Exploring compositional and functional characteristics of the rumen microbiome can improve the understanding of its role in rumen function and cattle feed efficiency. In this study, we applied ...metatranscriptomics to characterize the active rumen microbiomes of beef cattle with different feed efficiencies (efficient,
= 10; inefficient,
= 10) using total RNA sequencing. Active bacterial and archaeal compositions were estimated based on 16S rRNAs, and active microbial metabolic functions including carbohydrate-active enzymes (CAZymes) were assessed based on mRNAs from the same metatranscriptomic data sets. In total, six bacterial phyla (
,
,
,
,
, and
), eight bacterial families (
,
,
,
,
,
,
, and
), four archaeal clades (
,
,
, and
), 112 metabolic pathways, and 126 CAZymes were identified as core components of the active rumen microbiome. As determined by comparative analysis, three bacterial families (
,
, and
) tended to be more abundant in low-feed-efficiency (inefficient) animals (
< 0.10), and one archaeal taxon (
) tended to be more abundant in high-feed-efficiency (efficient) cattle (
< 0.10). Meanwhile, 32 microbial metabolic pathways and 12 CAZymes were differentially abundant (linear discriminant analysis score of >2 with a
value of <0.05) between two groups. Among them, 30 metabolic pathways and 11 CAZymes were more abundant in the rumen of inefficient cattle, while 2 metabolic pathways and 1 CAZyme were more abundant in efficient animals. These findings suggest that the rumen microbiomes of inefficient cattle have more diverse activities than those of efficient cattle, which may be related to the host feed efficiency variation.
This study applied total RNA-based metatranscriptomics and showed the linkage between the active rumen microbiome and feed efficiency (residual feed intake) in beef cattle. The data generated from the current study provide fundamental information on active rumen microbiome at both compositional and functional levels, which serve as a foundation to study rumen function and its role in cattle feed efficiency. The findings that the active rumen microbiome may contribute to variations in feed efficiency of beef cattle highlight the possibility of enhancing nutrient utilization and improve cattle feed efficiency through modification of rumen microbial functions.
Cancer susceptibility candidate 2 (CASC2), a recently discovered long non‐coding RNA (lncRNA), was confirmed to play numerous roles in several human cancers. However, the involvement and concrete ...mechanism of CASC2 in hepatocellular carcinoma (HCC) still need to be further elucidated. The relative expressions of CASC2 and miR‐24‐3p in HCC tissue and cell lines were determined by quantitative real‐time PCR (qRT‐PCR). The effects of CASC2 and miR‐24‐3p on HCC cells were further assessed via cell viability and apoptosis. In vivo tumorigenesis assay was performed to verify the inhibition effect of CASC2 on the tumor growth and further clarify the important role of miR‐24‐3p in this mechanism. Compared with the paired normal tissues, the relative expression of CASC2 significantly reduced in the HCC tissues, while miR‐24‐3p as determined by qRT‐PCR obviously increased in the HCC tissues. This observation was also found in HCC cell lines. Meanwhile, the expression of CASC2 was negatively related to miR‐24‐3p expression in the HCC tissues (r = −0.804, P < 0.001). CASC2 could negatively regulate the expression of miR‐24‐3p in vitro. Moreover, CASC2 overexpression resulted in the growth inhibitory and apoptosis‐inducing effects on HCC cells, but the up‐regulation of miR‐24‐3p greatly eliminated the CASC2‐induced effects. The tumorigenesis of HCC cells was restrained significantly by CASC2 overexpression as shown by decreased tumor volume and growth rate. However, miR‐24‐3p up‐regulation rescued the inhibition of CASC2 on the tumor growth in tumor‐bearing mice. LncRNA CASC2 inhibited the viability and induced the apoptosis of HCC cells through regulating miR‐24‐3p.
We investigated the involvement and concrete mechanism of CASC2 in HCC. CASC2 inhibited the viability and induced the apoptosis of HCC cells. The role of CASC2 in cell tumorigenesis was mediated by miR‐24‐3p.
We present space‐ and ground‐based multi‐instrument observations demonstrating the impact of the 2022 Tonga volcanic eruption on dayside equatorial electrodynamics. A strong counter electrojet (CEJ) ...was observed by Swarm and ground‐based magnetometers on 15 January after the Tonga eruption and during the recovery phase of a moderate geomagnetic storm. Swarm also observed an enhanced equatorial electrojet (EEJ) preceding the CEJ in the previous orbit. The observed EEJ and CEJ exhibited complex spatiotemporal variations. We combine them with the Ionospheric Connection Explorer neutral wind measurements to disentangle the potential mechanisms. Our analysis indicates that the geomagnetic storm had minimal impact; instead, a large‐scale atmospheric disturbance propagating eastward from the Tonga eruption site was the most likely driver for the observed intensification and directional reversal of the equatorial electrojet. The CEJ was associated with strong eastward zonal winds in the E‐region ionosphere, as a direct response to the lower atmosphere forcing.
Plain Language Summary
The Earth's E‐region ionosphere (∼100–150 km altitude) consists of both ionized and neutral gasses, and the two components are coupled through ion‐neutral collisions. The state of this region is closely influenced by neutral atmospheric activities from the lower atmosphere and the variability of the solar drivers. On 15 January 2022, the Tonga volcano had a massive eruption and injected an enormous amount of mass and energy into the atmosphere causing disturbances in the E‐region ionosphere or even higher. There was also a moderate geomagnetic storm that started 1 day before the eruption and ended days after. These conditions offer a unique opportunity to understand the different roles they play in controlling the ionosphere. Coordinated observations, including the atmosphere, ionosphere, and magnetosphere, were made from both space and on the ground during this event. We analyzed the magnetic field and neutral wind data and found that a large‐scale atmospheric disturbance generated by the volcano eruption was responsible for the observed directional reversal of the dayside equatorial electric field and electric current.
Key Points
Space‐ and ground‐based observations reveal dramatic equatorial electrojet variations caused by the Tonga volcanic eruption
Strong eastward turning of atmospheric zonal winds in the E‐region is responsible for the directional reversal of the equatorial electrojet
The observed complex spatiotemporal variations can be explained by a large‐scale disturbance propagating eastward from the eruption site
Ruminants utilize a wide variety of dietary substrates that are not digestible by the mammals, through microbial fermentation taking place in the rumen. Recent advanced molecular based approaches ...have allowed the characterization of rumen microbiota and its compositional changes under various treatment conditions.However, the knowledge is still limited on the impacts of variations in the rumen microbiota on host biology and function. This review summarizes the information to date on host-microbial interactions in the rumen and how we can apply such information to seek the opportunities to enhance the animal performance through manipulating the rumen function.
Cattle with high feed efficiencies (designated "efficient") produce less methane gas than those with low feed efficiencies (designated "inefficient"); however, the role of the methane producers in ...such difference is unknown. This study investigated whether the structures and populations of methanogens in the rumen were associated with differences in cattle feed efficiencies by using culture-independent methods. Two 16S rRNA libraries were constructed using ~800-bp amplicons generated from pooled total DNA isolated from efficient (n = 29) and inefficient (n = 29) animals. Sequence analysis of up to 490 randomly selected clones from each library showed that the methanogenic composition was variable: less species variation (22 operational taxonomic units OTUs) was detected in the rumens of efficient animals, compared to 27 OTUs in inefficient animals. The methanogenic communities in inefficient animals were more diverse than those in efficient ones, as revealed by the diversity indices of 0.84 and 0.42, respectively. Differences at the strain and genotype levels were also observed and found to be associated with feed efficiency in the host. No difference was detected in the total population of methanogens, but the prevalences of Methanosphaera stadtmanae and Methanobrevibacter sp. strain AbM4 were 1.92 (P < 0.05) and 2.26 (P < 0.05) times higher in inefficient animals, while Methanobrevibacter sp. strain AbM4 was reported for the first time to occur in the bovine rumen. Our data indicate that the methanogenic ecology at the species, strain, and/or genotype level in the rumen may play important roles in contributing to the difference in methane gas production between cattle with different feed efficiencies.
MicroRNAs (miRNAs) can post-transcriptionally regulate gene expression and have been shown to be critical regulators to the fine-tuning of epithelial immune responses. However, the role of miRNAs in ...bovine responses to E. coli and S. aureus, two mastitis causing pathogens, is not well understood.
The global expression of miRNAs in bovine mammary epithelial cells (MAC-T cells) challenged with and without heat-inactivated Staphylococcus aureus (S. aureus) or Escherichia coli (E. coli) bacteria at 0, 6, 12, 24, and 48 hr was profiled using RNA-Seq. A total of 231 known bovine miRNAs were identified with more than 10 counts per million in at least one of 13 libraries and 5 miRNAs including bta-miR-21-5p, miR-27b, miR-22-3p, miR-184 and let-7f represented more than 50% of the abundance. One hundred and thirteen novel miRNAs were also identified and more than one third of them belong to the bta-miR-2284 family. Seventeen miRNAs were significantly (P < 0.05) differentially regulated by the presence of pathogens. E. coli initiated an earlier regulation of miRNAs (6 miRNAs differentially regulated within the first 6 hrs post challenge as compared to 1 miRNA for S. aureus) while S. aureus presented a delayed response. Five differentially expressed miRNAs (bta-miR-184, miR-24-3p, miR-148, miR-486 and let-7a-5p) were unique to E. coli while four (bta-miR-2339, miR-499, miR-23a and miR-99b) were unique to S. aureus. In addition, our study revealed a temporal differential regulation of five miRNAs (bta-miR-193a-3p, miR-423-5p, miR-30b-5p, miR-29c and miR-un116) in unchallenged cells. Target gene predictions of pathogen differentially expressed miRNAs indicate a significant enrichment in gene ontology functional categories in development/cellular processes, biological regulation as well as cell growth and death. Furthermore, target genes were significantly enriched in several KEGG pathways including immune system, signal transduction, cellular process, nervous system, development and human diseases.
Using next-generation sequencing, our study identified a pathogen directed differential regulation of miRNAs in MAC-T cells with roles in immunity and development. Our study provides a further confirmation of the involvement of mammary epithelia cells in contributing to the immune response to infecting pathogens and suggests the potential of miRNAs to serve as biomarkers for diagnosis and development of control measures.
Perturbations in early life gut microbiota can have long-term impacts on host health. In this study, we investigated antimicrobial-induced temporal changes in diversity, stability, and compositions ...of gut microbiota in neonatal veal calves, with the objective of identifying microbial markers that predict diarrhea. A total of 220 samples from 63 calves in first 8 weeks of life were used in this study. The results suggest that increase in diversity and stability of gut microbiota over time was a feature of "healthy" (non-diarrheic) calves during early life. Therapeutic antimicrobials delayed the temporal development of diversity and taxa-function robustness (a measure of microbial stability). In addition, predicted genes associated with beta lactam and cationic antimicrobial peptide resistance were more abundant in gut microbiota of calves treated with therapeutic antimicrobials. Random forest machine learning algorithm revealed that Trueperella, Streptococcus, Dorea, uncultured Lachnospiraceae, Ruminococcus 2, and Erysipelatoclostridium may be key microbial markers that can differentiate "healthy" and "unhealthy" (diarrheic) gut microbiota, as they predicted early life diarrhea with an accuracy of 84.3%. Our findings suggest that diarrhea in veal calves may be predicted by the shift in early life gut microbiota, which may provide an opportunity for early intervention (e.g., prebiotics or probiotics) to improve calf health with reduced usage of antimicrobials.
In ruminants, early rumen development is vital for efficient fermentation that converts plant materials to human edible food such as milk and meat. Here, we investigate the extent and functional ...basis of host-microbial interactions regulating rumen development during the first 6 weeks of life.
The use of microbial metagenomics, together with quantification of volatile fatty acids (VFAs) and qPCR, reveals the colonization of an active bacterial community in the rumen at birth. Colonization of active complex carbohydrate fermenters and archaea with methyl-coenzyme M reductase activity was also observed from the first week of life in the absence of a solid diet. Integrating microbial metagenomics and host transcriptomics reveals only 26.3% of mRNA transcripts, and 46.4% of miRNAs were responsive to VFAs, while others were ontogenic. Among these, one host gene module was positively associated with VFAs, while two other host gene modules and one miRNA module were negatively associated with VFAs. Eight host genes and five miRNAs involved in zinc ion binding-related transcriptional regulation were associated with a rumen bacterial cluster consisting of Prevotella, Bacteroides, and Ruminococcus.
This three-way interaction suggests a potential role of bacteria-driven transcriptional regulation in early rumen development via miRNAs. Our results reveal a highly active early microbiome that regulates rumen development of neonatal calves at the cellular level, and miRNAs may coordinate these host-microbial interactions.
The energy of turbulence in the universe, which cascades from large fluid scales to small kinetic scales, is believed to be dissipated through conversion to thermal or nonthermal kinetic energy. ...However, identifying the dissipation processes and measuring the dissipation rate in turbulence remain challenging. Based on unprecedented high-quality measurements of space plasma turbulence by the Magnetospheric Multiscale mission, we propose a novel approach to measure the scale-dependent spectrum of the energy conversion rate between the fluctuating electromagnetic energy and plasma kinetic energy. The energy conversion rate spectrum is found to show a positive bulge around the ion kinetic scale, which clearly indicates the dissipation of the turbulent energy. The energy dissipation rate around the ion scale is estimated to be 0.5 × 106 J kg−1 s−1. This work provides basic information on local dissipation in magnetosheath turbulence and sets up a new paradigm for studying the dissipation of universal plasma turbulence.
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