The land snail genus Albinaria exhibits an extreme degree of morphological differentiation in Greece, especially in the island of Crete. Twenty-six representatives of 17 nominal species and a suspected hybrid were examined by sequence analysis of a PCR-amplified mitochondrial DNA fragment of the large rRNA subunit gene. Maximum parsimony and neighbor-joining phylogenetic analyses demonstrate a complex pattern of speciation and differentiation and suggest that Albinaria species from Crete belong to at least three distinct monophyletic groups, which, however, are not monophyletic with reference to the genus as a whole. There is considerable variation of genetic distance within and among "species" and groups. The revealed phylogenetic relations do not correlate well with current taxonomy, but exhibit biogeographical coherence. Certain small- and large-scale vicariance events can be traced, although dispersal and parapatric speciation may also be present. Our analysis suggests that there was an early and rapid differentiation of Albinaria groups across the whole of the range followed by local speciation events within confined geographical areas.

The nucleotide sequences of two developmentally early chorion cDNA clones from Bombyx mori define two distinct proline-rich chorion protein families, which we name CA and CB to indicate their homologies to the previously defined chorion protein families A and B, as well as the developmentally late and cysteine-rich HcA and HcB chorion families. Thus, the chorion gene superfamily has two symmetrical branches, each consisting of three families: the a branch (A, CA, HcA families) and the , ( branch (B, CB, HcB families).The evolution of the superfamily is discussed.The chorion or eggshell of silk moths is a complex extracellular structure: in the wild moth Antheraea polyphemus, as many as 186 polypeptides have been resolved by twodimensional gel electrophoresis (1); partial protein sequence analysis as well as extensive characterization of genomic and cDNA clones indicate that many of these components are encoded by distinct genes (reviewed in refs. 2 and 3).Despite this present-day complexity, there is an underlying evolutionary simplicity: a high proportion of the chorion genes are related by descent, constituting homologous gene families. This was first shown for the two predominant families known as A and B (2). Superficially distinct chorion proteins with very high cysteine content (Hc proteins) were shown by DNA sequencing to correspond to offshoots of the A and B families and were correspondingly named HcA and HcB (4-6). In each of these four families, the central part of the sequence (central domain) is most highly conserved, apparently for reasons of protein secondary structure (7). Extensive homologies are evident between A and HcA or B and HcB central domains. Furthermore, A and B central domains show distant similarities, suggesting that the chorion genes constitute a superfamily derived from a single ancestral gene (8, 9). The amino-and carboxyl-terminal sequences (left and right arms) are considerably more variable, but even they show similarities both within and among the chorion gene families.Little is known about the class of chorion proteins named C. That class is quite complex (42 of 186 electrophoretically resolved components in A. polyphemus; ref. 1), although it accounts for only ca. 10% of the chorion mass. It appears to play an important morphogenetic role: it constitutes the bulk of the early proteins that are responsible for formation of the initial chorion framework (10) and that are required for organization of the quantitatively dominant components, which are secreted later (11). Only one C component has been sequenced to date, in A. polyphemus, and has proved to be related to the B family (12).In the course of characterizing a complex set of genes expressed in early choriogenesis of Bombyx mori, we have sequenced two C-like cDNA clones. These clones show that the C class in fact includes two distinct families, related to the A and B families and accordingly named CA and CB. We discuss those two new families in the context of the evolutionary history of the entire superfamily. M...

The mitochondrial DNA (mtDNA) size of the terrestrial gastropod Albinaria turrita was determined by restriction enzyme mapping and found to be approximately 14.5 kb. Its partial gene content and organization were examined by sequencing three cloned segments representing about one-fourth of the mtDNA molecule. Complete sequences of cytochrome c oxidase subunit II (COII), and ATPase subunit 8 (ATPase8), as well as partial sequences of cytochrome c oxidase subunit I (COI), NADH dehydrogenase subunit 6 (ND6), and the large ribosomal RNA (lrRNA) genes were determined. Nine putative tRNA genes were also identified by their ability to conform to typical mitochondrial tRNA secondary structures. An 82-nt sequence resembles a noncoding region of the bivalve Mytilus edulis, even though it might contain a tenth tRNA gene with an unusual 5-nt overlap with another tRNA gene. The genetic code of Albinaria turrita appears to be the same as that of Drosophila and Mytilus edulis. The structures of COI and COII are conservative, but those of ATPase8 and ND6 are diversified. The sequenced portion of the lrRNA gene (1,079 nt) is characterized by conspicuous deletions in the 5' and 3' ends; this gene represents the smallest coelomate lrRNA gene so far known. Sequence comparisons of the identified genes indicate that there is greater difference between Albinaria and Mytilus than between Albinaria and Drosophila. An evolutionary analysis, based on COII sequences, suggests a possible nonmonophyletic origin of molluskan mtDNA. This is supported also by the absence of the ATPase8 gene in the mtDNA of Mytilus and nematodes, while this gene is present in the mtDNA of Albinaria and Cepaea nemoralis and in all other known coelomate metazoan mtDNAs.

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