The present immunocytochemical study concerns the distribution of serotonin in the epidermis of three species of teleost fish. Serotonin-like immunoreactivity was found in the club cells of Heteropneustes fossilis and Carapus acus but not in those from the sea eel Conger conger. This study is the first immunocytochemical identification of serotonin in the club cells of teleost epidermis. By comparing data from the literature (Zaccone et al. 1986, 1987, 1988) regarding the occurrence of serotonin and GRP/bombesin in the exocrine sacciform gland cells of piscine skin, it is worthy mentioning here that the serotonin contained in the club cells of the species studied may have the ability to affect the pheromonal or other possible functions of these cells. The presence of serotonin in these systems has been correlated with the capacity of the exocrine glands of fish skin to secrete, ectopically, amine messengers in contrast to those produced eutopically i.e. in the neuron-paraneuron system in some vertebrates (Fujita et al. 1988).

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The prevalence of eight mutations in 84 patients with beta-thalassaemia major and in 16 subjects with thalassaemia intermedia was investigated. All of the patients were Italian, originating from Eastern Sicily (Messina area) and some Calabrian regions. Genomic DNA was amplified by polymerase chain reaction (PCR). DNA molecular investigations were performed by allele-specific oligonucleotide (ASO) hybridization, to identify the following beta-thalassaemia mutations: CD39 (C-T), IVS1-110 (G-A), IVS1-6 (T-C), IVS1-1 (G-A), IVS2-745 (C-G), IVS2-1 (G-A), -87 (C-G), CD6 A (-A). Our data underline that in thalassemia intermedia two mutations were statistically prevalent: IVS1-6 T-->C (P < 0.001) and CD 6-A (P < 0.05). CD 39 was statistically prevalent in beta-thalassaemia major patients (P < 0.01). The difference between the two groups was not statistically significant for all the other mutations. Five different genotypes were recorded among thalassaemia intermedia and 15 among beta-thalassaemia major patients. Twenty-five percent of the intermedia patients and 4.5% of the major patients had homozygosity for mild mutations (group I); 62.5% of the intermedia patients and 26.2% of the major patients had combinations of mild/severe mutations (group II). In addition, homozygosity or double heterozygosity for severe mutations (group III) was found in 12.5% of the intermedia patients and 69% of the major patients. Some genotypes were restricted to thalassaemia intermedia, including heterozygosity -87/IVS1-6 and IVS1-6/CD 6-A. It is essential to understand the distribution and frequency of the relevant mutations in each population where beta-thalassaemias exist. This is of particular importance for genotype-phenotype correlation and for carrier detection, genetic counselling and prenatal diagnosis.