Natural hybridization in eastern-Mediterranean firs: The case of Abies borisii-regis

The genus Abies is represented in southern Balkans by A. alba, A. cephalonica, and A. borisii-regis. To infer the status of southern-Balkans firs, as well as the extent and patterns of introgression within this taxonomical complex, we analyzed genetic variation patterns of 29 indigenous fir populations in Bulgaria, Macedonia, Greece, and Calabria using a combination of maternally and biparentally inherited markers. Three mitochondrial lineages were observed, one comprising Calabrian populations and two distributed in the Balkans, coinciding with A. alba and A. cephalonica. The boundary between lineages is sharp; only two populations containing a mixture of haplotypes were found. Bayesian analysis of population structure based on seven nuclear microsatellite (nSSR) loci revealed the existence of two clusters whose proportions exhibited a latitudinal cline with a width of 2.3° ( ≈ 255 km). Populations in the center of the latitudinal cline exhibit the most symmetrical, the flattest, and the broadest distributions of cluster proportions within individual tree genomes. A neighbor-net network reflects the cline resulting from the Bayesian analysis. The observed variation patterns are not consistent with the hypothesis of A. borisii-regis as a monophyletic taxon or a stabilized hybridogenous species resulted from ancient hybridization; the taxon rather is a product of recent introgression.     

Elastoid Changes in the Gingiva of Aged Humans

Elastotic changes were demonstrable in the gingivae of both dentulous and edentulous jaws obtained from both male and female humans varying in age from 62–92 years. Sections of gingivae from all the aged individuals exhibited numerable thick fibers that stained positive with iron hematoxylin or orcein. These positive staining fibers were found in the lamina propria radiating into the connective tissue papillae, coursing throughout the zona reticularis, as well as appearing as black amorphous masses. Pretreatment of sections with acid hydrolysis before staining by the two elastic tissue stains led to a loss of stainable fibers for elastin. In contrast the gingivae of a young adult did not contain elastic positive fibers as seen in the aged gingivae. The thick elastotic fibers found in the aged gingivae were argyrophilic in nature when the sections were impregnated with silver nitrate indicating that they were collagenous in nature. It is felt that the elastoid-like fibers in aging gingiva are another phase in the altering of collagen during the aging process.     

Conformation and orientation of chlorophyll-proteins in photosystem I by circular dichroism and polarized infrared spectroscopies

The protein conformation and orientation of Photosystem I (PS I) particles have been investigated by a combination of ultraviolet circular dichroism and polarized infrared spectroscopies. These PS I particles have been studied before and after reconstitution in phosphatidylcholine vesicles. The native state of the pigments of PS I was characterized by monitoring the low-temperature fluorescence emission spectra as well as the visible CD and linear dichroism spectra at room temperature. Computed analysis of the ultraviolet CD spectra of PS I complex indicates that the secondary structure of the protein is largely α-helical (52 ± 4%) with a very low amount of β-structure. Polarized infrared difference spectra of oriented PS I show a significant orientation of these α-helical segments with the α-helix axes tilted on the average at approx. 35° from the membrane normal.     

Lignin peroxidase production by strains of Phanerochaete chrysosporium grown on glycerol

Summary Lignin peroxidase production by several strains of Phanerochaete chrysosporium was determined during growth on glycerol under conditions of nitrogen sufficiency. Fungal strains which grew poorest on glycerol produced the highest titres of lignin peroxidase whereas enzyme levels were much lower when marginally greater biomass values were recorded. In the case of P. chrysosporium strain INA-12, the nature of the nitrogen source had a pronounced effect on both growth and enzyme production. Highest biomass values were obtained when l-glutamate or l-glutamine served as the major nitrogen source but enzyme synthesis was normally repressed completely. Lignin peroxidase activity in this strain was maximal when the initial pH of the culture medium was adjusted to pH 5.0.     

Leptin modulates dose‐dependently the metabolic and cytolytic activities of NK‐92 cells

Leptin, a hormone‐cytokine produced primarily in the adipose tissue, has pleiotropic effects on many biological systems and in several cell types, including immune cells. Hyperleptinemia is associated with immune dysfunction and carcinogenesis. Natural killer (NK) cells are critical mediators of anti‐tumor immunity, and leptin receptor deficiency in mice leads to impaired NK function. It was thus decided to explore the in vitro effects of leptin on human NK cell function. NK‐92 cells were cultured during 48 h with different leptin concentrations [absence, 10 (physiological), 100 (obesity), or 200 ng/ml (pharmacology)]. Their metabolic activity was assessed using the resazurin test. NK‐92 cell cytotoxicity and intracellular IFN‐γ production were analyzed by flow cytometry. NK‐92 cell mRNA and protein expression levels of cytotoxic effectors were determined by RT‐qPCR and Western blot. In our conditions, leptin exerted a dose‐dependent stimulatory effect on NK‐92 cell metabolic activity. In addition, high leptin concentrations enhanced NK‐92 cell cytotoxicity against K562‐EGFP and MDA‐MB‐231‐EGFP target cells and inversely reduced cytotoxicity against the MCF‐7‐EGFP target. At 100 ng/ml, leptin up‐regulated both NK cell granzyme B and TRAIL protein expressions and concomitantly down‐regulated perforin expression without affecting Fas‐L expression. In response to PMA/ionomycin stimulation, the proportion of IFN‐γ expressing NK‐92 cells increased with 100 and 200 ng/ml of leptin. In conclusion, leptin concentration, at obesity level, variably increased NK‐92 cell metabolic activity and modulated NK cell cytotoxicity according to the target cells. The underlying mechanisms are partly due to an up‐regulation of TRAIL and IFN‐γ expression and a down‐regulation of perforin. J. Cell. Physiol. 228: 1202–1209, 2013. © 2012 Wiley Periodicals, Inc.     

S6 kinase deletion suppresses muscle growth adaptations to nutrient availability by activating AMP kinase

S6 kinase (S6K) deletion in metazoans causes small cell size, insulin hypersensitivity, and metabolic adaptations; however, the underlying molecular mechanisms are unclear. Here we show that S6K-deficient skeletal muscle cells have increased AMP and inorganic phosphate levels relative to ATP and phosphocreatine, causing AMP-activated protein kinase (AMPK) upregulation. Energy stress and muscle cell atrophy are specifically triggered by the S6K1 deletion, independent of S6K2 activity. Two known AMPK-dependent functions, mitochondrial biogenesis and fatty acid β-oxidation, are upregulated in S6K-deficient muscle cells, leading to a sharp depletion of lipid content, while glycogen stores are spared. Strikingly, AMPK inhibition in S6K-deficient cells restores cell growth and sensitivity to nutrient signals. These data indicate that S6K1 controls the energy state of the cell and the AMPK-dependent metabolic program, providing a mechanism for cell mass accumulation under high-calorie diet.     

Hyal-1 but not Hyal-3 deficiency has an impact on ovarian folliculogenesis and female fertility by altering the follistatin/activin/Smad3 pathway and the apoptotic process

Ovarian follicle development is a process regulated by various endocrine, paracrine and autocrine factors that act coordinately to promote follicle growth. However, the vast majority of follicles does not reach the pre-ovulatory stage but instead, undergo atresia by apoptosis. We have recently described a role for the somatic hyaluronidases (Hyal-1, Hyal-2, and Hyal-3) in ovarian follicular atresia and induction of granulosa cell apoptosis. Herein, we show that Hyal-1 but not Hyal-3 null mice have decreased apoptotic granulosa cells after the induction of atresia and an increased number of retrieved oocytes after stimulation of ovulation. Furthermore, young Hyal-1 null mice had a significantly higher number of primordial follicles than age matched wild-type animals. Recruitment of these follicles at puberty resulted in an increased number of primary and healthy preantral follicles in Hyal-1 null mice. Consequently, older Hyal-1 deficient female mice have prolonged fertility. At the molecular level, immature Hyal-1 null mice have decreased mRNA expression of follistatin and higher levels of phospho-Smad3 protein, resulting in increased levels of phospho-Akt in pubertal mice. Hyal-1 null ovarian follicles did not exhibit hyaluronan accumulation. For Hyal-3 null mice, compensation by Hyal-1 or Hyal-2 might be related to the lack of an ovarian phenotype. In conclusion, our results demonstrate that Hyal-1 plays a key role in the early phases of folliculogenesis by negatively regulating ovarian follicle growth and survival. Our findings add Hyal-1 as an ovarian regulator factor for follicle development, showing for the first time an interrelationship between this enzyme and the follistatin/activin/Smad3 pathway.