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The pituitary is a complex gland comprising different cell types each secreting specific hormones. The extensive network of signaling molecules and transcription factors required for determination and terminal differentiation of specific cell types is still not fully understood. The SRY-like HMG-box (SOX) transcription factor Sox4 plays important roles in many developmental processes and has two homologs in zebrafish, Sox4a and Sox4b. We show that the sox4b gene is expressed in the pituitary anlagen starting at 24 h after fertilization (hpf) and later in the entire head region including the pituitary. At 48 hpf, sox4b mRNA colocalizes with that for TSH (tshβ), glycoprotein subunit α (gsuα), and the Zn finger transcription factor Gata2a. Loss of Sox4b function, using morpholino knockdown or expression of a dominant-negative Sox4 mutant, leads to a drastic decrease in tshβ and gsuα expression and reduced levels of gh, whereas other anterior pituitary gland markers including prl, slβ, pomc, and lim3 are not affected. Sox4b is also required for expression of gata2a in the pituitary. Knockdown of gata2a leads to decreased tshβ and gsuα expression at 48 hpf, similar to sox4b morphants. Injection of gata2a mRNA into sox4b morphants rescued tshβ and gsuα expression in thyrotrope cells. Finally, sox4b or gata2a knockdown causes a significant decrease of gonadotropin expression (lhβ and fshβ) at 4 d after fertilization. In summary, our results indicate that Sox4b is expressed in zebrafish during pituitary development and plays a crucial role in the differentiation of thyrotrope and gonadotrope cells through induction of gata2a expression in the developing pituitary.

It is estimated that 15-20 millions of people are infected with human T-cell lymphotropic virus 1/2 (HTLV-1/2) worldwide, and 20-30% of them are Latin Americans. The seroprevalence rates vary according to geographic area, socio-demographic composition and individual risk behaviors. The impact of HTLV-1-associated diseases on the community, as well as the increasing concerns about blood transfusion safety due to infectious transmitted agents, has required mandatory screening assays of blood donors as an effective preventive strategy in HTLV-1 transmission. The aim of this study was to estimate the seroprevalence of HTLV-1/2 in blood donors from Valdivia, southern Chile during the first year of mandatory screening of HTLV by Chilean government. Blood samples were collected from blood donors between May 2009 and 2010 at the Regional Hospital of Valdivia, Chile. Serum samples were screened for antibodies against HTLV-1/2 by enzyme-linked immunosorbent assay MUREX HTLV I + II Abbott. Among 6,237 samples tested by serological assay, 28 samples were reactive; nevertheless, confirmatory techniques indicate that only 15 samples were positive to HTLV-1. Our study shows HTLV-1 seroprevalence of 0.24%, indicating a similar seroprevalence associated with blood donors than previous reports for our country.

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Human T-cell lymphotropic virus type 1 and 2 (HTLV-1/2) are oncogenic retroviruses linked etiologically to human diseases. In Chile, these viruses have been studied in ethnic populations, or patients diagnosed clinically with HTLV-1 associated myelopathy/tropical spastic paraparesis, but have not been studied in patients with malignant hematological diseases. The aim of this study was to determine the seroprevalence and viral prevalence of HTLV-1/2 among patients with malignant hematological diseases. Eighty-eight patients with malignant hematological diseases were tested by enzyme-linked immunosorbent assay (ELISA) for IgG anti-HTLV-1/2 and nested-PCR for the tax gene. The seroprevalence by ELISA was 3.4% and the viral prevalence by nested-PCR tax was 18.2%. HTLV-1 was found in 17% and HTLV-2 in 1% of the patients tested. HTLV-1/2 was found in 17.4% of patients with non-Hodgkin's lymphomas, 28.6% of patients with Hodgkin's lymphomas, 80% of patients with chronic lymphocytic leukemia, 11.4% of patients with acute lymphoblastic leukemia, and 22.2% of patients with acute myeloid leukemia. A high prevalence of HTLV-1/2 was found in patients with malignant hematological diseases. A high proportion of patients were seronegative to HTLV-1/2 infection, similar to other HTLV-1/2 associated disorders. Because 50% of patients positive for HTLV-1/2 were below 30 years old, it is suggested that vertical transmission could have played an important role in these patients.