Significant thermal rectification induced by phonon mismatch of functional groups in a single-molecule junction.

Single-molecule junctions (SMJs) may bring exotic physical effects. In this work, a significant thermal rectification effect is observed in a cross-dimensional system, comprising a diamond, a single-molecule junction, and a carbon nanotube (CNT). The molecular dynamics simulations indicate that the interfacial thermal resistance varies with the direction of heat flow, the orientation of the crystal planes of the diamond, and the length of the CNT. We find that the thermal rectification ratio escalates with the length of the CNT, achieving a peak value of 730% with the CNT length of 200 nm. A detailed analysis of phonon vibrations suggests that the primary cause of thermal rectification is the mismatched vibrations between the biphenyl and carbonyl groups. This discovery may offer theoretical insights for both the experimental exploration and practical application of SMJs in efficient thermal management strategy for high power and highly integrated chips.

Exploring Plant Meiosis: Insights from the Kinetochore Perspective.

The central player for chromosome segregation in both mitosis and meiosis is the macromolecular kinetochore structure, which is assembled by >100 structural and regulatory proteins on centromere DNA. Kinetochores play a crucial role in cell division by connecting chromosomal DNA and microtubule polymers. This connection helps in the proper segregation and alignment of chromosomes. Additionally, kinetochores can act as a signaling hub, regulating the start of anaphase through the spindle assembly checkpoint, and controlling the movement of chromosomes during anaphase. However, the role of various kinetochore proteins in plant meiosis has only been recently elucidated, and these proteins differ in their functionality from those found in animals. In this review, our current knowledge of the functioning of plant kinetochore proteins in meiosis will be summarized. In addition, the functional similarities and differences of core kinetochore proteins in meiosis between plants and other species are discussed, and the potential applications of manipulating certain kinetochore genes in meiosis for breeding purposes are explored.

Graphene and 2D Hexagonal Boron Nitride Heterostructure for Thermal Management in Actively Tunable Manner.

Thermal management is a critical task for highly integrated or high-power semiconductor devices. Low dimensional materials including graphene and single-layer hexagonal boron nitride (BN) are attractive candidates for this task because of their high thermal conductivity, semi-conductivity and other excellent physical properties. The similarities in crystal structure and chemistry between graphene and boron nitride provide the possibility of constructing graphene/BN heterostructures bearing unique functions. In this paper, we investigated the interfacial thermal transport properties of graphene/BN nanosheets via non-equilibrium molecular dynamics (NEMD) simulations. We observed a significant thermal rectification behavior of these graphene/BN nanosheets, and the rectification ratio increased with the system length increases up to 117%. This phenomenon is attributed to the mismatch of out-of-plane phonon vibration modes in two directions at the interface. In addition, we explored the underlying mechanism of the length dependence of the thermal transport properties. The results show promise for the thermal management of this two-dimensional heterostructure in an actively tunable manner.

Effect of sex on the gut microbiota characteristics of passerine migratory birds.

The gut microbiota, considered the "invisible organ" in the host animal, has been extensively studied recently. However, knowledge about the gut microbiota characteristics of passerine migratory birds during migration is limited. This study investigated the gut microbiota characteristics of three dominant migratory bird species (namely orange-flanked bluetail Tarsiger cyanurus, yellow-throated bunting Emberiza elegans, and black-faced bunting Emberiza spodocephala) in the same niche during spring migration and whether they were bird sex-specific. The compositions of gut microbiota species in these three migratory bird species and their male and female individuals were found to be similar. The main bacterial phyla were Proteobacteria, Firmicutes, Actinobacteria, and Bacteroidetes, and the main genera were Lactobacillus, Acinetobacter, Rickettsiella, and Mycobacterium; however, their relative abundance was different. Moreover, some potential pathogens and beneficial bacteria were found in all the three bird species. Alpha diversity analysis showed that in T. cyanurus, the richness and diversity of the gut microbiota were higher in male individuals than in female individuals, while the opposite was true for E. elegans and E. spodocephala. The alpha diversity analysis showed significant differences between male and female individuals of E. elegans (p < 0.05). The beta diversity analysis also revealed that the gut microbial community structure differed significantly between the male and female individuals of the three migratory bird species.

The Composition of Gut Microbiota Community Structure of Jankowski's Bunting (Emberiza jankowskii).

Gut microbiota play a central role in the health of animals. The bacteria that individuals acquire as they age may therefore have a profound effect on their future fitness. Since most birds are capable of flight, they can be widely distributed in and adapted to various ecosystems. Moreover, birds are also challenged by the need to digest a wide range of food resources in their guts. However, little is known regarding how the microbial community structure in birds, especially wild birds, changes with host age. Here, we used high-throughput sequencing of the 16S rRNA V3-V4 region to depict the microbial composition and structure in the adults and nestlings of Jankowski's bunting (Emberiza jankowskii), an endangered species of bird, during the breeding season. The results showed that the phyla Proteobacteria (52.45%), Firmicutes (13.87%), Bacteroidetes (5.76%), Actinobacteria (4.95%), Planctomycetes (4.36%), Euryarchaeota (3.20%), Acidobacteria (2.59%), Fusobacteria (2.24%), and Chloroflexi (1.8%) dominated the gut microbial communities in Jankowski's bunting. There was no significant difference in the alpha diversity and richness among different age groups. There was also no significant difference in species richness and diversity between the nestlings and adults. However, we observed different bacterial compositions at the genus level. The genera Photobacterium and Brochothrix were detected only in the nestling groups (at days 3, 6, and 9), while Diplorickettsia was detected only in the adult group. In summary, this study can provide additional information regarding the intestinal microorganisms of wild passerine and grassland birds and provide theoretical evidence for methods to protect Jankowski's bunting.

Low level of extra-pair paternity between nearest neighbors results from female preference for high-quality males in the yellow-rumped flycatcher (Ficedula zanthopygia).

Extra-pair copulation is considered to be a means by which females can modify their initial mate choice, and females might obtain indirect benefits to offspring fitness by engaging in this behavior. Here, we examined the patterns of extra-pair paternity and female preferences in the yellow-rumped flycatcher (Ficedula zanthopygia). We found that female yellow-rumped flycatchers are more likely to choose larger and relatively highly heterozygous males than their social mates as extra-pair mates, that the genetic similarity of pairs that produced mixed-paternity offspring did not differ from the similarity of pairs producing only within-pair offspring, and that extra-pair offspring were more heterozygous than their half-siblings. These findings support the good genes hypothesis but do not exclude the compatibility hypothesis. Most female yellow-rumped flycatchers attained extra-pair paternity with distant males rather than their nearest accessible neighboring males, and no differences in genetic and phenotypic characteristics were detected between cuckolded males and their nearest neighbors. There was no evidence that extra-pair mating by female flycatchers reduced inbreeding. Moreover, breeding density, breeding synchrony and their interaction did not affect the occurrence of extra-pair paternity in this species. Our results suggest that the variation in extra-pair paternity distribution between nearest neighbors in some passerine species might result from female preference for highly heterozygous males.

Polymorphism in the major histocompatibility complex (MHC class II B) genes of the Rufous-backed Bunting (Emberiza jankowskii).

Genetic diversity is one of the pillars of conservation biology research. High genetic diversity and abundant genetic variation in an organism may be suggestive of capacity to adapt to various environmental changes. The major histocompatibility complex (MHC) is known to be highly polymorphic and plays an important role in immune function. It is also considered an ideal model system to investigate genetic diversity in wildlife populations. The Rufous-backed Bunting (Emberiza jankowskii) is an endangered species that has experienced a sharp decline in both population and habitat size. Many historically significant populations are no longer present in previously populated regions, with only three breeding populations present in Inner Mongolia (i.e., the Aolunhua, Gahaitu and Lubei557 populations). Efforts focused on facilitating the conservation of the Rufous-backed Bunting (Emberiza jankowskii) are becoming increasingly important. However, the genetic diversity of E. jankowskii has not been investigated. In the present study, polymorphism in exon 2 of the MHCIIB of E. jankowskii was investigated. This polymorphism was subsequently compared with a related species, the Meadow Bunting (Emberiza cioides). A total of 1.59 alleles/individual were detected in E. jankowskii and 1.73 alleles/individual were identified in E. cioides. The maximum number of alleles per individual from the three E. jankowskii populations suggest the existence of at least three functional loci, while the maximum number of alleles per individual from the three E. cioides populations suggest the presence of at least four functional loci. Two of the alleles were shared between the E. jankowskii and E. cioides. Among the 12 unique alleles identified in E. jankowskii, 10.17 segregating sites per allele were detected, and the nucleotide diversity was 0.1865. Among the 17 unique alleles identified in E. cioides, eight segregating sites per allele were detected, and the nucleotide diversity was 0.1667. Overall, compared to other passerine birds, a relatively low level of MHC polymorphism was revealed in E. jankowskii, which was similar to that in E. cioides. Positive selection was detected by PAML/SLAC/FEL analyses in the region encoding the peptide-binding region in both species, and no recombination was detected. Phylogenetic analysis showed that the alleles from E. jankowskii and E. cioides belong to the same clade and the two species shared similar alleles, suggesting the occurrence of a trans-species polymorphism between the two Emberiza species.

Mitochondrial genome of the Emberiza jankowskii (Emberizidae: Emberiza).

Emberiza jankowskii is an Endangered species, whose population quantity decreased year by year in the limited distribution areas. The complete mitochondrial genome of E. jankowskii (16,776 bp in length) consists of 37 genes (13 protein-coding genes, 2 rRNA genes, and 22 tRNA genes) and a non-coding region (D-loop), which is similar to the typical mtDNA of vertebrates. All the protein-coding genes in E. jankowskii are distributed on the H-strand, except the ND6 subunit gene and ten tRNA genes, which are encoded on the L-strand. A preliminary phylogenetic analysis has been carried out with eight bunting species and other related species.