Desiccation tolerance of Botryococcus braunii (Trebouxiophyceae, Chlorophyta) and extreme temperature tolerance of dehydrated cells

Botryococcus braunii Kützing, a green colonial microalga, occurs worldwide in both freshwater and brackish water environments. Despite considerable attention to B. braunii as a potential source of renewable fuel, many ecophysiological properties of this alga remain unknown. Here, we examined the desiccation and temperature tolerances of B. braunii using two newly isolated strains BOD-NG17 and BOD-GJ2. Both strains survived through 6- and 8-month desiccation treatments but not through a 12-month treatment. Interestingly, the desiccation-treated cells of B. braunii gained tolerance to extreme temperature shifts, i.e., high temperature (40 °C) and freezing (−20 °C). Both strains survived for at least 4 and 10 days at 40 and −20 °C, respectively, while the untreated cells barely survived at these temperatures. These traits would enable long-distance dispersal of B. braunii cells and may account for the worldwide distribution of this algal species. Extracellular substances such as polysaccharides and hydrocarbons seem to confer the desiccation tolerance

Effect of Fe3+ on Phase Relations in the Lower Mantle : Implications for Redox Melting in Stagnant Slabs

Recent studies have revealed that Earth's deep mantle may have a wider range of oxygen fugacities than previously thought. Such a large heterogeneity might be caused by material subducted into the deep mantle. However, high-pressure phase relations are poorly known in systems including Fe3+ at the top of the lower mantle, where the subducted slab may be stagnant. We therefore conducted high-pressure and high-temperature experiments using a multi-anvil apparatus to study the phase relations in a Fe3+-bearing system at 26 GPa and 1573–2073 K, at conditions prevailing at the top of the lower mantle. At temperatures below 1923 K, MgSiO3-rich bridgmanite, an Fe3+-rich oxide phase, and SiO2 coexist in the recovered sample. Quenched partial melt was observed above 1973 K, which is significantly lower than the solidus temperature of an equivalent Fe3+-free bulk composition. The partial melt obtained from the Fe3+-rich bulk composition has a higher iron content than coexisting bridgmanite, similar to the Fe2+-dominant system. The results suggest that strong mantle oxygen fugacity anomalies might alter the subsolidus and melting phase relations under lower mantle conditions. We conclude that (1) a small amount of melt may be generated from an Al-depleted region of a stagnant slab, such as subducted former banded-iron-formation, and (2) Fe3+ is not transported into the deep part of the lower mantle because of its incompatibility during melting

ニュウサンキン コウボ ニヨリ ハッコウ ジュクセイ サセタ ショクブツ ハッコウ エキス ノ ユウコウ セイ ニ カンスル ケンキュウ

植物性食品を中心とした食生活は、生活習慣病の予防や治療に効果があるとされている。乳酸菌や酵母により発酵熟成させた植物発酵エキスは、多種多様な植物性原料を用いて、発酵と糖蔵という伝統的な食品保存技術を応用した発酵食品である。本研究では、植物発酵エキスの有効性(栄養的特性や保健機能)に関する研究を行った。植物発酵エキスには、58.5%の炭水化物、3.7%のタンパク質、1.3%の脂質をはじめ、18種類のタンパク質構成アミノ酸や種々のビタミン類、食物繊維、ファイトケミカル(ポリフェノール、テルペノイド等)が含まれていた。さらに、植物発酵エキスは抗酸化作用、血圧上昇抑制作用、抗菌作用、抗アレルギー作用、抗炎症作用、チロシナーゼ阻害作用を有していることを「in vitro 試験」により明らかにした。A plant-based diet is thought to be better for the prevention and treatment of lifestyle-related diseases. A plant-based extract fermented by lactic acid bacteria and yeast (PELY) was made from various plant materials and was fermented product applying to traditional food-preservation technique, that is, fermentation and sugaring. In this study, the characterization and physiological function of PELY were examined.PELY contained 58.8% carbohydrate, 3.7% protein, and 1.3% lipid. It contained 18 kinds of amino acids and vitamin A, B1, B2, B6, B12, E, K, niacin, pantothenic acid, and folic acid. It also did a lot of dietary fiber and phytochemicals (polyphenol, terpenoid, i.e.).Moreover, PELY had several physiological functions such as antioxidant, antihypertensive, antibacterial, anti-allergy, anti-inflammatory and anti-tyrosinase activities in vitro

The dynamics of the microbiome in Ixodidae are shaped by tick ontogeny and pathogens in Sarawak, Malaysian Borneo

Tick-borne diseases have recently been considered a potential emerging public health threat in Malaysia; however, fundamental studies into tick-borne pathogens and microbiome appear limited. In this study, six tick species (Ixodes granulatus, Haemaphysalis hystricis, Haemaphysalis shimoga, Dermacentor compactus, Dermacentor steini and Dermacentor atrosignatus) collected from two primary forests and an oil palm plantation in Sarawak, Malaysian Borneo, were used for microbiome analysis targeting bacterial 16S rDNA using next-generation sequencing (NGS). In addition, bacterial species were further characterized in conventional PCRs to identify potential pathogens. Sequences generated from NGS were first filtered with the Decontam package in R before subsequent microbial diversity analyses. Alpha and beta analyses revealed that the genus Dermacentor had the highest microbial diversity, and H. shimoga significantly differed in microbial composition from other tick species. Alpha and beta diversities were also significantly different between developmental stages of H. shimoga. Furthermore, we observed that some bacterial groups were significantly more abundant in certain tick species and developmental stages of H. shimoga. We tested the relative abundances using pairwise linear discriminant analysis effect size (LEfSe), which also revealed significant microbial composition differences between Borrelia -positive and Borrelia -negative I. granulatus ticks. Finally, pathogenic and potentially pathogenic bacteria circulating in different tick species, such as Rickettsia heilongjiangensis , Ehrlichia sp., Anaplasma sp. and Bartonella spp. were characterized by PCR and sequencing. Moreover, Coxiella and Francisella -like potential symbionts were identified from H. shimoga and D. steini, respectively. More studies are required to unravel the factors associated with the variations observed in this study

Complete Genomic Structure of the Bloom-forming Toxic Cyanobacterium Microcystis aeruginosa NIES-843

The nucleotide sequence of the complete genome of a cyanobacterium, Microcystis aeruginosa NIES-843, was determined. The genome of M. aeruginosa is a single, circular chromosome of 5 842 795 base pairs (bp) in length, with an average GC content of 42.3%. The chromosome comprises 6312 putative protein-encoding genes, two sets of rRNA genes, 42 tRNA genes representing 41 tRNA species, and genes for tmRNA, the B subunit of RNase P, SRP RNA, and 6Sa RNA. Forty-five percent of the putative protein-encoding sequences showed sequence similarity to genes of known function, 32% were similar to hypothetical genes, and the remaining 23% had no apparent similarity to reported genes. A total of 688 kb of the genome, equivalent to 11.8% of the entire genome, were composed of both insertion sequences and miniature inverted-repeat transposable elements. This is indicative of a plasticity of the M. aeruginosa genome, through a mechanism that involves homologous recombination mediated by repetitive DNA elements. In addition to known gene clusters related to the synthesis of microcystin and cyanopeptolin, novel gene clusters that may be involved in the synthesis and modification of toxic small polypeptides were identified. Compared with other cyanobacteria, a relatively small number of genes for two component systems and a large number of genes for restriction-modification systems were notable characteristics of the M. aeruginosa genome