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The extensive environmental adaptability of the genus Paenibacillus is related to the enormous diversity of its gene repertoires. Paenibacillus sp. SSG-1 has previously been reported, and its agar-degradation trait has attracted our attention. Here, the genome sequence of Paenibacillus sp. SSG-1, together with 76 previously sequenced strains, was comparatively studied. The results show that the pan-genome of Paenibacillus is open and indicate that the current taxonomy of this genus is incorrect. The incessant flux of gene repertoires resulting from the processes of gain and loss largely contributed to the difference in genomic content and genome size in Paenibacillus. Furthermore, a large number of genes gained are associated with carbohydrate transport and metabolism. It indicates that the evolution of glycometabolism is a key factor for the environmental adaptability of Paenibacillus species. Interestingly, through horizontal gene transfer, Paenibacillus sp. SSG-1 acquired an approximately 150 kb DNA fragment and shows an agar-degrading characteristic distinct from most other non-marine bacteria. This region may be transported in bacteria as a complete unit responsible for agar degradation. Taken together, these results provide insights into the evolutionary pattern of Paenibacillus and have implications for studies on the taxonomy and functional genomics of this genus.

Prototheca stagnorum belongs to the genus Prototheca that are achloroplyllous algae with phylogenetic affinities to Chlorella sp. Microalgae of the genus Prototheca spp are associated with rare algal infections of invertebrates termed protothecosis. In this study, the complete nucleotide sequence of the circular mitochondrial (mt) DNA of the chlorophyte alga P. stagnorum has been determined (80,023 base-pairs, A þ T content 13.77%). The genes identified encode three subunits of the cytochrome oxidase and apocytochrome b, eight subunits of the NADH dehydrogenase complex (nad1-7, nad4L), four ATPase subunits (atp1, atp4, atp6, atp8), three ribosomal RNAs (5 S (rrn5), small subunit (srn) and large subunit (lrn) RNA), 27 tRNAs, two succinate dehydrogenase and 10 ribosome proteins. The complete mitochondrial genome sequence will provide new molecular biology information to further understand the genetic diversity of the Prototheca sp. and to eliminate this population.

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Background Dunaliella salina is a high-quality industrial effector for carotenoid production. Although the accumulation of carotenoids in D. salina increases under red light conditions, the content of carotenoids in the algal cell decreases. The mechanism by which red light regulates carotenoid synthesis is still unclear.Results In this study, a transcription factor of DsGATA1 with a distinct structure was discovered in D. salina. The recognition motif of DsGATA1 was comparable to that of plant and fungal GATA, despite its evolutionary proximity to animal-derived GATA. The expression of DsGATA1 in D. salina was still noticeably decreased when exposed to red light. Analysis of physiological and biochemical transcriptomic data from overexpressed, interfering and wild-type strains of DsGATA1 revealed that DsGATA1 acts as a global regulator of D. salina carotenoid synthesis. The upregulated genes in the CBP pathway by DsGATA1 were involved in its regulation of the synthesis of carotenoids. DsGATA1 also enhanced carotenoid accumulation under red light by affecting N metabolism. DsGATA1 was found to directly bind to the promoter of nitrate reductase to activate its expression, promoting D. salina nitrate uptake and accelerating biomass accumulation. DsGATA1 affected the expression of the genes encoding GOGAT, GDH and ammonia transporter proteins. Moreover, our study revealed that the regulation of N metabolism by DsGATA1 led to the production of NO molecules that inhibited carotenoid synthesis. However, DsGATA1 significantly enhanced carotenoid synthesis by NO scavenger removal of NO. The D. salina carotenoid accumulation under red light was elevated by 46% in the presence of overexpression of DsGATA1 and NO scavengers.Conclusion It was found that a transcription factor of DsGATA1 from D. salina has a distinct structure and recognition motif. The novel gene encoding DsGATA1 enhanced the production of carotenoids under red light and endowed D. salina with high algal biomass. The regulation of terpenoid metabolism by DsGATA1 is different from that reported for GATA factors. DsGATA1 yet enhanced the production of NO in D. salina. Nevertheless, our results indicated that DsGATA1 could be an important target for engineering carotenoid production.

The fat sand rats (Psammomys obesus) can easily induce obesity and acquire type 2 diabetes mellitus when they are fed with high-carbohydrate diets. P. obesus is often used as an animal model for studies on diabetes and obesity. We described 16,592 bp of P. obesus mtDNA that contains 13 protein-coding genes (PGCs), two rRNA genes (12S rRNA and 16S rRNA), 22 transfer RNA (tRNA) genes, and one control region (D-loop). The complete mitochondrial genome sequence provided here would be useful for further understanding the evolution of ratite and conservation genetics of P. obesus. ARTICLE HISTORY

Carotenoids' is a general term for a class of valuable, natural fat-soluble pigments that are distributed widely in bacteria, fungi, algae [1][2][3][4], and photosynthetic plants. In humans, however, carotenoids can only be obtained from food. Studies to elucidate the regulation of carotenoid composition in model species and accumulate target components are critical because carotenoids have important physiological functions, including an antioxidant role, immune regulation, and prevention of cardiovascular disease, certain types of cancer, eye-related diseases, and light-induced skin damage [5].Carotenoids are divided into two major classes: xanthophylls, which contain oxygen, and carotenes, which mainly consist of hydrocarbons and no oxygen. β-Carotene, the most important and effective vitamin A precursor among the carotenes, plays a vital role in human health, protecting against age-related degenerative diseases, cardiovascular disease, vitamin A deficiency (VAD), and certain cancers [6,7]. β-Carotene is catalyzed directly by β-carotene hydroxylase (BCH) to generate β-cryptoxanthin, an antioxidant that may help prevent free radical damage to biomolecules including lipids, proteins, and nucleic acids [8,9]. Studies in animal models and humans have also shown that β-cryptoxanthin derived from food has better in vitro bioavailability than α-carotene and βcarotene. Zeaxanthin, a direct product of cryptoxanthin, is a new type of oil-soluble natural pigment, which often coexists with lutein, β-carotene, and β-cryptoxanthin in nature to form a carotenoid mixture. Zeaxanthin prevents the oxidation of lipids and vitamins in food and prolongs the preservation period of food, making it an ideal natural food preservative [10,11]. Recognition of the importance of the rich variety and functional diversity of carotenoids has resulted in increased demand and focus on how to improve the production of natural carotenoids.The accumulation of certain metabolites often affects the composition of the carotenoid biosynthesis pathway. The cyclization reaction of lycopene converts lycopene into α-carotene and β-carotene and is an essential reaction for the production of β-carotene, which has important physiological functions in algae [12,13]. The lycopene β cyclase (LCYB) gene is related directly to the production of β-carotene, and therefore it is necessary to study this enzyme. It has been reported that modification of the LCYB gene affects the accumulation of its metabolites and the response to abiotic stress in some photosynthetic plants. For example, in transgenic sweet potatoes, IbLCYB2 was shown to enhance abiotic stress tolerance and carotenoid content, including α-carotene, β-carotene, lutein, βcryptoxanthin, and zeaxanthin [14]. Heterologous overexpression of DcLCYB1 in carrots was reported to increase Carotenoids, which are natural pigments found abundantly in wide-ranging species, have diverse functions and high industrial potential. The carotenoid biosynthesis pathway is very complex and has multiple branches, while the ac...

Light-harvesting chlorophyll a/b-binding (LHC) superfamily proteins play a vital role in photosynthesis. Although the physiological and biochemical functions of LHC genes have been well-characterized, the structural evolution and functional differentiation of the products need to be further studied. In this paper, we report the genome-wide identification and phylogenetic analysis of LHC genes in photosynthetic organisms. A total of 1222 non-redundant members of the LHC family were identified from 42 species. According to the phylogenetic clustering of their homologues with Arabidopsis thaliana, they can be divided into four subfamilies. In the subsequent evolution of land plants, a whole-genome replication (WGD) event was the driving force for the evolution and expansion of the LHC superfamily, with its copy numbers rapidly increasing in angiosperms. The selection pressure of photosystem II sub-unit S (PsbS) and ferrochelatase (FCII) families were higher than other subfamilies. In addition, the transcriptional expression profiles of LHC gene family members in different tissues and their expression patterns under exogenous abiotic stress conditions significantly differed, and the LHC genes are highly expressed in mature leaves, which is consistent with the conclusion that LHC is mainly involved in the capture and transmission of light energy in photosynthesis. According to the expression pattern and copy number of LHC genes in land plants, we propose different evolutionary trajectories in this gene family. This study provides a basis for understanding the molecular evolutionary characteristics and evolution patterns of plant LHCs.