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Cecropin is a well-studied antimicrobial peptide that is synthesized in fat body cells and hemocytes of insects in response to hypodermic injury or bacterial infection. A 503 bp cDNA encoding for a cecropin-like peptide was isolated by employing annealing control primer (ACP)-based differential display PCR and 5'-RACE with immunized Papilio xuthus larvae. The open reading frame of the isolated cDNA encoded for a 62-amino acid prepropeptide with a putative 22-residue signal peptide, a 2-residue propeptide, and a 38-residue mature peptide with a theoretical mass of 4060.89 Da. The deduced amino acid sequence of the peptide evidenced a significant degree of identity with other lepidopteran cecropins. This peptide was named papiliocin. RTPCR results revealed that the papiliocin transcript was detected at significant levels after injection with bacterial lipopolysaccharide (LPS). On the basis of the deduced amino acid sequence of papiliocin, a 38-mer mature peptide was chemically synthesized via the Fmoc method, and its antimicrobial activity was analyzed. The synthetic papiliocin peptide evidenced a broad spectrum of activity against fungi, Gram-positive and Gram-negative bacteria, and also evidenced no hemolytic activity against human red blood cells.

We have determined the complete mitochondrial genome of the yellow-spotted long horned beetle, Psacothea hilaris (Coleoptera: Cerambycidae), an endangered insect species in Korea. The 15,856-bp long P. hilaris mitogenome harbors gene content typical of the animal mitogenome and a gene arrangement identical to the most common type found in insect mitogenomes. As with all other sequenced coleopteran species, the 5-bp long TAGTA motif was also detected in the intergenic space sequence located between tRNA(Ser)(UCN) and ND1 of P. hilaris. The 1,190-bp long non-coding A+T-rich region harbors an unusual series of seven identical repeat sequences of 57-bp in length and several stretches of sequences with the potential to form stem-and-loop structures. Furthermore, it contains one tRNA(Arg)-like sequence and one tRNA(Lys)-like sequence. Phylogenetic analysis among available coleopteran mitogenomes using the concatenated amino acid sequences of PCGs appear to support the sister group relationship of the suborder Polyphaga to all remaining suborders, including Adephaga, Myxophaga, and Archostemata. Among the two available infraorders in Polyphaga, a monophyletic Cucujiformia was confirmed, with the placement of Cleroidea as the basal lineage for Cucujiformia. On the other hand, the infraorder Elateriformia was not identified as monophyletic, thereby indicating that Scirtoidea and Buprestoidea are the basal lineages for Cucujiformia and the remaining Elateriformia.

Self-imcompatibility is a controlling genetic mechanism to prevent self-pollination for Chinese cabbage (Brassica campestris), one of the major vegetable crops in Korea. To maintain inbred lines of the crop plant, a method in that high CO2 gas is treated to the pistils to overcome the self-incompatibility and thereby self-pollens can successfully make germination and fertilization has been widely used in seed companies. Despite the common utilization of this method, any molecular and cellular studies on how the self-incompatibility is removed from the Chinese cabbage plant have not been done. In this study, we show that the increased CO2 gas causes a structural alteration of the papillae cell and thereby the self-incompatibility is removed from the Chinese cabbage plant, allowing the self-pollens to germinate and penetrate the papillae cell. Also, gene expression in the pistil treated with CO2 gas was studied by DD/RT-PCR and reverse northern hybridization experiments. The results suggest that the failure in self-incompatible reaction resulted not only from the structural alteration of the papillae cell but also from change in the pistil component production that is either positively or negatively regulated by the environmental stimulation.

In Brassica species, self-incompatibility in the recognition reaction between self and non-self pollens is determined by two genes, SLG and SRK, at the S locus. We have cloned and characterized a genomic DNA fragment containing a complete open reading frame of the SLG gene from Chinese cabbage. The genomic clone, named BcSLG2, was found to possess the region that shares a homology of 77% in amino acid identity with the SLG46 gene of Brassica campestris. Northern blot analysis revealed that the BcSLG2 gene expression is restricted to the pistil of Chinese cabbage flower. In situ hybridization showed that in the pistil, the gene is expressed predominantly in the stigmatic tissue. Much lower expression in the tapetum was also detectable at an immature stage of the flower development. Southern blot hybridization with the BcSLG2 DNA probe showed polymorphism in the SLG gene organization of the Chinese cabbage plants. These results will provide valuable information in understanding the S gene complex of the Chinese cabbage plants.

MADS genes encode regulatory factors that are involved in various developmental steps of the plant life cycle. During flower development, they regulate the early step of specifying floral meristem identity as well as the later step of determining the fate of floral organ primordia. Here, we report the isolation of two cDNA clones, NsMADS2 and NsMADS3, from a long-day tobacco species, Nicotiana sylvestris, which encode MADS domain-containing proteins. The NsMADS2 amino acid sequence showed 66% identity to SQUA and 64% to AP1. NsMADS3 showed a high degree of amino acid identity with FBP2 (98%), DEFH 72 (89%), DEFH 200 (88%), and AGL9 (76%). RNA blot analyses of NsMADS2 and NsMADS3 revealed that both transcripts were present in floral organs, but not in vegetative organs such as the leaf, root, stem, and 10 d old seedlings. The NsMADS2 transcript was localized in all four whorls and the NsMADS3 transcript was restricted in the three inner whorls of floral organs. The ectopic expression of NsMADS2 using the CaMV 35S promoter caused early flowering and lengthened internode length in transgenic tobacco plants. The ectopic expression of NsMADS3 also caused early flowering phenotype in transgenic tobacco plants, but the plants exhibited reduced apical dominance. Possible implications of these results in relation to the functions of NsMADS2 and NsMADS3 are discussed.