Alternative splicing level related to intron size and organism complexity

Background Alternative splicing is the process of selecting different combinations of splice sites to produce variably spliced mRNAs. However, the relationships between alternative splicing prevalence and level (ASP/L) and variations of intron size and organism complexity (OC) remain vague. Here, we developed a robust protocol to analyze the relationships between ASP/L and variations of intron size and OC. Approximately 8 Tb raw RNA-Seq data from 37 eumetazoan species were divided into three sets of species based on variations in intron size and OC. Results We found a strong positive correlation between ASP/L and OC, but no correlation between ASP/L and intron size across species. Surprisingly, ASP/L displayed a positive correlation with mean intron size of genes within individual genomes. Moreover, our results revealed that four ASP/L-related pathways contributed to the differences in ASP/L that were associated with OC. In particular, the spliceosome pathway displayed distinct genomic features, such as the highest gene expression level, conservation level, and fraction of disordered regions. Interestingly, lower or no obvious correlations were observed among these genomic features. Conclusions The positive correlation between ASP/L and OC ubiquitously exists in eukaryotes, and this correlation is not affected by the mean intron size of these species. ASP/L-related splicing factors may play an important role in the evolution of OC.

Ecological assessment of the lowland relit forest “Bosco delle Sorti della Partecipanza” in Trino (North-Western Italy), applying Diptera Syrphidae as bioindicators

The survey has been realized in the lowland relict forest Bosco delle Sorti della Partecipanza, a site situated in Trino (Piedmont, North-Western Italy), to assess the ecological conservation level of forest habitats using the Syrph the Net methodology. 67 species were recorded, using three Malaise traps, seven Emergence traps and several Net transect in the year 2020. Among these species, 6 are reported for the first time in Piedmont region, 19 are considered decreasing at European level and 2 are threatened in Europe. Forest habitats under scrutiny in the study area are oak-hornbeam mesophilic woodland and alluvial alder lowland. The data analysis allowed to compare observed with expected syrphids for each habitat. At the ecosystem level, the ecological integrity of the forest is moderately negative but the alluvial alder forest macrohabitat can be considered good and overall saproxylic and saprophagous species are particularly well-preserved. The presence of a high number of rare or decreasing species makes Trino wood an important source of biodiversity in Po Plain.

Annotation of snoRNA abundance across human tissues reveals complex snoRNA-host gene relationships

Background Small nucleolar RNAs (snoRNAs) are mid-size non-coding RNAs required for ribosomal RNA modification, implying a ubiquitous tissue distribution linked to ribosome synthesis. However, increasing numbers of studies identify extra-ribosomal roles of snoRNAs in modulating gene expression, suggesting more complex snoRNA abundance patterns. Therefore, there is a great need for mapping the snoRNome in different human tissues as the blueprint for snoRNA functions. Results We used a low structure bias RNA-Seq approach to accurately quantify snoRNAs and compare them to the entire transcriptome in seven healthy human tissues (breast, ovary, prostate, testis, skeletal muscle, liver, and brain). We identify 475 expressed snoRNAs categorized in two abundance classes that differ significantly in their function, conservation level, and correlation with their host gene: 390 snoRNAs are uniformly expressed and 85 are enriched in the brain or reproductive tissues. Most tissue-enriched snoRNAs are embedded in lncRNAs and display strong correlation of abundance with them, whereas uniformly expressed snoRNAs are mostly embedded in protein-coding host genes and are mainly non- or anticorrelated with them. Fifty-nine percent of the non-correlated or anticorrelated protein-coding host gene/snoRNA pairs feature dual-initiation promoters, compared to only 16% of the correlated non-coding host gene/snoRNA pairs. Conclusions Our results demonstrate that snoRNAs are not a single homogeneous group of housekeeping genes but include highly regulated tissue-enriched RNAs. Indeed, our work indicates that the architecture of snoRNA host genes varies to uncouple the host and snoRNA expressions in order to meet the different snoRNA abundance levels and functional needs of human tissues.

Structural analysis of viral ExoN domains reveals polyphyletic hijacking events

Nidoviruses and arenaviruses are the only known RNA viruses encoding a 3’-5’ exonuclease domain (ExoN). The proofreading activity of the ExoN domain has played a key role in the growth of nidoviral genomes, while in arenaviruses this domain partakes in the suppression of the host innate immune signaling. Sequence and structural homology analyses suggest that these proteins have been hijacked from cellular hosts many times. Analysis of the available nidoviral ExoN sequences reveals a high conservation level comparable to that of the viral RNA-dependent RNA polymerases (RdRp), which are the most conserved viral proteins. Two highly preserved zinc fingers are present in all nidoviral exonucleases, while in the arenaviral protein only one zinc finger can be identified. This is in sharp contrast with the reported lack of zinc fingers in cellular ExoNs, and opens the possibility of therapeutic strategies in the struggle against COVID-19.

Dynamics and modulation of the human snoRNome

BackgroundSmall nucleolar RNAs (snoRNAs) are mid-size non-coding RNAs required for ribosomal RNA modification, implying a ubiquitous tissue distribution linked to ribosome synthesis. However, increasing numbers of studies identify extra-ribosomal roles of snoRNAs in modulating gene expression, suggesting more complex snoRNA expression patterns. Therefore, there is a great need for mapping the snoRNome in different human tissues as the blueprint for snoRNA functions.ResultsWe used a low structure bias RNA-Seq approach to accurately quantify snoRNAs and compare them to the entire transcriptome in seven healthy human tissues (breast, ovary, prostate, testis, skeletal muscle, liver and brain). We identified 475 expressed snoRNAs categorized in two abundance classes that differ significantly in their function, conservation level and correlation with their host gene: 390 snoRNAs are uniformly expressed and 85 are enriched in the brain or reproductive tissues. Most tissue-enriched snoRNAs are embedded in lncRNAs and display strong correlation of abundance with them, whereas uniformly expressed snoRNAs are mostly embedded in protein-coding host genes and are mainly non- or anticorrelated with them. 59% of the non-correlated or anticorrelated protein-coding host gene/snoRNA pairs feature dual-initiation promoters, as opposed to only 16% of the correlated non-coding host gene/snoRNA pairs.ConclusionsOur results demonstrate that snoRNAs are not a single homogeneous group of housekeeping genes but include highly regulated tissue-enriched RNAs. Indeed, our work indicates that the architecture of snoRNA host genes varies to uncouple the host and snoRNA expressions in order to meet the different snoRNA abundance levels and functional needs of human tissues.

Structural analysis of viral ExoN domains reveals polyphyletic hijacking events

Nidoviruses and arenaviruses are the only known RNA viruses encoding a 3’-5’ exonuclease domain (ExoN). The proofreading activity of the ExoN domain has played a key role in the growth of nidoviral genomes, while in arenaviruses this domain partakes in the suppression of the host innate immune signaling. Sequence and structural homology analyses suggest that these proteins have been hijacked from cellular hosts many times. Analysis of the available nidoviral ExoN sequences reveals a high conservation level comparable to that of the viral RNA-dependent RNA polymerases (RdRp), which are the most conserved viral proteins. Two highly preserved zinc fingers are present in all nidoviral exonucleases, while in the arenaviral protein only one zinc finger can be identified. This is in sharp contrast with the reported lack of zinc fingers in cellular ExoNs, and opens the possibility of therapeutic strategies in the struggle against COVID-19.

The ethnobotanical perspective of indigenous herbs and spices of Tabaru ethnic group in Halmahera island, Indonesia

Herbs and spices have been used for many years as an important source of food ingredients. Recently, herbs and spices have been used as the source of medicinal materials due to its rich-bioactive compounds content. However, the knowledge about the scientific background of these herbs and spices uses in the local community is based on limited data. This work aims to study the perspective of the Tabaru ethnic group toward the use of herbs and spices as an additional food source. This study was conducted between November and December, 2018 in Halmahera Island. The data and information about the use of herbs and spices were collected from 48 locals whose ages ranged between 40 and 89 years. The main occupation of respondents was farming of mainly nutmeg, clove, and coconut. The data were analyzed based on plant uses which included spices, food, and drug use. Data on plant species were analyzed using the Cultural Food Significance Index (CFSI) formula. The results showed that the Tabaru ethnic group used approximately 14 plant species as herbs and spices. According to the CFSI values,herbs and spices in very high significance group include Curcuma longaL. (value of CFSI, 460.8), Cinnamomum burmanni(Nees & T. Nees) Neeex Blume, Myristica fragrans Houtt., Curcuma domestica Valeton, and Zingiber officinale Roscoe (CFSI, 259.2). Moreover, in the high significance category, Capsicum annuum L. is listed with high CFSI score reaching 86.4. In the moderate significance category, we found about four species, namely Ocimum americanum L. and Ocimum americanum L. (CFSI, 48.6), Etlingera heliconiifolia(K. Schum.) AD Poulsen (CFSI, 24.3), Alpinia galanga(L.) Willd. (CFSI, 23,625). Finally, two species of Etlingera elatior(Jack) R.M.Sm. (CFSI, 17.82) and Alpinia eremochlamys K.Schum. (CFSI, 15.53) were in the low significance group. In conclusion, the value of CFSI has a positive correlation to the utilization and the conservation level of herbs and spices of Tabaru ethnic group in Halmahera Island.

The Functional Examination of Conserved and Non-conserved lncRNA in Allotetraploid Gossypium hirsutum

Background The relationship between the lncRNA conservation level and its function is controversial. One of the technique barrier to address this question is how to define the conserved non-coding genes across species.Results We developed an evolutionary model using diploid and allotetraploid cotton species to identify 80% of the non-coding transcripts unique to the allotetraploid cotton in comparison with its diploid ancestors. This led us to define conserved lncRNA and non-conserved lncRNA based on their conservation throughout polyploid evolution. LncRNA expression was preferentially associated with the flanking protein-coding genes, indicating a regulatory role in cis in response to environmental stimuli. However, the conserved and non-conserved lncRNAs showed no difference in their levels of association with the expression of the flanking protein-coding genes. The 111 selected highly expressed conserved and non-conserved lncRNA candidates were subjected to a virus-induced gene silencing operation that was integrated with abiotic stress treatments. From the low-throughput, functional screening pilot test, we obtained candidate lncRNAs related to plant height, tolerance to drought and other abiotic stresses. Conclusions The conservation level of the lncRNAs may impact on their expression patterns and functions as individual case rather than in genome wide.

Identification of Lysine Acetylation Sites on MERS-CoV Replicase pp1ab

MERS is a life-threatening disease and MERS-CoV has the potential to cause the next pandemic. Protein acetylation is known to play a crucial role in host response to viral infection. Acetylation of viral proteins encoded by other RNA viruses have been reported to affect viral replication. It is therefore of interest to see whether MERS-CoV proteins are also acetylated. Viral proteins obtained from infected cells were trypsin-digested into peptides. Acetylated peptides were enriched by immunoprecipitation and subject to nano-LC-Orbitrap analysis. Bioinformatic analysis was performed to assess the conservation level of identified acetylation sites and to predict the upstream regulatory factors. A total of 12 acetylation sites were identified from 7 peptides, which all belong to the replicase polyprotein pp1ab. All identified acetylation sites were found to be highly conserved across MERS-CoV sequences in NCBI database. Upstream factors, including deacetylases of the SIRT1 and HDAC families as well as acetyltransferases of the TIP60 family, were predicted to be responsible for regulating the acetylation events identified. Western blotting confirms that acetylation events indeed occur on pp1ab protein by expressing NSP4 in HEK293 cells. Acetylation events on MERS-CoV viral protein pp1ab were identified for the first time, which indicate that MERS-CoV might use the host acetylation machinery to regulate its enzyme activity and to achieve optimal replication. Upstream factors were predicted, which might facilitate further analysis of the regulatory mechanism of MERS-CoV replication.