Search for Boosted Dark Matter in COSINE-100.

We search for energetic electron recoil signals induced by boosted dark matter (BDM) from the galactic center using the COSINE-100 array of NaI(Tl) crystal detectors at the Yangyang Underground Laboratory. The signal would be an excess of events with energies above 4 MeV over the well-understood background. Because no excess of events are observed in a 97.7 kg·yr exposure, we set limits on BDM interactions under a variety of hypotheses. Notably, we explored the dark photon parameter space, leading to competitive limits compared to direct dark photon search experiments, particularly for dark photon masses below 4 MeV and considering the invisible decay mode. Furthermore, by comparing our results with a previous BDM search conducted by the Super-Kamionkande experiment, we found that the COSINE-100 detector has advantages in searching for low-mass dark matter. This analysis demonstrates the potential of the COSINE-100 detector to search for MeV electron recoil signals produced by the dark sector particle interactions.

Genetic origin, admixture and population history of aurochs (Bos primigenius) and primitive European cattle.

This corrects the article DOI: 10.1038/hdy.2016.79.

Genetic origin, admixture and population history of aurochs (Bos primigenius) and primitive European cattle.

The domestication of taurine cattle initiated ~10 000 years ago in the Near East from a wild aurochs (Bos primigenius) population followed by their dispersal through migration of agriculturalists to Europe. Although gene flow from wild aurochs still present at the time of this early dispersion is still debated, some of the extant primitive cattle populations are believed to possess the aurochs-like primitive features. In this study, we use genome-wide single nucleotide polymorphisms to assess relationship, admixture patterns and demographic history of an ancient aurochs sample and European cattle populations, several of which have primitive features and are suitable for extensive management. The principal component analysis, the model-based clustering and a distance-based network analysis support previous works suggesting different histories for north-western and southern European cattle. Population admixture analysis indicates a zebu gene flow in the Balkan and Italian Podolic cattle populations. Our analysis supports the previous report of gene flow between British and Irish primitive cattle populations and local aurochs. In addition, we show evidence of aurochs gene flow in the Iberian cattle populations indicating wide geographical distribution of the aurochs. Runs of homozygosity (ROH) reveal that demographic processes like genetic isolation and breed formation have contributed to genomic variations of European cattle populations. The ROH also indicate recent inbreeding in southern European cattle populations. We conclude that in addition to factors such as ancient human migrations, isolation by distance and cross-breeding, gene flow between domestic and wild-cattle populations also has shaped genomic composition of European cattle populations.

Performance of PCR-REBA assay for screening and identifying pathogens directly in whole blood of patients with suspected sepsis.

AIMS: Rapid and accurate identification of a broad range of bacterial and fungal pathogens is the key to successful management of patients with bloodstream infections (BSIs). The aim of this study was to evaluate the diagnostic performance of PCR-REBA Sepsis-ID test for the detection of BSIs pathogens. METHODS AND RESULTS: EDTA anticoagulated blood for REBA Sepsis-ID assay and blood culture samples from 882 patients with suspected sepsis were simultaneously collected from January 2014 to December 2014. Of 115 patients with positive blood culture, 64 (55·7%) were Gram-positive bacteria, 35 (30·4%) were Gram-negative bacteria, 1 (0·9%) was Candida albicans and 15 (13·0%) were polymicrobial infections. The concordance rate of blood culture system and PCR-REBA Sepsis ID test was 83·0% (95% confidence interval (CI), 79·8-84·8, P < 0·0001). Compared to blood culture, the diagnosis of bacterial proven pathogens by PCR-REBA revealed 81·0% (95% CI, 73·4-86·8, P < 0·0001) sensitivity, 83·4% (95% CI, 80·0-85·4, P < 0·0001) specificity, 80·9% positive and 95·8% negative predictive values respectively. In 10 cases with PCR-REBA positive but blood culture negative, the levels of C-reactive protein were significantly elevated 18·5 mg dl(-1) (SD ± 13·7, 95% CI 1·8-41·9) and six cases has been proven to have pathogen by bacterial 16S rRNA sequencing. Although the sensitivity for pathogen identification was not significantly different between PCR-REBA and blood culture (P = 0·5), the combination of the two methods resulted in a significantly increased rate of pathogen detection (P = 0·002). The results of this study suggested that PCR-REBA may be helpful when added to blood culture in the diagnosis and management of sepsis. CONCLUSIONS: PCR-REBA Sepsis-ID test is a useful tool for the rapid identification of pathogenic isolates in whole blood to ensure adequate treatment for the causative agents of BSIs. SIGNIFICANCE AND IMPACT OF THE STUDY: Although the cost of molecular diagnostic assays is higher than the cost of conventional methods, clinical and economic cost-benefit analysis is still needed. PCR-REBA may provide essential information for accelerating therapeutic decisions to ensure effective treatment with antibiotics in the acute phase of pathogen infection.

Comparative effect of topical silicone gel and topical tretinoin cream for the prevention of hypertrophic scar and keloid formation and the improvement of scars.

BACKGROUND: Numerous modalities have been used to treat keloids and hypertrophic scars; however, optimal treatment has not yet been established. Therefore, prevention is the mainstay. Recently, silicone gel and tretinoin cream have been shown to be useful for the prevention of hypertrophic scars and keloids. However, there has been no comparative study of the two topical agents thus far. OBJECTIVE: To determine and compare the effectiveness of silicone gel and tretinoin cream for the prevention of hypertrophic scars and keloids resulting from postoperative wounds and for scar improvement. METHOD: This study included 26 patients with 44 different wounds. The postoperative wounds were divided into two treatment groups and one control group. The patients in the first and second treatment group applied silicone gel and tretinoin cream, respectively, twice a day on their wounds after their stitches were removed. In contrast, the control group patients did not apply anything. We used the Modified Vancouver Scar Scale to quantitatively examine the effectiveness of silicone gel and tretinoin cream just after stitches removal, and at 4, 8, 12 and 24 weeks after removal of the stitches. RESULTS: The silicone gel and tretinoin cream effectively prevented hypertrophic scars and keloids and improved scar effects in the two treatment groups compared with those in the control group. However, no significant difference was noted between the two treatment groups. CONCLUSION: To prevent hypertrophic scars and keloids and improve scars after surgery, application of a silicone gel or a tretinoin cream to the wounds is needed.

Clinical characteristics and risk of melanoma development from giant congenital melanocytic naevi in Korea: a nationwide retrospective study.

BACKGROUND: Giant congenital melanocytic naevi (GCMN) are known risk factors for the development of melanoma. However, melanoma risk among Asians is rarely evaluated. OBJECTIVES: To evaluate the clinical characteristics and risk of melanoma development from GCMN in Koreans, we performed a nationwide retrospective cohort study in Korea. GCMN were defined as those comprising ≥5% body surface area in children or measuring ≥20cm in adults. METHODS: In total, 131 patients with GCMN were enrolled, with a mean age of 10·3years (range: birth-70years). RESULTS: The posterior trunk was the most common site (67, 51·1%), followed by lateral trunk, anterior trunk, legs, both anterior and posterior trunk, buttocks, and arms. Satellite naevi were present in 69 cases (52·7%), and axial areas were more commonly involved in patients with satellite naevi than in those without satellite lesions. Atypical features such as rete ridge elongation and bridges were seen, and, among these, pagetoid spread and ballooning cell changes were more common in patients <4years old. Proliferative nodules were found in three cases. Melanomas had developed in three of 131 patients (2·3%; a 6-year-old girl, a 14-year-old girl and a 70-year-old man), and the incidence rate was 990 per 100000 person-years. Melanomas in these three patients consisted of two cutaneous melanomas and one extracutaneous meningeal melanoma. CONCLUSIONS: We should be aware of melanoma development from GCMN, and lifelong follow-up is required due to the risk of melanoma arising in GCMN.

A new mouse gene, SRG3, related to the SWI3 of Saccharomyces cerevisiae, is required for apoptosis induced by glucocorticoids in a thymoma cell line.

We isolated a new mouse gene that is highly expressed in thymocytes, testis, and brain. This gene, SRG3, showed a significant sequence homology to SWI3, a yeast transcriptional activator, and its human homolog BAF155. SRG3 encodes 1,100 amino acids and has 33-47% identity with SWI3 protein over three regions. The SRG3 protein contains an acidic NH2 terminus, a myb-like DNA binding domain, a leucine-zipper motif, and a proline- and glutamine-rich region at its COOH terminus. Rabbit antiserum raised against a COOH-terminal polypeptide of the SRG3 recognized a protein with an apparent molecular mass of 155 kD. The serum also detected a 170-kD protein that seems to be a mouse homologue of human BAF170. Immunoprecipitation of cell extract with the antiserum against the mouse SRG3 also brought down a 195-kD protein that could be recognized by an antiserum raised against human SWI2 protein. The results suggest that the SRG3 protein associates with a mouse SWI2. The SRG3 protein is expressed about three times higher in thymocytes than in peripheral lymphocytes. The expression of anti-sense RNA to SRG3 mRNA in a thymoma cell line, S49.1, reduced the expression level of the SRG3 protein, and decreased the apoptotic cell death induced by glucocorticoids. These results suggest that the SRG3 protein is involved in the glucocorticoid-induced apoptosis in the thymoma cell line. This implicates that the SRG3 may play an important regulatory role during T cell development in thymus.

Rdp1, a novel zinc finger protein, regulates the DNA damage response of rhp51(+) from Schizosaccharomyces pombe.

The Schizosaccharomyces pombe DNA repair gene rhp51(+) encodes a RecA-like protein with the DNA-dependent ATPase activity required for homologous recombination. The level of the rhp51(+) transcript is increased by a variety of DNA-damaging agents. Its promoter has two cis-acting DNA damage-responsive elements (DREs) responsible for DNA damage inducibility. Here we report identification of Rdp1, which regulates rhp51(+) expression through the DRE of rhp51(+). The protein contains a zinc finger and a polyalanine tract similar to ones previously implicated in DNA binding and transactivation or repression, respectively. In vitro footprinting and competitive binding assays indicate that the core consensus sequences (NGG/TTG/A) of DRE are crucial for the binding of Rdp1. Mutations of both DRE1 and DRE2 affected the damage-induced expression of rhp51(+), indicating that both DREs are required for transcriptional activation. In addition, mutations in the DREs significantly reduced survival rates after exposure to DNA-damaging agents, demonstrating that the damage response of rhp51(+) enhances the cellular repair capacity. Surprisingly, haploid cells containing a complete rdp1 deletion could not be recovered, indicating that rdp1(+) is essential for cell viability and implying the existence of other target genes. Furthermore, the DNA damage-dependent expression of rhp51(+) was significantly reduced in checkpoint mutants, raising the possibility that Rdp1 may mediate damage checkpoint-dependent transcription of rhp51(+).

Srg3, a mouse homolog of yeast SWI3, is essential for early embryogenesis and involved in brain development.

Srg3 (SWI3-related gene product) is a mouse homolog of yeast SWI3, Drosophila melanogaster MOIRA (also named MOR/BAP155), and human BAF155 and is known as a core subunit of SWI/SNF complex. This complex is involved in the chromatin remodeling required for the regulation of transcriptional processes associated with development, cellular differentiation, and proliferation. We generated mice with a null mutation in the Srg3 locus to examine its function in vivo. Homozygous mutants develop in the early implantation stage but undergo rapid degeneration thereafter. An in vitro outgrowth study revealed that mutant blastocysts hatch, adhere, and form a layer of trophoblast giant cells, but the inner cell mass degenerates after prolonged culture. Interestingly, about 20% of heterozygous mutant embryos display defects in brain development with abnormal organization of the brain, a condition known as exencephaly. Histological examination suggests that exencephaly is caused by the failure in neural fold elevation, resulting in severe brain malformation. Our findings demonstrate that Srg3 is essential for early embryogenesis and plays an important role in the brain development of mice.

An ikaros-containing chromatin-remodeling complex in adult-type erythroid cells.

We have previously described a SWI/SNF-related protein complex (PYR complex) that is restricted to definitive (adult-type) hematopoietic cells and that specifically binds DNA sequences containing long stretches of pyrimidines. Deletion of an intergenic DNA-binding site for this complex from a human beta-globin locus construct results in delayed human gamma- to beta-globin switching in transgenic mice, suggesting that the PYR complex acts to facilitate the switch. We now show that PYR complex DNA-binding activity also copurifies with subunits of a second type of chromatin-remodeling complex, nucleosome-remodeling deacetylase (NuRD), that has been shown to have both nucleosome-remodeling and histone deacetylase activities. Gel supershift assays using antibodies to the ATPase-helicase subunit of the NuRD complex, Mi-2 (CHD4), confirm that Mi-2 is a component of the PYR complex. In addition, we show that the hematopoietic cell-restricted zinc finger protein Ikaros copurifies with PYR complex DNA-binding activity and that antibodies to Ikaros also supershift the complex. We also show that NuRD and SWI/SNF components coimmunopurify with each other as well as with Ikaros. Competition gel shift experiments using partially purified PYR complex and recombinant Ikaros protein indicate that Ikaros functions as a DNA-binding subunit of the PYR complex. Our results suggest that Ikaros targets two types of chromatin-remodeling factors-activators (SWI/SNF) and repressors (NuRD)-in a single complex (PYR complex) to the beta-globin locus in adult erythroid cells. At the time of the switch from fetal to adult globin production, the PYR complex is assembled and may function to repress gamma-globin gene expression and facilitate gamma- to beta-globin switching.

Comparative RNA expression analyses from small-scale, single-donor platelet samples.

BACKGROUND: Comparisons of platelet RNAs could provide crucial information on platelet function, thrombopoiesis and the etiology of megakaryocyte (MK) or platelet disorders. OBJECTIVES: We developed a method for stringent purification of platelets from small blood samples from single donors. Purity of the platelet preparations was verified by an RT-PCR assay. We tested three methods to identify the differences in RNA between platelet sources. METHODS: Differential hybridization to cDNA macro-arrays and suppressive-subtractive hybridization PCR (SSH-PCR) were used to compare RNAs from normal platelets to those from a Bernard-Soulier syndrome (BSS) patient. Affymetrix GeneChip U133 plus 2.0 arrays were used to compare male and female platelet RNAs. RESULTS: Macroarrays identified approximately 7500 platelet transcripts, but failed to identify differentially expressed transcripts with confidence. SSH-PCR produced libraries almost exclusively of mitochondrial-derived transcripts, but included nuclear-encoded genes that could not be confirmed by immunoblotting of normal and BSS platelet lysates. The Affymetrix platform gave reproducible profiles from our small-scale purified platelet preparations, whereas a partially purified platelet preparation produced a drastically skewed transcript profile. The microarray analysis identified the heparanase precursor transcript as overexpressed in female platelets, and we observed variable yet consistently higher levels of heparanase protein in female platelets compared with male platelets in four independent donor pairs. CONCLUSIONS: This demonstrates for the first time that differential platelet transcript levels can identify changes in expression level of platelet proteins. Combined with our small-scale platelet preparation method, this establishes a system to compare platelets from the limited clinical sources to help elucidate molecular bases for platelet or megakaryocyte pathologies.

Gain- and loss-of-function of Rhp51, a Rad51 homolog in fission yeast, reveals dissimilarities in chromosome integrity.

Rad51 is crucial not only in homologous recombination and recombinational repair but also in normal cellular growth. To address the role of Rad51 in normal cell growth we investigated morphological changes of cells after overexpression of wild-type and a dominant negative form of Rad51 in fission yeast. Rhp51, a Rad51 homolog in Schizosaccharomyces pombe, has a highly conserved ATP-binding motif. Rhp51 K155A, which has a single substitution in this motif, failed to rescue hypersensitivity of a rhp51 mutant to methyl methanesulfonate (MMS) and UV, whereas it binds normally to Rhp51 and Rad22, a Rad52 homolog. Two distinct cellular phenotypes were observed when Rhp51 or Rhp51 K155A was overexpressed in normal cells. Overexpression of Rhp51 caused lethality in the absence of DNA-damaging agents, with acquisition of a cell cycle mutant phenotype and accumulation of a 1C DNA population. On the other hand, overexpression of Rhp51 K155A led to a delay in G(2) with decondensed nuclei, which resembled the phenotype of rhp51. The latter also exhibited MMS and UV sensitivity, indicating that Rhp51 K155A has a dominant negative effect. These results suggest an association between DNA replication and Rad51 function.

The stress-activated MAP kinase Sty1/Spc1 and a 3'-regulatory element mediate UV-induced expression of the uvi15(+) gene at the post-transcriptional level.

Exposure of Schizosaccharomyces pombe cells to UV light results in increased uvi15(+) gene expression at both the mRNA and protein levels, leading to elevated cell survival. This UV-induced expression of the uvi15(+) gene was reduced in Deltasty1 and Deltawis1 cells lacking the stress-activated protein kinase pathway, but not in DNA damage checkpoint mutants. To further understand the cellular mechanisms responsible for this UV-induced expression, the transcription rate and mRNA half-life were investigated. Transcription run-on assays revealed that the rate of uvi15(+) transcription was increased 1.8-fold regardless of Sty1 when cells were UV irradiated. The half-life of uvi15(+) mRNA was also increased 1.5-fold after UV irradiation, but it was decreased in the Deltasty1 background for both basal and UV-induced mRNAs, indicating that the stress-activated MAPK cascade can mediate UV-induced gene expression by increasing mRNA half-life. Deletion analyses identified a 54 nt element downstream of the distal poly(A) site, which was involved in the increased half-life of uvi15(+) mRNA. These results suggest that both Sty1 and the 3'-regulatory element regulate UV-induced expression of the uvi15(+) gene at the post-transcriptional level.

Fission yeast hrp1, a chromodomain ATPase, is required for proper chromosome segregation and its overexpression interferes with chromatin condensation.

Hrp1 of Schizosaccharomyces pombe is a member of the CHD protein family, characterized by a chromodomain, a Myb-like telobox-related DNA-binding domain and a SNF2-related helicase/ATPase domain. CHD proteins are thought to be required for modification of the chromatin structure in transcription, but the exact roles of CHD proteins are not known. Here we examine the sub-cellular localization and biochemical activity of Hrp1 and the phenotypes of hrp1 Delta and Hrp1-overexpressing strains. Fluorescence microscopy revealed that Hrp1 protein is targeted to the nucleus. We found that Hrp1 exhibited DNA-dependent ATPase activity, stimulated by both single- and double-stranded DNA. Overexpression of Hrp1 caused slow cell growth accompanied by defective chromosome condensation in anaphase resulting in a 'cut' (celluntimelytorn) phenotype and chromosome loss. The hrp1 Delta mutation also caused abnormal anaphase and mini-chromosome loss phenotypes. Electron micrographs demonstrated that aberrantly shaped nucleoli appeared in Hrp1-overexpressing cells. Therefore, these results suggest that Hrp1 may play a role in mitotic chromosome segregation and maintenance of chromatin structure by utilizing the energy from ATP hydrolysis.

Replicon size and excision repair as factors in the inhibition and recovery of DNA synthesis from ultraviolet damage.

Initiation of DNA replication and chain growth, analyzed by alkaline sucrose gradient sedimentation, was interrupted to different extents in different cell types by irradiation with ultraviolet light. Within the first hour of irradiation DNA replication was reduced in a manner that depended on the average number of lesions per replicating unit (replicon). At low numbers of lesions per replicon, inhibition of replicon initiation was the predominant response; at higher numbers of lesions per replicon, blockage of chain growth was also observed. After irradiation with a dose that initially blocked chain growth, the rate at which cells recovered their ability to synthesize increasingly more and larger size DNA was a function both of replicon size and of excision repair capacity. Cells with small replicons recovered more rapidly than cells with large replicons, and excision repair-deficient cells recovered less rapidly than excision-competent cells. These observations indicate that excision repair capacity and replicon size play major roles in the response of DNA replication to ultraviolet damage.

Xeroderma pigmentosum variants have a slow recovery of DNA synthesis after irradiation with ultraviolet light.

Human cells (normal and xeroderma pigmentosum variant) irradiated with ultraviolet light and pulse-labelled with [3H]thymidine underwent transient decline and recovery of molecular weights of newly synthesized DNA and rates of [3H]thymidine incorporation. The ability to synthesize normal-sized DNA recovered more rapidly in both cell types than thymidine incorporation. During recovery cells steadily increased in their ability to replicate normal-sized DNA on damaged templates. The molecular weight versus time curves fitted exponential functions with similar rate constants in normal and heterozygous xeroderma pigmentosum cells, but with a slower rate in two xeroderma pigmentosum variant cell lines. Caffeine added during the post-irradiation period eliminated the recovery of molecular weights in xeroderma pigmentosum variant but not in normal cells. The recovery of the ability to synthesize normal-sized DNA represents a combination of a number of cellular regulatory processes, some of which are constitutive, and one of which is altered in the xeroderma pigmentosum variant such that recovery becomes slow and caffeine sensitive.

Involvement of a cAMP-responsive DNA element in mediating TRH responsiveness of the human thyrotropin alpha-subunit gene.

TRH is known to stimulate the transcription of the TSH gene in pituitary cells. To examine TRH-responsive elements of the human TSH alpha-subunit gene, we have used transient transfection of GH3 rat pituitary tumor cells. Using this system, TRH treatment stimulated expression of a reporter gene containing 846 base pairs from the 5'-flanking region of the human glycoprotein hormone alpha-subunit gene linked to luciferase. Analysis of 5'-deletions of the alpha-subunit sequence revealed that at least two DNA regions with upstream limits between positions -223 to -190 and positions -151 to -135 are important for regulation by TRH. The more proximal region includes a previously defined cAMP-response element (CRE) while the more upstream region contains an element with sequence similarity to the binding site for the pituitary transcription factor, Pit-1. The TRH responsiveness of each individual region was tested by inserting fragments upstream of a thymidine kinase-luciferase reporter gene. The -151 to -100 region had basal enhancer activity and permitted a 3.4-fold response to TRH. The -223 to -168 region did not permit a TRH response, but possessed basal enhancer activity. The combination of both regions resulted in a 5-fold stimulation by TRH. To assess the contributions of different signal transduction pathways, various combinations of treatments were examined. Combined treatment with TRH and forskolin led to an additive activity. Treatment with TRH plus phorbol 12-myristate-13-acetate resulted in the same level of reporter gene activity as with either agent alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Management of Meloidogyne incognita on tomato by root-dip treatment in culture filtrate of the blue-green alga, Microcoleus vaginatus.

The nematicidal potential of culture filtrates of the blue-green alga, Microcoleus vaginatus (Cyanobacterium) was tested against Meloidogyne incognita on tomato in pots under greenhouse conditions. Prior to the transplantation of tomato seedling, roots were dipped in different concentrations (0.2%, 0.5%, 1%, 2%, 10%, 50% and 100%) of culture filtrate of M. vaginatus for 30 min. Root-dip treatment reduced the root galling and final population of M. incognita and increased vegetative growth of plants and root-mass production compared with the control. The beneficial effect of root-dip treatment increased with the increase in the concentration of culture filtrate. Root galling and final nematode populations were reduced by 65.9% and 97.5%, respectively when treated at the highest concentration.

Differential expression of the rhp51+ gene, a recA and RAD51 homolog from the fission yeast Schizosaccharomyces pombe.

The rhp51+ gene encodes three transcripts of 1.9, 1.6 and 1.3 kb which have at least six polyadenylation sites. Primer-extension analysis revealed that two transcription start points (tsp) at - 166 and - 136 were responsible for the DNA damage inducibility of this gene. Northern blot analyses showed that the three transcripts were expressed differentially in response to a variety of DNA damage. During the mitotic cell cycle, only the largest transcript exhibited periodic expression, reaching the maximal level in front of the cdc22+ transcript which peaks at the G1/S boundary. Unexpectedly, the steady-state levels of the three transcripts were differentially regulated during the growth cycle. The largest and smallest transcripts accumulated in large quantity at the diauxic shift and during the entry into stationary phase, respectively. To localize the regions responsible for the differential expression of rhp51+, we constructed rhp51::ura4 and ura4::rhp51 hybrid genes, and analyzed their expression patterns in response to methyl methanesulfonate (MMS)-induced DNA damage. The results showed that the promoter region and 5' half of rhp51+ are sufficient to confer damage-responsiveness while the 3' end of the gene alone can direct the formation of multiple, discrete 3' ends of the transcripts. From these results, we conclude that this novel one gene-multiple product system is possible through the cooperation of both the promoter and 3' terminal regions.

Cloning and sequence analysis of rhp51+, a Schizosaccharomyces pombe homolog of the Saccharomyces cerevisiae RAD51 gene.

A homology (rhp51+) of the RAD51 gene in Schizosaccharomyces pombe was cloned by screening a Sz. pombe genomic library using the 3'-end of RAD51 from Saccharomyces cerevisiae as a probe. As in S. cerevisiae, the sequence of rhp51+ showed two MluI cell-cycle boxes and a putative DNA damage-responsive element in its upstream region. The open reading frame codes for a 365-amino-acid (aa) polypeptide with an estimated molecular mass of 40,555 Da. The deduced aa sequence shows 27, 66, 75 and 80% identity with Escherichia coli RecA, S. cerevisiae Rad51 and the Rad51 homologs from chicken and humans, respectively. The aa sequence encoded by rhp51+ contains A- and B-type nucleotide-binding consensus sequences, as found in other RAD51 homologs. Northern blot analysis showed that rhp51+ encodes a 1.7-kb transcript. Methyl methanesulfonate treatment increased the level of this transcript three- to fivefold. Southern hybridization analysis suggests that a single copy of rhp51+ exists in the Sz. pombe genome.