The nanohertz stochastic gravitational-wave background from cosmic string Loops and the abundant high redshift massive galaxies

Very recently, the Pulsar Timing Array (PTA) experiments reported strong evidence for the presence of the nanohertz stochastic gravitational wave background (SGWB). In this work we show that the cosmic string loops can account for the nanohertz SGWB data with a $G\mu \sim 2\times 10^{-12}$ and the loops number density $N \sim 10^{4}$. Though the presence of cosmic string loops can also effectively enhance the number density of massive galaxies at high redshifts, we do not find a reasonable parameter space to self-consistently interpret both the SGWB data and the JWST observations. This implies either an extension of the model adopted in this work or the different physical origins of these two phenomena

The complete mitochondrial genome of the Xinyuan honey bee, Apis mellifera sinisxinyuan (Insecta: Hymenoptera: Apidae)

We analyzed the complete mitochondrial genome of the recently discovered Xinyuan honey bee, Apis mellifera sinisxinyuan using single molecule real-time sequencing. The mitochondrial genome of A. m. sinisxinyuan is a circular molecule of 16,886 bp, comprising 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes and a control region rich in A + T. Phylogenetic analysis using 13 protein-coding genes supports a close relationship to another M-lineage honey bee, A. m. mellifera

Disruption of Gene <i>pqq</i>A or <i>pqq</i>B Reduces Plant Growth Promotion Activity and Biocontrol of Crown Gall Disease by <i>Rahnella aquatilis</i> HX2

<div><p><i>Rahnella aquatilis</i> strain HX2 has the ability to promote maize growth and suppress sunflower crown gall disease caused by <i>Agrobacterium vitis, A. tumefaciens,</i> and <i>A. rhizogenes</i>. Pyrroloquinoline quinone (PQQ), a cofactor of aldose and alcohol dehydrogenases, is required for the synthesis of an antibacterial substance, gluconic acid, by HX2. Mutants of HX2 unable to produce PQQ were obtained by in-frame deletion of either the <i>pqq</i>A or <i>pqq</i>B gene. In this study, we report the independent functions of <i>pqq</i>A and <i>pqq</i>B genes in relation to PQQ synthesis. Interestingly, both the <i>pqq</i>A and <i>pqq</i>B mutants of <i>R. aquatilis</i> eliminated the ability of strain HX2 to produce antibacterial substance, which in turn, reduced the effectiveness of the strain for biological control of sunflower crown gall disease. The mutation also resulted in decreased mineral phosphate solubilization by HX2, which reduced the efficacy of this strain as a biological fertilizer. These functions were restored by complementation with the wild-type <i>pqq</i> gene cluster. Additionally, the phenotypes of HX2 derivatives, including colony morphology, growth dynamic, and pH change of culture medium were impacted to different extents. Our findings suggested that <i>pqq</i>A and <i>pqq</i>B genes individually play important functions in PQQ biosynthesis and are required for antibacterial activity and phosphorous solubilization. These traits are essential for <i>R. aquatilis</i> efficacy as a biological control and plant growth promoting strain. This study enhances our fundamental understanding of the biosynthesis of an environmentally significant cofactor produced by a promising biocontrol and biological fertilizer strain.</p></div

RP-HPLC detection of PQQ synthesized by <i>R. aquatilis</i> HX2 and derivative strains.

<p>Arrows indicate 5-acetonyl-PQQ.</p

Green house pot experiment: effect of HX2 and derivative strains on maize plant height and weight and soil total P and soluble P.

<p>Mean ± standard error values followed by different letters indicate statistically significant (<i>P</i><0.05).</p>a<p>CK is negative control, LB medium only.</p><p>Green house pot experiment: effect of HX2 and derivative strains on maize plant height and weight and soil total P and soluble P.</p

The Impacts of the Freezing–Thawing Process on Benthic Macroinvertebrate Communities in Riffles and Pools: A Case Study of China’s Glacier-Fed Stream

Glacier-fed streams are one of the environments most sensitive to global climate change. However, the effects of the freezing–thawing process on benthic macroinvertebrate communities in different habitats of glacier-fed streams are unclear. In this paper, we investigated benthic macroinvertebrates in riffles and pools of a glacier-fed stream in Xinjiang, China, during the pre-freezing period (November, 2018), freezing period (January 2019), and thawing period (April, 2019). Our results showed that the freezing–thawing process resulted in a decline in benthic macroinvertebrate species richness and diversity, both of which were attributed to the effects of the freezing–thawing process on habitat stability, water quality, and cycling of the stream ecosystems. During the whole freezing–thawing process, the indicator taxa of riffles were Rhithrogena sp. and Baetis sp., while the only indicator taxon of pools was Chironomus sp. The species richness, Margalef diversity, and EPT richness (Ephemeroptera, Plecoptera, and Trichoptera) of benthic macroinvertebrates in riffles were higher than those in pools, due to the higher habitat heterogeneity in the riffles. However, the density in riffles was significantly lower than that in pools during the freezing period (p < 0.05). Additionally, pools were dominated by taxa with higher resilience and resistance traits, such as “bi- or multi-voltine”, “abundant occurrence in drift”, and “small size at maturity”. This result indicated that pools provide a temporary refuge for benthic macroinvertebrates in the extreme environment of glacier-fed streams. The freezing–thawing process plays an essential role in the formation of the structure and function of the stream ecosystem. Our results can help us to further understand the winter ecological process of headwater streams, and provide a reference for stream biodiversity conservation in cold regions