Saliva ferning, an unorthodox estrus detection method in water buffaloes (Bubalus bubalis).

Estrus detection is a major problem in buffalo husbandry because of inconsistent expression of estrous signs at different seasons, and a high prevalence of the silent heat and postpartum anestrus in this species. Around 50% of the estrus events in buffaloes are currently undetected in the field conditions, resulting in a huge economic loss. Although the cervicovaginal fluid fern patterns confirm the estrus for a breeding decision, the fluid discharge is absent during the silent-heat condition. Therefore, the present study focused on the crystallization patterns of the saliva as an alternative method for estrus detection in buffaloes. Saliva is a body fluid available regularly, and its ferning ability before ovulation was established in women. In this study, eight female nonpregnant Murrah buffaloes (Bubalus bubalis) were considered during two experimental periods of 3 months each. One period was in summer with five animals, and another period was in rainy season with three animals. Estrus was determined by the estrus symptoms, ovarian ultrasonography, and salivary estradiol (E2) to progesterone (P4) ratio. A total of 450 saliva samples were collected from these animals on the daily basis. The salivary smear was prepared with 20 µL of the cell-free saliva on a clean glass slide, and its microscopic images were captured at a magnification of × 200. The images were used for fractal analysis as the salivary crystallization or fern patterns follow the fractal geometry. Saliva at estrus showed a typical symmetrical fern-like crystallization patterns with significantly (P < 0.05) lower fractal dimension values. Salivary estradiol levels and E2/P4 ratio were significantly (P < 0.05) higher at the estrus stage than those at the diestrus stage. An average period of an estrous cycle was 21.7 ± 2.7 days (n = 18 estrous cycles) in buffaloes on the basis of distinct salivary crystallization patterns. The proportion of estrus detection by the salivary fern patterns was very significantly (P < 0.01) higher (0.84) than the proportion of estrus detection (0.5) in the field conditions. Altogether, salivary fern patterns along with the current methods can help reduce estrus detection problem in buffaloes.

NMR observation of HIV-1 gp120 conformational flexibility resulting from V3 truncation.

The envelope spike of HIV-1, which consists of three external gp120 and three transmembrane gp41 glycoproteins, recognizes its target cells by successively binding to its primary CD4 receptor and a coreceptor molecule. Until recently, atomic-resolution structures were available primarily for monomeric HIV-1 gp120, in which the V1, V2 and V3 variable loops were omitted (gp120core ), in complex with soluble CD4 (sCD4). Differences between the structure of HIV gp120core in complex with sCD4 and the structure of unliganded simian immunodeficiency virus gp120core led to the hypothesis that gp120 undergoes a major conformational change upon sCD4 binding. To investigate the conformational flexibility of gp120, we generated two forms of mutated gp120 amenable for NMR studies: one with V1, V2 and V3 omitted ((mut) gp120core ) and the other containing the V3 region [(mut) gp120core (+V3)]. The TROSY-(1)H-(15)N-HSQC spectra of [(2)H, (13)C, (15)N]Arg-labeled and [(2)H, (13)C, (15)N]Ile-labeled unliganded (mut) gp120core showed many fewer crosspeaks than the expected number, and also many fewer crosspeaks in comparison with the labeled (mut) gp120core bound to the CD4-mimic peptide, CD4M33. This finding suggests that in the unliganded form, (mut) gp120core shows considerable flexibility and motions on the millisecond time scale. In contrast, most of the expected crosspeaks were observed for the unliganded (mut) gp120core (+V3), and only a few changes in chemical shift were observed upon CD4M33 binding. These results indicate that (mut) gp120core (+V3) does not show any significant conformational flexibility in its unliganded form and does not undergo any significant conformational change upon CD4M33 binding, underlining the importance of V3 in stabilizing the gp120core conformation.