Phylogeny of the true water bugs(Hemiptera-Heteroptera:Nepomorpha) based on four Hox genes

The phylogenetic relationships among the Nepomorpha （Hemiptera： Heteroptera） were analyzed based on nuclear protein coding genes-partial sequences of four Hox genes： abd-A, Dfd, Ubx and pb. Fifteen taxa, of which eleven were ingroups representing ten of the eleven families, were selected to produce a phylogenetic inference of nepomorphan superfamilial or familial relationships via parsimony and Bayesian techniques. Our results supported the monophylies of Nepomorpha, Naucoroidea （Aphelocheiridae ＋ Naucoridae）, Nepoidea （Belostomatidae ＋ Nepidae）, Ochteroidea （Ochteridae ＋ Gelastocoridae） and Pieoidea （Pleidae ＋ Helotrephidae）; the most basal lineage of Ochteroidea; Notonectoidea contained Notonectidae only and formed a new sister relationship with （Pleoidea ＋ Naucoroidea）; and the sister relationship of （Nepoidea ＋ Corixoidea）. The Hox genes are suitable molecular markers to resolve phylogenetic relationships at superfamily or family levels in Heteroptera.

Hox genes and study of Hox genes in crustacean

Homeobox genes have been discovered in many species. These genes are known to play a major role in specifying regional identity along the anterior-posterior axis of animals from a wide range of phyla.The products of the homeotic genes are a set of evolutionarily conserved transcription factors that control elaborate developmental processes and specify cell fates in metazoans. Crustacean, presenting a variety of body plans not encountered in any other class or phylum of the Metazoa, has been shown to possess a single set of homologous Hox genes like insect. The ancestral crustacean Hox gene complex comprised ten genes: eight homologous to the hometic Hox genes and two related to nonhomeotic genes presented within the insect Hox complexes. The crustacean in particular exhibits an abundant diversity segment specialization and tagmosis. This morphological diversity relates to the Hox genes. In crustacean body plan, different Hox genes control different segments and tagmosis.

HOX genes in the skin

Deep skin wounds heal by scar formation with a Joss of its original appearance, structure and function.However, when the same damage occurs to the skin of an early gestational fetus, complete regeneration can be observed. Despite significant research in the field of skin regeneration, many mysteries remain, such as the loss of wound healing ability with maturity, the differences in healing at different parts of the body, and the presence of hypertrophic scars and keloids in some races but not in others. The finding of HOX genes in the skin provides new explanations to these conundrums.

Evolutionary changes of Hox genes and relevant regulatory factors provide novel insights into mammalian morphological modifications

The diversity of body plans of mammals accelerates the innovation of lifestyles and the extensive adaptation to different habitats,including terrestrial,aerial and aquatic habitats.However,the genetic basis of those phenotypic modifications,which have occurred during mammalian evolution,remains poorly explored.In the present study,we synthetically surveyed the evolutionary pattern of Hox clusters that played a powerful role in the morphogenesis along the head-tail axis of animal embryos and the main regulatory factors(Mll,Bmi1 and E2f6)that control the expression of Hox genes.A deflected density of repetitive elements and lineage-specific radical mutations of Mll have been determined in marine mammals with morphological changes,suggesting that evolutionary changes may alter Hox gene expression in these lineages,leading to the morphological modification of these lineages.Although no positive selection was detected at certain ancestor nodes of lineages,the increasedωvalues of Hox genes implied the relaxation of functional constraints of these genes during the mammalian evolutionary process.More importantly,49 positively-selected sites were identified in mammalian lineages with phenotypic modifications,indicating adaptive evolution acting on Hox genes and regulatory factors.In addition,3 parallel amino acid substitutions in some Hox genes were examined in marine mammals,which might be responsible for their streamlined body.

Hox and ParaHox Genes in Evolution,Development and Genomics

The discovery of the homeobox motif and its presence in each gene of the Hox clusters revolutionized the fields of developmental biology and evolutionary developmental biology （1, 2）, providing a rapid entrance into investigating the mechanisms of development of almost any animal taxon as well as dramatically altering conceptions on the extent of genetic conservation across the animal kingdom.

Functional Investigation of a Cotton Fiber HOX Gene

Most of the plant homeodomain-containing proteins play important roles in regulating cell differentiation and organ development,and Arabidopsis GLABRA2(GL2),a member of the class IV homeodomain-Leucine zipper(HD-ZIP) proteins,is a trichome and non-root hair cell regulator.We

Phylogeny of the Insect Homeobox Gene (Hox) Cluster

The homeobox （Hox） genes form an evolutionarily conserved family encoding transcription factors that play major roles in segmental identity and organ specification across species. The canonical grouping of Hox genes present in the HOM-C cluster of Drosophila or related clusters in other organisms includes eight “typical” genes, which are localized in the order labial （lab）, proboscipedia （pb ）, Deformed （ Dfd）, Sex combs reduced （Scr）, Antennapedia （Antp）, Ultrabithorux （Ubx）, abdominalA （abdA）, and AbdominalB （AbdB）. The members of Hox cluster are expressed in a distinct anterior to posterior order in the embryo. Analysis of the relatedness of different members of the Hox gene cluster to each other in four evolutionarily diverse insect taxa revealed that the loci pb/Dfd and AbdB, which are farthest apart in linkage, had a high degree of evolutionary relatedness, indicating that pb/Dfd type anterior genes and AbdB are closest to the ancestral anterior and posterior Hox genes, respectively. The greater relatedness of other posterior genes Ubx and abdA to the more anterior genes such as Antp and Scr suggested that they arose by gene duplications in the more anterior members rather than the posterior AbdB.

Further evidence for paternal DNA transmission in gynogenetic grass carp

Gynogenesis is an important breeding method in aquaculture and has been widely applied to many fish species.If gynogenetic progenies are to inherit paternal partial genomic DNA,this will increase genetic variation and will provide a useful outcome for breeding.In this study,we investigated the genetic variation in homeobox(Hox)gene clusters(Hox A4 a,Hox A9 a,Hox A11 b,Hox B1 b,Hox C4 a,Hox C6 b,and Hox D10 a)among koi carp(Cyprinus carpio haematopterus,KOC;the stimulation sperm source),grass carp(Ctenopharyngodon idellus),and gynogenetic grass carp(GGC).We found paternal DNA(a special DNA fragment and Hox C6 b)derived from KOC and a recombinant gene belonging to Hox C6 b in GGC.We are the first to report the recombinant Hox C6 b in GGC.Our study provides further evidence for paternal DNA transmission to gynogenetic progenies,which is a finding with great significance for the genetic breeding of fish.

Are we really seeing the big picture？ Some reflections on the current debates in evolutionary biology

After more than one hundred fifty years of the publication of On the Origin of Species by Darwin, scientists are still arguing on the relative importance of mutation and natural selection, on the driving force of organismal evolution, on microevo- lution and macroevolution, etc. Such periodically repeated debates appeared to have introduced more chaos than musings. What happened and why？ Have we really considered our views, opinions and arguments under the big picture of evolution before pos- ing the questions？ Or are we talking past each other？ We do need some reflections. While we believe that the current evolutionary theory is doing fine, perhaps a refinement or re-encapsulation of its knowledge framework can help promote a better understanding of the evolutionary science as a whole and blow offthe mist over the big picture [Current Zoology 61 （1）： 217-220, 2015 ].