phoenixin(smim20), a gene coding for a novel reproductive ligand, is expressed in the brain of adult zebrafish.

Gonadotropin-releasing hormone (GnRH) is a highly conserved neuroendocrine decapeptide that is essential for the onset of puberty and the maintenance of the reproductive state. In addition to its role as hypothalamic releasing hormone, GnRH has multiple functions including modulator of neural activity within the nervous system and of resulting behaviors. These multiple functions are reflected by the existence of multiple isoforms. Despite its importance as a critical hypothalamic releasing hormone, the gnrh1 gene has been lost in zebrafish, and its reproductive function is not compensated for by other GnRH isoforms (GnRH2 and GnRH3), suggesting that, surprisingly, zebrafish do not use any of the GnRH peptides to control reproduction and fertility. Previously we proposed that Phoenixin/SMIM20, a novel peptide identified in mammals and the ligand for the orphan GPR173, is a potential candidate to control the initiation of sexual development and fertility in the zebrafish. Here we confirm the sequence of the zebrafish phoenixin/smim20 gene and by RT-PCR show that it is expressed early in development through adulthood. Subsequently we show that phoenixin/smim20 is expressed in the adult brain including the regions of the hypothalamus important in the control of fertility and reproduction.

Role of human-milk lactadherin in protection against symptomatic rotavirus infection.

BACKGROUND: Human milk contains a 46 kDa mucin-associated glycoprotein, lactadherin, which binds specifically to rotavirus and inhibits its replication. This study tested the hypothesis that lactadherin protects against symptoms of rotavirus infection. METHODS: 200 infants in Mexico City were recruited at birth and monitored by regular stool EIA for rotavirus, serology, and recording of feeding and stool patterns. Milk samples were obtained from the mothers weekly until 4 weeks post partum then monthly. The sample taken immediately before an infant's episode of rotavirus infection was assayed for lactadherin, butyrophilin, mucin, and secretory IgA. An infection was defined as symptomatic if diarrhoea occurred in the 5 days before or after detection of the virus. FINDINGS: 31 infants developed rotavirus infection; 15 were symptomatic and 16 had no symptoms. The median concentration of lactadherin in the milk samples (obtained 4-41 days [median 13] before the infection) was 48.4 (range 5.6-180) microg/mL in the asymptomatic group and 29-2 (6.2-103-4) microg/mL in the symptomatic group. Although these medians did not differ significantly, in logistic regression analysis adjusted for age at infection and secretory IgA concentration there was a significant difference between the groups (p=0O01). No association between symptom status and concentrations of butyrophilin, mucin, or secretory IgA was found. INTERPRETATION: Protection against rotavirus by human milk is associated with the glycoprotein lactadherin. This association is independent of products of the secretory immune system.