一个新的玉米silky1基因等位突变体的遗传分析与分子鉴定

前期试验发现一个玉米雄性不育突变体(malesterile mutant),命名为msm-6。经过连续多代杂合单株自交发现该突变体性状能稳定遗传,遗传模式分析表明该突变体为单个隐性1核基因控制。以msm-6与自交系B73杂交构建F2遗传定位群体,利用BSA(BulkSegregant Analysis)方法,筛选到与msm-6位点连锁的4个SSR标记,即C6-24、C6-30、C6-34和C6-40。进一步采用444个F2单株对这4个连锁标记验证,将msm-6定位于标记C6-24与C6-34之间,即玉米第6染色体68.5~98.1Mb之间。通过基因组序列信息分析发现,在此定位区间内存在一个已报道的Silky1基因。Silky1基因编码MADS-BOX蛋白,是参与花器官建成ABCD模型的B功能基因,该基因的突变会造成雄花不育、雌花花丝增多等表型。利用杂合体+/silky1-mum3与纯合突变体msm-6/msm-6杂交进行等位测验,杂交后代中正常植株与突变植株分离比例符合1∶1。基因组序列以及转录本序列分析发现,msm-6突变体中第6个内含子5'端供体位点AG/GTAAG(外显子/内含子交接处)的序列+1位G突变为C,导致第6外显子被错误剪切掉,产生了第6个外显子缺失的Silky1异常转录本。以上实验证据表明,msm-6与所报道的由mutator转座子插入造成的Silky1突变体silky1-mum2、silky1-mum3和silky1-mum4的突变方式不同,是一个新的Silky1基因等位突变体。msm-6的发现与鉴定为进一步深入解析玉米穗花器官决定的遗传机制提供丰富的实验材料,同时也为RNA加工过程中剪接位点保守性提供重要证据。

Metabolic rate and evaporative water loss in the silky starling （Sturnus sericeus）

To better understand the physiological characteristics of the silky starling（Sturnus sericeus）, its body temperature（Tb）, basal metabolic rate（BMR）, evaporative water loss（EWL） and thermal conductance（C） elicited by different ambient temperatures（Ta）（5-30 ℃） were determined in the present study. Our results showed that they have a high Tb（41.6±0.1 ℃）, a wide thermal neutral zone（TNZ）（20-27.5 ℃） and a relatively low BMR within the TNZ（3.37±0.17 mL O2/g·h）. The EWL was nearly stable below the TNZ（0.91±0.07 mg H2O/g·h） but increased remarkably within and above the TNZ. The C was constant below the TNZ, with a minimum value of 0.14±0.01 mL O2/g·h·℃. These findings indicate that the BMR, Tb and EWL of the silky starling were all affected by Ta, especially when Ta was below 20℃ and the EWL plays an important role in thermal regulation.

Study of the Influence of Silkworm Feeding Conditions on the Quality of Cocoons and Properties of the Cocoon Shell

The article presents the results of a study of the influence of silkworm feeding conditions enriched with mulberry leaves on the quality of cocoons and properties of the cocoon shell.

玉米突变体库创制及雄性不育突变体鉴定

通过钴60辐射诱变京科糯2000获得了一个糯玉米突变体库。从该突变体库中鉴定出71个不同类型的雄性完全不育的突变体。通过候选基因分析和表型-突变基因共分离鉴定,从无花粉突变体中鉴定到一个ms8突变体,一个花药缺失突变体鉴定为silky1突变体。两个突变体均表现出雄性完全不育,而营养生长和雌穗结实正常,适用于雄性核不育杂交制种技术的研究和应用。

Inverted duplication including Endothelin 3 closely related to dermal hyperpigmentation in Silkie chickens

The dermal hyperpigmentation phenotype in chickens is controlled by the dominant fibromelanosis allele.One of the ten unique characteristics of Silkie chickens is the fibromelanosis phenotype,which is pigmentation in the dermal layer of the skin and connective tissue.In this study,we found a mutation of fibromelanosis,a genomic rearrangement that included an inverted duplication of endothelin3(EDN3),is responsible.We show that,as a stimulator of melanoblast proliferation,EDN3 expression was increased in silkie embryos and in both skin and muscle throughout adulthood.EDN3 expression led to an increase in expression of the downstream genes EDNRB2 and TYRP2,and was closely relate with the hyperpigmentation phenotype.We examined eight different Chinese chicken breeds showing hyperpigmentation and conclude that this structural genetic variant exists in all fibromelanosis chicken breeds.

Genomic regions associated with the sex-linked inhibitor of dermal melanin in Silkie chicken

A unique characteristic of the Silkie chicken is its fibromelanosis phenotype.The dermal layer of its skin,its connective tissue and shank dermis are hyperpigmented.This dermal hyperpigmentation phenotype is controlled by the sex-linked inhibitor of dermal melanin gene(ID)and the dominant fibromelanosis allele.This study attempted to confirm the genomic region associated with ID.By genotyping,ID was found to be closely linked to the region between GGA_rs16127903 and GGA_rs14685542(8406919 bp)on chromosome Z,which contains ten functional genes.The expression of these genes was characterized in the embryo and 4 days after hatching and it was concluded that MTAP,encoding methylthioadenosinephosphorylase,would be the most likely candidate gene.Finally,target DNA capture and sequence analysis was performed,but no specific SNP(s)was found in the targeted region of the Silkie genome.Further work is necessary to identify the causal ID mutation located on chromosome Z.

A comparative study to determine the effects of breed and feed restriction on glucose metabolism of chickens

The glucose metabolism of poultry draws wide attention as they have nearly twice the fasting blood glucose than that of mammals.To define the relationship between glucose metabolism and breed of chicken,the outcomes from different growth rate chickens showed that Arbor Acres(AA)broilers,a well-known fast-growing breed,had a lower fasting blood glucose concentration and glucose clearance rate when compared to Silky chickens,a Chinese traditional medicinal chicken with black skin and a slow growth rate.Moreover,AA broilers had a relatively slow rise in blood glucose in response to oral glucose solution than the Silky chickens on 21 and 42 d(P<0.05),which is probably attributed to downregulated expression of pancreatic insulin(INS),and upregulated transcription of phosphoenolpyruvate carboxy kinase 1(PCK1)and glucose transporter 2(GLUT2)in the liver of AA broilers(P<0.05).In response to feeding restriction from 7 to 21 d,both the fasting blood glucose and the response speed of AA broilers to oral glucose were increased on d 21(P<0.05),and the serum glucose concentrations after 3 weeks compensatory growth were improved by early feed restriction in AA broilers.Feed restriction could also upregulate the mRNA level of pancreatic INS on d 21 and 42,as well as decrease the expressions of PCK1,glucose-6-phosphatase catalytic(G6PC),and GLUT2 in the liver on d 21(P<0.05)when compared to the free feeding group.These results revealed that Silky chickens have a stronger capability to regulate glucose homeostasis than AA broilers,and feed restriction could improve the fasting blood glucose and the response to oral glucose of AA broilers.

A microarray study of altered gene expression during melanoblasts migration in normal pigmented White Leghorn and hyperpigmented mutant Silky Fowl

Melanoblasts originating from neural crest cells can migrate through the mesenchyme of the developed embryo and give rise to melanocytes.Unlike the melanocytes that are confined to the integument in other vertebrates,melanocytes in Silky Fowl can reach the ventral regions of the embryos owing to differences in gene expression in the process of melanoblasts migration.In this study,we used microarray profiling to identify differences in gene expression between White Leghorn and Silky Fowl.Differential expression of 2517 microarray probes(P<0.01,Fold Change>2)was observed in Silky Fowl compared to White Leghorn.After filtration by cluster analysis,functional annotation and pathway analysis,eight differentially expressed genes were identified to be closely related to the development of melanocytes.Moreover,differences in expression of immune genes were also detected between Silky Fowl and White Leghorn.The differentially expressed genes associated with melanocyte development were verified by q-PCR,and results were highly consistent with the microarray data.The genes with significantly altered expression involved in melanoblast migration and development suggested that different microenvironments resulted in the abnormal melanoblast migration in Silky Fowl,although there were no big differences in melanoblast development between these two breeds.The candidate genes discovered in this study are beneficial to understand the molecular mechanism of hyperpigmentation in Silky Fowl.