Multiple mating and sperm displacement in a natural population of Drosophila melanogaster

Summary Mother-offspring data for alcohol dehydrogenase genotypes of a vineyard cellar population of D. melanogaster are best explained by a model that allows 21% of females in the population to mate twice with an 83% level of sperm displacement. A population model with multiple mating and sperm displacement is examined theoretically. A formula for the effective population size is derived under this model. Multiple mating increases the effective population size relative to single mating.     

MicroID2: A Novel Biotin Ligase Enables Rapid Proximity-Dependent Proteomics

Identifying protein–protein and other proximal interactions is central to dissecting signaling and regulatory processes in cells. BioID is a proximity-dependent biotinylation method that uses an “abortive” biotin ligase to detect proximal interactions in cells in a highly reproducible manner. Recent advancements in proximity-dependent biotinylation tools have improved efficiency and timing of labeling, allowing for measurement of interactions on a cellular timescale. However, issues of size, stability, and background labeling of these constructs persist. Here we modified the structure of BioID2, derived from Aquifex aeolicus BirA, to create a smaller, highly active, biotin ligase that we named MicroID2. Truncation of the C terrminus of BioID2 and addition of mutations to alleviate blockage of biotin/ATP binding at the active site of BioID2 resulted in a smaller and highly active construct with lower background labeling. Several additional point mutations improved the function of our modified MicroID2 construct compared with BioID2 and other biotin ligases, including TurboID and miniTurbo. MicroID2 is the smallest biotin ligase reported so far (180 amino acids [AAs] for MicroID2 versus 257 AAs for miniTurbo and 338 AAs for TurboID), yet it demonstrates only slightly less labeling activity than TurboID and outperforms miniTurbo. MicroID2 also had lower background labeling than TurboID. For experiments where precise temporal control of labeling is essential, we in addition developed a MicroID2 mutant, termed lbMicroID2 (low background MicroID2), that has lower labeling efficiency but significantly reduced biotin scavenging compared with BioID2. Finally, we demonstrate utility of MicroID2 in mass spectrometry experiments by localizing MicroID2 constructs to subcellular organelles and measuring proximal interactions.     

The presence of 12β-deoxydecarbamoylsaxitoxin in the Japanese toxic dinoflagellate Alexandrium determined by simultaneous analysis for paralytic shellfish toxins using HILIC-LC–MS/MS

A differential screening study using high-resolution (HR)-hydrophilic interaction chromatography (HILIC)-electrospray ionization (ESI)–quadrupole time-of-flight mass spectrometry (Q-TOF MS) was conducted to identify saxitoxin (STX) analogues in the marine dinoflagellate toxic sub-clone Alexandrium tamarense Axat-2 and the non-toxic sub-clone UAT-014-009 derived from the same Japanese isolate. One unknown compound was identified only in the toxic sub-clone and was found to have the molecular formula C₉H₁₆N₆O₂. This structure differed from that of decarbamoyl STX (dcSTX; C₉H₁₆N₆O₃) by the loss of a single oxygen. A 12-deoxy-dcSTX standard (a mixture of 12α- and β-deoxy-dcSTX) was chemically prepared from dcSTX by reduction with sodium borohydride. The unknown compound in the toxic strain of A. tamarense was identified as 12β-deoxy-dcSTX by comparison of its HR-HILIC-LC–MS retention time and HR–MS/MS spectrum with those of the chemically prepared standard, and the identification was confirmed by high-sensitivity HPLC analysis with post-column fluorescent derivatization. Moreover, two Japanese isolates of A. catenella showing toxin profiles different from that of A. tamarense were also found to contain 12β-deoxy-dcSTX. Previously, 12β-deoxy-dcSTX was isolated from the freshwater cyanobacterium Lyngbya wollei, which produces a unique set of STX analogues. This study is the first evidence of the presence of 12β-deoxy-dcSTX in marine dinoflagellates.     

Morphology,phylogeny and novel chemical compounds from Coolia malayensis (Dinophyceae) from Okinawa,Japan

Marine benthic dinoflagellates within the genus Coolia have been reported to produce natural products, some of which are known to be toxic (i.e., cooliatoxin). To date, five species of Coolia have been reported in tropical and temperate waters around the world; however, very few studies have combined detailed morphological and molecular data with chemical analyses. In this study, a clonal culture of Coolia malayensis was isolated and mass cultivated from a coral reef on the island of Okinawa, Japan. Analysis of the thecal plate morphology and molecular phylogeny from 28S rDNA strongly supported the close relationship between this new isolate of C. malayensis from Okinawa and other isolates of C. malayensis from around the world. Following methanol extraction of 250 L of mass culture, chemical analyses using NanoLiquid chromatography mass spectrometry revealed the mass profiles of water-soluble and ethyl acetate-soluble parts. High-resolution mass spectrometry derived the molecular formulas of three novel disulphated polyether analogs of yessotoxin (C₅₆H₇₈O₁₈S₂ 1102.4 (Compound 1), C₅₇H₈₀O₁₈S₂ 1116.4 (Compound 2), and C₅₇H₇₈O₁₉S₂ 1130.4 (Compound 3)); two potential homologous compounds (Compounds 4 and 5) were also observed on the high-resolution mass, albeit with low signal intensity. The five compounds in the C. malayensis from Okinawa are composed of less oxygen, compared to cooliatoxin and other analogs of yessotoxin, suggesting the metabolites produced by C. malayensis are unique to those previously reported from other strains of Coolia.     

The first crenarchaeon capable of growth by anaerobic carbon monoxide oxidation coupled with H2 production

The ability to grow by anaerobic CO oxidation with production of H₂ from water is known for some thermophilic bacteria, most of which belong to Firmicutes, as well as for a few hyperthermophilic Euryarchaeota isolated from deep-sea hydrothermal habitats. A hyperthermophilic, neutrophilic, anaerobic filamentous archaeon strain 1505 = VKM B-3180 = KCTC 15798 was isolated from a terrestrial hot spring in Kamchatka (Russia) in the presence of 30% CO in the gas phase. Strain 1505 could grow lithotrophically using carbon monoxide as the energy source with the production of hydrogen according to the equation CO + H₂O → CO₂ + H₂; mixotrophically on CO plus glucose; and organotrophically on peptone, yeast extract, glucose, sucrose, or Avicel. The genome of strain 1505 was sequenced and assembled into a single chromosome. Based on 16S rRNA gene sequence analysis and in silico genome-genome hybridization, this organism was shown to be closely related to the Thermofilum adornatum species. In the genome of Thermofilum sp. strain 1505, a gene cluster (TCARB_0867-TCARB_0879) was found that included genes of anaerobic (Ni,Fe-containing) carbon monoxide dehydrogenase and genes of energy-converting hydrogenase ([Ni,Fe]-CODH–ECH gene cluster). Compared to the [Ni,Fe]-CODH–ECH gene clusters occurring in the sequenced genomes of other H₂-producing carboxydotrophs, the [Ni,Fe]-CODH–ECH gene cluster of Thermofilum sp. strain 1505 presented a novel type of gene organization. The results of the study provided the first evidence of anaerobic CO oxidation coupled with H₂ production performed by a crenarchaeon, as well as the first documented case of lithotrophic growth of a Thermofilaceae representative.     

Accuracies in Po-210 determination for lead-210 dating

Various laboratory techniques have been utilized worldwide for measuring lead-210 in sub-recent deposits through its grand-daughter product polonium-210. Isotope dilution alpha spectrometry proved a suitable tool for absolute determination of lead-210 for the dating of aquatic deposits. Moreover, isotope dilution alpha spectrometry along with speciation experiments can be used to resolve depositional anomalies arising from supported lead-210/Ra-226 disequilibrium levels and unsupported lead-210 mobile fractions. Isotope dilution alpha spectrometry of sub-recent sediment and peat deposits has been critically evaluated for more than ten years. Our results show that type, size and composition of deposits analyzed as well as radiochemical procedures used, together with alpha counting techniques, are important factors influencing lead-210 determinations and tailing corrections using its granddaughter product polonium-210. Optimization of these parameters is of prime importance to achieve economic and accurate analyses, especially at low lead-210 concentrations and small sample sizes.