The insect digestive system is the first line of defence protecting cells and tissues of the body from a broad spectrum of toxins and antinutritional factors in its food. To gain insight into the nature and breadth of genes involved in adaptation to dietary challenge, a collection of 20 352 cDNAs was prepared from the midgut tissue of cowpea bruchid larvae (Callosobruchus maculatus) fed on regular diet and diets containing antinutritional compounds. Transcript responses of the larvae to dietary soybean cystatin (scN) were analysed using cDNA microarrays, followed by quantitative real-time PCR (RT-PCR) confirmation with selected genes. The midgut transcript profile of insects fed a sustained sublethal scN dose over the larval life was compared with that of insects treated with an acute high dose of scN for 24 h. A total of 1756 scN-responsive cDNAs was sequenced; these clustered into 967 contigs, of which 653 were singletons. Many contigs (451) did not show homology with known genes, or had homology only with genes of unknown function in a Blast search. The identified differentially regulated sequences encoded proteins presumptively involved in metabolism, structure, development, signalling, defence and stress response. Expression patterns of some scN-responsive genes were consistent in each larval stage, whereas others exhibited developmental stage-specificity. Acute (24 h), high level exposure to dietary scN caused altered expression of a set of genes partially overlapping with the transcript profile seen under chronic lower level exposure. Protein and carbohydrate hydrolases were generally up-regulated by scN whereas structural, defence and stress-related genes were largely down-regulated. These results show that insects actively mobilize genomic resources in the alimentary tract to mitigate the impact of a digestive protease inhibitor. The enhanced or restored digestibility that may result is possibly crucial for insect survival, yet may be bought at the cost of weakened response to other stresses.

Growth differentiation factor 9 (GDF9) which controls the fecundity of Belclare, Cambridge, Santa Ines, Moghani, Ghezel and Thoka ewes was studied as a candidate gene for the prolificacy of Small Tail Han sheep. According to the sequence of ovine GDF9 gene, six pairs of primers were designed to detect single nucleotide polymorphisms of two exons of GDF9 gene in both high fecundity breed (Small Tail Han sheep) and low fecundity breed (Dorset sheep) by polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP). Only the products amplified by primers 2-1 and 2-2 displayed polymorphisms. For primer 2-1, three genotypes (AA, AB and BB) were detected in both sheep breeds. Sequencing revealed one silent mutation (G477A) in exon 2 of GDF9 gene in the BB genotype in comparison with the AA, which was known as G3 mutation of GDF9 gene in Belclare and Cambridge ewes. The relationship of least squares means for litter size was AA > AB > BB in Small Tail Han sheep (P > 0.05). For primer 2-2, two genotypes (CC and CD) were detected in both sheep breeds. Sequencing revealed one novel single nucleotide mutation (G729T) in exon 2 of GDF9 gene in the CD genotype in comparison with the CC, which resulted in an amino acid change (Gln243His). The ewes with mutation heterozygous genotype CD had 0.77 (P < 0.01) lambs more than those with wild type CC in Small Tail Han sheep. These results preliminarily indicated that allele D of GDF9 gene was a potential genetic marker for improving litter size in Small Tail Han sheep.

Insects are capable of readjusting their digestive regimes in response to dietary challenge. Cowpea bruchids (Callosobruchus maculatus) strongly induce C. maculatus cathepsin B-like cysteine protease 1 (CmCatB1) transcripts when fed diet containing a soybean cysteine protease inhibitor soyacystatin N (scN). CmCatB1 shares significant sequence similarity with cathepsin B-like cysteine proteases. In this study, we isolated another cDNA, namely CmCatB2 that encodes a protein sequence otherwise identical to CmCatB1, but lacking a 70-amino-acid internal section. CmCatB1 and CmCatB2 probably resulted from alternate splicing events. Only the CmCatB1 transcript, however, exhibited differential expression in response to dietary scN. Further, this expression was only detectable in larvae, which is the developmental stage associated with food ingestion. The scN-activated and developmentally regulated CmCatB1 expression pattern suggests it may have a unique function in insect counter-defence against antinutritional factors. Heterologously expressed recombinant CmCatB1 protein exhibited enzymatic activity in a pH-dependent manner. Activity of the protein was inhibited by both the cysteine protease inhibitor E-64 and the cathepsin B-specific inhibitor CA-074, verifying its cathepsin B-like cysteine protease nature. Interestingly, the enzymatic activity was unaffected by the presence of scN. Together, we have provided functional evidence suggesting that CmCatB1 confers inhibitor-insensitive enzymatic activity to cowpea bruchids, which is crucial for insect survival when challenged by dietary protease inhibitors.

Most cashmere goats are found in northern China and Mongolia. They are regarded as precious resources for their production of high quality natural fibre for the textile industry. It was the first time that the genetic diversity and population structure of nine Chinese cashmere populations has been assessed using 14 ISAG/FAO microsatellite markers. In addition, two Iranian populations and one West African goat population were genotyped for comparison. Results indicated that the genetic diversity of Chinese cashmere goats was rich, but less than those of the Iranian goat populations. All pairwise F(ST) values between the Chinese cashmere goat populations reached a highly significant level (P < 0.001), suggesting that they should all be considered as separate breeds. Finally, clustering analysis divided Chinese cashmere goats into at least two clusters, with the Tibetan Hegu goats alone in one cluster. An extensive admixture was detected among the Chinese goat breeds (except the Hegu), which have important implications for breeding management.

Single nucleotide polymorphisms of 5' regulatory region of follicle-stimulating hormone receptor (FSHR) gene were detected in two high prolificacy sheep breeds (Small Tail Han and Hu sheep) and two low prolificacy sheep breeds (Corriedale and Chinese Merino sheep) by polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP). The results indicated that there were three genotypes (AA, AB and BB) detected by primer 1 in Hu sheep while only one genotype (AA) in other three sheep breeds, and frequencies of AA, AB and BB genotypes in Hu sheep were 0.700, 0.225 and 0.075, respectively. There were three genotypes (EE, EF and EG) detected by primer 3 in Small Tail Han sheep while only EE genotype occurred in other three sheep breeds, and frequencies of EE, EF and EG genotypes in Small Tail Han sheep were 0.775, 0.200 and 0.025, respectively. No polymorphism was detected in four sheep breeds by primer 2 and primer 4. The sequencing results showed that there were two nucleotide mutations (g. -681T>C and g. -629C>T) in genotype BB compared with AA for primer 1. As for primer 3, two mutations (g. -197G>A and g. -98T>C) in genotype EF compared with EE and two mutations (g. -200G>A and g. -197G>A) in genotype EG compared with EE. The heterozygous ewes with EG or EF had 0.89 (P < 0.05) or 0.42 (P < 0.05) lambs more than homozygous ewes (EE genotype) in Small Tail Han sheep, respectively, while there was no significant difference on litter size between EG and EF ewes.

The bone morphogenetic protein receptor IB (BMPR-IB) gene was studied as a candidate gene for the prolificacy of goats. According to mRNA sequence of ovine BMPR-IB gene, ten pairs of primers were designed to detect single nucleotide polymorphisms (SNPs) of exon 1, exon 2, exon 6 to exon 10 and 3' untranslated region (UTR) of the BMPR-IB gene in both high prolificacy breed (Jining Grey goat) and low prolificacy breeds (Wendeng Dairy and Inner Mongolia Cashmere goats) by polymerase chain reaction (PCR)-single strand conformation polymorphism (SSCP) method. Only the products amplified by primers P8 and P10 of the 3'UTR displayed polymorphisms. For primer P8, three genotypes (AA, AB and BB) were detected in Jining Grey and Wendeng Dairy goats, two genotypes (AA and AB) were in Inner Mongolia Cashmere goats. Sequencing revealed one mutation (71C→T) of the BMPR-IB gene in genotype BB compared with AA. The differences of least squares mean (LSM) for litter size between genotypes AA, AB and BB were non-significant (P > 0.05) in Jining Grey goats. For primer P10, three genotypes (CC, CD and DD) were detected in Jining Grey and Wendeng Dairy goats and one genotype (CC) in Inner Mongolia Cashmere goats. Sequencing revealed one mutation (130T→C) of the BMPR-IB gene in genotype DD compared with CC. The differences of LSM for litter size between genotypes CC, CD and DD were non-significant (P > 0.05) in Jining Grey goats. These results preliminarily showed that the detected loci of the BMPR-IB gene had no significant effect on prolificacy of Jining Grey goats.

Genetic variability, based on prolamines, was studied among 40 populations of Agropyron mongolicum Keng that were collected from the extensive geographic areas of northern China. A high level of genetic diversity was detected in these A. mongolicum populations. In total, 81 electrophoretic bands were observed following acid polyacrylamide gel electrophoresis (A-PAGE), among which 20, 16, 10, and 35 allelic variants were separated into a-, b-, c-, and x-fractions of prolamine. Each A. mongolicum population had unique electrophoretic pattern, which exhibited enough genetic diversity for identification and classification of populations in A. mongolicum. The proportion of diversity among and within geographic regions from which the populations of A. mongolicum originated indicated that 52.1% of the total variation was found within regions, and 47.9% among regions. According to the dentrogram based on the Nei' genetic distance matrix, the A. mongolicum populations from different regions were distinctly clarified. At Nei's distance of 0.75, the populations of A. mongolicum were divided into two groups. The UPGMA phenogram and the principal coordinate analysis (PCA) indicated that the populations from similar eco-geographical situations were clustered together.

Two pairs of primers (P1 and P2) were designed to detect single nucleotide polymorphisms of exon 2 and intron 2 of bone morphogenetic protein 4 (BMP4) gene in both high fecundity breed (Jining Grey goat) and low fecundity breeds (Boer, Angora and Inner Mongolia Cashmere goats) by single strand conformation polymorphism. Results showed that no polymorphism was detected for exon 2 (primer P1) of BMP4 gene in four goat breeds. For intron 2 (primer P2), three genotypes (AA, AB and BB) were detected in Jining Grey and Inner Mongolia Cashmere goats, two genotypes (AB and BB) in Angora goats, and only one genotype (AA) in Boer goats. Sequencing revealed one mutation (2203G>A) of BMP4 gene in the genotype BB in comparison to the genotype AA. The differences of litter size between AA, AB and BB genotypes were not significant (P > 0.05) in Jining Grey goats. A pair of primer (P3) was designed to detect polymorphism in the 3' flanking region of BMP4 gene that contained dinucleotide repeated sequence (CA) in the four goat breeds by microsatellite analysis. For primer P3, three genotypes (CC, CD and DD) were detected in four goat breeds. Sequencing revealed one more CA dinucleotide in genotype DD than in genotype CC. The Jining Grey does with genotype CC had 0.55 (P < 0.05) or 0.72 (P< 0.05) kids more than those with genotype CD or DD. These results preliminarily indicated that allele C of BMP4 gene is a potential DNA marker for improving litter size in goats.