Genetic studies in Lotus japonicus and pea have identified Nin as a core symbiotic gene required for establishing symbiosis between legumes and nitrogen fixing bacteria collectively called Rhizobium. Sequencing of additional Lotus cDNAs combined with analysis of genome sequences from Arabidopsis and rice reveals that Nin homologues in all three species constitute small gene families. In total, the Arabidopsis and rice genomes encode nine and three NIN-like proteins (NLPs), respectively. We present here a bioinformatics analysis and prediction of NLP evolution. On a genome scale we show that in Arabidopsis, this family has evolved through segmental duplication rather than through tandem amplification. Alignment of all predicted NLP protein sequences shows a composition with six conserved modules. In addition, Lotus and pea NLPs contain segments that might characterize NIN proteins of legumes and be of importance for their function in symbiosis. The most conserved region in NLPs, the RWP-RK domain, has secondary structure predictions consistent with DNA binding properties. This motif is shared by several other small proteins in both Arabidopsis and rice. In rice, the RWP-RK domain sequences have diversified significantly more than in Arabidopsis. Database searches reveal that, apart from its presence in Arabidopsis and rice, the motif is also found in the algae Chlamydomonas and in the slime mold Dictyostelium discoideum. Thus, the origin of this putative DNA binding region seems to predate the fungus-plant divide.

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GC, GC–MS, and HPLC–LLSD analyses were used to identify and quantify cuticular and internal lipids in males and females of the blow-fly (Lucilia sericata). Sixteen free fatty acids, seven alcohols and cholesterol were identified and quantitatively determined in the cuticular lipids of L. sericata. Cuticular fatty acids ranged from C6 to C20 and included unsaturated entities such as 16:1n-9, 18:1n-9, 20:4n-3 and 20:5n-3. Cuticular alcohols (only saturated and even-numbered) ranged from C12 to C20 in males and C10 to C22 in females. Only one sterol was found in the cuticular lipids of both males and females. 23 free fatty acids, five alcohols and cholesterol were identified in the internal lipids. Internal fatty acids were present in large amounts—7.4 mg/g (female) and 10.1 mg/g (male). Only traces of internal alcohols (from C14 to C26 in males, from C14 to C22 in females) were found in L. sericata. Large amounts of internal cholesterol were identified in L. sericata males and females (0.49 and 0.97 mg/g of the insect body, respectively).

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