Study of the differential transcription in liver of growth hormone receptor (GHR), insulin-like growth factors (IGF1, IGF2) and insulin-like growth factor receptor (IGF1R) genes at different postnatal developmental ages in pig breeds

The objective of this study was to determine hepatic expression levels of GHR, IGF1R, IGF1 and IGF2 genes in young growing gilts at different developmental ages (60–210 days) in five pig breeds: Polish Large White (PLW), Polish Landrace (PL), Pulawska (Pul), Duroc (Dur) and Pietrain (Pie). We studied the differences among pig breeds as well as within each breed for pigs in different developmental ages. Obtained results revealed major differences among breeds in hepatic gene expression of porcine GHR, IGF1R, IGF1 and IGF2 genes in different developmental ages. The differences among breeds of GHR expression were significantly higher in PLW, PL at the age of 60, 90, 120 days as compared to Pul, Dur and Pie. In turn, the highest level of IGF1R expression was observed in PL at age of 150, 180 and 210 days, whereas in case of IGF1 the highest level was recorded in Pie gilts at the age of 60 and 90 days. Moreover trait associated study revealed highly significant correlations between hepatic expressions of IGF1R and IGF2 genes and carcass composition traits (P < 0.01) The results of study suggest that porcine GHR, IGF1R, IGF1 and IGF2 genes may be potential candidate genes for postnatal growth and carcass composition traits. Therefore, the implementation of the hepatic expression of GH/IGF genes into the pig breeding and gene assisted selection program in different pig breeds should be considered. However, further population wide study is needed to clarify the hepatic expression association with economic traits, such as body growth, meat quality and carcass composition traits.     

Genes in the insulin and insulin-like growth factor pathway and odds of metachronous colorectal neoplasia

Insulin and insulin-like growth factor (IGF) genes are implicated in colorectal carcinogenesis. Gene-by-gene interactions that influence the insulin/IGF pathways were hypothesized as modifiers of colorectal neoplasia risk. We built a classification tree to detect interactions in 18 IGF and insulin pathway-related genes and metachronous colorectal neoplasia among 1,439 subjects pooled from two chemoprevention trials. The probability of colorectal neoplasia was greatest (71.8%) among carriers of any A allele for rs7166348 (IGF1R) and AA genotype for rs1823023 (PIK3R1). In contrast, carriers of any A at rs7166348 (IGF1R), any G for the PIK3R1 variant, and AA for rs10426094 (INSR) had the lowest probability (14.3%). Logistic regression modeling showed that any A at rs7166348 (IGF1R) with the AA genotype at rs1823023 (PIK3R1) conferred the highest odds of colorectal neoplasia (OR 3.7; 95% CI 2.2–6.5), compared with carriage of GG at rs7166348 (IGF1R). Conversely, any A at rs7166348 (IGFR1), any G allele at rs1823023 (PIK3R1), and the AA genotype at rs10426094 (INSR) conferred the lowest odds (OR 0.22; 95% CI 0.07–0.66). Stratifying the analysis by parent study and intervention arm showed highly consistent trends in direction and magnitude of associations, with preliminary evidence of genotype effects on measured IGF-1 levels in a subgroup of subjects. These results were compared to those from multifactor dimensionality reduction, which identified different single nucleotide polymorphisms in the same genes (INSR and IGF1R) as effect modifiers for colorectal neoplasia. These results support a role for genetic interactions in the insulin/IGF pathway genes in colorectal neoplasia risk.     

Modulation of extracellular matrix genes reflects the magnitude of physiological adaptation to aerobic exercise training in humans

Background  

Regular exercise reduces cardiovascular and metabolic disease partly through improved aerobic fitness. The determinants of exercise-induced gains in aerobic fitness in humans are not known. We have demonstrated that over 500 genes are activated in response to endurance-exercise training, including modulation of muscle extracellular matrix (ECM) genes. Real-time quantitative PCR, which is essential for the characterization of lower abundance genes, was used to examine 15 ECM genes potentially relevant for endurance-exercise adaptation. Twenty-four sedentary male subjects undertook six weeks of high-intensity aerobic cycle training with muscle biopsies being obtained both before and 24 h after training. Subjects were ranked based on improvement in aerobic fitness, and two cohorts were formed (n = 8 per group): the high-responder group (HRG; peak rate of oxygen consumption increased by +0.71 ± 0.1 L min^-1; p < 0.0001) while the low-responder group (LRG; peak rate of oxygen consumption did not change, +0.17 ± 0.1 L min^-1, ns). ECM genes profiled included the angiopoietin 1 and related genes (angiopoietin 2, tyrosine kinase with immunoglobulin-like and EGF-like domains 1 (TIE1) and 2 (TIE2), vascular endothelial growth factor (VEGF) and related receptors (VEGF receptor 1, VEGF receptor 2 and neuropilin-1), thrombospondin-4, α2-macroglobulin and transforming growth factor β2.     

The IGF1 pathway genes and their association with age of puberty in cattle

Insulin‐like growth factor I (somatomedin C) (IGF1) influences gonadotrophin‐releasing hormone (GnRH) neurons during puberty, and GnRH release guides pubertal development. Therefore, genes of the IGF1 pathway are biological candidates for the identification of single‐nucleotide polymorphisms (SNPs) affecting age of puberty. In a genome‐wide association study, genotyped heifers were Tropical Composite (TCOMP, n = 866) or Brahman (BRAH, n = 843), with observation of age at first corpus luteum defining puberty. We examined SNPs in or near genes of the IGF1 pathway and report seven genes associated with age at puberty in cattle: IGF1R, IGFBP2, IGFBP4, PERK (HUGO symbol EIF2AK3), PIK3R1, GSK3B and IRS1. SNPs in the IGF1 receptor (IGF1R) showed the most promising associations: two SNPs were associated with puberty in TCOMP (P < 0.05) and one in BRAH (P = 0.00009). This last SNP explained 2% of the genetic variation (R² = 2.04%) for age of puberty in BRAH. Hence, IGF1R was examined further. Additional SNPs were genotyped, and haplotypes were analysed. To test more SNPs in this gene, four new SNPs from dbSNP were selected and genotyped. Single SNP and haploytpe analysis revealed associations with age of puberty in both breeds. There were two haplotypes of 12 IGF1R SNPs associated with puberty in BRAH (P < 0.05) and one in TCOMP (P < 0.05). One haplotype of two SNPs was associated (P < 0.01) with puberty in BRAH, but not in TCOMP. In conclusion, the IGF1 pathway appeared more relevant for age of puberty in Brahman cattle, and IGF1R showed higher significance when compared with other genes from the pathway.     

InDels within caprine IGF2BP1 intron 2 and the 3′-untranslated regions are associated with goat growth traits

Insulin-like growth factor 2 mRNA binding protein 1 (IGF2BP1) is involved in the Hedgehog pathway and has been shown to regulate the RNA stability of several growth-related target genes. It is located in a quantitative trait locus showing a strong association with traits related to body size in ducks. Fibroblast growth factor receptor 1 (FGFR1) also participates in Hedgehog signaling pathways and has been reported to be associated with organic growth and development. FGFR1-knockout mice have been shown to have severe postnatal growth defects, including an approximately 50% reduction in body weight and bone mass. Meanwhile, nonsense-mediated mRNA decay factor (SMG6) can maintain genomic stability, which is associated with organic growth and development. Therefore, we hypothesized that IGF2BP1, FGFR1 and SMG6 genes may play important roles in the growth traits of goats. In this study, the existence of two insertion/deletion (InDel) variants within IGF2BP1, one InDel within FGFR1 and two InDels within SMG6 was verified and their correlation with growth traits was analyzed in 2429 female Shaanbei white cashmere goats. Results showed both the 15 bp InDel in intron 2 and the 5 bp InDel in the 3′ regulatory region within IGF2BP1 were significantly associated with growth traits (P < 0.05) and goats with the combinatorial homozygous insertion genotypes of these two loci had the highest body weight (P = 0.046). The other InDels within FGFR1 and SMG6 were not obviously associated with growth traits (P > 0.05). Therefore, the two InDels in IGF2BP1 were vital mutations affecting goat growth traits.     

Common genetic variation in eight genes of the <Emphasis Type="Italic">GH</Emphasis>/<Emphasis Type="Italic">IGF1</Emphasis> axis does not contribute to adult height variation

Stature (adult height) is one of the most heritable human traits, yet few genes, if any, have been convincingly associated with adult height variation in the general population. Here, we selected 150 tag SNPs from eight candidate genes in the growth hormone (GH)/insulin-like growth factor-1 (IGF1) axis (GHR, GHRH, GHRHR, IGF1, IGFALS, IGFBP3, JAK2, STAT5B), and genotyped them in ∼2,200 individuals ascertained for short or tall stature. Nominally significant tag SNPs were then tested in three additional replication cohorts, including a family-based panel to rule out spurious associations owing to population stratification. Across the four height cohorts (N = 6,075 individuals), we did not observe any consistent associations between stature and common variants (≥5% minor allele frequency) in these eight genes, including a common deletion of the growth hormone receptor gene exon 3. Tests of epistatic interactions between these genes did not yield any results beyond those expected by chance. Although we have not tested all genes in the GH/IGF1 axis, our results indicate that common variation in these GH/IGF1 axis genes is not a major determinant of stature, and suggest that if common variation contributes to adult height variation in the general population, the variants are in other, possibly unanticipated genes. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Relation between phylogenetic position, lipid metabolism and butyrate production by different Butyrivibrio-like bacteria from the rumen

The Butyrivibrio group comprises Butyrivibrio fibrisolvens and related Gram-positive bacteria isolated mainly from the rumen of cattle and sheep. The aim of this study was to investigate phenotypic characteristics that discriminate between different phylotypes. The phylogenetic position, derived from 16S rDNA sequence data, of 45 isolates from different species and different countries was compared with their fermentation products, mechanism of butyrate formation, lipid metabolism and sensitivity to growth inhibition by linoleic acid (LA). Three clear sub-groups were evident, both phylogenetically and metabolically. Group VA1 typified most Butyrivibrio and Pseudobutyrivibrio isolates, while Groups VA2 and SA comprised Butyrivibrio hungatei and Clostridium proteoclasticum, respectively. All produced butyrate but strains of group VA1 had a butyrate kinase activity <40 U (mg protein)⁻¹, while strains in groups VA2 and SA all exhibited activities >600 U (mg protein)⁻¹. The butyrate kinase gene was present in all VA2 and SA bacteria tested but not in strains of group VA1, all of which were positive for the butyryl-CoA CoA-transferase gene. None of the bacteria tested possessed both genes. Lipase activity, measured by tributyrin hydrolysis, was high in group VA2 and SA strains and low in Group VA1 strains. Only the SA group formed stearic acid from LA. Linoleate isomerase activity, on the other hand, did not correspond with phylogenetic position. Group VA1 bacteria all grew in the presence of 200 μg LA ml⁻¹, while members of Groups VA2 and SA were inhibited by lower concentrations, some as low as 5 μg ml⁻¹. This information provides strong links between phenotypic and phylogenetic properties of this group of clostridial cluster XIVa Gram-positive bacteria.     

Effect of rhizobia and rock biofertilizers with <Emphasis Type="Italic">Acidithiobacillus</Emphasis> on cowpea nodulation and nutrients uptake in a tableland soil

Chemical fertilizers have been used in the cultivation of plants due to their high solubility and effect on crops yield. Biofertilizers with phosphate rock (PR) and potash rock (KR) plus sulfur inoculated with Acidithiobacillus may improve plant growth and contribute to addition of available P and K in soil. The effectiveness of biofertilizers from phosphate and potash rocks mixed with sulfur and Acidithiobacillus was studied in a Typic Fragiuldult soil of the Brazilian Northeast Tableland. Cowpea (cv. “IPA 206”) was grown with and without rhizobia inoculation. Treatments were: (a) phosphate rock (1000 kg ha⁻¹); (b) Biofertilizers-B_P (250 and 500 kg ha⁻¹); (c) triple superphosphate-TSP (250 kg ha⁻¹); (d) potash rock (1000 kg ha⁻¹); (e) biofertilizer-B_K (250; 500 and 750 kg ha⁻¹); (f) potassium chloride-KCl (250 kg K₂0 ha⁻¹); (g) control without P or K fertilization (P₀K₀). The soil was maintained under water submersion covered with black plastic (solarization process) for a period of 30 days. Biofertilizers (B_p and B_K) and soluble fertilizers increased plant growth and NPK uptake. Biofertilizers reduced soil pH, especially when applied in highest rates. Biofertilizers and TSP+KCl showed the best values of available P and K in soil. Rhizobial inoculation was effective on cowpea, but no nodules were formed by bacteria native from the soil, probably due to the effect of the solarization process. From obtained PK biofertilizers could be used as alternative for cowpea fertilization in Tableland soils.     

Growth factor binding and bioactivity in human kidney epithelial cell cultures

Summary Insulinlike growth factors (IGF) and epidermal growth factor (EGF) are produced in renal tissue, as are specific receptors for these hormones. To evaluate the significance of these observations to regulation of renal tubular cell proliferation, we have examined the interaction of IGF and EGF with cultured human proximal tubular epithelial cells (HPT). HPT cells showed specific binding of IGF-1, insulin, and EGF. IGF-1 binding was inhibited by antibody to the type 1 IGF receptor (α-IR3). Insulin receptors and type 1 IGF receptors were identified by bifunctional cross-linking. IGF-1, insulin, and EGF stimulated [³H]thymidine incorporation by 77, 73, and 87%, respectively. Haft maximal stimulation by IGF-1, insulin, and EGF was produced with 4×10⁻⁹ M, 2.5×10⁻⁸ M, and 8×10⁻¹⁰ M concentrations of these hormones. α-IR3 inhibited stimulation of thymidine incorporation by IGF-1 and insulin but had no effect in EGF-stimulated thymidine incorporation. EGF and high concentrations of insulin both stimulated cell proliferation by 83 and 79%, respectively. These data are consistent with regulation of tubular epithelial proliferation by IGF-1, insulin, and EGF and suggest that the mitogenic activity of both insulin and IGF-1 is mediated by the type 1 IGF receptor. Supported by grants CA37887 and DK32889 from the National Institutes of Health, Bethesda, MD, and by a Medical University of South Carolina institutional grant.     

Palm oil mill effluent (POME) cultured marine microalgae as supplementary diet for rotifer culture

Malaysia is the world’s leading producer of palm oil products that contribute US$ 7.5 billion in export revenues. Like any other agro-based industries, it generates waste that could be utilized as a source of organic nutrients for microalgae culture. Present investigation delves upon Isochrysis sp. culture in POME modified medium and its utilization as a supplement to Nanochloropsis sp. in rotifer cultures. The culture conditions were optimized using a 1 L photobioreactor (Temp: 23°C, illumination: 180 ∼ 200 μmol photons m⁻²s⁻¹, n = 6) and scaled up to 10 L outdoor system (Temp: 26–29°C, illumination: 50 ∼ 180 μmol photons m⁻²s⁻¹, n = 3). Algal growth rate in photobioreactor (μ = 0.0363 h⁻¹) was 55% higher compared to outdoor culture (μ = 0.0163 h⁻¹), but biomass production was 1.3 times higher in outdoor culture (Outdoor = 91.7 mg m⁻²d⁻¹; Photobioreactor = 69 mg m⁻²d⁻¹). Outdoor culture produced 18% higher lipid; while total fatty acids (FA) was not significantly affected by the change in culture systems as both cultures yield almost similar concentrations of fatty acids per gram of sample (photobioreactor = 119.17 mg g⁻¹; outdoor culture = 104.50 mg g⁻¹); however, outdoor cultured Isochrysis sp. had 26% more polyunsaturated fatty acids (PUFAs). Rotifers cultured in Isochrysis sp./ Nanochloropsis sp. (1:1, v/v) mixture gave similar growth rate as 100% Nanochoropsis sp. culture (μ = 0.40 d⁻¹), but had 45% higher counts of rotifers with eggs (t = 7, maximum). The Isochrysis sp. culture successfully lowered the nitrate (46%) and orthophosphate (83%) during outdoor culture.     

Transformation of carotenoid biosynthetic genes using a micro-cross section method in kiwifruit (Actinidia deliciosa cv. Hayward)

Genetic transformation using a micro-cross section (MCS) technique was conducted to improve the carotenoid content in kiwifruit (Actinidia deliciosa cv. Hayward). The introduced carotenoid biosynthetic genes include geranylgeranyl diphosphate synthase (GGPS), phytoene desaturase (PDS), ζ-carotene desaturase (ZDS), β-carotene hydroxylase (CHX), and phytoene synthase (PSY). The transformed explants were selected on half-strength MS medium containing 0.001 mg l⁻¹ of 2,4-D and 0.1 mg l⁻¹ of zeatin, either 5 mg l⁻¹ hygromycin or 25 mg l⁻¹ kanamycin, and 500 mg l⁻¹ cefotaxime. The genomic PCR, genomic Southern blot analysis, and RT-PCR were performed to confirm the integration and expression of the transgenes. The transformation efficiencies of either kanamycin- or hygromycin-resistant shoots ranged from 2.9 to 22.1% depending on the target genes, and from 2.9 to 24.2% depending on the reporter genes. The selection efficiencies ranged from 66.7 to 100% for the target genes and from 95.8 to 100% for the reporter genes. Changes of carotenoid content in the several PCR-positive plants were determined by UPLC analysis. As a result, transgenic plants expressing either GGPS or PSY increased about 1.2- to 1.3-fold in lutein or β-carotene content compared to non-transgenic plants. Our results suggest that the Agrobacterium-mediated transformation efficiency of kiwifruit can be greatly increased by this MCS method and that the carotenoid biosynthetic pathway can be modified in kiwifruit by genetic transformation. Our results further suggest that GGPS and PSY genes could be major target genes to increase carotenoid contents in kiwifruit.     

Development of an STS map of an interspecific progeny of Malus

Simple sequence repeat (SSR) markers developed from Malus, as well as Prunus, Pyrus and Sorbus, and some other sequence-tagged site (STS) loci were analysed in an interspecific F₁ apple progeny from the cross ‘Fiesta’ × ‘Totem’ that segregated for several agronomic characters. A linkage map was constructed using 259 STS loci (247 SSRs, four SCARs and eight known-function genes) and five genes for agronomic traits—scab resistance (Vf), mildew resistance (Pl-2), columnar growth habit (Co), red tissues (Rt) and green flesh background colour (Gfc). Ninety SSR loci and three genes (ETR1, Rt and Gfc) were mapped for the first time in apple. The transferability of markers from other Maloideae to Malus was found to be around 44%. The loci are spread across 17 linkage groups, corresponding to the basic chromosome number of Malus and cover 1,208 cM, approximately 85% of the estimated length of the apple genome. Interestingly, we have extended the top of LG15 with eight markers covering 25 cM. The average map density is 4.7 cM per marker; however, marker density varies greatly between linkage groups, from 2.5 in LG14 to 8.9 in LG7, with some areas of the genome still in need of further STS markers for saturation. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. An erratum to this article can be found at     

Characterization of a human hepatoma cell line with acquired resistance to growth inhibition by transforming growth factor beta 1 (TGF-β1)

Summary A new cell line (Hep 3B-TR), which is resistant to growth-inhibition by transforming growth factor beta 1 (TGF-β1) up to 10 ng/ml (400 pM), was isolated from parental Hep 3B human hepatoma cells, which are sensitive to growth-inhibition by TGF-β1. In the presence of TGF-β1 (1 to 10 ng/ml), the growth of the parental cell line (Hep 3B-TS) was inhibited by more than 95%. Under the same conditions, the growth rate of the resistant clone (Hep 3B-TR) however, was identical in the presence or absence of TGF-β1 and was almost the same as that of the Hep 3B-TS cells in the absence of TGF-β1. Affinity crosslinking with 5 pM ¹²⁵I-labeled TGF-β1 showed that the TGF-β1 receptors type I (TGF-βRI) and type II (TGF-βRII) were not present on the cell surface of the Hep 3B-TR cells, whereas they were present on the sensitive HEP 3B-TS cells. Hep 3B-TS cells had detectable TGF-βRII mRNA, which was not found in Hep 3B-TR cells. RNA analysis showed different effects on the expression of TGF-β1, c-fos, c-myc, and protein disulfide isomerase (PDI) genes in the two cell lines in response to TGF-β1 protein. Addition of TGF-β1 (1 ng/ml) strongly increased the expression of TGF-β1 mRNA in Hep 3B-TS cells, but not in Hep 3B-TR cells. In Hep 3B-TS cells, c-fos mRNA was not detected either in the presence or absence of TGF-β1 protein. However, abundant c-fos mRNA was detected in Hep 3B-TR cells, which was not altered by TGF-β1 protein. TGF-β1 protein inhibited the expression of c-myc and PDI mRNAs in Hep 3B-TS cells, whereas although the c-myc and PDI mRNAs were much more abundant in Hep 3B-TR cells, their expression was not affected by TGF-β1 protein. These results suggest that the mechanisms of escape from growth-inhibition by TGF-β1 in Hep 3B-TR hepatoma cells probably involve loss of binding by TGF-β1 to its cell surface receptors.     

In vitro efficacy of <Emphasis Type="Italic">Hyptis suaveolens</Emphasis> L. (Poit.) essential oil on growth and morphogenesis of <Emphasis Type="Italic">Fusarium oxysporum</Emphasis> f.sp. <Emphasis Type="Italic">gladioli</Emphasis> (Massey) Snyder &; Hansen

Hyptis suaveolens L. (Poit.) essential oil was tested in vitro on the growth and morphogenesis of Fusarium oxysporum f.sp. gladioli (Massey) Snyder & Hansen, which causes Fusarium corm rot and yellows in various susceptible cultivars of gladiolus. The fungitoxicity of the oil was measured by percentage radial growth inhibition using the poisoned food technique (PF) and volatile activity assay (VA). The mycelial growth of the test fungus was completely inhibited at 0.998 and 0.748 μg ml⁻¹ concentration of oil in PF and VA, respectively. Essential oil was found to be fungicidal in nature at 1.247 and 0.998 μg ml⁻¹ concentration of oil in PF and VA, respectively. Determination of conidial germination in the presence of oil was also carried out and it was found that the oil exhibited 100% inhibition of conidial germination at 0.450 μg ml⁻¹ concentration. The effect of essential oil on the yield of mycelial weight was observed and it was found that at 0.873 μg ml⁻¹ concentration no mycelium was recorded and 100% inhibition was observed. The fungitoxicity of oil did not change even on exposure to 100°C temperature or to autoclaving, and the oil also retained its fungicidal nature even after storage of 24 months. The main changes observed under light microscopy after oil treatment were a decrease and loss of conidiation and anomalies in the hyphae such as a decrease in the diameter of hyphae and granulation of cytoplasm. The treatment of the oil also showed highly reduced cytoplasm in the hyphae, showing clear retraction of the cytoplasm from the hyphae and ultimately in some areas hyphae without cytoplasm were also found. GC-MS studies of the essential oil revealed that the oil consisted of 24 compounds with 1,8-cineole as major component accounting for 44.4% of the total constituents.     

Biofiltering efficiency, uptake and assimilation rates of Ulva clathrata (Roth) J. Agardh (Clorophyceae) cultivated in shrimp aquaculture waste water

The growth, biofiltering efficiency and uptake rates of Ulva clathrata were studied in a series of outdoor tanks, receiving waste water directly from a shrimp (Litopenaeus vannamei) aquaculture pond, under constant aeration and two different water regimes: (1) continuous flow, with 1 volume exchange a day (VE day^-1) and (2) static regime, with 1 VE after 4 days. Water temperature, salinity, pH, dissolved inorganic nitrogen (DIN), phosphate (PO₄), chlorophyll-a (chl-a), total suspended solids (TSS), macroalgal biomass (fresh weight) and tissue nutrient assimilation were monitored over 12 days. Ulva clathrata was highly efficient in removing the main inorganic nutrients from effluent water, stripping 70–82% of the total ammonium nitrogen (TAN) and 50% PO₄ within 15 h. Reductions in control tanks were much lower (Tukey HSD, P < 0.05). After 3 days, the mean uptake rates by the seaweed biomass under continuous flow were 3.09 mg DIN g DW day⁻¹ (383 mg DIN m⁻² day⁻¹) and 0.13 mg PO₄ g DW day⁻¹ (99 mg PO₄ m⁻² day⁻¹), being significantly higher than in the static regime (Tukey HSD, P < 0.05). The chl-a decreased in seaweed tanks, suggesting that U. clathrata inhibited phytoplankton growth. Correlations between the cumulative values of DIN removed from the water and total nitrogen assimilated into the seaweed biomass (r = 0.7 and 0.8, P < 0.05), suggest that nutrient removal by U. clathrata dominated over other processes such as phytoplankton and bacterial assimilation, ammonia volatilization and nutrient precipitation.     

Polymorphic variants of folate metabolism genes and the risk of laryngeal cancer

Carcinogenesis may result from abnormal methylation of cancer-related genes regulatory sequence. Though, the polymorphic variants of genes encoding enzymes of folate and methionine metabolism may have an effect on DNA methylation. Using PCR-RFLPs, we examined the polymorphism distribution of genes encoding methionine synthase (MTR); 5,10-methylenetetrahydrofolate dehydrogenase, 5,10-methenyltetrahydrofolate cyclohydrolase and 10-formyltetrahydrofolate synthetase (MTHFD1); and methylenetetrahydrofolate reductase (MTHFR) in patients with larynx cancer (n = 131) and controls (n = 250). Patients with MTR 2756AG or GG genotypes displayed a 1.856 -fold increased risk of larynx cancer (95% CI = 1.1860–2.903, P = 0.0076). However, we did not observe an increased risk for the homozygous GG genotype OR = 1.960 (95% CI = 0.6722–5.713, P = 0.2535). Moreover, we did not observe statistical differences in distribution of MTHFR 677C>T, 1298A>C and MTHFD1 1958G>A allele and genotype frequencies in patients and controls. Our findings confirm the significance of the role of the methyl cycle in etiopathogenesis of laryngeal cancer.     

Behavioural and population responses to changing availability of <Emphasis Type="Italic">Artemia</Emphasis> prey by moulting black-necked grebes, <Emphasis Type="Italic">Podiceps nigricollis</Emphasis>

Chemical communication may inform about the location of prey, predators, co-specifics, and mate partners in zooplankton. In this study, we evaluated several life-history traits of the rotifer, Brachionus calyciflorus, exposed to conditioned media by a rotifer predator (Asplanchna brightwelli) and a cladocera competitor (Daphnia similis), quantifying population growth and life-table demography at two algal food levels (2.0 and 0.5 × 10⁶ cells ml⁻¹ of Chlorella pyrenoidosa). At both food levels, B. calyciflorus grown in predator-conditioned media had lower population abundance and slower population growth rate than controls. Conversely, the competitor-conditioned media treatments produced both higher rotifer population abundance and faster population growth rate than controls. Life-history parameters varied significantly depending on the presence of predator and competitor-conditioned media. The Asplanchna-conditioned media significantly decreased gross reproductive rate (GRR): 8–9 offsprings per female; net reproductive rate (R ₀): 6–7 offsprings per female; population growth rate (r): 0.34–0.37 day⁻¹; and increased generation time (T): 5.5–5.6 days. On the other hand, The Daphnia-conditioned media significantly increased the GRR (13–14 offsprings per female); net reproductive rate (8–9 offsprings per female); population growth rate (0.42–0.43 day⁻¹); and decreased generation time (4.9–5.0 days). However, the effects of food level on the life-history characteristic were not significant in both treatments. Maximum values of the population abundance and the population growth rate are significantly influenced by the predator densities and pre-culture time. This study suggests that rotifers use variable life-history strategies (low reproduction and high survivorship versus high reproduction and low survivorship) based on the presence of predators and competitors.