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Cetaceans (whales, dolphins, and porpoises) have undergone a radical transformation from the typical terrestrial mammalian body plan to a streamlined body, while exhibiting dramatic interspecific size differences. However, the molecular mechanisms underlying the diversification of cetacean body size are largely unknown. Here, by using genomic and phenotypic data for 22 cetaceans, we performed phylogenetic genome-body size analysis and explored the genetic basis of the high diversity of body size in cetaceans. A functional enrichment analysis showed that body size-related genes in cetaceans are enriched in pathways associated with immunity, cell growth, and metabolism, suggesting that they contributed to body size diversification. Genes showing correlated evolution with body size were mainly involved in immune surveillance, tumor suppression function, and development of hypertumors. The role of these genes in tumor control resolves Peto's paradox (i.e., the lack of a correspondence between an expansion in body size and, thereby, cell number and an increased cancer incidence). Our results provide novel insights into the evolution of substantial body size variation in cetaceans.

Background Mammals have wide variations in testicular position, with scrotal testes in some species and ascrotal testes in others. Although cryptorchidism is hazardous to human health, some mammalian taxa are natural cryptorchids. However, the evolution of testicular position and the molecular mechanisms underlying the maintenance of health, including reproductive health, in ascrotal mammals are not clear. Results In the present study, comparative genomics and evolutionary analyses revealed that genes associated with the extracellular matrix and muscle, contributing to the development of the gubernaculum, were involved in the evolution of testicular position in mammals. Moreover, genes related to testicular position were significantly associated with spermatogenesis and sperm fertility. These genes showed rapid evolution and the signature of positive selection, with specific substitutions in ascrotal mammals. Genes associated with testicular position were significantly enriched in functions and pathways related to cancer, DNA repair, DNA replication, and autophagy. Conclusions Our results revealed that alterations in gubernaculum development contributed to the evolution of testicular position in mammals and provided the first support for two hypotheses for variation in testicular position in mammals, the “cooling hypothesis”, which proposes that the scrotum provides a cool environment for acutely heat-sensitive sperm and the “training hypothesis”, which proposes that the scrotum develops the sperm by exposing them to an exterior environment. Further, we identified cancer resistance and DNA repair as potential protective mechanisms in natural cryptorchids. These findings provide general insights into cryptorchidism and have implications for health and infertility both in humans and domestic mammals.

Unsuccessful descent of testes in humans and other scrotal mammals can result in cryptorchidism, consequent abnormalities and a high risk of malignancy. However, many male adult mammals possessing natural ascrotal testes are as viable and healthy as other scrotal mammals. This study performed an evolutionary analysis on the desert hedgehog (DHH) signaling pathway, an important regulator for testicular development, mainly in laurasiatherians. Significant positive selection, accelerated evolutionary rates, and specific amino acid substitutions were identified in ascrotal species, some of which caused radical changes in physicochemical and biological properties. Considering that most signs of positive selection were identified in genes responsible for or related to negative regulation, we suggest that the enhanced negative regulation of the DHH signaling pathway drives, at least in part, the evolution of ascrotal testes in laurasiatherians and other mammals. This study could provide some novel insights into the evolution of natural healthy ‘cryptorchidism’ in mammals and into the convergent molecular evolution of the complex trait.

Silicon oxycarbide (SiOC) is considered as a potential anode material in lithium-ion batteries because of its high theoretical capacity and good structural stability. Despite many such assets, its ...

A meta-analysis study of essential exploration can offer experiences into the present status of information, which has various views. To date, there exist several opinions regarding the corpora persistence in cetaceans. This study explores the viewpoints and reports on corpora persistence and compares the data over the mammalian groups. The corpora persistence in cetaceans remains unexplored from an evolutionary perspective. Hence this research, suggests the upcoming evolutionary studies on genes signifying the functional gene expression of morphological and physiological variations in corpus luteum (CL)/albicans (CA) of diverse species.

In recent years the concept of virtual coupling, where multiple train units are virtually coupled into a platoon with very short following distances, has received considerable attention in the railway transportation field. This study introduces this concept into the train scheduling problem to improve line capacity and reduce congestion in urban metro networks. With consideration of the time-dependent passenger demand, train (platoon) loading capacity, and limited rolling stock resources, specifically, a mixed integer linear programming model is developed to simultaneously generate the platoon (de)coupling strategies, orders of trains, and their arrival/departure times at each station in the metro network. Several model improvement strategies, for example, model linearization and determination of big-[Formula: see text] values, are proposed to enhance the computational efficiency of the model. Finally, numerical experiments based on historical passenger data from the Beijing metro network are implemented to verify the effectiveness of the approach. The results demonstrate that the introduction of train platoons of different sizes can evidently reduce station congestion, while the percentage improvement greatly depends on the distribution of passenger demand.

Copper sulfides (Cu x S) have gained increasing attention for using as anodes of rechargeable batteries owing to their high theoretical capacity and good electron conductivity. However, the structure instability and sluggish reaction kinetics seriously deteriorate their electrochemical performance. To tackle with these inherent drawbacks, an elaborate hierarchical architecture composed of N, S co-doped carbon nanofibers and well-dispersed Cu9S5 nanocrystallines (Cu9S5/CNFs) was fabricated. After sulfurization, the Cu9S5 nanoparticles that uniformly distributed on the CNFs surface are well-encapsulated inside the graphitic carbon shell. For the hierarchical Cu9S5/CNFs, the ion diffusion pathways can be shortened by the nano-sized Cu9S5 while the graphitized carbon shell can provide rapid electron transfer as well as accommodate the volume variation of Cu9S5 upon cycling. Additionally, the heteroatom within CNFs can provide abundant edges and defects for adsorbing lithium/sodium ions, thus boosting the reaction kinetics of batteries. Benefiting from all of these merits, the Cu9S5/CNFs composite obtained under 600 °C (Cu9S5/CNFs-600) used as anode for lithium-ion batteries (LIBs) demonstrates high specific capacity (709.2 mAh g−1 at 0.1 A g−1 after 100 cycles), good rate performance (509.1 mAh g−1 at 2 A g−1) and excellent durability (540.2 mAh g−1 at 1 A g−1 after 800 cycles with a ultrahigh capacity retention of 92.5%). And it also exhibits stable cycling performance (with a capacity retention of 90.5% after 1500 cycles at 1 A g−1) and excellent rate performance in sodium-ion batteries (SIBs). This work provides a promising strategy to prepare high-performance copper sulfides-based anode materials for LIBs and SIBs.

Along with sophisticated echolocation found in bats and toothed whales, the common shrew (Sorex araneus) was confirmed to possess echolocation ability based on behavioral and experimental evidence such as high-frequency twittering and close-range spatial orientation. However, whether echolocation in the common shrew is convergent with bats and dolphins at the molecular level remains poorly understood. In this study, we gathered the coding region sequences of 11 hearing-related genes from genome data and previous studies. Convergent evolutionary analyses identified 13 amino acid residues (seven in CDH23, five in OTOF, and one in PRESTIN) under strong convergent evolution shared among the common shrew and other echolocating mammals (bats and dolphins). Furthermore, a phylogenetic tree was constructed based on the combined amino acid dataset of convergent/parallel substitutions, sites with parallel radical property changes, and sites supporting echolocator-convergence; it supported the converged topology of the simple echolocator Sorex araneus and sophisticated echolocating bats with high posterior probability. This study gives evidence at the molecular level that the common shrew echolocate and provides novel insights into the convergent evolution between the common shrew and bats and dolphins.

Constructing a lithium metal host is an effective strategy to address the infinite volume change and subsequent vast rupture of solid electrolyte interphase (SEI) for the unsupported Li0/Li+ chemistry, whereas the controllable deposition/dissolution of lithium still need to be improved by the functionalization of the host. Herein, a 3D oxidized polyacrylonitrile fiber network incorporated with LiF (OPAN-LiF) is demonstrated to guide a bottom-up deposition of Li into a flat and dense structure well confined in the host. The oxidation process introduces polar functional groups to the fibers, rendering good wettability with the electrolyte and opulent Li+ access. The incorporation of LiF further tailors lithium deposition and inhibits the formation of dead lithium. The OPAN-LiF electrode can deliver areametric capacity up to 14 mAh cm−2 at 1 mA cm−2 and be stably cycled at current density as high as 5 mA cm−2 with 1 mAh cm−2. Coupled with LiFePO4 cathode, the full cells can present high capacity retention beyond 89% after 1600 cycles at 5C. It is expected that the synthesized 3D functionalized composite scaffolds can be combined with other advanced electrolytes and cathodes to develop high performance lithium metal batteries.

Pattern recognition receptors (PRRs) are specialized receptors that represent a key component of the host innate immune system. Whether molecular evolutionary history of different PRR classes have involved different genetic mechanisms underlying diverse pathogen environment in mammals, and whether distinct ecology of mammals may have imposed divergent selective pressures on the evolution of the PRRs, remained unknown. To test these hypotheses, we investigated the characterization of 20 genes belonging to four PRR classes in mammals. Evidence of positive selection was found in most (17 of 20) PRR genes examined, and most positively selected sites (84%) undergoing radical changes were found to fall in important functional regions, consistent with the co-evolutionary dynamics between the hosts and their microbial counterparts. We found different evolutionary patterns in different PRR classes, with the highest level of positive selection in C-type lectin receptor (CLR) family, suggesting that the capability of CLRs in response to a wide variety of ligands might explain their malleability to selection pressures. Tests using branch models that partitioned the data along habitat and social behavior found significant evidence of divergent selective pressures of PRRs among mammalian groups. Interestingly, species-specific evolution was detected on RIG-I-like helicase genes (RLRs) in cetaceans, suggesting that RLRs might play a critical role in the defense against widespread marine RNA viruses during their divergence and radiation into marine habitats. This study provides a comprehensive look at the evolutionary patterns and implications of mammalian PRRs, and highlights the importance of ecological influences in molecular adaptation.

The oxidative phosphorylation (OXPHOS) pathway is an efficient way to produce energy via adenosine triphosphate (ATP), which is critical for sustaining an energy supply for cetaceans in a hypoxic environment. Several studies have shown that natural selection may shape the evolution of the genes involved in OXPHOS. However, how network architecture drives OXPHOS protein sequence evolution remains poorly explored. Here, we investigated the evolutionary patterns of genes in the OXPHOS pathway across six cetacean genomes within the framework of a functional network. Our results show a negative correlation between the strength of purifying selection and pathway position. This result indicates that downstream genes were subjected to stronger evolutionary constraints than upstream genes, which may be due to the dual function of ATP synthase in the OXPHOS pathway. Additionally, there was a positive correlation between codon usage bias and omega (ω = dN/dS) and a negative correlation with synonymous substitution rate (dS), indicating that the stronger selective constraint on genes (with less biased codon usage) along the OXPHOS pathway is attributable to an increase in the rate of synonymous substitution. Surprisingly, there was no significant correlation between protein-protein interactions and the evolutionary estimates, implying that highly connected enzymes may not always show greater evolutionary constraints. Compared with that observed for terrestrial mammals, we found that the signature of positive selection detected in five genes (ATP5J, LHPP, PPA1, UQCRC1 and UQCRQ) was cetacean-specific, reflecting the importance of OXPHOS for survival in hypoxic, aquatic environments.