A bacterial strain, BIT-26T, was isolated from the gut of plastic-eating mealworm Tenebrio molitor L. The taxonomic position of this new isolate was investigated by using a polyphasic approach. Cells of the strain were Gram-stain-negative, facultatively anaerobic, motile rods with peritrichous flagella. The 16S rRNA gene sequence (1412 bp) of strain BIT-26T showed the highest similarity (97.4 %) to
Erwinia piriflorinigrans
CFBP 5888T, followed by
Citrobacter sedlakii
NBRC 105722T (97.3 %),
Mixta calida
LMG 25383T (97.3 %),
Cronobacter muytjensii
ATCC 51329T (97.2 %) and
Mixta theicola
QC88-366 T (97.2 %). The results of phylogenetic analyses, based on the 16S rRNA gene and concatenated sequences of four housekeeping genes (atpD, gyrB, infB and rpoB), placed strain BIT-26T within the genus
Mixta
of the family
Erwiniaceae
. This affiliation was also supported by the chemotaxonomic data. Strain BIT-26T had similar predominant fatty acids, including C12 : 0, C14 : 0, C16 : 0, C17 : 0 cyclo and C19 : 0 cyclo ω8c, to species of the genus
Mixta
. In silico DNA–DNA hybridization and average nucleotide identity calculations plus physiological and biochemical tests allowed the genotypic and phenotypic differentiation of strain BIT-26T from other species of the genus
Mixta
with validly published names. Therefore, strain BIT-26T is considered to represent a novel species, for which the name Mixta tenebrionis sp. nov is proposed. The type strain is BIT-26T (=CGMCC 1.17041T=KCTC 72449T).
Most birds sit on their eggs during incubation, a behaviour that likely evolved among non-avian dinosaurs. Several 'brooding' specimens of smaller species of oviraptorosaurs and troodontids reveal these non-avian theropods sat on their eggs, although little is known of incubation behaviour in larger theropod species. Here we examine egg clutches over a large body size range of oviraptorosaurs in order to understand the potential effect of body size on incubation behaviour. Eggshell porosity indicates that the eggs of all oviraptorosaurs were exposed in the nest, similar to brooding birds. Although all oviraptorosaur clutches consist of radially arranged eggs in a ring configuration, clutch morphology varies in that the central opening is small or absent in the smallest species, becomes significantly larger in larger species, and occupies most of the nest area in giant species. Our results suggest that the smallest oviraptorosaurs probably sat directly on the eggs, whereas with increasing body size more weight was likely carried by the central opening, reducing or eliminating the load on the eggs and still potentially allowing for some contact during incubation in giant species. This adaptation, not seen in birds, appears to remove the body size constraints of incubation behaviour in giant oviraptorosaurs.
Microplastics
(MPs) are ubiquitous in the environment and pose
substantial threats to the water ecosystem. However, the impact of
natural aging of MPs on their toxicity has rarely been considered.
This study found that visible light irradiation with hydrogen peroxide
at environmentally relevant concentration for 90 days significantly
altered the physicochemical properties and mitigated the toxicity
of polyamide (PA) fragments to infantile zebrafish. The size of PA
particles was reduced from ∼8.13 to ∼6.37 μm,
and nanoparticles were produced with a maximum yield of 5.03%. The
end amino groups were volatilized, and abundant oxygen-containing
groups (e.g., hydroxyl and carboxyl) and carbon-centered free radicals
were generated, improving the hydrophilicity and colloidal stability
of degraded MPs. Compared with pristine PA, the depuration of degraded
MPs mediated by multixenobiotics resistance was much quicker, leading
to markedly lower bioaccumulation in fish and weaker inhibition on
musculoskeletal development. By integrating transcriptomics and transgenic
zebrafish [Tg(lyz:EGFP)] tests,
differences in macrophages-triggered proinflammatory effects, apoptosis
via IL-17 signaling pathway, and antioxidant damages were identified
as the underlying mechanisms for the attenuated toxicity of degraded
MPs. This work highlights the importance of natural degradation on
the toxicity of MPs, which has great implications for risk assessment
of MPs.
A bacterial strain, BIT-B35T, was isolated from the gut of plastic-eating larvae of the Coleoptera insect Zophobas atratus. Its taxonomic position was determined by using a polyphasic approach. Cells were white-pigmented, Gram-stain-negative, motile short rods with terminal flagella. The 16S rRNA gene sequence (1411 bp) of strain BIT-B35T showed highest similarity (98.1%) to
Escherichia fergusonii
ATCC 35469T and
Citrobacter koseri
LMG 5519T. The results of phylogenetic analyses, based on the 16S rRNA gene, concatenated sequences of seven housekeeping genes (atpD, gyrB, infB, rpoB, pyrG, fusA and leuS) and genome sequences, placed strain BIT-B35T in a separate lineage among the family of
Enterobacteriaceae
. The major fatty acids were C16 : 0, C17 : 0 cyclo and C19 : 0 cyclo ω8c. The genomic DNA G+C content of strain BIT-B35T was 57.1 mol%. The chemotaxonomic data plus results of physiological and biochemical tests also distinguished strain BIT-B35T from members of other genera within the family
Enterobacteriaceae
. Therefore, strain BIT-B35T is considered to represent a novel species of a novel genus within the family
Enterobacteriaceae
, for which the name Intestinirhabdus alba gen. nov., sp. nov. is proposed. The type strain is BIT-B35T (=CGMCC 1.17042T=KCTC 72448T).
Summary
Synthetic promoters are considered ideal candidates in driving robust gene expression. Most of the available synthetic promoters are minimal promoters, for which the upstream sequence of the 5′ end of the core region is usually excluded. Although the upstream sequence has been shown to mediate transcription of natural promoters, its impact on synthetic promoters has not been widely studied. Here, a library of chromosomal DNA fragments is randomly fused with the 5′ end of the J23119 synthetic promoter, and the transcriptional performance of the promoter is evaluated through β‐galactosidase assay, fluorescence intensity and chemical biosynthesis. Results show that changes in the upstream sequence can induce significant variation in the promoter strength of up to 5.8‐fold. The effect is independent of the length of the insertions and the number of potential transcription factor binding sites. Several DNA fragments that are able to enhance the transcription of both the natural and the synthetic promoters are identified. This study indicates that the synthetic minimal promoters are susceptible to the surrounding sequence context. Therefore, the upstream sequence should be treated as an indispensable component in the design and application of synthetic promoters, or as an independent genetic part for the fine‐tuning of gene expression.
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