The present study was undertaken to examine CYP1A1 and XRCC1 polymorphisms as potential genetic susceptibility markers for laryngeal squamous cell carcinoma (SCC). Eighty-eight patients with laryngeal SCC and 178 randomly selected healthy blood donors from the same Caucasian population (Porto, Northern Portugal) were analysed for CYP1A1 (MspI and NcoI) and XRCC1 (Arg194Trp and Arg399Gln) polymorphisms, using PCR-RFLP techniques. CYP1A1 MspI MH (mutant homozygous) and CYP1A1 NcoI HT (heterozygous) genotypes were more frequent in patients than in controls, with those carrying a CYP1A1 NcoI HT genotype having a 2.3-fold higher risk for tumour development. On the other hand, polymorphisms in XRCC1 codon 399 and codon 194 do not seem to play a role in the aetiology of smoking-related laryngeal SCC, once its distribution was similar in both analysed groups. All the significant associations observed were exclusively due to differences between controls and larynx glottic cancer patient subgroup. Furthermore, lower lifetime tobacco consumption was observed in laryngeal SCC patients carrying the MspI and NcoI polymorphisms, than in those who did not show the polymorphic variants. This investigation seems to support the importance of CYP1A1 gene polymorphism as a potential genetic marker of laryngeal cancer development, specially concerning smokers who have inherited the at-risk genotypes CYP1A1 MspI MH or CYP1A1 NcoI HT, who do appear to be more susceptible to the development of SCC of the glottic larynx.

Coffee seeds are sensitive to desiccation and to storage. Advances in the technique of cryopreservation of these seeds have been achieved in recent years, and the aim of this study was to evaluate Coffea arabica seeds cryopreserved through direct immersion in liquid nitrogen after rapid and slow drying. Seeds of the cultivars 'Arara', 'Catiguá', 'Catuaí Amarelo' and 'Mundo Novo' underwent rapid and slow drying to 20% moisture content (dry basis); they were then immersed in liquid nitrogen for 24 hours and after that, reheated in a water bath. C. arabica seeds have better physiological quality after slow drying, but rapid drying is better for cryopreservation of these seeds. The seeds of the cultivars investigated have different levels of tolerance, but all can be cryopreserved; 'Catuaí Amarelo' is the most tolerant and 'Arara' the most sensitive to cryopreservation, regardless of the drying speed. The activity of the enzymes catalase, peroxidase and esterase increased after drying and after cryopreservation. Rapid drying in silica gel to 20% moisture content, followed by direct immersion in liquid nitrogen, allows cryopreservation of coffee seeds in a fast, simple and economical manner.

ABSTRACT. Fusarium oxysporum f. sp cubense (Foc), the causal agent of Panama disease, is responsible for economic losses in banana crops worldwide. The identification of genes that effectively act on pathogenicity and/or virulence may contribute to the development of different strategies for disease control and the production of resistant plants. The objective of the current study was to analyze the importance of SGE1 gene expression in Foc virulence through post-transcriptional silencing using a double-stranded RNA hairpin. Thirteen transformants were selected based on different morphological characteristics, and sporulation in these transformants was significantly reduced by approximately 95% (P < 0.05) compared to that of the wild-type strain. The relative SGE1 expression levels in the transformant strains were reduced by 27 to 47% compared to those in the wild-type strain. A pathogenicity analysis revealed that the transformants were able to reach the rhizomes and pseudostems of the inoculated banana plants. However, the transformants induced initial disease symptoms in the banana plants approximately 10 days later than that by the wild-type Foc, and initial disease symptoms persisted even at 45 days after inoculation. These results indicate that the SGE1 gene is directly involved in the virulence of Foc. Therefore, SGE1 may be a potential candidate for host-induced gene silencing in banana plants.