Comparison of a vitellogenin gene between two distantly related rhabditid nematode species

Winter, Carlos Eduardo; Penha, Carlos; Blumenthal, Thomas

doi:10.1093/oxfordjournals.molbev.a025628

Cited by 23 publications

(39 citation statements)

References 43 publications

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“…We have begun to answer this question by identifying both a conserved operon and SL2 transsplicing in another free-living nematode, Dolichorhabditis. Dolichorhabditis is a free-living rhabditid nematode belonging to the same family as C. elegans (36,41). Although the two species are morphologically similar, C. elegans 28S rRNA differs from Dolichorhabditis 28S rRNA at 48 of 241 positions (K. Thomas, personal communication).…”

Section: Discussionmentioning

confidence: 99%

“…Although the two species are morphologically similar, C. elegans 28S rRNA differs from Dolichorhabditis 28S rRNA at 48 of 241 positions (K. Thomas, personal communication). Comparison of the C. elegans and Dolichorhabditis vit-6 genes demonstrates that whereas the primary structure of the encoded protein is related, it is so distant that even its codon usage and intron positions are quite different (36). Recently, an analysis of the 18S rRNA from Dolichorhabditis showed that it is a rhabditid species, most closely related to the parasitic strongylids (M. Blaxter, P. DeLey, L. Liu, and J. Garey, personal communication).…”

Section: Discussionmentioning

confidence: 99%

“…Construction of the Dolichorhabditis genomic library has been described (36). A 204-bp BamHI-SalI digested C. elegans rpp-1 cDNA PCR product (oligos: rp21-6Sal, 5Ј-CCCGGTCGACT-TACGATTGAAGAATGGC-3Ј and rp21-7Bam, 5Ј-CCCG-GGATCCGAGACAGAAGTGATGAGG-3Ј) was labeled using the Prime-It Random Primer Labeling Kit (Stratagene).…”

Section: Methodsmentioning

confidence: 99%

“…Although Dolichorhabditis is a small free-living nematode, it is much more evolutionarily distant from C. elegans than is C. briggsae. This conclusion is based on the sequence of SL1 and SL2 RNAs, as well as a comparison of the vit-6 genes from the two species, where most introns interrupt the gene at different locations and even the preferred codon usage is somewhat different (36). Molecular phylogenetic analysis of full-length small subunit ribosomal RNA sequences (M. Blaxter, P. DeLey, L. Liu, and J. Garey, personal communication) places Dolichorhabditis in a clade of rhabditid nematodes that includes the genera Rhabditis (free-living bacteriovores) and Heterorhabditis (entomopathogenic nematodes), as well as the order Strongylida (encompassing vertebrate-parasitic species such as Haemonchus contortus and Ostertagia circumcincta).…”

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Operons and SL2 trans-splicing exist in nematodes outside the genus Caenorhabditis

Evans

Zorio

MacMorris

et al. 1997

Proc. Natl. Acad. Sci. U.S.A.

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The genomes of most eukaryotes are composed of genes arranged on the chromosomes without regard to function, with each gene transcribed from a promoter at its 5 end. However, the genome of the free-living nematode Caenorhabditis elegans contains numerous polycistronic clusters similar to bacterial operons in which the genes are transcribed sequentially from a single promoter at the 5 end of the cluster. The resulting polycistronic pre-mRNAs are processed into monocistronic mRNAs by conventional 3 end formation, cleavage, and polyadenylation, accompanied by trans-splicing with a specialized spliced leader (SL), SL2. To determine whether this mode of gene organization and expression, apparently unique among the animals, occurs in other species, we have investigated genes in a distantly related free-living rhabditid nematode in the genus Dolichorhabditis (strain CEW1). We have identified both SL1 and SL2 RNAs in this species. In addition, we have sequenced a Dolichorhabditis genomic region containing a gene cluster with all of the characteristics of the C. elegans operons. We show that the downstream gene is trans-spliced to SL2. We also present evidence that suggests that these two genes are also clustered in the C. elegans and Caenorhabditis briggsae genomes. Thus, it appears that the arrangement of genes in operons pre-dates the divergence of the genus Caenorhabditis from the other genera in the family Rhabditidae, and may be more widespread than is currently appreciated.In bacteria and archaea, the genomes are primarily organized in arrays of genes whose products have related functions. These gene clusters, called operons, are cotranscribed from an upstream promoter and the resulting polycistronic mRNA is translated by ribosomes initiating at or near the 5Ј end of the RNA. These operons serve to efficiently coregulate proteins that function together. In contrast, eukaryotes have genomes composed of genes arranged apparently at random, with each transcribed by a promoter at its 5Ј end. However, in a group of primitive eukaryotic protozoa, the trypanosomes, genes are transcribed polycistronically (1-3). In this case, the polycistronic pre-mRNA is processed by 3Ј end formation and trans-splicing to create conventional eukaryotic monocistronic mRNAs. The trans-splicing reaction that creates the 5Ј ends of the mRNAs is related to the cis-splicing of higher eukaryotes; it proceeds through a 2Ј-5Ј branched intermediate, the splice sites have the same consensus sequences, and it is catalyzed by some of the same small nuclear ribonucleoprotein particles (4, 5).Trans-splicing was first discovered in trypanosomatids (4, 6), and later shown to occur also in Caenorhabditis elegans and other nematodes (ref. 7; reviewed in refs. 8 and 9), in Euglena (10), and in flatworms (11,12). In contrast to trypanosomes, in which only trans-splicing is present, the genes in the other organisms also contain cis-spliced introns. It was presumed that these genes were monocistronic and arranged randomly on the chromosomes as in other...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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Operons and SL2 trans-splicing exist in nematodes outside the genus Caenorhabditis

Evans

Zorio

MacMorris

et al. 1997

Proc. Natl. Acad. Sci. U.S.A.

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“…Several analyses based on the conserved N-terminal regions of Vtgs revealed a closer relationship between the Vtgs from nematodes and insects compared with Vtgs from vertebrates (61,68). In contrast, other analyses suggest a closer relationship between the Vtgs from nematodes and vertebrates compared with Vtgs from insects (4,(71)(72)(73). The difference between the two groups of analyses may be explained by the fact that the Vtg trees were unrooted (73), rooted using an insect Vtg rather than a non-Vtg LLTP (72), or interpreted without taking the included apoB outgroup into account (4,73).…”

Section: Three Families Of Lltpsmentioning

confidence: 99%

Molecular diversity and evolution of the large lipid transfer protein superfamily

Smolenaars

Madsen

Rodenburg

et al. 2007

Journal of Lipid Research

158

160

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Circulatory lipid transport in animals is mediated to a substantial extent by members of the large lipid transfer (LLT) protein (LLTP) superfamily. These proteins, including apolipoprotein B (apoB), bind lipids and constitute the structural basis for the assembly of lipoproteins. The current analyses of sequence data indicate that LLTPs are unique to animals and that these lipid binding proteins evolved in the earliest multicellular animals. In addition, two novel LLTPs were recognized in insects. Structural and phylogenetic analyses reveal three major families of LLTPs: the apoB-like LLTPs, the vitellogenin-like LLTPs, and the microsomal triglyceride transfer protein (MTP)-like LLTPs, or MTPs. The latter are ubiquitous, whereas the two other families are distributed differentially between animal groups. Besides similarities, remarkable variations are also found among LLTPs in their major lipid-binding sites (i.e., the LLT module as well as the predicted clusters of amphipathic secondary structure): variations such as protein modification and number, size, or occurrence of the clusters. Strikingly, comparative research has also highlighted a multitude of functions for LLTPs in addition to circulatory lipid transport. The integration of LLTP structure, function, and evolution reveals multiple adaptations, which have come about in part upon neofunctionalization of duplicated genes. Moreover, the change, exchange, and expansion of functions illustrate the opportune application of lipid-binding proteins in nature.Accordingly, comparative research exposes the structural and functional adaptations in animal lipid carriers and brings up novel possibilities for the manipulation of lipid transport.

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Evolution of developmental mechanisms in nematodes

F�lix

1999

J. Exp. Zool.

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The recent findings that key developmental genes are conserved across animal phyla have led to descriptions of evolutionary change in development based on the recruitment of these few molecules. This approach, however, encounters problems in assigning homology across long evolutionary distances. By contrast, reproducibility of the cell lineage of free-living soil nematodes (order Rhabditida) and conservation of larval blast cells across nematode species permit evolutionary comparisons of developmental mechanisms among nematodes at the cellular level. Such comparative studies uncover an unexpected flexibility of developmental mechanisms: Large evolutionary differences have been described between invariant and noninvariant lineages, in the cellular mechanisms specifying a given cell (for instance, the gonadal anchor cell), in the subcellular events leading to asymmetric divisions (for instance, the first division of the egg), and in redundant networks of cell interactions (for instance, those specifying the centered pattern of vulva precursor fates). Interestingly, redundancy of developmental mechanisms favored by selective pressure allows in turn for evolution of these mechanisms. Such evolutionary changes in developmental mechanisms specifying cell fates can occur in the absence of obvious morphological change, which rather correlates with evolution of cell fates per se: death, division, migration, and differentiation (for instance, in the reduction of the posterior gonadal arm in monodelphic species or in change in vulva position).

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Comparison of a vitellogenin gene between two distantly related rhabditid nematode species

Cited by 23 publications

References 43 publications

Operons and SL2 trans-splicing exist in nematodes outside the genus Caenorhabditis

Operons and SL2 trans-splicing exist in nematodes outside the genus Caenorhabditis

Molecular diversity and evolution of the large lipid transfer protein superfamily

Evolution of developmental mechanisms in nematodes

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