Cryptococcus neoformans is an opportunistic fungal pathogen that causes approximately 625,000 deaths per year from nervous system infections. Here, we leveraged a unique, genetically diverse population of C. neoformans from sub-Saharan Africa, commonly isolated from mopane trees, to determine how selective pressures in the environment coincidentally adapted C. neoformans for human virulence. Genome sequencing and phylogenetic analysis of 387 isolates, representing the global VNI and African VNB lineages, highlighted a deep, nonrecombining split in VNB (herein, VNBI and VNBII). VNBII was enriched for clinical samples relative to VNBI, while phenotypic profiling of 183 isolates demonstrated that VNBI isolates were significantly more resistant to oxidative stress and more heavily melanized than VNBII isolates. Lack of melanization in both lineages was associated with loss-of-function mutations in the BZP4 transcription factor. A genome-wide association study across all VNB isolates revealed sequence differences between clinical and environmental isolates in virulence factors and stress response genes. Inositol transporters and catabolism genes, which process sugars present in plants and the human nervous system, were identified as targets of selection in all three lineages. Further phylogenetic and population genomic analyses revealed extensive loss of genetic diversity in VNBI, suggestive of a history of population bottlenecks, along with unique evolutionary trajectories for mating type loci. These data highlight the complex evolutionary interplay between adaptation to natural environments and opportunistic infections, and that selection on specific pathways may predispose isolates to human virulence.

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A glabrous, yellow-seeded doubled haploid (DH) line and a hairy, black-seeded DH line in Chinese cabbage (B. rapa) were used as parents to develop a DH line population that segregated for both hairiness and seed coat color traits. The data showed that both traits completely co-segregated each other, suggesting that one Mendelian locus controlled both hairiness and seed coat color in this population. A fine genetic map was constructed and a SNP marker that was located inside a Brassica ortholog of TRANSPARENT TESTA GLABRA 1 (TTG1) in Arabidopsis showed complete linkage to both the hairiness and seed coat color gene, suggesting that the Brassica TTG1 ortholog shared the same gene function as its Arabidopsis counterpart. Further sequence analysis of the alleles from hairless, yellow-seeded and hairy, black-seeded DH lines in B. rapa showed that a 94-base deletion was found in the hairless, yellow-seeded DH lines. A nonfunctional truncated protein in the hairless, yellow-seeded DH lines in B. rapa was suggested by the coding sequence of the TTG1 ortholog. Both of the TTG1 homologs from the black and yellow seeded B. rapa lines were used to transform an Arabidopsis ttg1 mutant and the results showed that the TTG1 homolog from the black seeded B. rapa recovered the Arabidopsis ttg1 mutant, while the yellow seeded homolog did not, suggesting that the deletion in the Brassica TTG1 homolog had led to the yellow seeded natural mutant. This was the first identified gene in Brassica species that simultaneously controlled both hairiness and seed coat color traits.

Nationwide prospective surveillance of all-age patients with acute respiratory infections was conducted in China between 2009‒2019. Here we report the etiological and epidemiological features of the 231,107 eligible patients enrolled in this analysis. Children <5 years old and school-age children have the highest viral positivity rate (46.9%) and bacterial positivity rate (30.9%). Influenza virus, respiratory syncytial virus and human rhinovirus are the three leading viral pathogens with proportions of 28.5%, 16.8% and 16.7%, and Streptococcus pneumoniae, Mycoplasma pneumoniae and Klebsiella pneumoniae are the three leading bacterial pathogens (29.9%, 18.6% and 15.8%). Negative interactions between viruses and positive interactions between viral and bacterial pathogens are common. A Join-Point analysis reveals the age-specific positivity rate and how this varied for individual pathogens. These data indicate that differential priorities for diagnosis, prevention and control should be highlighted in terms of acute respiratory tract infection patients’ demography, geographic locations and season of illness in China.

Cajal bodies (CBs) are distinct sub-nuclear structures that are present in eukaryotic living cells and are often associated with the nucleolus. CBs play important roles in RNA metabolism and formation of RNPs involved in transcription, splicing, ribosome biogenesis, and telomere maintenance. Besides these primary roles, CBs appear to be involved in additional functions that may not be directly related to RNA metabolism and RNP biogenesis. In this review, we assess possible roles of plant CBs in RNA regulatory pathways such as nonsense-mediated mRNA decay and RNA silencing. We also summarize recent progress and discuss new non-canonical functions of plant CBs in responses to stress and disease. It is hypothesized that CBs can regulate these responses via their interaction with poly(ADP ribose)polymerase (PARP), which is known to play an important role in various physiological processes including responses to biotic and abiotic stresses. It is suggested that CBs and their components modify PARP activities and functions.

Though the ''RNA world'' hypothesis has gained a central role in ideas concerning the origin of life, the scenario concerning its emergence remains uncertain. It has been speculated that the first scene may have been the emergence of a template-dependent RNA synthetase ribozyme, which catalyzed its own replication: thus, ''RNA replicase.'' However, the speculation remains uncertain, primarily because of the large sequence length requirement of such a replicase and the lack of a convincing mechanism to ensure its self-favoring features. Instead, we propose a nucleotide synthetase ribozyme as an alternative candidate, especially considering recent experimental evidence suggesting the possibility of effective nonenzymatic templatedirected synthesis of RNA. A computer simulation was conducted to support our proposal. The conditions for the emergence of the nucleotide synthetase ribozyme are discussed, based on dynamic analysis on a computer. We suggest the templatedependent RNA synthetase ribozyme emerged later, perhaps after the emergence of protocells.

Emaravirus is a recently described genus of negative-strand RNA plant viruses. Emaravirus P4 protein localizes to plasmodesmata, suggesting that it could be a viral movement protein (MP). In the current study, we showed that the P4 protein of raspberry leaf blotch emaravirus (RLBV) rescued the cell-to-cell movement of a defective potato virus X (PVX) that had a deletion mutation in the triple gene block 1 movement-associated protein. This demonstrated that RLBV P4 is a functional MP. Sequence analyses revealed that P4 is a distant member of the 30K superfamily of MPs. All MPs of this family contain two highly conserved regions predicted to form b-strands, namely b1 and b2. We explored by alanine mutagenesis the role of two residues of P4 (Ile106 and Asp127) located in each of these strands. We also made the equivalent substitutions in the 29K MP of tobacco rattle virus, another member of the 30K superfamily. All substitutions abolished the ability to complement PVX movement, except for the I106A substitution in the b1 region of P4. This region has been shown to mediate membrane association of 30K MPs; our results show that it is possible to make non-conservative substitutions of a well-conserved aliphatic residue within b1 without preventing the membrane association or movement function of P4.

Quantitative real-time reverse transcriptase polymerase chain reaction (qRT-PCR) is an effective method for quantifying expression levels of target genes. The accuracy of qRT-PCR results is largely dependent on the selection of stable reference genes. The stability of reference gene expression may vary with plant species and environmental conditions. The objective of this study was to select stable reference genes for qRT-PCR analysis of target genes in different organs under different abiotic stresses for a perennial grass species, bermudagrass (Cynodon dactylon). The stability of eight potential reference genes (TUB, ACT, GAPDH, EF1α, TIP41, PP2A, CACS and UPL7) was evaluated under four different abiotic stresses (salt, drought, cold and heat) and in leaves and roots of bermudagrass. Four programs (geNorm, NormFinder, BestKeeper and RefFinder) were employed to evaluate the stability of reference gene expression and to identify the most stable reference genes for bermudagrass. Eight potential reference genes exhibited differential expression stability in leaves and roots under salt, drought, cold and heat stress. The expression levels of PP2A and CACS were stable in roots and leaves under salt stress, in leaves under drought stress and in roots exposed to cold and heat stress. EF1α and TIP41 expression was stable in roots of drought-stressed plants. UPL7, TUB and GAPDH were stably expressed in leaves under cold stress. Expression levels of PP2A and TIP41 were stable in leaves under heat stress. The use of the reference genes identified as internal controls for examination of gene expression patterns and quantification of expression levels of target genes will enable accurate qRT-PCR analysis in bermudagrass.