Defensin is a kind of cationic, inducible antimicrobial peptide found in a large range of living organisms that contributes to host defense by disrupting the cytoplasmic membrane of microorganisms. With their broad an...Defensin is a kind of cationic, inducible antimicrobial peptide found in a large range of living organisms that contributes to host defense by disrupting the cytoplasmic membrane of microorganisms. With their broad antimicrobial spectrum and strong pharmaceutical effects, antimicrobial peptides, including defensins, represent a source of novel antibiotic agents. A novel full-length 430 base pairs cDNA of an insect defensin was cloned using polymerase chain reaction (PCR) from the cDNA library of houseflies (Musca domestica) that had been challenged by E. coli and Staphylococcus aureus. Sequence analysis revealed that the open reading frame of the cDNA encoded a 92-amino acid peptide, which contained an NH 2-terminal signal sequence (1-22) followed by a propeptide and the mature peptide (53-92). The sequence identity with other insect defensin is between 51% and 73%. The mature peptide, with a predicted molecular weight of 4\^0 kDa, and pI of 8\^69, has 1 negative charged amino acid and 4 positice ones. The putative housefly defensin is characterized by 6 invariant cysteine residues forming 3 disulfide bonds, Cys1-Cys4, Cys2-Cys5 and Cys3-Cys6. These results suggest that the novel full-length cDNA of the defensin gene, denominated Mdde, has been successfully cloned from houseflies.展开更多
Defensins play a vital role in the early stage of infection before adaptive immune responses are generated. Thus far, only limited detailed genomic data for avian defensin genes have been described. Here, using bacter...Defensins play a vital role in the early stage of infection before adaptive immune responses are generated. Thus far, only limited detailed genomic data for avian defensin genes have been described. Here, using bacterial ar- tificial chromosome libraries, we found that a 95 kb and 177 kb sequences in the golden pheasant （Chrysolophus pictus, Galliformes） and hwamei （Garrulax canorus, Passeriformes） corresponds to 16 and 30 defensin genes, respectively. Fluorescence in situ hybridization assigned defensin gene clusters in the golden pheasant and hwamei to chromosomes 2q and 3q, respectively. In combination with the previous chicken （Gallus gallus, Galliformes） and zebra finch （Taeniopygia guttata, Passeriformes） defensin clusters, the comparative genomic analysis revealed that lineage- specific duplications and deletions have given rise to clearly different genomic structures. On the basis of genomic char- acteristics, we further found that transposable elements act as agents of evolution, causing direct and indirect copy number variations in defensin genes via duplications. Tissue ex- pression analysis showed that the Passeriformes-specific duplicated AvBD1 and AvBD3 genes are mainly expressed in the upper and lower respiratory tract, tongue, and spleen. Our analyses indicate that the duplication-and-deletion of defensin genes conformed to the birth-and-death evolutionary process and that transposable elements induced theduplication of defensin genes. Moreover, the respiratory system-specific expression pattern of Passeriformes-specific expanded AvBD1 and AvBD3 genes suggests their important role in maintaining the singing trait of songbirds. The understanding of the genomic structure, expression, and evolution of defensin genes can provide a crucial immunological foundation to study and prevent avian diseases.展开更多
The aim of the study was to evaluate the impact of organic selenium supplementation （selenium yeast） vs. inorganic selenium （selenium selenite） on the expression of selected defensin genes in milk somatic cells （...The aim of the study was to evaluate the impact of organic selenium supplementation （selenium yeast） vs. inorganic selenium （selenium selenite） on the expression of selected defensin genes in milk somatic cells （MSC） of dairy cows. Sixteen Polish Holstein-Friesian cows in second parity, with similar milk yield and milk composition were randomly divided into two equal groups. At the beginning of experiment, the animals were in the middle of their lactation curve （150, standard deviation （SD） = 26 d） and this experiment lasted 90 d. The basic diet, for both groups, consisted of corn silage, wilted grass silage and concentrates. The diet of control group was supplemented with commercial mineral and vitamin mixture with inorganic selenium and the for the experimental group daily selenium need was covered by the addition of Se-yeast （6 mg Se/cow/d）. Milk samples were collected three times during experiment （before experiment; on day 55; after the end the experiment）. Total RNA was isolated from milk somatic cells and the levels of transcripts of bovine β1-defensin （DEFB1）, β4-defensin （BNBD4）, β5-defensin （BNBDS）, β10-defensin （BNBD10） and lingual antimicrobial peptide （LAP） were measured with real time PCR, using glyceraldehyde 3-phosphate dehydrogenase （GAPDH） as a reference gene. The expressions of almost all studied genes were influenced by environmental conditions （very low and negative temperature）. However, BNBD4 （P 〈 0.05） and LAP （P ≤ 0.001 ） genes were influenced by selenium supplementation but in opposite ways, depending on the form of Se. These findings support that selenium is an important factor affecting the mRNA level in MSC, but the effect of the form of selenium might depend on genes.展开更多
文摘Defensin is a kind of cationic, inducible antimicrobial peptide found in a large range of living organisms that contributes to host defense by disrupting the cytoplasmic membrane of microorganisms. With their broad antimicrobial spectrum and strong pharmaceutical effects, antimicrobial peptides, including defensins, represent a source of novel antibiotic agents. A novel full-length 430 base pairs cDNA of an insect defensin was cloned using polymerase chain reaction (PCR) from the cDNA library of houseflies (Musca domestica) that had been challenged by E. coli and Staphylococcus aureus. Sequence analysis revealed that the open reading frame of the cDNA encoded a 92-amino acid peptide, which contained an NH 2-terminal signal sequence (1-22) followed by a propeptide and the mature peptide (53-92). The sequence identity with other insect defensin is between 51% and 73%. The mature peptide, with a predicted molecular weight of 4\^0 kDa, and pI of 8\^69, has 1 negative charged amino acid and 4 positice ones. The putative housefly defensin is characterized by 6 invariant cysteine residues forming 3 disulfide bonds, Cys1-Cys4, Cys2-Cys5 and Cys3-Cys6. These results suggest that the novel full-length cDNA of the defensin gene, denominated Mdde, has been successfully cloned from houseflies.
基金supported by the National Natural Science Foundation of China(31070334)
文摘Defensins play a vital role in the early stage of infection before adaptive immune responses are generated. Thus far, only limited detailed genomic data for avian defensin genes have been described. Here, using bacterial ar- tificial chromosome libraries, we found that a 95 kb and 177 kb sequences in the golden pheasant （Chrysolophus pictus, Galliformes） and hwamei （Garrulax canorus, Passeriformes） corresponds to 16 and 30 defensin genes, respectively. Fluorescence in situ hybridization assigned defensin gene clusters in the golden pheasant and hwamei to chromosomes 2q and 3q, respectively. In combination with the previous chicken （Gallus gallus, Galliformes） and zebra finch （Taeniopygia guttata, Passeriformes） defensin clusters, the comparative genomic analysis revealed that lineage- specific duplications and deletions have given rise to clearly different genomic structures. On the basis of genomic char- acteristics, we further found that transposable elements act as agents of evolution, causing direct and indirect copy number variations in defensin genes via duplications. Tissue ex- pression analysis showed that the Passeriformes-specific duplicated AvBD1 and AvBD3 genes are mainly expressed in the upper and lower respiratory tract, tongue, and spleen. Our analyses indicate that the duplication-and-deletion of defensin genes conformed to the birth-and-death evolutionary process and that transposable elements induced theduplication of defensin genes. Moreover, the respiratory system-specific expression pattern of Passeriformes-specific expanded AvBD1 and AvBD3 genes suggests their important role in maintaining the singing trait of songbirds. The understanding of the genomic structure, expression, and evolution of defensin genes can provide a crucial immunological foundation to study and prevent avian diseases.
文摘The aim of the study was to evaluate the impact of organic selenium supplementation （selenium yeast） vs. inorganic selenium （selenium selenite） on the expression of selected defensin genes in milk somatic cells （MSC） of dairy cows. Sixteen Polish Holstein-Friesian cows in second parity, with similar milk yield and milk composition were randomly divided into two equal groups. At the beginning of experiment, the animals were in the middle of their lactation curve （150, standard deviation （SD） = 26 d） and this experiment lasted 90 d. The basic diet, for both groups, consisted of corn silage, wilted grass silage and concentrates. The diet of control group was supplemented with commercial mineral and vitamin mixture with inorganic selenium and the for the experimental group daily selenium need was covered by the addition of Se-yeast （6 mg Se/cow/d）. Milk samples were collected three times during experiment （before experiment; on day 55; after the end the experiment）. Total RNA was isolated from milk somatic cells and the levels of transcripts of bovine β1-defensin （DEFB1）, β4-defensin （BNBD4）, β5-defensin （BNBDS）, β10-defensin （BNBD10） and lingual antimicrobial peptide （LAP） were measured with real time PCR, using glyceraldehyde 3-phosphate dehydrogenase （GAPDH） as a reference gene. The expressions of almost all studied genes were influenced by environmental conditions （very low and negative temperature）. However, BNBD4 （P 〈 0.05） and LAP （P ≤ 0.001 ） genes were influenced by selenium supplementation but in opposite ways, depending on the form of Se. These findings support that selenium is an important factor affecting the mRNA level in MSC, but the effect of the form of selenium might depend on genes.
