Short-term effects of thyroid hormones during development: Focus on signal transduction

Extranuclear or nongenomic effects of thyroid hormones are mediated by receptors located at the plasma membrane or inside cells, and are independent of protein synthesis. Recently the αVβ3 integrin was identified as a cell membrane receptor for thyroid hormones, and a wide variety of nongenomic effects have now been shown to be induced through binding of thyroid hormones to this receptor. However, also other thyroid hormone receptors can produce nongenomic effects, including the cytoplasmic TRα and TRβ receptors and probably also a G protein-coupled membrane receptor, and increasing importance is now given to thyroid hormone metabolites like 3,5-diiodothyronine and reverse T₃ that can mimick some nongenomic effects of T₃ and T₄. Signal transduction from the αVβ3 integrin may proceed through at least three independent pathways (protein kinase C, Src or mitogen-activated kinases) but the details are still unknown. Thyroid hormones induce nongenomic effects on at least three important Na⁺-dependent transport systems, the Na⁺/K⁺-ATPase, the Na⁺/H⁺ exchanger, and amino acid transport System A, leading to a mitogenic response in embryo cells; but modulation of the same transport systems may have different roles in other cells and at different developmental stages. It seems that thyroid hormones in many cases can modulate nongenomically the same targets affected by the nuclear receptors through long-term mechanisms. Recent results on nongenomic effects confirm the old theory that the primary role of thyroid hormones is to keep the steady-state level of functioning of the cell, but more and more mechanisms are discovered by which this goal can be achieved.     

Branched-chain amino acid supplementation promotes survival and supports cardiac and skeletal muscle mitochondrial biogenesis in middle-aged mice

Recent evidence points to a strong relationship between increased mitochondrial biogenesis and increased survival in eukaryotes. Branched-chain amino acids (BCAAs) have been shown to extend chronological life span in yeast. However, the role of these amino acids in mitochondrial biogenesis and longevity in mammals is unknown. Here, we show that a BCAA-enriched mixture (BCAAem) increased the average life span of mice. BCAAem supplementation increased mitochondrial biogenesis and sirtuin 1 expression in primary cardiac and skeletal myocytes and in cardiac and skeletal muscle, but not in adipose tissue and liver of middle-aged mice, and this was accompanied by enhanced physical endurance. Moreover, the reactive oxygen species (ROS) defense system genes were upregulated, and ROS production was reduced by BCAAem supplementation. All of the BCAAem-mediated effects were strongly attenuated in endothelial nitric oxide synthase null mutant mice. These data reveal an important antiaging role of BCAAs mediated by mitochondrial biogenesis in mammals.     

Comparison of selective procedures for isolation and enumeration of Legionella species from hot water systems

E. LEONI AND P.P. LEGNANI. 2001 . Various sample pre-treatment techniques and different growth media for the isolation of Legionellae from hot water supplies in public buildings were compared. A total of 102 hot water samples from taps and showers was examined. The highest recovery frequency was obtained with the heat pre-treatment method and using the selective medium GVPC. However, the results differed according to the concentration of legionellas. In the case of low plate counts (≤5000 cfu l⁻¹), the heat pre-treatment technique gave a significantly higher percentage of positive samples compared with other techniques ( P  < 0·05). With increasing concentration, the differences between the procedures decreased until they became statistically not significant for concentrations above 50 000 cfu l⁻¹. The direct inoculum method allowed a significantly higher detection of concentrations ( P  < 0·001) compared with heat and acid decontamination methods, which brought about a 67–68% reduction in detectable Legionellae. Heat decontamination techniques show greater sensitivity and specificity. However, they underestimate the number of legionellas. In environmental surveillance programmes, this underestimate must be taken into consideration when assessing the health risk.     

Effect of vitrification solutions and cooling upon in vitro matured prepubertal ovine oocytes

The vitrification procedure effects on molecular and cytoskeletal components and on developmental ability of in vitro matured prepubertal ovine oocytes were evaluated. MII oocytes were divided into three groups: (1) vitrified in cryoloops (VTR); (2) exposed to vitrification solutions and rehydrated without being plunged into liquid nitrogen (EXP); (3) without further treatment as a control (CTR). Two hours after treatment, membrane integrity, assessed by propidium iodide/Hoechst staining, was lower in VTR and EXP than in CTR (70.6%, 88.5% and 95.2%, respectively). Cleavage rate after fertilization was statistically different among all groups (21.4%, 45.4% and 82.8% for VTR, EXP and CTR groups respectively; P<0.01). Blastocyst rate in VTR (0.0%) and EXP (2.8%) groups was lower (P<0.01) than in CTR (22.8%). Maturation promoting factor activity was lower (P<0.01) in VTR and EXP groups compared with CTR at both 0 h (82.2%, 83.6% and 100%, respectively) and 2 h (60% and 53.9% and 100%, respectively) after warming. Immediately after warming VTR and EXP oocytes showed a lower rate of normal spindle and chromosome configuration compared to CTR (59.1%, 48.0% and 83.3%, respectively; P<0.01). After 2 h of culture in standard conditions the percentage of oocytes with normal spindle and chromosome organization decreased in both VTR and EXP groups compared to CTR (36.4%, 42.8% versus 87.5%, respectively). In conclusion the exposition to the tested cryoprotectant solution and the vitrification in cryoloops modified cytoskeletal components and alter biochemical pathways that compromise the developmental capacity of prepubertal in vitro matured ovine oocytes.     

Dissecting drug and vehicle metabolic effects in rats by a metabonomic approach

A combined application of high resolution (1)H NMR spectroscopy and multivariate statistical techniques focused on establishing a consistent statistical approach to metabonomic studies was tested. The data reduction, which is preliminary to the application of multivariate analysis to NMR spectra, was carried out by means of two complementary methods: pure Pattern Recognition (PR) and Assigned Signal Analysis (ASA). The simultaneous use of both approaches allowed us to obtain additional information in the analysis of metabonomic data, compared to the use of PR alone. This additional information consists in the possibility of a biochemical interpretation of the effects induced by treatment with xenobiotics, such as drugs or drug vehicles, on the metabolic networks of the systems under investigation. This approach allowed us to ascertain that a single-dose treatment with ST1959 vehicled by Sesame oil affects the production of hepatic glucose associated to an increment of the amino acid ketogenic process.     

Species boundaries and phylogeography of the "Euscorpius carpathicus complex" (Scorpiones: Euscorpiidae) in Italy

Euscorpius tergestinus (C.L. Koch, 1837), Euscorpius concinnus (C.L. Koch, 1837) and Euscorpius sicanus (C.L. Koch, 1837), three presumed closely related species belonging to the "carpathicus group", occur in the Italian peninsula with a largely parapatric distribution and some zones of range overlap. These areas of sympatry represent interesting opportunities to investigate species boundaries in natural populations. Here we report on a study exploring genetic variation in sympatric populations of the three species from central Tuscany. Additional collecting sites, from different localities across Italy, were also included in the analysis in order to explore the phylogeographic structure of the group. Species boundaries and evolutionary relationships were examined by sequence comparison of mitochondrial 16S rRNA and nuclear ITS-1 rRNA gene fragments. DNA sequence data show no evidence of genetic introgression between different evolutionary lineages from the area of range overlap, suggesting the absence of either past or ongoing inter-specific gene flow. It is therefore probable that reproductive barriers exist, preventing gene pools from amalgamating. Furthermore, our results support the recent morphological distinction of E. tergestinus, as traditionally classified, into two different species: E. tergestinus and E. concinnus. Both mitochondrial and nuclear sequence data clearly indicate that the two taxa represent well-supported and deeply divergent lineages. Euscorpius sicanus seems to represent a monophyletic taxon, but the high genetic variability observed within this taxon calls for future investigation. The present distribution patterns across the Italian peninsula were mainly interpreted as the consequence of climatic oscillations.     

Inferring species decline from collection records: roller dung beetles in Italy (Coleoptera, Scarabaeidae)

The decline of roller dung beetles (Coleoptera, Scarabaeidae) in Italy, at national and regional level, was described using a database of both literature and unpublished data, since the late of 19th century. The probability of finding roller species was assessed for each decade of the 20th century in order to detect changes in their distribution and status. An analysis of decline was performed using a complementary approach of different extinction indexes, according to IUCN criteria. During the 20th century, both the absolute number of records and the UTM cells where roller beetles were found increased clearly as a consequence of the escalation of entomological surveys. Nevertheless, comparing R species (rollers) with all the scarab dung beetles from the first to the last quarter of the 20th century, the relative frequency of roller records decreased by 31%, while the relative number of occupied UTM cells dropped by 23%. Six roller species showed a significant decline in Italy from the first to the second part of the 20th century, and nine in the last 30years. Other two species disappeared from the majority of the northern regions. Finally, the values of all the extinction indexes were strongly correlated and detected a high risk of extinction in Italy for six species. A gradual change in land use during the last three decades, consisting of a reduced extension of grasslands in favour of either intensive agriculture or reforestation after abandonment of livestock raising, was likely the main factor inducing decline and local extinction of roller species.     

Recreational angling and spearfishing on social media: insights on harvesting patterns,social engagement and sentiments related to the distributional range shift of a marine invasive species

Reviews in Fish Biology and Fisheries - Fisheries are among the human activities that are most strongly affected by ongoing climate-related changes in the presence and abundance of fish species...