Phylogenetic diversification of immunoglobulin genes and the antibody repertoire

Immunoglobulins are encoded by a large multigene system that undergoes somatic rearrangement and additional genetic change during the development of immunoglobulin-producing cells. Inducible antibody and antibody-like responses are found in all vertebrates. However, immunoglobulin possessing disulfide-bonded heavy and light chains and domain-type organization has been described only in representatives of the jawed vertebrates. High degrees of nucleotide and predicted amino acid sequence identity are evident when the segmental elements that constitute the immunoglobulin gene loci in phylogenetically divergent vertebrates are compared. However, the organization of gene loci and the manner in which the independent elements recombine (and diversify) vary markedly among different taxa. One striking pattern of gene organization is the "cluster type" that appears to be restricted to the chondrichthyes (cartilaginous fishes) and limits segmental rearrangement to closely linked elements. This type of gene organization is associated with both heavy- and light-chain gene loci. In some cases, the clusters are "joined" or "partially joined" in the germ line, in effect predetermining or partially predetermining, respectively, the encoded specificities (the assumption being that these are expressed) of the individual loci. By relating the sequences of transcribed gene products to their respective germ-line genes, it is evident that, in some cases, joined-type genes are expressed. This raises a question about the existence and/or nature of allelic exclusion in these species. The extensive variation in gene organization found throughout the vertebrate species may relate directly to the role of intersegmental (V<==>D<==>J) distances in the commitment of the individual antibody-producing cell to a particular genetic specificity. Thus, the evolution of this locus, perhaps more so than that of others, may reflect the interrelationships between genetic organization and function.      

Systematics and evolutionary history of butterflies in the “Taygetis clade” (Nymphalidae: Satyrinae: Euptychiina): Towards a better understanding of Neotropical biogeography

The so-called “Taygetis clade” is a group of exclusively Neotropical butterflies classified within Euptychiina, one of the largest subtribes in the subfamily Satyrinae. Since the distribution of the ten genera belonging to this group ranges throughout the entire Neotropics, from lowlands to lower montane habitats, it offers a remarkable opportunity to study the region’s biogeographic history as well as different scenarios for speciation in upland areas. We inferred a robust and well-sampled phylogeny using DNA sequences from four genes (4035 bp in total) using maximum parsimony and Bayesian inference. We estimated divergence times using the Bayesian relaxed clock method calibrated with node ages from previous studies. Ancestral ranges of distribution were estimated using the dispersal–extinction–cladogenesis (DEC) model as implemented in the program Lagrange. We propose several taxonomic changes and recognize nine well-supported natural genera within the “Taygetis clade”: Forsterinaria (subsuming Guaianaza syn. nov.), Parataygetis, Posttaygetis, Harjesia (excluding Harjesia griseola and Harjesia oreba), Pseudodebis (including Taygetomorpha syn. nov.,), Taygetina (subsuming Coeruleotaygetis syn. nov., Harjesia oreba comb. nov., Taygetis weymeri comb. nov. and Taygetis kerea comb. nov.), Taygetis (excluding Taygetis ypthima, Taygetis rectifascia, Taygetis kerea and Taygetis weymeri), and two new genera, one containing Harjesia griseola, and the other Taygetis ypthima and Taygetis rectifascia. The group diversified mainly during late Miocene to Pliocene, coinciding with the period of drastic changes in landscape configuration in the Neotropics. Major dispersals inferred from the Amazon basin towards northwestern South America, the Atlantic forests and the eastern slope of the Andes have mostly shaped the evolution and diversification of the group. Furthermore, expansion of larval dietary repertoire might have aided net diversification in the two largest genera in the clade, Forsterinaria and Taygetis.     

Cladistic analysis of the Neotropical butterfly genus Adelpha (Lepidoptera: Nymphalidae), with comments on the subtribal classification of Limenitidini

Abstract.  A two-stage cladistic analysis of 114 characters from adult and immature stage morphology provided phylogenetic hypotheses for the diverse Neotropical nymphalid butterfly genus Adelpha Hübner. Higher-level cladistic relationships were inferred for thirty Adelpha species and twenty other species of Limenitidini, confirming the monophyly of Adelpha as currently conceived and indicating several montane Asian species as potential sister taxa for the genus. Cladistic relationships between all eighty-five Adelpha species were then inferred using three outgroup combinations. Basal and terminal nodes were reasonably resolved and supported, but a low proportion of non-wing pattern characters resulted in weak resolution and support in the middle of the tree. The most basal members of Adelpha feed on the temperate or montane plant family Caprifoliaceae, suggesting that a switch from this family early in the evolutionary history was important in subsequent diversification into tropical lowland habitats. The cladograms confirm suspicions of earlier authors that dorsal mimetic wing patterns have convergently evolved a number of times in Adelpha . The subtribal classification of Limenitidini is discussed and both Lebadea (from Parthenina) and Neptina are transferred to Limenitidina, whereas Cymothoe , Bhagadatta and Pseudoneptis (all formerly Limenitidina) are regarded as incertae sedis .     

A phylogenetic reassessment of Hyalenna Forbes and Dircenna Doubleday, with a revision of Hyalenna (Lepidoptera: Nymphalidae: Ithomiinae)

Abstract.  A morphological study of adults and immature stages and a cladistic analysis were conducted to clarify the relationships amongst members of the sister nymphalid butterfly genera Dircenna Doubleday and Hyalenna Forbes. Two species formerly included in Dircenna , Ithomia paradoxa Staudinger and Dircenna hugia Schaus, clustered with Ithomia perasippa , the type species of Hyalenna . Therefore, the first two species are transferred from Dircenna to Hyalenna ( comb.n .). Hyalenna and Dircenna as now conceived are both monophyletic and well supported by morphological apomorphies and branch support measures. The taxonomy and classification of Hyalenna are reviewed and seven species and twenty-four taxa are recognized, including one new species, Hyalenna buckleyi sp.n. , and eleven new subspecies: Hyalenna paradoxa incachaca ssp.n. , H. perasippa valencia ssp.n. , H. perasippa ortygiosa ssp.n. , H. perasippa solitaria ssp.n. , H. buckleyi pomacocha ssp.n. , H. alidella exsulans ssp.n. , H. alidella cinereola ssp.n. , H. alidella vesca ssp.n. , H. sulmona balsamica ssp.n. , H. sulmona hyalina ssp.n. and H. sulmona tersa ssp.n. A key for the identification of all taxa, and illustrations of male and female genitalia for all species and adult specimens of all taxa (where known), are presented. The natural history of each species is summarized and the immature stages of H. paradoxa and H. sulmona are described for the first time.     

Genomic heterogeneity and instability in colorectal cancer: spectral karyotyping, glutathione transferase-Ml and ras

Genomic instability in cancer is frequently described as being either chromosomal instability or microsatellite instability, although when events within chromosomes are monitored, extensive intrachromosomal instability is also found. Spectral karyotyping was used to visualize how extensively genomic instability gives rise to intratumor genomic heterogeneity in sporadic colorectal carcinomas. Two factors were then examined which might relate to intrachromosomal instability in colorectal cancers: the presence of the glutathione transferase-Ml gene to detoxify potential carcinogens, and the presence of activated ras which has been associated with chromosomal instability when first expressed. Intrachromosomal genomic instability was previously determined by inter-(simple sequence repeat) PCR (inter-SSR PCR) and by fractional allelic loss rate for 348 markers. GSTM1 status was determined for each of 49 tumors through use of specific PCR, and 28 of the tumors showed the GSTM1 null genotype. A significant association was found between GSTMl-null status and elevated inter-(simple sequence repeat) PCR instability. In contrast, no association was found with fractional allelic loss rate. The first exons of the K-ras and H-ras oncogenes were sequenced in 72 colorectal cancers; 19 of the tumors had a mutation in codon 12 of the K-ras gene (24.5%), but no H-ras mutations were found. A weak correlation (p=0.10) was observed between mutant K-ras and inter-(simple sequence repeat) PCR genomic instability, and no association existed with fractional allelic loss rate.     

Production of Diamino propionic acid ammonia lyase by a new strain of Salmonella typhimurium PU011

Background  

Seeds of the legume plant Lathyrus sativus, which is grown in arid and semi arid tropical regions, contain Diamino Propionic acid (DAP). DAP is a neurotoxin, which, when consumed, causes a disease called Lathyrism. Lathryrism may manifest as Neurolathyrism or Osteolathyrism, in which the nervous system, and bone formation respectively, are affected. DAP ammonia lyase is produced by a few microorganisms such as Salmonella typhi, Salmonella typhimurium and Pseudomonas, and is capable of detoxifying DAP.     

The use of energy stores in the puerulus of the spiny lobster Jasus edwardsii across the continental shelf of New Zealand

Nektonic pueruli of the spiny lobster, Jasus edwardsii, were caught from two locations about 20 km apart across the continental shelf on the south east of the North Island, New Zealand. The pueruli were assayed for total protein, glucose, glycogen, and lipid content. Only the lipid content differed between pueruli caught onshore and offshore (mean difference=3.1 mg or 3.4% of dry mass). The average difference in lipid content measured over this distance was used to calculate the rate of energy consumption and timing for pueruli to actively swim from the continental shelf to shore. These results confirmed previous theoretical estimates and indirect measures. Furthermore, the rate of energy consumption would allow all of the pueruli caught offshore to swim to shore based on their total measured lipids. However, some individuals with low energy stores may be energetically compromised at arrival which may affect their subsequent moulting and survival. The results of this study indicate that lipid is the primary format for energy storage of the nektonic puerulus of the spiny lobster and that these lipid reserves have sufficient energetic capacity to allow the puerulus to actively swim the distance across the shelf to settle on the coast.