MIR1868 negatively regulates rice cold tolerance at both the seedling and booting stages

Low temperature causes rice yield losses of up to 30%–40%,therefore increasing its cold tolerance is a breeding target.Few genes in rice are reported to confer cold tolerance at both the vegetative and reproductive stages.This study revealed a rice-specific 24-nt miRNA,miR1868,whose accumulation was suppressed by cold stress.Knockdown of MIR1868 increased seedling survival,pollen fertility,seed setting,and grain yield under cold stress,whereas its overexpression conferred the opposite phenotype.Knockdown of MIR1868 increased reactive oxygen species(ROS)scavenging and soluble sugar content under cold stress by increasing the expression of peroxidase genes and sugar metabolism genes,and its overexpression produced the opposite effect.Thus,MIR1868 negatively regulated rice cold tolerance via ROS scavenging and sugar accumulation.

More than a simple egg:Underlying mechanisms of cold tolerance in avian embryos

Avian embryos,which develop within eggs,exhibit remarkable tolerance to extremely low temperatures.Despite being a common trait among all birds,the mechanisms underlying this cold tolerance in avian embryos remain largely unknown.To gain a better understanding of this phenomenon and the coping mechanisms involved,we reviewed the literature on severe cold tolerance in embryos of both wild and domestic birds.We found that embryos of different bird orders exhibit tolerance to severe cold during their development.In response to cold stress,embryos slow down their heartbeat rates and metabolism.In severe cold temperatures,embryos can suspend these processes,entering a torpid-like state of cardiac arrest.To compensate for these developmental delays,embryos extend their regular incubation periods.Depending on their embryonic age,embryos of all bird species can tolerate acute severe cold regimes;only a few tolerate chronic severe cold regimes.We also discussed various extrinsic and intrinsic factors that affect the tolerance of bird embryos to low temperatures before and after incubation.Cold tolerance appears to be a heritable trait shared by wild and domestic embryos of all bird classes,regardless of egg size or development(altricial/precocial).Driven by environmental variability,cold tolerance in avian embryos is an optimal physiological and ecological strategy to mitigate the adverse effects of cold conditions on their development in response to fluctuating environmental temperatures.

MdWRKY40is directly promotes anthocyanin accumulation and blocks MdMYB15L, the repressor of MdCBF2, which improves cold tolerance in apple

Cold stress is an important factor that limits apple production. In this study, we examined the tissue-cultured plantlets of apple rootstocks ‘M9T337' and ‘60-160', which are resistant and sensitive to cold stress, respectively. The enriched pathways of differentially expressed genes(DEGs) and physiological changes in ‘M9T337' and ‘60-160' plantlets were clearly different after cold stress(1°C) treatment for 48 h, suggesting that they have differential responses to cold stress. The differential expression of WRKY transcription factors in the two plantlets showed that MdWRKY40is and MdWRKY48 are potential regulators of cold tolerance. When we overexpressed MdWRKY40is and MdWRKY48in apple calli, the overexpression of MdWRKY48 had no significant effect on the callus, while MdWRKY40is overexpression promoted anthocyanin accumulation, increased callus cold tolerance, and promoted the expression of anthocyanin structural gene MdDFR and cold-signaling core gene MdCBF2. Yeast one-hybrid screening and electrophoretic mobility shift assays showed that MdWRKY40is could only bind to the MdDFR promoter. Yeast twohybrid screening and bimolecular fluorescence complementation showed that MdWRKY40is interacts with the CBF2inhibitor MdMYB15L through the leucine zipper(LZ). When the LZ of MdWRMY40is was knocked out, MdWRKY40is overexpression in the callus did not affect MdCBF2 expression or callus cold tolerance, indicating that MdWRKY40is acts in the cold signaling pathway by interacting with MdMYB15L. In summary, MdWRKY40is can directly bind to the MdDFR promoter in order to promote anthocyanin accumulation, and it can also interact with MdMYB15L to interfere with its inhibitory effect on MdCBF2, indirectly promoting MdCBF2 expression, and thereby improving cold tolerance.These results provide a new perspective for the cold-resistance mechanism of apple rootstocks and a molecular basis for the screening of cold-resistant rootstocks.

A systematic identification of cold tolerance genes in peanut using yeast functional screening system

Peanut(Arachis hypogaea L.)is a thermophilic crop,and low temperature leads to a significant reduction in annual yields.Despite a few cold tolerant germplasms or cultivars have been discovered and developed,molecular mechanisms governing peanut cold tolerance is poorly understood.Identification of keys genes involved in cold tolerance is the first step to address the underlying mechanism.In this study,we isolated and characterized 157 genes with potentials to confer cold tolerance in peanut by using a yeast functional screening system.GO(Gene ontology)and KEGG(Kyoto encyclopedia of genes and genomes)enrichment analysis of these genes revealed that ribosome and photosynthesis proteins might play essential roles in peanut cold response.Transcriptome results indicated that 60 cold tolerance candidate genes were significantly induced or depressed by low temperature.qRT-PCR analysis demonstrated that several candidate genes could be also regulated by salt or drought stress.Individual overexpression of two UDP-glycosyltransferases(AhUGT2 and AhUGT268)in transgenic yeast cells could enhance their tolerance to multiple abiotic stress.In conclusion,this study advances our understanding of the mechanisms associated with the cold stress responses in peanut,and offers valuable gene resources for genetic improvement of abiotic stress tolerance in crops.

Population genomics reveals that natural variation in PRDM16 contributes to cold tolerance in domestic cattle

Environmental temperature serves as a major driver of adaptive changes in wild organisms.To discover the mechanisms underpinning cold tolerance in domestic animals,we sequenced the genomes of 28 cattle from warm and cold areas across China.By characterizing the population structure and demographic history,we identified two genetic clusters,i.e.,northern and southern groups,as well as a common historic population peak at 30 kilo years ago.Genomic scan of cold-tolerant breeds determined potential candidate genes in the thermogenesis-related pathways that were under selection.Specifically,functional analysis identified a substitution of PRDM16(p.P779 L)in northern cattle,which maintains brown adipocyte formation by boosting thermogenesis-related gene expression,indicating a vital role of this gene in cold tolerance.These findings provide a basis for genetic variation in domestic cattle shaped by environmental temperature and highlight the role of reverse mutation in livestock species.

Large-scale evaluation of pea(Pisum sativum L.)germplasm for cold tolerance in the field during winter in Qingdao

As a cool-season crop, pea(Pisum sativum L.) can tolerate frost at the vegetative stage but experiences yield loss when freezing stress occurs at the reproductive stage. Cold-tolerance improvement of pea varieties is important for stable yield and expansion of the winter pea planting area. Under natural low-temperature conditions during winter in Qingdao,Shandong, China, we evaluated the cold tolerance of 3672 pea germplasm accessions in the field and categorized them as displaying high resistance(214), moderate resistance(835), or susceptibility(2623). The highly and moderately resistant genotypes were validated in the following year. We found that genotypes from the winter production region showed higher cold tolerance than genotypes from the spring production region. The accessions identified as having high levels of cold tolerance are recommended as potential genetic resources in cold-tolerance breeding of pea.

Effects of Phosphate Fertilizer on Cold Tolerance and Its Related Physiological Parameters in Rice Under Low Temperature Stress

The study was designated to explore the physiological mechanism of cold tolerance enhanced by phosphate in rice. An experiment was conducted to investigate the effects of different levels of phosphate fertilizer on cold tolerance and its related physiological parameters in rice seedings (chilling-sensitive cv. Changbai 9 and chilling-tolerant cv. Jijing 81) under low temperature stress. At the same time, the identification of cold tolerance was conducted. Compared with the normal temperature treatment, the relative chlorophyll content, photosynthesis rate, Fv/Fm and qP decreased and index of unsaturated fatty acid increased in rice under low temperature stress. The effect of chilling-sensitive cultivars was more than that of chilling-tolerant cultivars, more phosphorus fertilizer properly improved seedling quality of rice, slowed relative chlorophyll content dropping degree of rice seeding, increased photosynthesis rate, Fv/Fm, qP and index of unsaturated fatty acids, and enhanced the ability to chilling-tolerant cultivars under low temperature. The effect on chilling-tolerant cultivars was significantly higher than that on chilling sensitive cultivars by applying more phosphorus fertilizer. Phosphate regulated photosynthetic physiology and membrane fluidity to reduce injury by low temperature, and increasd the cold tolerance capacity of rice.

The Comparison of Cold tolerance of Three Species of Evergreen Broad-leaved Woody Plants

[Objectives]This study aimed to select evergreen broad-leaved woody plants with higher ornamental value and stronger cold tolerance for introduction from the south to the north,and to apply them to urban greening,so as to enrich the plant community structure of the landscape in the northern region.[Methods]Three species of evergreen broad-leaved woody plants,i.e.,Ligustrum lucidum,Ilex cornuta and Eriobotrya japonica,were selected as the experimental materials.The morphological performances and the changes of the physiological indexes were observed and measured during the overwintering period in the open field in Beijing.The relationship between the indexes and the low temperature was also analyzed.The strength of cold tolerance of the three species was compared.[Results]The electrical conductivity,the contents of MDA and proline were negatively correlated with the corresponding low temperature.The contents of soluble sugar and soluble protein increased with the dropping temperature,but they had little response to the short-term temperature rise.[Conclusions]Combined with morphological and physiological indexes,it was found that the changes of the contents of proline and soluble sugar among the physiological indexes were closely related to the cold tolerances of the three tree species of broad-leaved woody plants.The cold tolerance of I.cornuta was the strongest,E.japonica was the second,and that of L.lucidum was the worst.

Identification Cold Tolerance of Pineapple Germplasms at Seedling Stage

Pineapple plant was always injured due to low temperature. Breeding varieties with high cold tolerance was the supreme way to resolve this problem and identifying cold tolerance of germplasms collected was necessary. In this study, SSR locus around homologous sequences of cold-tolerant genes was searched and screened using MD-2 (cold-tolerant variety) and Tainong 17 (cold-sensitive variety). Seventy three pairs of primers of which PCR results were different between these two varieties were gotten. PCRs were performed using these as primers and genomic DNA of germplasms collected as templates. Six pairs of primers were found that their PCR results were in good consistent with cold tolerance. Using GLM (General linear model) association mapping analysis, two SSR markers linked to cold tolerance were found. Their efficiency was verified further using pineapple germplasms with high cold tolerance which had been validated in field by cold wave. They will be used in cold-tolerant breeding of pineapple in the future.

Evaluation of Cold Tolerance in Wild Sugarcane Germplasm Resources under Field Conditions

In January 2016,Kunming underwent 52 hours of rain and snow weather below 0℃.In order to identify the cold tolerance of different wild sugarcane germplasm resources in low temperature and snow disasters,cold injuries of 38 shares of wild sugarcane germplasm resources,which were collected during2012-2013 and preserved in the germplasm resource nursery of Sugarcane Research Institute,Yunnan Agricultural University,were surveyed to evaluate the cold tolerance based on sugarcane cold tolerance index(CTI)=0.5×shoot tip growing point injury index+0.3×node injury index+0.2×internode injury index.The results showed that cold tolerance indexes of four wild sugarcane varieties demonstrated a descending order of Erianthus arundinaceum Retz.(0.7),Erianthus rockii Keng(0.5),Saccharums pontaneum L.(0.3),Erianthusf ulvus Nees.(0).Greater cold tolerance indexes indicate poorer cold tolerance.Thus,Erianthus arundinaceumhad the poorest cold tolerance,while Erianthus fulvus exhibited the strongest cold tolerance.In addition,there were significant differences in cold tolerance among different Saccharum spontaneumclones.The 23 Saccharum spontaneumclones could be divided into four grades,including 1clone with the poorest cold tolerance that accounted for 4.3%,5clones with poor cold tolerance that accounted for 21.7%,14 clones with strong cold tolerance that accounted for 60.9%,and 3clones with the strongest cold tolerance that accounted for 13.0%(2012-23,2012-32,2012-37).Especially,2012-23 exhibited extremely strong cold tolerance.This study provided the scientific basis for screening of cold-tolerant wild sugarcane germplasm resources and selection of cold-tolerant parents.

Comparison of Cold Tolerance in Three Ground-cover Chrysanthemum Cultivars during Wintering in the Open Field

[Objectives]Among many chrysanthemum types,the ground-cover chrysanthemum cultivar group has the characteristics of dwarf plant,long flowering period,rich color and strong resistance to stress.This study aimed to screen out cultivars with strong cold tolerance in order that they can be used for planting in urban green space and economic forests in northern cold areas,so as to enrich the plant community structures of landscape in cold regions.[Methods]Three ground-cover chrysanthemum cultivars,i.e.,‘Meiaihuang’,‘Xinhong’and‘Zixunzhang’,were selected as the experimental materials.During the wintering period in the field in Beijing,they were observed and measured for the changes of the morphological manifestations and the physiological indices,and the relationship between the indices and low temperature was analyzed.The cold tolerance of the three ground-cover chrysanthemum cultivars was also comprehensively evaluated.[Results]During the open-field overwintering period,the root activity of the three ground-cover chrysanthemum cultivars increased slowly with cooling,decreased at the freezing low temperature,and then increased again in early spring.With natural cooling,the membrane injury percentages(MIPs)of the leaves and foot shoots increased significantly,and the contents of malondialdehyde(MDA)increased;the contents of soluble sugar(SS)and proline(Pro)gradually accumulated,and the contents of SS and Pro in foot shoots increased significantly in late winter;and the superoxide dismutase(SOD)activity showed a similar trend of rising slowly at first and then increasing significantly.There were correlations between MIPs in the leaves and foot shoots of the three cultivars and other physiological indices:a significant negative correlation with MDA content,and a significant positive correlation with SS content,Pro content and SOD activity.[Conclusions]Combining the morphological manifestations and physiological indices,the cold tolerance of the three ground-cover chrysanthemum cultivars was evaluated by the subordinate function method.The results showed that the cold tolerance of the three ground-cover chrysanthemum cultivars ranked as‘Meiaihuang’>‘Xinhong’>‘Zixunzhang’.The strong cold tolerance of foot shoots and roots was the main reason that the three ground-cover chrysanthemum cultivars could overwinter in the open field.

CHH methylation of genes associated with fatty acid and jasmonate biosynthesis contributes to cold tolerance in autotetraploids of Poncirus trifoliata

Polyploids have elevated stress tolerance,but the underlying mechanisms remain largely elusive.In this study,we showed that naturally occurring tetraploid plants of trifoliate orange(Poncirus trifoliata(L.) Raf.) exhibited enhanced cold tolerance relative to their diploid progenitors.Transcriptome analysis revealed that whole-genome duplication was associated with higher expression levels of a range of well-characterized cold stress-responsive genes.Global DNA methylation profiling demonstrated that the tetraploids underwent more extensive DNA demethylation in comparison with the diploids under cold stress.CHH methylation in the promoters was associated with up-regulation of related genes,whereas CG,CHG,and CHH methylation in the 3’-regions was relevant to gene down-regulation.Of note,genes involved in unsaturated fatty acids(UFAs) and jasmonate(JA)biosynthesis in the tetraploids displayed different CHH methylation in the gene flanking regions and were prominently up-regulated,consistent with greater accumulation of UFAs and JA when exposed to the cold stress.Collectively,our findings explored the difference in cold stress response between diploids and tetraploids at both transcriptional and epigenetic levels,and gained new insight into the molecular mechanisms underlying enhanced cold tolerance of the tetraploid.These results contribute to uncovering a novel regulatory role of DNA methylation in better cold tolerance of polyploids.

Selective footprints and genes relevant to cold adaptation and other phenotypic traits are unscrambled in the genomes of divergently selected chicken breeds

Background The genomes of worldwide poultry breeds divergently selected for performance and other phenotypic traits may also be affected by,and formed due to,past and current admixture events.Adaptation to diverse environments,including acclimation to harsh climatic conditions,has also left selection footprints in breed genomes.Results Using the Chicken 50K_CobbCons SNP chip,we genotyped four divergently selected breeds:two aboriginal,cold tolerant Ushanka and Orloff Mille Fleur,one egg-type Russian White subjected to artificial selection for cold tolerance,and one meat-type White Cornish.Signals of selective sweeps were determined in the studied breeds using three methods:(1)assessment of runs of homozygosity islands,(2)F_(ST) based population differential analysis,and(3)haplotype differentiation analysis.Genomic regions of true selection signatures were identified by two or more methods or in two or more breeds.In these regions,we detected 540 prioritized candidate genes supplemented them with those that occurred in one breed using one statistic and were suggested in other studies.Amongst them,SOX5,ME3,ZNF536,WWP1,RIPK2,OSGIN2,DECR1,TPO,PPARGC1A,BDNF,MSTN,and beta-keratin genes can be especially mentioned as candidates for cold adaptation.Epigenetic factors may be involved in regulating some of these important genes(e.g.,TPO and BDNF).Conclusion Based on a genome-wide scan,our findings can help dissect the genetic architecture underlying various phenotypic traits in chicken breeds.These include genes representing the sine qua non for adaptation to harsh environments.Cold tolerance in acclimated chicken breeds may be developed following one of few specific gene expression mechanisms or more than one overlapping response known in cold-exposed individuals,and this warrants further investigation.

Anatomical Structure Comparison Between Leaves of Two Winter Wheat Cultivars with Different Cold/Freezing Tolerance Under Low Temperature Stress

Winter wheat (Triticum aestivum) cultivars Dongnongdongmai 1 with strong cold/freezing tolerance and Jimai 22 with weak cold/freezing tolerance were used for investigating the difference of microstructure and ultrastructure between leaves of two cultivars under low temperature stress (5℃ and -15℃) using optical and electron microscope. The results showed that there was no obvious difference between leaves of Dongnongdongmai 1 and Jimai 22 in microstructure. However, the difference between those leaves was distinct in ultrastructure. The grana lamella and stroma lamella were stacked regularly and arranged parallelly along the long axis of chloroplasts in cv. Dongnongdongmai 1, while the arrangement directions of thylakoids in Jimai 22's leaves were so irregular as to form various angles with the long axis of chloroplasts. At -15℃, the mitochondrias were swelled to be round and the structure of cristaes became blurry in both cultivars' leaves, while some cristaes of Jimai 22 disappeared. These results would provide theoretical evidence for selecting cold/freezing tolerant winter wheat germplasm resources.

OsNAC5 orchestrates OsABI5 to fine-tune cold tolerance in rice

Due to its tropical origins,rice(Oryza sativa)is susceptible to cold stress,which poses severe threats to production.OsNAC5,a NAC-type transcription factor,participates in the cold stress response of rice,but the detailed mechanisms remain poorly understood.Here,we demonstrate that OsNAC5 positively regulates cold tolerance at germination and in seedlings by directly activating the expression of ABSCISIC ACID INSENSITIVE 5(OsABI5).Haplotype analysis indicated that single nucleotide polymorphisms in a NAC-binding site in the OsABI5 promoter are strongly associated with cold tolerance.OsNAC5 also enhanced OsABI5 stability,thus regulating the expression of cold-responsive(COR)genes,enabling fine-tuned control of OsABI5 action for rapid,precise plant responses to cold stress.DNA affinity purification sequencing coupled with transcriptome deep sequencing identified several OsABI5 target genes involved in COR expression,including DEHYDRATION-RESPONSIVE ELEMENT BINDING FACTOR 1A(OsDREB1A),OsMYB20,and PEROXIDASE 70(OsPRX70).In vivo and in vitro analyses suggested that OsABI5 positively regulates COR gene transcription,with marked COR upregulation in OsNAC5-overexpressing lines and downregulation in osnac5 and/or osabi5 knockout mutants.This study extends our understanding of cold tolerance regulation via OsNAC5 through the OsABI5-CORs transcription module,which may be used to ameliorate cold tolerance in rice via advanced breeding.

Development of a New Cold-Tolerant Maize(Zea mays L.)Germplasm Using the ICE1 Gene from Arabidopsis thaliana

To develop cold-tolerant maize germplasms and identify the activation of INDUCER OF CRT/DRE-BINDING FACTOR EXPRESSION(ICE1)expression in response to cold stress,RT-PCR was used to amplify the complete open reading frame sequence of the ICE1 gene and construct the plant expression vector pCAMBIA3301-ICE1-Bar.Immature maize embryos and calli were transformed with the recombinant vector using Agrobacterium tumefaciens-mediated transformations.From the regenerated plantlets,three T1 lines were screened and identi-fied by PCR.A Southern blot analysis showed that a single copy of the ICE1 gene was integrated into the maize(Zea mays L.)genomes of the three T1 generations.Under low temperature-stress conditions(4°C),the relative conductivity levels decreased by 27.51%–31.44%,the proline concentrations increased by 12.50%–17.50%,the malondialdehyde concentrations decreased by 16.78%–18.37%,and the peroxidase activities increased by 19.60%–22.89%in the T1 lines compared with those of the control.A real-time quantitative PCR analysis showed that the ICE1 gene was ectopically expressed in the roots,stems,and leaves of the T1 lines.ICE1 positively regulates the expression of the CBF genes in response to cold stress.Thus,this study showed the successful transformation of maize with the ICE1 gene,resulting in the generation of a new maize germplasm that had increased tolerance to cold stress.

Transcription factor CabHLH035 promotes cold resistance and homeostasis of reactive oxygen species in pepper

Plant basic helix-loop-helix(bHLH)transcription factors(TFs)play central roles in various abiotic stresses.However,its role in plant cold resistance is largely unknown.Previously,we characterised CaNAC035 in pepper,which positively regulates tolerance to cold,salt and drought stresses tolerance.Here,we identified CabHLH035,a CaNAC035-interacting protein in pepper.To explore its functions in cold stress tolerance,we silenced the gene in pepper via virus-induced gene silencing(VIGS)and overexpressed the gene in Arabidopsis.The results showed that CabHLH035 expression was induced by cold treatment,and silencing of CabHLH035 decreased cold stress tolerance.Conversely,overexpression of CabHLH035 in Arabidopsis increased cold stress tolerance.To investigate homologs genes of C-repeat binding factor(CBF)pathway proteins and reactive oxygen species(ROS)marker gene expression blocking by CabHLH035,we performed yeast one-hybrid(Y1H),dual luciferase and electrophoretic mobility shift assay experiments.The results showed that CabHLH035 bound to the region upstream of the CaCBF1A and CaAPX promoters.Additionally,CaCBF1A bound to the CaDHN4 promoter.Taken together,our results showed that CabHLH035 plays a crucial role in cold stress tolerance and its potential as a target for breeding cold-resistant crops.The findings provide a basis for studying the functions and regulatory network of cold stress tolerance in pepper.

Effect of 6-BA on Physiological Changes in Two Palm Seedlings Under Varied Temperaures

The effects of 6-benzylaminopurine(6-BA) on several physiological indexes of Caryota mitis and C.obtusa seedlings treated at varied temperatures were conducted,the leaves of the two palm species were sprayed with 0,25,50 and 100 mg · L^(-1)6-BA solutions,the activities of superoxide dismutase(SOD),peroxidase(POD),and the contents of malondialdehyde(MDA),proline,soluble protein,chlorophyll and chlorophyll a/b were determined under 25℃,5℃ and 25℃ for 24 h,respectively.The dynamics of a series of important physiological components derived from the leaves were studied.It was indicated that all the above mentioned physiological indexes varied with different concentrations of 6-BA and temperature.The fuzzy comprehensive evaluation values for different concentrations of 6-BA at the recovery temperature 25℃ were 0.33,0.28,0.92 and 0.33,respectively for C.mitis,and 0.20,0.49,0.56 and 0.63,respectively for C.obtusa.It was concluded that leaves sprayed with different concentrations of 6-BA could affect the cold tolerance of palm seedlings.The optimal concentration of 6-BA was different for different palm species.

Expression of multi-domain type III antifreeze proteins from the Antarctic eelpout (Lycodichths dearborni) in transgenic tobacco plants improves cold resistance

Type III antifreeze proteins(AFPIIIs)are a group of small globular proteins found in some polar fishes to protect them against freezing damage.Transgenic expression of AFPs has been shown to confer cold tolerance to commercially important plants and animals.We have previously isolated multiple AFPIII genes in the Antarctic eelpout(Lycodichthys dearborni)that encode larger AFPIII isoforms with up to 12 of the conventional domains.Here we have introduced the fish AFPIII genes that encode for the monomer(ld1),dimer(ld2),trimer(ld3)and tetramer(ld4)AFPIII isoforms in tobacco plants.Pot-grown 4-week-old transgenic tobacco plants were exposed to cold stress at 4◦C for 30 days and the results show that ld1,ld2,ld3 and ld4 transgenic plants present relatively lower electrolyte leakage and lower content of malondialdehyde(MDA),but accumulated higher content of proline when compared to control plants.This indicates considerable improved membrane integrity under low temperature stress and improvement of the plant cold resistance.The plants transformed with the AFPIII tetramer-and trimer-domains demonstrated a higher cold-tolerant levels when compared with plants transformed with the dimer-and monomer AFPIII domains.Our study further supports that fish AFPIIIs,especially the multidomain proteins,protect cells from non-freezing hypothermic stresses,apart from there well-known function as ice inhibitors molecules at freezing temperature.

Female ticks (Ixodes scapularis) infected with Borrelia burgdorferi have increased overwintering survival, with implications for tick population growth

The tick, Ixodes scapularis, vectors pathogens such as Borrelia burgdorferi, the bacterium that causes Lyme disease. Over the last few decades I. scapularis has expanded its range, introducing a novel health threat into these areas. Warming temperatures appear to be one cause of its range expansion to the north. However, other factors are also involved. We show that unfed adult female ticks infected with B. burgdorferi have greater overwintering survival than uninfected female ticks. Locally collected adult female ticks were placed in individual microcosms and allowed to overwinter in both forest and dune grass environments. In the spring we collected the ticks and tested both dead and living ticks for B. burgdorferi DNA. Infected ticks had greater overwintering survival compared with uninfected ticks every winter for three consecutive winters in both forest and dune grass environments. We discuss the most plausible explanations for this result. The increased winter survival of adult female ticks could enhance tick population growth. Our results suggest that, in addition to climate change, B. burgdorferi infection itself may be promoting the northern range expansion of I. scapularis. Our study highlights how pathogens could work synergistically with climate change to promote host range expansion.