Single nucleotide polymorphisms in bovine <Emphasis Type="Italic">PRL</Emphasis> gene and their associations with milk production traits in Chinese Holsteins

Prolactin (PRL) plays a crucial role in the initiation and maintenance of lactation in mammals. In this study, seven PCR fragments representing most important functional domains of PRL gene were screened for single nucleotide polymorphisms (SNPs) in Chinese Holsteins by single-strand conformation polymorphisms and amplicons sequencing, and their genetic effects on milk production traits were evaluated. A total of four SNPs, including two in the promoter (−1043A>G and −402A>G), one in intron 1 (+2723C>T) and one in exon 4 (+8398G>A) were identified in PRL gene. Statistical results showed significant associations between the promoter genotypes and the milk performance traits in Chinese Holsteins. Cows with genotype P1-GG showed higher milk yields (P < 0.01), while cows with genotype P1-AA showed higher fat contents (P < 0.01). Haplotype analysis of two SNPs in promoter region revealed that the Hap(AG) was significantly associated with increased milk yields and Hap(AA) was associated with increased fat contents (P < 0.01). This is the second study reporting SNPs in the 5′-regulatory region of PRL gene, which interfere with milk production traits.     

Cyclooxygenase-2 gene and epithelial ovarian carcinoma risk

In this study, we aimed to investigate a possible association of the COX-2 polymorphisms (−765G→C and −1195A→G) and with the risk of developing epithelial ovarian carcinoma (EOC). COX-2 gene polymorphisms was investigated in 111 healthy women and 57 patients with EOC. Individuals who had −765 CG, −1195 AA genotype, and −765 C allele had increased risk for ovarian carcinoma (P < 0.01) and individuals with −765 GG, −1195 AG genotypes and −1195 G allele seem to be protected from ovarian carcinoma (P < 0.01). Haplotype analysis confirmed the association of COX-2 gene variants with ovarian carcinoma and revealed that the frequencies of −765C: −1195A haplotype frequencies was significantly higher in patients as compared with those of controls (P = 0.048). We state that there appears to be a modulating role for the COX-2 −1195A→G and −765G→C polymorphisms in the development of EOC. To the best of our knowledge, this is the first study to show such an association.     

Effect of polymorphism in the peroxisome proliferator-activated receptor gamma gene on litter size of pigs

The association of polymorphisms in peroxisome proliferator-activated receptor γ (PPARγ) gene with litter size was studied in Large White and Landrace pig. Three SNP loci (P1, P2 and P7) on PPARγ₂ gene were determined by PCR–SSCP and the results showed that there were A → G mutations at 220 and 324 bp in 5′-regulator region and at 147 bp in exon 6, respectively. Allele frequencies were analysed in two breeds. Information on 2341 litter records from 564 sows was used to analyse the trait total number born (TNB) and number born alive (NBA). In Large White, TNB and NBA of genotype BB for P2 locus were the lowest, and the TNB and NBA of third and following parities and all parities were 0.74 and 0.51 piglets per litter less (P < 0.001) than those of the highest genotype AB, respectively, but for P1 and P7 locus the beneficial genotype AA were more 0.4–0.8 piglets per litter (P < 0.05) than the inferior genotype AB. In landrace, TNB and NBA of the first parity of genotype BB for P1 locus were 2.0 piglets per litter higher than AA (P < 0.05), but for all parities the TNB and NBA of genotype BB were 0.66 and 0.97 piglets per litter (P < 0.05) higher than AA, respectively. At P2 locus, the TNB and NBA of the second parity of genotype AA were obviously higher than those of AB (P < 0.05). And at P7 locus, the TNB and NBA of each parity of genotype AA were both about 2 piglets per litter more than those of BB (P < 0.05). The results indicated that PPARγ gene was significantly associated with litter size in pigs.     

A novel single nucleotide polymorphism in exon 7 of LPL gene and its association with carcass traits and visceral fat deposition in yak (Bos grunniens) steers

Lipoprotein lipase (LPL) is considered as a key enzyme in the lipid deposition and metabolism in tissues. It is assumed to be a major candidate gene for genetic markers in lipid deposition. Therefore, the polymorphisms of the LPL gene and associations with carcass traits and viscera fat content were examined in 398 individuals from five yak (Bos grunniens) breeds using PCR–SSCP analysis and DNA sequencing. A novel nucleotide polymorphism (SNP)-C→T (nt19913) was identified located in exon 7 in the coding region of the LPL gene, which replacement was responsible for a Phe-to-Ser substitution at amino acid. Two alleles (A and B) and three genotypes designed as AA, AB and BB were detected in the PCR products. The frequencies of allele A were 0.7928, 0.7421, 0.7357, 0.6900 and 0.7083 for Tianzhu white yak (WY), Gannan yak (GY), Qinghai-Plateau yak (PY), Xinjiang yak (XY) and Datong yak (DY), respectively. The SNP loci was in Hardy–Weinberg equilibrium in five yak populations (P > 0.05). Polymorphism of LPL gene was shown to be associated with carcass traits and lipid deposition. Least squares analysis revealed that there was a significant effect on live-weight (LW) (P < 0.01), average daily weight gain (ADG) and carcass weight (P < 0.05). Individuals with genotype BB had lower mean values than those with genotype AA and AB for loin eye area and viscera fat weight (% of LW) in 25–36 months (P < 0.05). The results indicated that LPL gene is a strong candidate gene that affects carcass traits and fat deposition in yak.     

Association study of single nucleotide polymorphisms in JAK2 and STAT5B genes and their differential mRNA expression with mastitis susceptibility in Chinese Holstein cattle

The JAK–STAT pathway plays a key role in mediating immune responses. The genetic effects of single nucleotide polymorphisms (SNPs) in JAK2 and STAT5B were investigated for serum cytokines, mastitis indicators and productions traits in a population of 468 Chinese Holstein cattle. Pooled DNA sequencing revealed one SNP (BTA8:g.39645396A>G) in JAK2 and two SNPs (BTA19:g.43673888A>G and BTA19:g.43660093T>C) in STAT5B. A fixed effect model considering the effects of SNPs, parity, herd, season and year of calving was used by way of the general linear model procedure of sas . Genotype frequencies of these SNPs in the population were in Hardy–Weinberg equilibrium (P > 0.05). A novel SNP (g.39645396A>G) in JAK2 was predicted to change the amino acid from lysine to asparagine and was significantly associated with the somatic cell count (SCC) and somatic cell score (SCS), whereas g.43673888A>G in STAT5B was significantly associated with SCC, SCS and interleukin‐4 (IL‐4) (P < 0.05). The dominant effect of g.39645396A>G in JAK2 was significant for SCS, and its additive effect was significant for SCC, whereas the dominant effect of g.43673888A>G in STAT5B was significant for SCS and IL‐4 (P < 0.05). The combination of g.39645396A>G in JAK2 and g.43673888A>G in STAT5B showed a significant effect on SCC, SCS, IL‐4 and TNF‐α (P < 0.05). As for mRNA expression analysis, the AA genotype g.39645396A>G and GG genotype g.43673888A>G indicated higher mRNA expression level and were significantly different from other genotypes (P < 0.05). The results imply that JAK2 and STAT5B genes could be useful candidate genes, and the identified polymorphisms might potentially be strong genetic markers for selection of dairy cattle against mastitis development.     

An association between polymorphism of the heme oxygenase-1 and -2 genes and age-related macular degeneration

Iron may be implicated in the generation of oxidative stress by the catalyzing the Haber–Weiss or Fenton reaction. On the other hand, oxidative stress has been implicated in the pathogenesis of age-related macular degeneration (AMD) and heme oxygenase-1 (HO-1), encoded by the HMOX1 gene and heme oxygenase-2 (HO-2), encoded by the HMOX2 gene are important markers of iron-related oxidative stress and its consequences. Therefore, variability of the HMOX1 and HMOX2 genes might be implicated in the pathogenesis of AMD through the modulation of the cellular reaction to oxidative stress. In the present work, we investigated the association between AMD and a G → C transversion at the 19 position in the HMOX1 gene (the 19G>C-HMOX1 polymorphism, rs2071747) and a A → G transition at the −42 + 1444 position in the HMOX2 gene (the −42 + 1444A>G-HMOX2 polymorphism, rs2270363) and its modulation by some environmental factors. 279 patients with AMD and 105 controls were recruited in this study and the polymorphisms were typed by restriction fragment length polymorphism and allele-specific polymerase chain reaction (PCR). We observed an association between the occurrence of dry AMD and the G/A genotype of the −42 + 1444A>G-HMOX2 polymorphism (odds ratio (OR) 2.72), whereas the G/G genotype reduced the risk of dry AMD (OR 0.41). The G/C genotype and the C allele of the 19 G>C-HMOX1 polymorphism and the G/G genotype and the G allele of the −42 + 1444A>G-HMOX2 polymorphism were associated with progression of AMD from dry to wet form (OR 4.83, 5.20, 2.55, 1.69, respectively). On the other hand, the G/G genotype and the G allele of the 19 G>C-HMOX1 polymorphism and the A/G genotype and the A allele of the −42 + 1444A>G-HMOX2 polymorphism protected against AMD progression (OR 0.19, 0.19, 0.34, 0.59, respectively). Therefore, the 19G>C-HMOX1 and the −42 + 1444A>G-HMOX2 polymorphisms may be associated with the occurrence and progression of AMD.     

Mutations in the exon 10 of prolactin receptor gene change the egg production performance in Wanjiang white goose

To select the molecular genetic markers related to egg performance of Wanjiang white goose, prolactin receptor gene (PRLR) was adopted to be a candidate gene in our study. Five pairs of primers (P1–P5) were designed to detect the SNPs of PRLR gene by PCR-SSCP method. The results revealed that polymorphisms were discovered in the PCR products amplified with P4 primers in PRLR exon 10, three genotypes were found: AA, AB and AC. The sequence of AB genotype is the same as original sequence (DQ660982) in NCBI. There are five mutations in AA genotype: C → A at 840 bp, C → T at 862 bp, T → C at 875 bp, T → A at 963 bp, A → T at 989 bp, resulting in amino acid mutations: His → Asn, Thr → Ile, Asn → Lys, Thr → Ser, and synonymous mutation at 875 bp. Sequencing revealed five mutations in AC genotype: G → T at 816 bp, A → T at 861 bp, C → T at 862 bp, T → C at 875 bp, A → G at 948 bp, causing amino acid mutations of Val → Phe, Thr → Phe, synonymous mutations at 875 and 963 bp. Besides, there are an N-glycosylation site (NQSR), three casein kinase II phosphorylation sites including SIIE, SKTE, and SLMD in AA genotype; three casein kinase II phosphorylation sites including SIIE, SKTE, and TLMD in AB genotype; three casein kinase II phosphorylation sites including SIFE, SKTE, and TLMD in AC genotype. The annual egg yielding of AB genotype geese are significantly more than those of AA and AC genotype geese on the average (P < 0.05). It is suggested for the first time that PRLR is a promising candidate gene that can affect egg performance in Wanjiang white goose.     

Polymorphisms of <Emphasis Type="Italic">STAT5A</Emphasis> gene and their association with milk production traits in Holstein cows

The STAT5A gene was studied as a candidate gene for five milk production traits (milk yield at 305 days, protein percentage, fat percentage, lactose percentage and dry matter percentage) in Holstein cows. According to the sequence of bovine STAT5A gene, two pairs of primers (P1 and P2) were designed to detect polymorphisms of STAT5A gene in 401 Holstein cows by PCR-RFLP and PCR-SSCP. The results showed that the products amplified by primers P1 and P2 displayed polymorphisms. For P1, three genotypes (AA, AG, and GG) were detected, and the frequency of AA/AG/GG was 0.252/0.486/0.262, respectively. Sequence analysis revealed a single nucleotide substitution A–G at 14217 bp (GenBank NC_007317) of bovine STAT5A gene while compared GG genotype with AA genotype. The differences of the least squares means for the four milk production traits (milk yield at 305 days, fat percentage, lactose percentage and dry matter percentage) between AA, AG and GG were not significant (P > 0.05). Least squares mean of protein percentage for AG or GG was significantly higher than that for AA (P < 0.05); the difference of the least squares mean for protein percentage was not significant between AG and GG (P > 0.05). For P2, three genotypes (CC, CT, and TT) were detected in Holstein cows, and the frequency of CC/CT/TT was 0.751/0.234/0.015, respectively. Sequencing revealed an insertion CCT at 17266 (NC_007317) of bovine STAT5A gene while compared CC genotype with TT genotype. The differences of the least squares means for the three milk production traits (protein percentage, lactose percentage and dry matter percentage) between CC, CT and TT were not significant (P > 0.05). Least squares mean of milk yield at 305 days for TT or CT was significantly higher than that for CC (P < 0.05); the difference of the least squares mean for milk yield at 305 days was not significant between TT and CT (P > 0.05). Least squares mean of fat percentage for CC or CT was significantly higher than that for TT (P < 0.05); the difference of the least squares mean for fat percentage was not significant between CC and CT (P > 0.05). The results preliminarily indicated that allele G of A14217G polymorphic site of STAT5A gene is a potential DNA marker for improving protein percentage in dairy cattle, 17266indelCCT polymorphic site of STAT5A gene is a potential DNA marker for improving milk yield at 305 days and fat percentage in dairy cattle.     

Analysis of genetic variability at codon 42 within caprine <Emphasis Type="Italic">prion protein</Emphasis> gene in relation to production traits in Chinese domestic breeds

In this study, genetic variability at codon 42 within prion protein (PRNP) gene and its associations with production traits were investigated in 2002 goats from four Chinese domestic breeds. The frequencies of allele “A” ranged from 0.353 to 0.562 in analyzed goat breeds with Hardy–Weinberg equilibrium (P > 0.05) except Xinong Sannen (XNSN) dairy breed. The establishment of relationships between different genotypes and growth traits was performed in Inner Mongolia white Cashmere (IMWC) breed and revealed an association of the polymorphism with body weight at 7-year-old goats (P = 0.033). The individuals with genotype GG showed heavier body weight than those with genotype AA. Moreover, association analysis detected two significant associations between different genotypes and cashmere yield and fiber length in IMWC breed (P = 0.009, P = 0.048, respectively). In addition, three significant associations of different genotypes with density of milk (a.m. and p.m.), solids-not-fat of milk (P = 0.013, P = 0.009 and P = 0.002), respectively, were found in XNSN breed. Genotype GG had better milk quality than others. These findings suggested that the polymorphism of codon 42 within PRNP was a useful DNA marker for eliminating or selecting excellent individuals in relation to production traits in marker-assist selection breeding of goat.     

Preliminary study on polymorphism analysis of SpRunt-1 gene by PCR–SSCP in <Emphasis Type="Italic">Strongylocentrotus intermedius</Emphasis> and its association with growth traits

In current study, the SpRunt-1 gene was screened for the polymorphisms using PCR-single strand conformation polymorphism (PCR–SSCP) and DNA sequencing methods in Strongylocentrotus intermedius (S. intermedius). Three polymorphisms were found with two site mutations, G833A and C1505T mutation, and an insertion mutation (GT) between 931 nt and 932 nt. These two site mutations are synonymous mutations and the insertion mutation is frame shift mutation. One way ANOVA analysis of correlation between the single nucleotide polymorphisms (SNPs) and growth traits showed that the gonad weight of AA genotype (G at 833 nt) was significantly higher than that of BB genotype (A at 833 nt) (P = 0.029). The body weight of the CC genotype (C at 1505 nt) was significantly higher than that of DD genotype (T at 1505 nt) (P < 0.01) and the shell height of CD genotype was significantly higher than that of DD genotype (P = 0.032). These results provided the evidence that S. intermedius SpRunt-1 gene could be selected as a candidate gene for the growth traits.     

The F279Y polymorphism of the <Emphasis Type="Italic">GHR</Emphasis> gene and its relation to milk production and somatic cell score in German Holstein dairy cattle

The bovine growth hormone receptor (GHR) gene has been identified as a strong positional and functional candidate gene influencing milk production. A non-synonymous single nucleotide polymorphism (SNP) in exon 8 leads to a phenylalanine to tyrosine amino acid substitution (F279Y) in the receptor. The aim of the study was to estimate the effects of the F279Y mutation on milk yield, fat, protein, casein, and lactose yield and content, as well as somatic cell score (SCS), in a German Holstein dairy cattle population. The analysis of 1,370 dairy cows confirmed a strong association of the F279Y polymorphism with milk yield, as well as with fat, protein, and casein contents. Furthermore, increasing effects on lactose yield and content for the 279Y allele were found. Even though the tyrosine variant occurred as the minor allele (16.5%), its substitution effects were 320 kg (305 d), 0.02 kg per day, and 0.07 kg per day for milk, casein, and lactose yields, respectively. The same allele had negative effects on fat, protein, and casein contents. Finally, the high-milk-yield tyrosine allele was also associated with lower SCS (p < 0.05). The data support the high potential of the F279Y polymorphism as a marker for the improvement of milk traits in selection programs.     

Polymorphisms of MRF4 and H-FABP genes association with growth traits in Qinchuan cattle and related hybrids

PCR–RFLP was applied to analyse polymorphisms within the MRF4 and heart fatty acid-binding protein (H-FABP) gene for correlation studies with growth traits in three-month-old Qinchuan (QQ), Qinchuan × Limousin (LQ) and Qinchuan × Red Angus (AQ) cattle. The results showed that 874 bp PCR products of MRF4 digested with XbaI and 2,075 bp PCR products of H-FABP digested with HaeIII were polymorphic in the three populations. Moreover, the frequencies of allele A at MRF4 locus and allele B at H-FABP locus in the QQ, AQ, and LQ populations were 0.8358/0.8888/0.8273 and 0.8358/0.7500/0.8195 respectively. Allele A at MRF4 locus and allele B at H-FABP locus were dominant in the three populations. No statistically significant differences in growth traits were observed among the genotypes of the all three populations at H-FABP locus. However, the association of MRF4 polymorphism with growth traits was then determined in all three populations. The body weight, withers height, heart girth and height at hip cross of individuals with genotype AA were higher than those with genotype AB or BB (P < 0.05). Therefore, we suggest that the MRF4 gene may function in the control or expression of growth traits, particularly body weight, withers height, heart girth and height at hip cross.     

荷斯坦牛Nramp1基因遗传多态性及其与乳房炎相关性的研究

利用PCR-SSCP技术检测了344头中国荷斯坦牛Nramp1基因exon 11的基因多态性, 并分析了其不同基因型与乳房炎及产奶量性状的关系。结果表明: 实验群体发现3种基因型AA、AB、BB, 其中A等位基因为优势等位基因, 等位基因频率为0.767, 而B等位基因频率则为0.233。经χ2适合性检验, 群体处于Hardy-Weinberg平衡状态(P>0.05)。测序结果显示: 扩增片段分别在200 bp(C/G)和254 bp(T/G)存在碱基突变, 并导致了氨基酸改变, 分别为丙氨酸替换为脯氨酸(Ala356Pro)、亮氨基酸替换为蛋氨酸(Leu374Met)。通过构建最小二乘线性模型, 进行Nramp1基因多态性与产奶量、体细胞评分(SCS)的相关性分析表明, AA型个体的SCS最小二乘均值显著低于BB﹑AB型(P<0.05), 而AA型﹑AB个体的产奶量最小二乘均值显著高于BB型(P<0.01, P<0.05), AA基因型可作为乳房炎抗性的优良基因型。因此, 可将Nramp1作为奶牛乳房炎候选基因应用于分子标记辅助选择育种。     

Effects of genetic variability of the carpine homeobox transcription factor <Emphasis Type="Italic">HESX1</Emphasis> gene on performance traits

HESX1 plays a key role in the development of the forebrain and pituitary gland and produces potential effects on performance traits. The objective of this study was to detect and assess the associations of the possible polymorphisms of six loci within HESX1 gene with performance traits in Chinese 1,119 goats. Only one novel SNP (NM_001494116:g.307049A > G) locating on IVS1 + 348A > G was identified and detected by HaeIII forced-RFLP-PCR. The frequencies of allele “G” varied from 0.025 to 0.245 in analyzed populations with the Hardy–Weinberg equilibrium (P > 0.05). Genotypic and allelic frequencies were found to be significantly different in four breeds (χ² = 147.674, df = 6, P < 0.001; χ² = 157.250, df = 3, P < 0.001, respectively), implying that the distribution of genotypic and allelic frequencies of goat HESX1 gene was significantly associated with different goat utilities (cashmere, meat and dairy). Association analysis results revealed no significant effects of caprine HESX1 gene on body sizes in XNSN population (P > 0.05) and cashmere traits in IMWC population (P > 0.05). Significant statistical of HESX1 gene with body weight was found (*P < 0.05). The genotype AA showed significantly higher body weight than those of AG in 2-year-old age (*P < 0.05), while the AA genotype was senior to AG genotype in 4-year-old body weight trait (*P < 0.05). These suggestions indicated that the HESX1 gene has significant effect on goat body weight depending on ages, which is accordance with the function repressor of the HESX1.     

Association between IGF-IR, m-calpain and UCP-3 gene polymorphisms and growth traits in Nanyang cattle

The objective of this study was to estimate the allele and genotype frequencies of the IGF-IR/TaqI, m-calpain/HhaI, and UCP-3/BglI polymorphisms and to determine associations between these polymorphisms and growth traits in Chinese indigenous cattle breeds. Genotyping was performed on 321 animals including 135 Nanyang, 80 Qinchuan, and 106 Jiaxian cattle. No significant differences in growth traits were observed between the genotypes of IGF-IR/TaqI polymorphism in Nanyang cattle. The m-calpain/HhaI, and UCP-3/BglI polymorphisms were associated with body weight, withers height, and body length of 6 months (P < 0.05 or P < 0.01), body length of 18 months (P < 0.05), and body length and heart girth of 24 months (P < 0.01) in Nanyang cattle. In addition, Nanyang cattle aged 12 months with AB genotype of m-calpain/HhaI polymorphism had higher body length and heart girth than those with BB genotype (P < 0.01). The withers height were greater (P < 0.01) in Nanyang cattle aged 12 months with genotype AB of UCP-3/BglI polymorphism than those with genotype BB. The Nanyang cattle aged 24 months with genotype AA had higher withers height than those with genotype BB (P < 0.05). In conclusion, the m-calpain/HhaI and UCP-3/BglI polymorphisms may be used as DNA markers for selection in the breeding process of Nanyang cattle.     

Three novel SNPs in the coding region of <Emphasis Type="Italic">PPARγ</Emphasis> gene and their associations with meat quality traits in cattle

The peroxisome proliferator-activated receptor γ (PPARγ) is a nuclear hormone receptor that regulates adipogenesis and many other biological processes. In the present study, we carried out PCR–SSCP and DNA sequencing analyses to examine SNPs in coding region of the PPARγ gene. A total of 660 individuals from five Chinese cattle breeds were genotyped. We identified three SNPs and their associations with meat quality traits were analyzed in 108 Qinchuan cattle. Two missense mutations and one synonymous mutation were found: 200 A > G (genotypes AA, AB and BB) resulting in D7G change, the silent substitution 42895 C > T (genotypes JJ and JI) and 72472 G > T (genotypes CC, DC and DD) producing Q448H change, respectively. The frequencies of PPARγ-A allele were 0.86, 0.83, 0.80, 0.72 and 0.87 for Qinchuan, Nanyang, Jiaxian, Luxi and Xianan populations, respectively. The frequencies of PPARγ-J allele varied from 0.87 to 0.96 in the five populations. In the 72472 G > T locus, the frequencies of PPARγ-C allele were higher than PPARγ-D allele in the five populations, and ranged from 0.58 to 0.82. Least squares analysis revealed that in 42895 C > T locus, there was a significant effect on tenderness in 18-20 months Qinchuan cattle (P < 0.01), and in the 72472 G > T locus, animals with the genotype DC had lower mean values than these with genotype CC (P < 0.01) for back fat thickness in 18–20 months, and animals with the genotype DD had lower mean values than these with genotypes CC and DC (P < 0.01) for water holding capacity in 21–24 months (P < 0.01). The SNPs we have identified may contribute to establishing a more efficient selection program for improving of genetic characteristics in indigenous Chinese cattle     

Mice hypomorphic for Atr have increased DNA damage and abnormal checkpoint response

The ATR checkpoint pathway responds to DNA damage during the S/G2 phases of the cell cycle and is activated early in tumorigenesis. Investigation of ATR’s role in development and tumorigenesis is complicated by the lethality of homozygous knockout mice and the limited effects of heterozygous deficiency. To overcome this limitation, we sought to create mice with a hypomorphic Atr mutation based on the ATR mutation in the human disease Seckel syndrome-1 (SCKL1). Homozygous SCKL1 mice were generated by targeted knock-in of the A → G SCKL1 mutation. Western blot and RT-PCR analysis established that homozygotes have no reduction in Atr protein or increase in missplicing as is seen in humans. Thus, the A → G substitution alone is not sufficient to reproduce in mice the effects that are seen in humans. However, homozygous SCKL1 mice that retain the neo cassette used for targeting have an estimated 66-82% reduction in total Atr protein levels due to missplicing into the neo cassette. Under conditions of APH-induced replication stress, primary fibroblasts from homozygous mice displayed an increase in overall chromosome damage and an increase in gaps and breaks at specific common fragile sites. In addition, mutant cells display a significant delay in checkpoint induction and an increase in DNA damage as assayed by Chk1 phosphorylation and γ-H2ax levels, respectively. These mice provide a novel model system for studies of Atr deficiency and replication stress. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Reduced folate carrier 80A→G polymorphism,plasma folate,and risk of placental abruption

Folate deficiency and maternal smoking are strong risk factors for placental abruption. We assessed whether the reduced folate carrier [NM_194255.1: c.80A→G (i.e., p.His27Arg)] (RFC-1) polymorphism was associated with placental abruption, and evaluated if maternal smoking modified the association between plasma folate and abruption. Data were derived from the New Jersey-Placental Abruption Study—a multicenter, case-control study of placental abruption (2002–2007). Maternal DNA was assayed for the RFC-1 c.80A→G polymorphism using a PCR-dependent diagnostic test. Maternal folate (nmol/l) was assessed from maternal plasma, collected immediately following delivery. Due to assay limitations, folate levels at ≥60 nmol/l were truncated at 60 nmol/l. Therefore, case–control differences in folate were assessed from censored log-normal regression models following adjustment for potential confounders. Distribution of the mutant allele (G) of the RFC-1 c.80A→G polymorphism was similar between cases (52.3%; n = 196) and controls (50.5%; n = 191), as was the homozygous mutant (G/G) genotype (OR 1.1, 95% CI 0.6–2.2). In a sub-sample of 136 cases and 140 controls, maternal plasma folate levels (mean ± standard error) corrected for assay detection limits were similar between placental abruption cases (63.6 ± 5.1 nmol/l) and controls (58.3 ± 4.7 nmol/l; P = 0.270), and maternal smoking did not modify this relationship (interaction P = 0.169). We did not detect any association between the RFC-1 c.80A→G polymorphism and placental abruption, nor was an association between plasma folate and abruption risk evident. These findings may be the consequence of high prevalence of prenatal multivitamin and folate supplementation in this population (over 80%). It is therefore not surprising that folate deficiency may be rare and that the RFC-1 c.80A→G polymorphism is less biologically significant for placental abruption.