Role of Milk Whey in the Transmission of Human Cytomegalovirus Infection by Breast Milk

Breast-fed infants are susceptible to human cytomegalovirus (HCMV) infection via breast milk. In our previous study, HCMV was isolated more frequently from breast milk at later than one month after delivery than from colostrum or early breast milk. To clarify the role of milk cells and whey in vertical infection by breast feeding, we separated breast milk into milk cells and whey and examined each fraction for the presence of HCMV. We collected breast milk from mothers who breast-fed their infants (aged from 3 days to 2 months). The breast milk was centrifuged and separated into the middle layer (layer of milk whey) and the pellet (containing milk cells). We attempted to isolate HCMV from whey and to detect HCMV immediate early (IE) DNA in both milk whey and cells. HCMV was isolated from 7 out of 35 (20.0%) whey samples and HCMV IE DNA was detected from 15 out of 35 (42.9%) whey and/or milk cells. Detection rates of HCMV IE DNA in the whey layer and milk cells were 39.1% (25 out of 64) and 17.2% (11 out of 64), respectively. HCMV IE DNA was not detected in colostrum, but was detected in breast milk samples one month after delivery. Therefore, cell-free HCMV shed into milk whey may have a more important role in vertical infection by breast milk than cell-associated HCMV in the milk.     

Inhibition of second meiotic division and a switching over to flagellar formation in secondary spermatocytes of newt by cycloheximide

10.0 micro M cycloheximide (CH) was found to completely inhibit the second meiotic division of newt spermatocytes. Under continuous incubation with CH from the beginning of interphase II, secondary spermatocytes fail to initiate chromosomal condensation and thus remain in interphase II. After 12-15 h of incubation, a single motile flagellum, about 5 micrometers in length, was observed on each of the secondary spermatocytes. These flagella grew to a length of 60-80 micrometers, but thereafter ceased to grow, whereas ordinarily spermatids grew flagella up to 500 micrometers in length in the absence of CH [1]. When CH was applied within 2 h following telophase I, the percentage of meiosis II inhibition was almost 100% and when applied even later, it became less, which showed that the early half period during interphase II was sensitive to CH. Regardless of the length of incubation time with CH, flagella were found to grow within a period of 12-15 h following telophase I. Upon removal of CH, even after 60 h of incubation, the flagella of the secondary spermatocytes shortened and disappeared completely. These spermatocytes underwent the second meiotic divisions. Also, flagella grew on the resulting spermatids. The possibility that a particular centriole which participated in the first meiotic division changes into a basal body for flagellar formation under the influence of CH and vice versa upon removal of it, is discussed in the following.