Mating system and two types of gametogenesis in the fresh water diatom Ulnaria ulna (Bacillariophyta)

Sexual reproduction and mating system of the freshwater diatom Ulnaria ulna (Nitzsch) Compère were studied by using clonal cultures. Mating system of the species involves homo- and heterothallic modes of reproduction; and both male and female clones were capable of homothallic reproduction. Two types of gametogenesis corresponding to two mating types were investigated. Analysis of the crossing table, gamete morphology, and sex distribution in the progeny resulted from intraclonal reproduction provided evidences that anisogamy and two mating types were determined in U. ulna genetically; male and female clones were hetero- and homogametic correspondently. Specific active movement of male gametes caused by the formation and retraction of pseudopodia-like structures on the gamete surface was described. The absence of reproductive isolation between clones gathered from geographically distant populations suggests continuity and broad distribution of the species.Вивчені статеве розмноження і система схрещування прісноводної діатомеї Ulnaria ulna (Nitzsch) Compère з використанням клонових культур. Система схрещування виду складається з гомо- та гетероталічних способів відтворення, причому як чоловічі, так і жіночі клони здатні відтворюватися гомоталічно. Вивчені два типи гаметогенезу, які відповідали розділенню клонів за статевою ознакою. Аналіз таблиці схрещування, морфології гамет і розподілу статі у потомстві, отриманому при внутрішньоклоновому відтворенні, служать доказом того, що анізогамія і поділ на дві статі зумовлені у U. ulna генетично; чоловічий і жіночий клони є гетеро- і гомогаметними відповідно. Описано також активний рух чоловічих статевих клітин, викликаний утворенням і втягуванням на поверхні гамет структур, подібних псевдоподіям. Відсутність репродуктивної ізоляції між клонами, зібраними з географічно віддалених популяцій, передбачає цілісність та широке розповсюджeння виду

Quantum computation with mesoscopic superposition states

We present a strategy to engineer a simple cavity-QED two-bit universal quantum gate using mesoscopic distinct quantum superposition states. The dissipative effect on decoherence and amplitude damping of the quantum bits are analyzed and the critical parameters are presented.Comment: 9 pages, 5 Postscript and 1 Encapsulated Postscript figures. To be published in Phys. Rev.

Haslea silbo, a novel cosmopolitan species of blue diatoms

Specimens of a new species of blue diatoms from the genus Haslea Simonsen were discovered in geographically distant sampling sites, first in the Canary Archipelago, then North Carolina, Gulf of Naples, the Croatian South Adriatic Sea, and Turkish coast of the Eastern Mediterranean Sea. An exhaustive characterization of these specimens, using a combined morphological and genomic approach led to the conclusion that they belong to a single new to science cosmopolitan species, Haslea silbo sp. nov. A preliminary characterization of its blue pigment shows similarities to marennine produced by Haslea ostrearia, as evidenced by UV–visible spectrophotometry and Raman spectrome-try. Life cycle stages including auxosporulation were also observed, providing data on the cardinal points of this species. For the two most geographically distant populations (North Carolina and East Mediterranean), complete mitochondrial and plastid genomes were sequenced. The mitogenomes of both strains share a rare atp6 pseudogene, but the number, nature, and positions of the group II introns inside its cox1 gene differ between the two populations. There are also two pairs of genes fused in single ORFs. The plastid genomes are characterized by large regions of recombination with plasmid DNA, which are in both cases located between the ycf35 and psbA genes, but whose content differs between the strains. The two sequenced strains hosts three plasmids coding for putative serine recombinase protein whose sequences are compared, and four out of six of these plasmids were highly conserved

Sexual Behavior and Its Determinants During COVID-19 Restrictions Among Men Who Have Sex With Men in Amsterdam

Objective: To investigate the impact of Dutch COVID-19 restrictions on sexual behavior and HIV/sexually transmitted infection (STI) acquisition among men who have sex with men (MSM) participating in the Amsterdam Cohort Studies (ACS) on HIV in Amsterdam. Methods: ACS participants complete a questionnaire on sexual behavior and are tested for HIV/STI biannually. They may also be tested at the STI clinic in-between study visits. On May 29, 2020, ACS participants were invited to complete an online questionnaire on health, COVID-19 risk perceptions, and sexual behavior. Determinants of reporting casual sex partners (CSP) during COVID-19 restrictions were examined using logistic regression. Results : Of 683 MSM, 353 (52%; median age, 47 years; interquartile range, 38-53 years) completed the questionnaire. Since COVID-19, 73% reported a reduction in the number of CSP. CSP during COVID-19 restrictions were reported by 133 MSM (38%) and, in multivariable analysis, was associated with not having a college/university degree, being single, lower perceived importance of avoiding COVID-19, number of CSP before COVID-19, and current preexposure prophylaxis use (P < 0.05 for all). During COVID-19 restrictions, no HIV infections were diagnosed, and the STI positivity rate was 8%. Conclusion : Since COVID-19, the number of CSP decreased among MSM, and there may have been a temporary reduction in HIV/STI transmission. Some MSM were not fully compliant to social distancing regulations and reported CSP, which was related to prior sexual behavior and low perceived importance of avoiding COVID-19. For these men, it is important to maintain accessible HIV/STI-related testing and care during times of lockdown

Sexual Behavior and Its Determinants During COVID-19 Restrictions Among Men Who Have Sex With Men in Amsterdam

Objective: To investigate the impact of Dutch COVID-19 restrictions on sexual behavior and HIV/sexually transmitted infection (STI) acquisition among men who have sex with men (MSM) participating in the Amsterdam Cohort Studies (ACS) on HIV in Amsterdam. Methods: ACS participants complete a questionnaire on sexual behavior and are tested for HIV/STI biannually. They may also be tested at the STI clinic in-between study visits. On May 29, 2020, ACS participants were invited to complete an online questionnaire on health, COVID-19 risk perceptions, and sexual behavior. Determinants of reporting casual sex partners (CSP) during COVID-19 restrictions were examined using logistic regression. Results : Of 683 MSM, 353 (52%; median age, 47 years; interquartile range, 38-53 years) completed the questionnaire. Since COVID-19, 73% reported a reduction in the number of CSP. CSP during COVID-19 restrictions were reported by 133 MSM (38%) and, in multivariable analysis, was associated with not having a college/university degree, being single, lower perceived importance of avoiding COVID-19, number of CSP before COVID-19, and current preexposure prophylaxis use (P < 0.05 for all). During COVID-19 restrictions, no HIV infections were diagnosed, and the STI positivity rate was 8%. Conclusion : Since COVID-19, the number of CSP decreased among MSM, and there may have been a temporary reduction in HIV/STI transmission. Some MSM were not fully compliant to social distancing regulations and reported CSP, which was related to prior sexual behavior and low perceived importance of avoiding COVID-19. For these men, it is important to maintain accessible HIV/STI-related testing and care during times of lockdown