Alteration of the phenology of leaf senescence and fall in winter deciduous species by climate change: effects on nutrient proficiency

Leaf senescence in winter deciduous species signals the transition from the active to the dormant stage. The purpose of leaf senescence is the recovery of nutrients before the leaves fall. Photoperiod and temperature are the main cues controlling leaf senescence in winter deciduous species, with water stress imposing an additional influence. Photoperiod exerts a strict control on leaf senescence at latitudes where winters are severe and temperature gains importance in the regulation as winters become less severe. On average, climatic warming will delay and drought will advance leaf senescence, but at varying degrees depending on the species. Warming and drought thus have opposite effects on the phenology of leaf senescence, and the impact of climate change will therefore depend on the relative importance of each factor in specific regions. Warming is not expected to have a strong impact on nutrient proficiency although a slower speed of leaf senescence induced by warming could facilitate a more efficient nutrient resorption. Nutrient resorption is less efficient when the leaves senesce prematurely as a consequence of water stress. The overall effects of climate change on nutrient resorption will depend on the contrasting effects of warming and drought. Changes in nutrient resorption and proficiency will impact production in the following year, at least in early spring, because the construction of new foliage relies almost exclusively on nutrients resorbed from foliage during the preceding leaf fall. Changes in the phenology of leaf senescence will thus impact carbon uptake, but also ecosystem nutrient cycling, especially if the changes are consequence of water stress

Polymorphic variants of genes involved in homocysteine metabolism in celiac disease

Celiac disease (CD) is a polygenic chronic enteropathy conferring an increased risk for various nutrient deficiency states. Hyperhomocysteinemia is a frequent finding in CD and may be related to the development of venous thrombosis, cardiovascular disease, and stroke in untreated CD patients. Recently, a possible excess in the frequency of the MTHFR c.677C>T (rs1801133) gene variant in CD patients was reported. The purpose of this study was to determine if there exist differences in the distribution of polymorphic variants of genes involved in homocysteine/methyl group metabolism between CD patients and the general population. A set of 10 gene polymorphisms (MTHFR rs1801133, MTR rs1805087, MTHFD1 rs2236225, MTRR rs1801394, CBS 844ins68, BHMT1 rs7356530 and rs3733890, BHMT2 rs526264 and rs625879, and TCN2 rs1801198) was tested in 134 patients with CD and 160 matched healthy controls. The frequency of the MTR rs1805087 GG genotype in CD patients was lower than in controls (0.01 and 0.06, respectively), although statistical significance was not achieved (P = 0.06). For the other analyzed polymorphisms, there was no evidence of difference in both allelic and genotypic distribution between cases and controls. The exhaustive Multifactor Dimensionality Reduction analysis revealed no combination of interactive polymorphisms predicting the incidence of CD. In contrast to the well-documented clinical observations of increased risks of vascular disease in patients with longstanding untreated CD, in our group of patients no significant association with CD was found for all tested polymorphic variants of genes involved in homocysteine metabolism. These findings should be replicated in studies with a larger sample size

Nucleotide variants of the cancer predisposing gene CDH1 and the risk of non-syndromic cleft lip with or without cleft palate

The CDH1 gene plays an important role during carcinogenesis and craniofacial morphogenesis. Germline mutations in this gene have been described in families presenting syndromic diffuse gastric cancer and orofacial clefts. The aim of this study was to evaluate the association between nucleotide variants of CDH1 and the risk of non-syndromic cleft lip with or without cleft palate (NSCL/P). Six single nucleotide polymorphisms (SNPs) of the CDH1 gene (rs16260, rs9929218, rs7186053, rs4783573, rs16958383, and rs1801552) were genotyped using the TaqMan SNP genotyping assays in 250 patients with NSCL/P and 540 controls from the Polish population. Comparison between patient and control groups showed that the CDH1 rs1801552 variant, under the assumption of recessive model, was associated with a two-fold decrease in the risk of NSCL/P (OR= 0.481, 95 % CI 0.281-0.824, p = 0.007). This association remained statistically significant even after the multiple testing correction. No significant associations with NSCL/P risk were found for the other five tested SNPs. We found a strong association between the cancer predisposing gene CDH1 and the risk of NSCL/P in the Polish population. This result, together with previous observations of co-occurrence of orofacial clefts and a variety of cancer types, suggests the need for replication studies testing rs1801552 in NSCL/P cohorts with a known cancer history

PAX9 polymorphism and susceptibility to sporadic non-syndromic severe anodontia: a case-control study in southwest China

Our research aimed to look into the clinical traits and genetic mutations in sporadic non-syndromic anodontia and to gain insight into the role of mutations of PAX9, MSX1, AXIN2 and EDA in anodontia phenotypes, especially for the PAX9. MATERIAL AND METHODS: The female proband and her family members from the ethnic Han families underwent complete oral examinations and received a retrospective review. Venous blood samples were obtained to screen variants in the PAX9, MSX1, AXIN2, and EDA genes. A case-control study was performed on 50 subjects with sporadic tooth agenesis (cases) and 100 healthy controls, which genotyped a PAX9 gene polymorphism (rs4904210). RESULTS: Intra-oral and panoramic radiographs revealed that the female proband had anodontia denoted by the complete absence of teeth in both the primary and secondary dentitions, while all her family members maintained normal dentitions. Detected in the female proband were variants of the PAX9 and AXIN2 including A240P (rs4904210) of the PAX9, c.148C>T (rs2240308), c.1365A>G (rs9915936) and c.1386C>T (rs1133683) of the AXIN2. The same variants were present in her unaffected younger brother. The PAX9 variations were in a different state in her parents. Mutations in the MSX1 and EDA genes were not identified. No significant diferences were found in the allele and genotype frequencies of the PAX9 polymorphism between the controls and the subjects with sporadic tooth agenesis. CONCLUSIONS: These results suggest that the association of A240P with sporadic tooth agenesis still remains obscure, especially for different populations. The genotype/phenotype correlation in congenital anodontia should be verified

Transcriptional analysis of the human PAX9 promoter

OBJECTIVES: PAX9 belongs to the Pax family of transcriptional factor genes. This gene is expressed in embryonic tissues such as somites, pharyngeal pouch endoderm, distal limb buds and neural crest-derived mesenchyme. Polymorphisms in the upstream promoter region of the human PAX9 have been associated with human non-syndromic tooth agenesis. In the present study, we verified the in vitro mRNA expression of this gene and the luciferase activity of two constructs containing promoter sequences of the PAX9 gene. MATERIAL AND METHODS: Embryonic tissues were obtained from digits, face, and midbrain/hindbrain regions. Fragments containing PAX9 promoter sequences were cloned into reporter plasmids and were transfected into the different cell cultures. mRNA were extracted from primary cell cultures. RESULTS: The semi-quantitative RT-PCR results showed that in vitro E13.5 limb bud and CNS cells express PAX9, but cells derived from the facial region do not. Moreover, the luciferase assay showed that protein activity of the constructed vector was weaker than pgl3 -basic alone. CONCLUSIONS: The present results suggest that the promoter sequences analyzed are not sufficient to drive PAX9 gene transcription