GCH1 plays a role in the high-altitude adaptation of Tibetans

Tibetans are welt adapted to high-altitude hypoxia. Previous genome-wide scans have reported many candidate genes for this adaptation, but only a few have been studied. Here we report on a hypoxia gene （GCH1, GTP-cyclohydrolase I）, involved in maintaining nitric oxide synthetase （NOS） function and normal blood pressure, that harbors many potentially adaptive variants in Tibetans. We resequenced an 80.8 kb fragment covering the entire gene region of GCH1 in 50 unrelated Tibetans Combined with previously published data, we demonstrated many GCHI variants showing deep divergence between highlander Tibetans and lowlander Han Chinese. Neutrality tests confirmed a signal of positive Darwinian selection on GCH1 in Tibetans. Moreover, association analysis indicated that the Tibetan version of GCH1 was significantly associated with multiple physiological traits in Tibetans, including blood nitric oxide concentration, blood oxygen saturation and hemoglobin concentration. Taken together, we propose that GCH1 plays a role in the genetic adaptation of Tibetans to high altitude hypoxia.

EP300 contributes to high-altitude adaptation in Tibetans by regulating nitric oxide production

The genetic adaptation of Tibetans to high altitude hypoxia likely involves a group of genes in the hypoxic pathway, as suggested by earlier studies. To test the adaptive role of the previously reported candidate gene EP300 （histone acetyltransferase p300）, we conducted resequencing of a 108.9 kb gene region of EP300 in 80 unrelated Tibetans. The allele-frequency and haplotype-based neutrality tests detected signals of positive Darwinian selection on EP300 in Tibetans, with a group of variants showing allelic divergence between Tibetans and lowland reference populations, including Han Chinese, Europeans, and Africans. Functional prediction suggested the involvement of multiple EP300 variants in gene expression regulation. More importantly, genetic association tests in 226 Tibetans indicated significant correlation of the adaptive EP300 variants with blood nitric oxide （NO） concentration. Collectively, we propose that EP300 harbors adaptive variants in Tibetans, which might contribute to high-altitude adaptation through regulating NO production.

Function of Lactate Dehydrogenase in Cardiac and Skeletal Muscle of Phrynocephalus Lizard in Relation to High-Altitude Adaptation

Poikilothermic animals living in high-altitude environments can be greatly affected by the anaerobic metabolism and lactate recycling, which are catalyzed by an enzyme called lactate dehydrogenase(LDH). However, the function and possible regulatory mechanisms of their anaerobic glycolysis remained elusive. We compared the difference in LDH between a native high-altitude(4 353 m) lizard, Phrynocephalus erythrurus, and a closely related species, Phrynocephalus przewalskii that lives in intermediate altitude environment(1 400 m). The activity of LDH, the concentration of lactate, the distribution of isoenzyme, and the mRNA amounts of Ldh-A and Ldh-B were determined. In cardiac muscle, the lactate-forming activity of P. erythrurus in LDH was higher than of P. przewalskii LDH at all three temperatures tested(10 °C, 25 °C and 35 °C), while lactate-oxidation activity of LDH was significantly different between the two species only at 25 °C and 35 °C. In skeletal muscle, both lactate-forming and lactate-oxidation rates of P. erythrurus were lower than that of P. przewalskii. There was a higher proportion of H subunit and a significantly higher expression of Ldh-B, with a concomitant decrease of lactate concentration in P. erythrurus. These results indicate that P. erythrurus may have a strong potential for anaerobic metabolism, which is likely adapted to the hypoxic environment at high altitudes. Furthermore, P. erythrurus is capable of oxidizing more lactate than P. przewalskii. The Ldh-A cDNA of the two species consists of a 999 bp open reading frame(ORF), which encodes 332 amino acids, while Ldh-B cDNA consists of a 1 002 bp ORF encoding 333 amino acids. LDHA has the same amino acid sequence between the two species, but three amino acid substitutions(V12 I, N21S and N318K) were observed in LDHB. Structure analysis of LDH indicated that the substitutions of residues Val12 and Asp21 in P. erythrurus could be responsible for the highaltitude adaptation. The LDH characteristics of LDH in P. erythrurus suggest unique adaptation strategies of anaerobic metabolism in hypoxia and cold environments at high altitudes for poikilothermic animals.

Genomes reveal selective sweeps in kiang and donkey for high-altitude adaptation

Over the last several hundred years,donkeys have adapted to high-altitude conditions on the Tibetan Plateau.Interestingly,the kiang,a closely related equid species,also inhabits this region.Previous reports have demonstrated the importance of specific genes and adaptive introgression in divergent lineages for adaptation to hypoxic conditions on the Tibetan Plateau.Here,we assessed whether donkeys and kiangs adapted to the Tibetan Plateau via the same or different biological pathways and whether adaptive introgression has occurred.We assembled a de novo genome from a kiang individual and analyzed the genomes of five kiangs and 93 donkeys(including 24 from the Tibetan Plateau).Our analyses suggested the existence of a strong hard selective sweep at the EPAS1 locus in kiangs.In Tibetan donkeys,however,another gene,i.e.,EGLN1,was likely involved in their adaptation to high altitude.In addition,admixture analysis found no evidence for interspecific gene flow between kiangs and Tibetan donkeys.Our findings indicate that despite the short evolutionary time scale since the arrival of donkeys on the Tibetan Plateau,as well as the existence of a closely related species already adapted to hypoxia,Tibetan donkeys did not acquire adaptation via admixture but instead evolved adaptations via a different biological pathway.

Recent selection and introgression facilitated high-altitude adaptation in cattle

During the past 3000 years,cattle on the Qinghai-Xizang Plateau have developed adaptive phenotypes under the selective pressure of hypoxia,ultraviolet(UV)radiation,and extreme cold.The genetic mechanism underlying this rapid adaptation is not yet well understood.Here,we present whole-genome resequencing data for 258 cattle from 32 cattle breeds/populations,including 89 Tibetan cattle representing eight populations distributed at altitudes ranging from 3400 m to 4300 m.Our genomic analysis revealed that Tibetan cattle exhibited a continuous phylogeographic cline from the East Asian taurine to the South Asian indicine ancestries.We found that recently selected genes in Tibetan cattle were related to body size(HMGA2 and NCAPG)and energy expenditure(DUOXA2).We identified signals of sympatric introgression from yak into Tibetan cattle at different altitudes,covering 0.64%–3.26%of their genomes,which included introgressed genes responsible for hypoxia response(EGLN1),cold adaptation(LRP11),DNA damage repair(LATS1),and UV radiation resistance(GNPAT).We observed that introgressed yak alleles were associated with noncoding variants,including those in present EGLN1.In Tibetan cattle,three yak introgressed SNPs in the EGLN1 promoter region reduced the expression of EGLN1,suggesting that these genomic variants enhance hypoxia tolerance.Taken together,our results indicated complex adaptation processes in Tibetan cattle,where recently selected genes and introgressed yak alleles jointly facilitated rapid adaptation to high-altitude environments.

Multi-omic Analyses Shed Light on The Genetic Control of High-altitude Adaptation in Sheep

Sheep were domesticated in the Fertile Crescent and then spread globally,where they have been encountering various environmental conditions.The Tibetan sheep has adapted to high altitudes on the Qinghai-Tibet Plateau over the past 3000 years.To explore genomic variants associated with high-altitude adaptation in Tibetan sheep,we analyzed Illumina short-reads of 994 whole genomes representing∼60 sheep breeds/populations at varied altitudes,PacBio High fidelity(HiFi)reads of 13 breeds,and 96 transcriptomes from 12 sheep organs.Association testing between the inhabited altitudes and 34,298,967 variants was conducted to investigate the genetic architecture of altitude adaptation.Highly accurate HiFi reads were used to complement the current ovine reference assembly at the most significantly associatedβ-globin locus and to validate the presence of two haplotypes A and B among 13 sheep breeds.The haplotype A carried two homologous gene clusters:(1)HBE1,HBE2,HBB-like,and HBBC,and(2)HBE1-like,HBE2-like,HBB-like,and HBB;while the haplotype B lacked the first cluster.The high-altitude sheep showed highly frequent or nearly fixed haplotype A,while the low-altitude sheep dominated by haplotype B.We further demonstrated that sheep with haplotype A had an increased hemoglobin–O_(2) affinity compared with those carrying haplotype B.Another highly associated genomic region contained the EGLN1 gene which showed varied expression between high-altitude and low-altitude sheep.Our results provide evidence that the rapid adaptive evolution of advantageous alleles play an important role in facilitating the environmental adaptation of Tibetan sheep.

Genome-wide DNA methylation landscape of four Chinese populations and epigenetic variation linked to Tibetan high-altitude adaptation

DNA methylation(DNAm)is one of the major epigenetic mechanisms in humans and is important in diverse cellular processes.The variation of DNAm in the human population is related to both genetic and environmental factors.However,the DNAm profiles have not been investigated in the Chinese population of diverse ethnicities.Here,we performed double-strand bisulfite sequencing(DSBS)for 32 Chinese individuals representing four major ethnic groups including Han Chinese,Tibetan,Zhuang,and Mongolian.We identified a total of 604,649 SNPs and quantified DNAm at more than 14 million Cp Gs in the population.We found global DNAm-based epigenetic structure is different from the genetic structure of the population,and ethnic difference only partially explains the variation of DNAm.Surprisingly,non-ethnic-specific DNAm variations showed stronger correlation with the global genetic divergence than these ethnic-specific DNAm.Differentially methylated regions(DMRs)among these ethnic groups were found around genes in diverse biological processes.Especially,these DMR-genes between Tibetan and nonTibetans were enriched around high-altitude genes including EPAS1 and EGLN1,suggesting DNAm alteration plays an important role in high-altitude adaptation.Our results provide the first batch of epigenetic maps for Chinese populations and the first evidence of the association of epigenetic changes with Tibetans'high-altitude adaptation.

A de novo assembled genome of the Tibetan Partridge (Perdix hodgsoniae) and its high-altitude adaptation

The Tibetan Partridge(Perdix hodgsoniae)is an endemic species distributed in high-altitude areas of 3600–5600 m on the Qinghai–Tibet Plateau.To explore how the species is adapted to the high elevation environment,we as-sembled a draft genome based on both the Illumina and PacBio sequencing platforms with its population genetics and genomics analysis.In total,134.74 Gb short reads and 30.81 Gb long reads raw data were generated.The 1.05-Gb assembled genome had a contig N50 of 4.56 Mb,with 91.94%complete BUSCOs.The 17457 genes were annotated,and 11.35%of the genome was composed of repeat sequences.The phylogenetic tree showed that P.hodgsoniae was located at the basal position of the clade,including Golden Pheasant(Chrysolophus pictus),Common Pheasant(Phasianus colchicus),and Mikado Pheasant(Syrmaticus mikado).We found that 1014,2595,and 2732 of the 6641 one-to-one orthologous genes were under positive selection in P.hodgsoniae,detected using PAML,BUSTED,and aBSREL programs,respectively,of which 965 genes were common under positive selec-tion with 3 different programs.Several positively selected genes and immunity pathways relevant to high-altitude adaptation were detected.Gene family evolution showed that 99 gene families experienced significant expansion events,while 6 gene families were under contraction.The total number of olfactory receptor genes was relatively low in P.hodgsoniae.Genomic data provide an important resource for a further study on the evolutionary history of P.hodgsoniae,which provides a new insight into its high-altitude adaptation mechanisms.

Genomic convergence underlying high-altitude adaptation in alpine plants

Evolutionary convergence is one of the most striking examples of adaptation driven by natural selection.However, genomic evidence for convergent adaptation to extreme environments remains scarce.Here, we assembled reference genomes of two alpine plants, Saussurea obvallata(Asteraceae)and Rheum alexandrae(Polygonaceae), with 37,938 and 61,463 annotated protein-coding genes. By integrating an additional five alpine genomes,we elucidated genomic convergence underlying high-altitude adaptation in alpine plants. Our results detected convergent contractions of diseaseresistance genes in alpine genomes, which might be an energy-saving strategy for surviving in hostile environments with only a few pathogens present.We identified signatures of positive selection on a set of genes involved in reproduction and respiration(e.g., MMD1, NBS1, and HPR), and revealed signatures of molecular convergence on genes involved in self-incompatibility, cell wall modification,DNA repair and stress resistance, which may underlie adaptation to extreme cold, high ultraviolet radiation and hypoxia environments. Incorporating transcriptomic data, we further demonstrated that genes associated with cuticular wax and flavonoid biosynthetic pathways exhibit higher expression levels in leafy bracts, shedding light on the genetic mechanisms of the adaptive “greenhouse” morphology. Our integrative data provide novel insights into convergent evolution at a high-taxonomic level,aiding in a deep understanding of genetic adaptation to complex environments.

Comparative DNA methylation reveals epigenetic adaptation to high altitude in snub-nosed monkeys

DNA methylation plays a crucial role in environmental adaptations.Here,using whole-genome bisulfite sequencing,we generated comprehensive genome-wide DNA methylation profiles for the high-altitude Yunnan snub-nosed monkey(Rhinopithecus bieti)and the closely related golden snub-nosed monkey(R.roxellana).Our findings indicated a slight increase in overall DNA methylation levels in golden snub-nosed monkeys compared to Yunnan snub-nosed monkeys,suggesting a higher prevalence of hypermethylated genomic regions in the former.Comparative genomic methylation analysis demonstrated that genes associated with differentially methylated regions were involved in membrane fusion,vesicular formation and trafficking,hemoglobin function,cell cycle regulation,and neuronal differentiation.These results suggest that the high-altitude-related epigenetic modifications are extensive,involving a complete adaptation process from the inhibition of single Ca^(2+)channel proteins to multiple proteins collaboratively enhancing vesicular function or inhibiting cell differentiation and proliferation.Functional assays demonstrated that overexpression or down-regulation of candidate genes,such as SNX10,TIMELESS,and CACYBP,influenced cell viability under stress conditions.Overall,this research suggests that comparing DNA methylation across closely related species can identify novel candidate genomic regions and genes associated with local adaptations,thereby deepening our understanding of the mechanisms underlying environmental adaptations.

Genome of Plant Maca （Lepidium meyenil） Illuminates Genomic Basis for High-Altitude Adaptation in the Central Andes

Maca （Lepidium meyenii Walp, 2n = 8x = 64）, belonging to the Brassicaceae family, is an economic plant cultivated in the central Andes sierra in Peru （4000-4500 m）. Considering that the rapid uplift of the central Andes occurred 5-10 million years ago （Ma）, an evolutionary question arises regarding how plants such as maca acquire high-altitude adaptation within a short geological period. Here, we report the high-quality genome assembly of maca, in which two closely spaced maca-specific whole-genome duplications （WGDs; ~6.7 Ma） were identified. Comparative genomic analysis between maca and closely related Brassicaceae species revealed expansions of maca genes and gene families involved in abiotic stress response, hormone signaling pathway, and secondary metabolite biosynthesis via WGDs. The retention and subsequent functional divergence of many duplicated genes may account for the morphological and physiological changes （i.e., small leaf shape and self-fertility） in maca in a high-altitude environment. In addition, some duplicated maca genes were identified with functions in morphological adaptation （i.e., LEAF CURLING RESPONSIVENESS） and abiotic stress response （i.e., GL YClNE-RICH RNA-BINDING PROTEINS and DNA-DAMAGE-REPAIR/TOLERATION2） under positive selection. Collectively, the maca genome provides use- ful information to understand the important roles of WGDs in the high-altitude adaptation of plants in the Andes.

Clinical efficacy of intradermal type Ⅰ collagen injections in treating skin photoaging in patients from high-altitude areas

BACKGROUND Photoaging,a result of chronic sun exposure,leads to skin damage and pigmentation changes.Traditional treatments may have limitations in high-altitude areas like Yunnan Province.Intradermal Col Ⅰ injections stimulate collagen production,potentially improving skin quality.This study aims to assess the efficacy and safety of this treatment for photoaging.AIM To evaluate the efficacy and safety of intradermal typeΙcollagen(ColΙ)injection for treating photoaging.METHODS This prospective,self-controlled study investigated the impact of intradermal injections of ColΙon skin photodamage in 20 patients from the Yunnan Province.Total six treatment sessions were conducted every 4 wk±3 d.Before and after each treatment,facial skin characteristics were quantified using a VISIA skin detector.Skin thickness data were assessed using the ultrasound probes of the Dermalab skin detector.The Face-Q scale was used for subjective evaluation of the treatment effect by the patients.RESULTS The skin thickness of the right cheek consistently increased after each treatment session compared with baseline.The skin thickness of the left cheek significantly increased after the third through sixth treatment sessions compared with baseline.The skin thickness of the right zygomatic region increased after the second to sixth treatment sessions,whereas that of the left zygomatic region showed a significant increase after the fourth through sixth treatment sessions.The skin thickness of both temporal regions significantly increased after the fifth and sixth treatment sessions compared with baseline(P<0.05).These findings were also supported by skin ultrasound images.The feature count for the red areas and wrinkle feature count decreased following the treatment(P<0.05).VISIA assessments also revealed a decrease in the red areas after treatment.The Face-QSatisfaction with Facial Appearance Overall and Face-Q-Satisfaction with Skin scores significantly increased after each treatment session.The overall appearance of the patients improved after treatment.CONCLUSION Intradermal ColΙinjection improves photoaging,with higher patient satisfaction and fewer adverse reactions,and could be an effective treatment method for populations residing in high-altitude areas.

Atmospheric transmission algorithm for pulsed X-rays from high-altitude nuclear detonations based on scattering correction

In high-altitude nuclear detonations,the proportion of pulsed X-ray energy can exceed 70%,making it a specific monitoring signal for such events.These pulsed X-rays can be captured using a satellite-borne X-ray detector following atmospheric transmission.To quantitatively analyze the effects of different satellite detection altitudes,burst heights,and transmission angles on the physical processes of X-ray transport and energy fluence,we developed an atmospheric transmission algorithm for pulsed X-rays from high-altitude nuclear detonations based on scattering correction.The proposed method is an improvement over the traditional analytical method that only computes direct-transmission X-rays.The traditional analytical method exhibits a maximum relative error of 67.79% compared with the Monte Carlo method.Our improved method reduces this error to within 10% under the same conditions,even reaching 1% in certain scenarios.Moreover,its computation time is 48,000 times faster than that of the Monte Carlo method.These results have important theoretical significance and engineering application value for designing satellite-borne nuclear detonation pulsed X-ray detectors,inverting nuclear detonation source terms,and assessing ionospheric effects.

Population genomic data reveal low genetic diversity,divergence and local adaptation among threatened Reeves's Pheasant(Syrmaticus reevesii)

Population genomic data could provide valuable information for conservation efforts;however,limited studies have been conducted to investigate the genetic status of threatened pheasants.Reeves’s Pheasant(Syrmaticus reevesii)is facing population decline,attributed to increases in habitat loss.There is a knowledge gap in understanding the genomic status and genetic basis underlying the local adaptation of this threatened bird.Here,we used population genomic data to assess population structure,genetic diversity,inbreeding patterns,and genetic divergence.Furthermore,we identified candidate genes linked with adaptation across the current distribution of Reeves’s Pheasant.The present study assembled the first de novo genome sequence of Reeves’s Pheasant and annotated 19,458 genes.We also sequenced 30 individuals from three populations(Dabie Mountain,Shennongjia,Qinling Mountain)and found that there was clear population structure among those populations.By comparing with other threatened species,we found that Reeves’s Pheasants have low genetic diversity.Runs of homozygosity suggest that the Shennongjia population has experienced serious inbreeding.The demographic history results indicated that three populations experienced several declines during the glacial period.Local adaptative analysis among the populations identified 241 candidate genes under directional selection.They are involved in a large variety of processes,including the immune response and pigmentation.Our results suggest that the three populations should be considered as three different conservation units.The current study provides genetic evidence for conserving the threatened Reeves’s Pheasant and provides genomic resources for global biodiversity management.

Irrigated Agriculture Facing the Challenge of Climate Change: Adaptation Strategies for Farmers in the Irrigated Perimeters of Môle Saint-Nicolas, Haiti

Môle Saint-Nicolas, like all other communes in the Republic of Haiti, faces increasing climate variability, impacting agricultural production and water resources. Consequently, there is a pressing need for adaptation to these climatic changes. This research aims to showcase the adaptation strategies deployed by farmers to cope with the increasing climate variability. Surveys were conducted through group and individual discussions with a randomly selected cohort of 150 farmers. Two types of analysis were performed: quantitative and qualitative. The quantitative data analysis was conducted using Statistical Package for the Social Sciences (SPSS) software. The findings reveal that farmers have perceived changes in rainfall patterns, temperature, wind, and their environment. These changes manifest as irregular rainfall, higher temperatures, prolonged drought periods, violent winds accompanied by rain, premature cessation of rains, and reduced flow from water sources. In response, the most common adaptation strategies adopted include selecting new cultivars, early-maturing varieties, crop rotation and diversification, canal dredging, new soil preparation methods, upstream water source protection, and micro-watershed management. The significance of this research lies in its contribution to enhancing farmers’ adaptive capacities by alerting stakeholders in the irrigated perimeters about the consequences of climate change, thereby incorporating the real needs of farmers in future projects.

The ABA synthesis enzyme allele OsNCED2^(T)promotes dryland adaptation in upland rice

Upland rice shows dryland adaptation in the form of a deeper and denser root system and greater drought resistance than its counterpart,irrigated rice.Our previous study revealed a difference in the frequency of the OsNCED2 gene between upland and irrigated populations.A nonsynonymous mutation(C to T,from irrigated to upland rice)may have led to functional variation fixed by artificial selection,but the exact biological function in dryland adaptation is unclear.In this study,transgenic and association analysis indicated that the domesticated fixed mutation caused functional variation in OsNCED2,increasing ABA levels,root development,and drought tolerance in upland rice under dryland conditions.OsNCED2-overexpressing rice showed increased reactive oxygen species-scavenging abilities and transcription levels of many genes functioning in stress response and development that may regulate root development and drought tolerance.OsNCED2^(T)-NILs showed a denser root system and drought resistance,promoting the yield of rice under dryland conditions.OsNCED2^(T)may confer dryland adaptation in upland rice and may find use in breeding dryland-adapted,water-saving rice.

Exercise-induced adaptation of neurons in the vertebrate locomotor system

Vertebrate neurons are highly dynamic cells that undergo several alterations in their functioning and physiologies in adaptation to various external stimuli.In particular,how these neurons respond to physical exercise has long been an area of active research.Studies of the vertebrate locomotor system’s adaptability suggest multiple mechanisms are involved in the regulation of neuronal activity and properties during exercise.In this brief review,we highlight recent results and insights from the field with a focus on the following mechanisms:(a)alterations in neuronal excitability during acute exercise;(b)alterations in neuronal excitability after chronic exercise;(c)exercise-induced changes in neuronal membrane properties via modulation of ion channel activity;(d)exercise-enhanced dendritic plasticity;and(e)exercise-induced alterations in neuronal gene expression and protein synthesis.Our hope is to update the community with a cellular and molecular understanding of the recent mechanisms underlying the adaptability of the vertebrate locomotor system in response to both acute and chronic physical exercise.

Comparative proteomics reveals the response and adaptation mechanisms of white Hypsizygus marmoreus against the biological stress caused by Penicillium

White Hypsizygus marmoreus is a popular edible mushroom.Its mycelium is easy to be contaminated by Penicillium,which leads to a decrease in its quality and yield.Penicillium could compete for limited space and nutrients through rapid growth and produce a variety of harmful gases,such as benzene,aldehydes,phenols,etc.,to inhibit the growth of H.marmoreus mycelium.A series of changes occurred in H.marmoreus proteome after contamination when detected by the label-free tandem mass spectrometry(MS/MS)technique.Some proteins with up-regulated expression worked together to participate in some processes,such as the non-toxic transformation of harmful gases,glutathione metabolism,histone modification,nucleotide excision repair,clearing misfolded proteins,and synthesizing glutamine,which were mainly used in response to biological stress.The proteins with down-regulated expression are mainly related to the processes of ribosome function,protein processing,spliceosome,carbon metabolism,glycolysis,and gluconeogenesis.The reduction in the function of these proteins affected the production of the cell components,which might be an adjustment to adapt to growth retardation.This study further enhanced the understanding of the biological stress response and the growth restriction adaptation mechanisms in edible fungi.It also provided a theoretical basis for protein function exploration and edible mushroom food safety research.

Low-Rank Optimal Transport for Robust Domain Adaptation

When encountering the distribution shift between the source(training) and target(test) domains, domain adaptation attempts to adjust the classifiers to be capable of dealing with different domains. Previous domain adaptation research has achieved a lot of success both in theory and practice under the assumption that all the examples in the source domain are welllabeled and of high quality. However, the methods consistently lose robustness in noisy settings where data from the source domain have corrupted labels or features which is common in reality. Therefore, robust domain adaptation has been introduced to deal with such problems. In this paper, we attempt to solve two interrelated problems with robust domain adaptation:distribution shift across domains and sample noises of the source domain. To disentangle these challenges, an optimal transport approach with low-rank constraints is applied to guide the domain adaptation model training process to avoid noisy information influence. For the domain shift problem, the optimal transport mechanism can learn the joint data representations between the source and target domains using a measurement of discrepancy and preserve the discriminative information. The rank constraint on the transport matrix can help recover the corrupted subspace structures and eliminate the noise to some extent when dealing with corrupted source data. The solution to this relaxed and regularized optimal transport framework is a convex optimization problem that can be solved using the Augmented Lagrange Multiplier method, whose convergence can be mathematically proved. The effectiveness of the proposed method is evaluated through extensive experiments on both synthetic and real-world datasets.

Comparative genomic analysis revealed that dietary habits affected the adaptation of Bifidobacterium bifidum to the intestinal tract in different geographic populations

Recent research on the genome of Bifidobacterium bifidum has mainly focused on the isolation sources(intestinal tract niche)recently,but reports on the isolation region are limited.This study analyzed the differences in the genome of B.bifidum isolated from different geographical populations by comparative genomic analysis.Results at the genome level indicated that the GC content of American isolates was significantly higher than that of Chinese and Russian isolates.The phylogenetic tree,based on 919 core genes showed that B.bifidum might be related to the geographical characteristics of isolation region.Furthermore,functional annotation analysis demonstrated that copy numbers of carbohydrate-active enzymes(CAZys)involved in the degradation of polysaccharide from plant and host sources in B.bifidum were high,and 18 CAZys showed significant differences across different geographical populations,indicating that B.bifidum had adapted to the human intestinal environment,especially in the groups with diets rich in fiber.Dietary habits were one of the main reasons for the differences of B.bifidum across different geographical populations.Additionally,B.bifidum exhibited high diversity,evident in glycoside hydrolases,the CRISPR-Cas system,and prophages.This study provides a genetic basis for further research and development of B.bifidum.