derivative shown to have antitumor properties. This study demonstrated that aloin exerted inhibition of cell proliferation, adhesion and invasion abilities of B16-F10 melanoma cells under non-cytotoxic concentrations. Furthermore, aloin induced melanoma cell differentiation through the enhancement of melanogenesis and transglutaminase activity. To improve the growth-inhibiting effect of anticancer agents, we found that the combined treatment of cells with aloin and low doses of cisplatin increases the antiproliferative activity of aloin. The results suggest that aloin possesses antineoplastic and antimetastatic properties, exerted likely through the induction of melanoma cell differentiation.     

Amylolytic activity and carbohydrate levels in relation to coleoptile anoxic elongation in Oryza sativa genotypes

Among starchy seeds, rice has the unique capacity to germinate successfully under complete anaerobiosis. In this conditions, starch degradation is supported by a complete set of starch-degrading enzymes that are absent or inactive in cereals except rice. A characterization of carbohydrate metabolism and starch-degrading enzyme activity across twenty-nine genotypes of Oryza sativa L. is presented here. The zymogram of amylolytic activities present in rice embryos and endosperms under anaerobic conditions seven days after sowing (DAS) revealed marked differences among cultivars. Coleoptile elongation was positively correlated with total amylolytic activities and α-amylase activity in embryos, and negatively correlated with α-amylase activity in endosperm. Moreover, carbohydrate content in embryos was found to be positively correlated with total amylolytic activities under anaerobic conditions, while a negative relationship was recorded in the endosperm. Carbohydrate status in rice seedlings has a primary importance in sustaining coleoptile elongation towards the surface. The relationship between carbohydrate level in embryo and anoxic germination, as well as with total amylolytic activities present in rice embryo under anaerobic condition 7 DAS, is consistent with the role of sugar metabolism to support rice germination under oxygen-deprived environment.     

CDC25B Overexpression Stabilises Centrin 2 and Promotes the Formation of Excess Centriolar Foci

CDK-cyclin complexes regulate centriole duplication and microtubule nucleation at specific cell cycle stages, although their exact roles in these processes remain unclear. As the activities of CDK-cyclins are themselves positively regulated by CDC25 phosphatases, we investigated the role of centrosomal CDC25B during interphase. We report that overexpression of CDC25B, as is commonly found in human cancer, results in a significant increase in centrin 2 at the centrosomes of interphase cells. Conversely, CDC25B depletion causes a loss of centrin 2 from the centrosome, which can be rescued by treatment with the proteasome inhibitor MG132. CDC25B overexpression also promotes the formation of excess centrin 2 “foci”. These foci can accumulate other centrosome proteins, including γ-tubulin and PCM-1, and can function as microtubule organising centres, indicating that these represent functional centrosomes. Formation of centrin 2 foci can be blocked by specific inhibition of CDK2 but not CDK1. CDK2-mediated phosphorylation of Monopolar spindle 1 (Mps1) at the G1/S transition is essential for the initiation of centrosome duplication, and Mps1 is reported to phosphorylate centrin 2. Overexpression of wild-type or non-degradable Mps1 exacerbated the formation of excess centrin 2 foci induced by CDC25B overexpression, while kinase-dead Mps1 has a protective effect. Together, our data suggest that CDC25B, through activation of a centrosomal pool of CDK2, stabilises the local pool of Mps1 which in turn regulates the level of centrin 2 at the centrosome. Overexpression of CDC25B may therefore contribute to tumourigenesis by perturbing the natural turnover of centrosome proteins such as Mps1 and centrin 2, thus resulting in the de novo assembly of extra-numerary centrosomes and potentiating chromosome instability.