Photoautotrophic cultivation of Chlamydomonas reinhardtii in open ponds of greenhouse.

Chlamydomonas reinhardtii is one of the most characterized green algae. The open-pond cultivation can be challenging due to sensitivity of strain to fluctuating environmental conditions and unavailability of low-cost photoautotrophic media. In this study, the photoautotrophic growth of C. reinhardtii was evaluated in 1-m2 open ponds placed in greenhouse. Sodium bicarbonate (NaHCO3) was evaluated as an alternative buffering agent to tris. The effect of buffer and pH was tested. The growth was studied in the presence of various nitrogen [urea and ammonium bicarbonate (NH4HCO3)] sources. In the study, it was found that 125-ppm NaHCO3 as an optimum concentration. The buffering agent in the media was found to have major impact on growth. Without buffering agent, culture did not grow, and pH drop was observed. The sodium bicarbonate-buffered media reported to have the lowest bacterial contamination (18.3%), highest AFDW per OD (0.39 ± 0.027 g/L) and higher Fv/Fm (0.714 ± 0.016), whereas these values were found to be 62%, 0.19 ± 0.02 g/L and 0.537 ± 0.053 for tris-grown culture, respectively. The pH 7.0-7.5 was determined as an optimum, whereas pH 6.5-7.0 and 8.0-8.5 were found to affect the growth and induce palmelloidy. The OD and AFDW of culture grown in NH4HCO3 were found equivalent to a standard nitrogen source (NH4Cl), whereas culture shown poor growth in urea. Based on these data, NH4HCO3 media recipe and the optimized cultivation parameters were selected for photoautotrophic cultivation of Chlamydomonas in greenhouse open ponds.

Geographic and behavioral differences associated with sexually transmitted infection prevalence among Indian men who have sex with men in Chennai and Mumbai.

India has one of the largest numbers of men who have sex with men (MSM) globally; however, geographic data on sexually transmitted infection (STI) prevalence and associations with sexual behavior are limited. Six-hundred and eight MSM in Chennai and Mumbai underwent screening for a behavioral trial and were assessed for bacterial STIs (syphilis, chlamydia, gonorrhea), HIV, and past-month self-reported condomless anal sex (CAS). Mumbai (37.8%) had a greater prevalence of any STI than Chennai (27.6%) (prevalence ratio [PR] = 1.37, 95% CI: 1.09, 1.73). This pattern also emerged for gonorrhea and chlamydia separately but not syphilis. Conversely, Mumbai MSM reported lower rates of CAS (mean = 2.2) compared to Chennai MSM (mean = 14.0) (mean difference = -11.8, 95% CI: -14.6, -9.1). The interaction of city by CAS on any STI prevalence (PR = 2.09, 95% CI: 1.45, 3.01, p < .0001) revealed that in Chennai, higher rates of CAS were not associated with STI prevalence, but in Mumbai they were (PR = 2.49, 95% CI: 1.65, 3.76, p < .0001). The higher prevalence of bacterial STIs but lower frequency of CAS in Mumbai (versus Chennai), along with the significant interaction of CAS with city on STI rates, suggests that there are either differences in disease burden or differences by city with respect to self-reported assessment of CAS. Regardless, the high prevalence rates of untreated STIs and condomless sex among MSM suggest the need for additional prevention intervention efforts for MSM in urban India.

Stereoselective synthesis of the C14-C23 fragment of biselyngbyolide A and B enabled by transition metal catalysis.

Transition met al catalysis has enabled the highly stereoselective and protecting group-free synthesis of the C14-C23 fragment of the apoptosis-inducing natural products biselyngbyolide A and B. A Pd-catalyzed Stille reaction between a vinyl stannane and a crotyl carbonate formed the skipped diene with complete control of the the trisubstituted bond and excellent control over the branched/linear products. A Cu-catalyzed Stahl oxidation was used to form the requisite aldehyde needed for a Ag-catalyzed asymmetric allylation. The latter provided the final fragment with excellent stereochemical control.

Rapid, enantioselective synthesis of the C1-C13 fragment of biselyngbyolide B.

A rapid synthesis of the C1-C13 fragment of biselynbyolide A and B is reported. The judicious use of catalytic transformations for C-C bond formation and stereocenter generation greatly minimizes the use of protecting groups and oxidation state changes, as compared to previously reported routes to similar fragments.