Molecular cloning of urea transporters from the kidneys of baleen and toothed whales

Urea transport in the kidney is important for the production of concentrated urine. This process is mediated by urea transporters (UTs) encoded by two genes, UT-A (Slc14a2) and UT-B (Slc14a1). Our previous study demonstrated that cetaceans produce highly concentrated urine than terrestrial mammals, and that baleen whales showed higher concentrations of urinary urea than sperm whales. Therefore, we hypothesized that cetaceans have unique actions of UTs to maintain fluid homeostasis in marine habitat. Kidney samples of common minke (Balaenoptera acutorostrata), sei (B. borealis), Bryde's (B. brydei) and sperm whales (Physeter macrocephalus) were obtained to determine the nucleotide sequences of mRNAs encoding UT. The sequences of 2.5-kb cDNAs encode 397-amino acid proteins, which are 90-94% identical to the mammalian UT-A2s. Two putative glycosylation sites are conserved between the whales and the terrestrial mammals, whereas consensus sites for protein kinases are not completely conserved; only a single protein kinase A consensus site was identified in the whale UT-A2s. Two protein kinase C consensus sites are present in the baleen whale UT-A2s, however, a single protein kinase C consensus site was identified in the sperm whale UT-A2. These different phosphorylation sites of whale UT-A2s may result in the high concentrations of urinary urea in whales, by reflecting their urea permeability.     

Analysis of the C4 genes in baleen whales using a human cDNA probe

We have used a human C4 cDNA probe to investigate the complement component C4 gene in four members of the family Balaenopteridae: fin whale (Balaenoptera physalus), sei whale (B. borealis), minke whale (B. acutorostrata), and bryde's whale (B. edeni). Restriction mapping of genomic DNA from the first three species suggests the presence of only one locus in these species, and also shows that the C4 genes in the three species are very similar. We have used 14 restriction endonucleases to investigate the restriction fragment length polymorphism (RFLP) of fin whales, 13 enzymes for sei whales, and 8 enzymes for the minke whale. No polymorphism was seen in DNA from the five minke whale samples, but Rsa I and Taq I restriction enzymes gave polymorphism in fin and sei whales whereas Hind III and Msp I restriction enzymes showed polymorphism in sei whales only. Only one bryde's whale sample was available for investigation. The study of DNA available from mother-fetus pairs from the two polymorphic species demonstrated a simple, two-allele transmission of RFLP alleles.     

Odontobius (Nematoda, Monhysteridae) from the baleen plates of whales and its relationship to Gammarinema living on crustaceans

Based on new material, the poorly known nematode species Odontobius ceti Roussel de Vauzème, 1834 is redescribed. It lives on the baleen plates of the baleen whales. It is argued that it belongs to the Monhysteridae sensu Lorenzen. Within this family, Odontobius appears to be most closely related to Gammarinema, species of which live externally on peracarid and decapod crustaceans. It is suggested that Odontobius ceti or its ancestor lived externally on crustaceans which were (or still are?) of nutritional importance to baleen whales and that in the course of feeding on these crustaceans the nematode became adapted to its current biotope.     

Spectroscopic and molecular dynamics evidence for a sequential mechanism for the A-to-B transition in DNA

The A-to-B form transition has been examined in three DNA duplexes, d(CGCGAATTCGCG)₂, d(CGCGAATTGCGC), and d(CGCAAATTTCGC), using circular dichroism spectroscopy, ultraviolet resonance Raman (UVRR) spectroscopy, and molecular dynamics (MD) simulation. Circular dichroism spectra confirm that these molecules adopt the A form under conditions of reduced water activity. UVRR results, obtained under similar conditions, suggest that the transition involves a series of intermediate forms between A and B. Cooperative and distinct transitions were observed for the bases and the sugars. Independent MD simulations on d(CGCGAATTCGCG)₂ show a spontaneous change from the A to B form in aqueous solution and describe a kinetic model that agrees well with UVRR results. Based on these observations, we predict that the mechanism of the transition involves a series of A/B hybrid forms and is sequential in nature, similar to previous crystallographic studies of derivatized duplexes. A simulation in which waters were restrained in the major groove of B DNA shows a rapid, spontaneous change from B to A at reduced water activity. These results indicate that a quasiergodic sampling of the solvent distribution may be a problem in going from B to A at reduced water activity in the course of an MD simulation.     

Morphological and molecular evidence for a new species of Perenniporia (Basidiomycota) from Tibet, southwestern China

A new polypore, Perenniporia tibetica, collected in Xizang (Tibet), southwestern China, is described and illustrated on the basis of morphological and molecular characters. Perenniporia tibetica is characterized by an annual growth habit, resupinate basidiocarps with a creambuff to pinkish-buff pore surface and white to cream-colored rhizomorphs, a dimitic hyphal system with slightly dextrinoid and distinctly cyanophilous skeletal hyphae, and basidiospores that are ellipsoid, truncate or not, strongly dextrinoid, and cyanophilous, 6.7–8.7 × 5.3–6.8 μm. Its preliminary phylogenetic relationships are inferred based on sequence data from the ribosomal ITS and LSU regions, both suggesting that P. tibetica forms a distinct lineage in the genus Perenniporia.     

Morphological evidence for a substance P projection from medial septum to hippocampus.

The medial septal nucleus provides one of the major afferents to the hippocampal formation. The two major types of neurons present in the medial septum are cholinergic and GABAergic, but other types of neurons are also present. A small population of substance P-containing neurons is present along the border between the medial and lateral septum, but it is unclear whether these project to the hippocampus. The present study, by employing both anterograde and retrograde tracing techniques, combined with immunocytochemistry for substance P, provides direct morphological evidence for a substance P projection from the lateral region of medial septum to a portion of CA2/3a, which is restricted to the mid-septotemporal portion of the hippocampus.     

The evolutionary transition from RNA to DNA in early cells

Summary The evolution of genetic material can be divided into at least three major phases: first, genomes of nucleic acid-like molecules; secondly, genomes of RNA; and finally, double-stranded DNA genomes such as those present in all contemporary cells. Using properties of nucleic acid molecules, we attempt to explain the evolutionary transition from RNA alone as a cellular informational macromolecule prior to the evolution of cell systems based on double-stranded DNA. The idea that ribonucleic acid-based cellular genomes preceded DNA is based on the following: (1) protein synthesis can occur in the absence of DNA but not of RNA; (2) RNA molecules have some catalytic properties; (3) the ubiquity of purine and pyridine nucleotide coenzymes as well as other similar ribonucleotide cofactors in metabolic pathways; and (4) the fact that the biosynthesis of deoxyribonucleotides always proceeds via the enzymatic reduction of ribonucleotides.The RNA prior to DNA hypothesis can be further developed by understanding the selective pressures that led to the biosynthesis of deoxyribose, thymine, and proofreading DNA polymerases. Taken together these observations suggest to us that DNA was selected as an informational molecule in cells to stabilize earlier RNA-protein replicating systems. These arguments include the facts that (1) the 2-deoxy-containing phosphodiester backbone is more stable in aqueous conditions and in the presence of transition metal ions (such as Zn²⁺) than its ribo-equivalents; (2) the absence of proofreading activity in RNA polymerases leads to a higher rate of mutation in RNA genomes relative to DNA; (3) information in RNA degrades because of the tendency of cytosine to deaminate to uracil and the lack of a correcting enzyme; and (4) UV irradiation produces a larger number of photochemical changes in RNA molecules relative to double-stranded DNA. The absence of atmospheric UV attenuation during the early Earth environment (Hadean and early Archean) would have imposed an intense selection pressure favoring duplex DNA over other genetic information storage systems.If RNA preceded DNA as a reservior of cellular genetic information, then an RNA-replicating oligopeptide must have been one of the earliest protoenzymes from which RNA polymerase presumably evolved. We conclude that RNA polymerases are among the oldest classes of enzymes.     

Morphological evidence for the evolutionary origin of Astigmata (Acari: Acariformes)

A century ago, Antonio Berlese first discussed the close phylogenetic relationship between the large mite groups Oribatida and Astigmata. Since then, information having phylogenetic value has greatly increased and the paradigms within which we interpret it have changed. Herein I refine the general hypothesis that Astigmata originated within oribatid mites and suggest Malaconothridae as a possible sister group. Among the 14 apomorphies used to support the origin of Astigmata within oribatid mites are possession of lateral opisthosomal glands, regression of hysterosomal setal pair f1, paired prelarval denticles, partially internalized chelicerae with incomplete adaxial walls, an atelobasic rutellum, pretarsal condylophores that articulate posteriorly with the tarsus, a dorsally fused palp tibia and tarsus and transdehiscent ecdysis. A further 13 apomorphies support the origin of Astigmata at some level within Malaconothroidea. These include absence of an oblique labiogenal articulation, presence of a distal rutellar lamella, shortening of the palp tarsus, larval regression of hysterosomal seta f2, loss of the bothridial seta in all instars, and several losses and modifications of leg setae. The hypothesis brings to light evolutionary questions that were previously obscured by incorrect or inappropriate classifications. The nomenclatural problems that arise from it are best solved by considering Astigmata as a subgroup within Oribatida.     

Morphological, cytogenetic, and molecular evidence for introgressive hybridization in birch.

Extensive morphological variation of tetraploid birch (Betula pubescens) in Iceland is believed to be due to gene flow from diploid dwarf birch (B. nana) by means of introgressive hybridization. A combined morphological and cytogenetic approach was used to investigate this phenomenon in two geographically separated populations of natural birch woodland in Iceland. The results not only confirmed introgressive hybridization in birch, but also revealed bidirectional gene flow between the two species via triploid interspecific hybrids. The populations showed continuous morphological variation connecting the species, but karyotypically they consisted of only three types of plants: diploids, triploids, and tetraploids. No aneuploids were found. Some of the tetraploid plants had B. pubescens morphology as expected, but most of them had intermediate characters. Most of the diploid plants were B. nana, but some were intermediates and a few had B. pubescens morphology. The triploid plants were either intermediates or they resembled one of the two species. Similar introgressive variation was observed among the diploid and triploid progeny of open-pollinated B. nana in a garden. Birch samples including field plants and artificial hybrids were further examined using a molecular method based on genomic Southern hybridization. The experiments verified introgression at the DNA level.     

Genetic evidence for the ancestral loss of short-wavelength-sensitive cone pigments in mysticete and odontocete cetaceans

All mammals ancestrally possessed two types of cone pigments, an arrangement that persists in nearly all contemporary species. However, the absence of one of these cone types, the short-wavelength-sensitive (SWS) cone, has recently been established in several delphinoid cetacean species, indicating that the loss of this pigment type may be widespread among cetaceans. To evaluate the functional condition of SWS cones in cetaceans, partial SWS cone-opsin gene sequences were obtained from nuclear DNA for 16 species representing 12 out of the 14 extant mysticete (baleen) and odontocete (toothed) families. For all these species one or more mutations were identified that indicate that their SWS cone-opsin genes are pseudogenes and thus do not code for functional visual pigment proteins. Parsimonious interpretation of the distribution of some of these mis-sense mutations indicates that the conversion of cetacean SWS coneopsin genes to pseudogenes probably occurred before the divergences of the mysticete and odontocete suborders. Thus, in the absence of dramatic homoplasy, all modern cetaceans lack functional SWS cone visual pigments and, by extension, the visual capacities that such pigments typically support.     

Morphological and molecular evidence converge upon a robust phylogeny of the megadiverse Holometabola

We present the largest morphological character set ever compiled for Holometabola. This was made possible through an optimized acquisition of data. Based on our analyses and recently published hypotheses based on molecular data, we discuss higher‐level phylogeny and evolutionary changes. We comment on the information content of different character systems and discuss the role of morphology in the age of phylogenomics. Microcomputer tomography in combination with other techniques proved highly efficient for acquiring and documenting morphological data. Detailed anatomical information (356 characters) is now available for 30 representatives of all holometabolan orders. A combination of traditional and novel techniques complemented each other and rapidly provided reliable data. In addition, our approach facilitates documenting the anatomy of model organisms. Our results show little congruence with studies based on rRNA, but confirm most clades retrieved in a recent study based on nuclear genes: Holometabola excluding Hymenoptera, Coleopterida (= Strepsiptera + Coleoptera), Neuropterida excl. Neuroptera, and Mecoptera. Mecopterida (= Antliophora + Amphiesmenoptera) was retrieved only in Bayesian analyses. All orders except Megaloptera are monophyletic. Problems in the analyses are caused by taxa with numerous autapomorphies and/or inapplicable character states due to the loss of major structures (such as wings). Different factors have contributed to the evolutionary success of various holometabolan lineages. It is likely that good flying performance, the ability to occupy different habitats as larvae and adults, parasitism, liquid feeding, and co‐evolution with flowering plants have played important roles. We argue that even in the “age of phylogenomics”, comparative morphology will still play a vital role. In addition, morphology is essential for reconstructing major evolutionary transformations at the phenotypic level, for testing evolutionary scenarios, and for placing fossil taxa.
© The Willi Hennig Society 2010.     

The evolutionary transition from subsocial to eusocial behaviour in Dictyoptera: phylogenetic evidence for modification of the "shift-in-dependent-care" hypothesis with a new subsocial cockroach

Cockroaches have always been used to understand the first steps of social evolution in termites because they are close relatives with less complex and integrated social behaviour. Termites are all eusocial and ingroup comparative analysis would be useless to infer the origin of their social behaviour. The cockroach genus Cryptocercus was used as a so-called "prototermite" model because it shows key-attributes similar to the termites (except Termitidae): wood-feeding, intestinal flagellates and subsocial behaviour. In spite of these comparisons between this subsocial cockroach and eusocial termites, the early and remote origin of eusocial behaviour in termites is not well understood yet and the study of other relevant "prototermite" models is however needed. A molecular phylogenetic analysis was carried out to validate a new "prototermite" model, Parasphaeria boleiriana which shows a peculiar combination of these key-attributes. It shows that these attributes of Parasphaeria boleiriana have an independent origin from those of other wood-eating cockroaches and termites. The case of P. boleiriana suggests that a short brood care was selected for with life on an ephemeral wood resource, even with the need for transmission of flagellates. These new phylogenetic insights modify evolutionary hypotheses, contradicting the assumption made with Cryptocercus model that a long brood care is necessary for cooperation between broods in the "shift-in-dependent-care" hypothesis. An ephemeral wood resource is suggested to prompt generation overlap and the evolution of cooperation, even if brood care is shortened.     

Morphological and molecular evidence for hybridization and introgression in Central European Arctium (Asteraceae)

Three species of burdock (Arctium lappa, A. tomentosum, and A. minus; Asteraceae), which commonly occur in sympatry in Central Europe, are thought to hybridize frequently, hence raising questions about their integrity. We surveyed mixed, monotypic, and/or single plant stands of these species in Central Germany to assess their extent of hybridization and introgression, and also the likelihood of insect host shifts between them. Individual plants were characterized by multivariate analyses of morphological and RAPD variation in combination with RAPD-based character-index-scores. All analyses recognized the three species as distinct units, but also identified a limited number of first (or early) generation hybrids between sympatric A. lappa and either A. tomentosum or A. minus, respectively, as well as one introgressant of A. tomentosum into A. lappa. While pre-zygotic isolation may partly account for the rarity of first generation crosses (F₁'s), the near absence of later generation hybrid segregants or introgressants likely reflects post-zygotic isolation due to the disruption of co-adapted gene complexes and/or habitat-mediated superiority shared by the ruderal parentals. As the tephritid fly Tephritis bardanae oviposits on both A. tomentosum (T) and A. minus (M), but not on A. lappa (L), the occurrence of L × M and L × T hybrids and/or introgressants may have important evolutionary consequences regarding the acquisition of a new host, i.e. A. lappa, by these insects.     

Diversity and duplication of DQB and DRB-like genes of the MHC in baleen whales (suborder: Mysticeti)

The molecular diversity and phylogenetic relationships of two class II genes of the baleen whale major histocompatibility complex were investigated and compared to toothed whales and out-groups. Amplification of the DQB exon 2 provided sequences showing high within-species and between-species nucleotide diversity and uninterrupted reading frames consistent with functional class II loci found in related mammals (e.g., ruminants). Cloning of amplified products indicated gene duplication in the humpback whale and triplication in the southern right whale, with average nucleotide diversity of 5.9 and 6.3%, respectively, for alleles of each species. Significantly higher nonsynonymous divergence at sites coding for peptide binding (32% for humpback and 40% for southern right) suggested that these loci were subject to positive (overdominant) selection. A population survey of humpback whales detected 23 alleles, differing by up to 21% of their inferred amino acid sequences. Amplification of the DRB exon 2 resulted in two groups of sequences. One was most similar to the DRB3 of the cow and present in all whales screened to date, including toothed whales. The second was most similar to the DRB2 of the cow and was found only in the bowhead and right whales. Both loci showed low diversity among species and apparent loss of function or altered function including interruption of reading frames. Finally, comparison of inferred protein sequence of the DRB3-like locus suggested convergence with the DQB, perhaps resulting from intergenic conversion or recombination.Electronic Supplementary Material Supplementary material is available for this article at     

Morphological evidence for the biological role of caniniform teeth in combtooth blennies (Blenniidae, Teleostei)

Combtooth blennies have recurved, fang-like caniniform teeth at the rear end of a single row of incisiform teeth. The lengths and positions of these canines were measured in the lower jaws of males of 14 species of Mediterranean Blenniidae. In four species, lower jaw canines were measured in males and females, while in one species, the upper jaw canines of both sexes were also measured. Relative (to body length) canine length in males tends to be significantly greater (10–40%) than in females. There are significant interspecific differences in relative canine length, with smaller species tending to have relatively larger teeth. No significant correlation was obtained between canine length and importance of animal prey in the diet, nor with 'hole fit' of males, which may be related with the intensity of paternal care. We suggest that canines in combtooth blennies are predominately used for predator deterrence and agonistic interactions.     

Autocatalytic networks: the transition from molecular self-replication to molecular ecosystems

The transition from inanimate to animate chemistry is thought to involve self-organised networks of molecular species whose collective emergent property gives rise to the overall characteristics of living systems. In the past, simple autocatalytic networks have been constructed that display basic forms of cooperative behaviour. These include reciprocal catalysis, autocratic, and hypercyclic networks. The design and emergent properties of these novel molecular networks are reviewed here.     

Morphological and molecular evidence of differentiation during etoposide-induced apoptosis in human lymphoblastoid cells

The relationship between apoptosis and cell differentiation has been a subject for continuous debate, with evidence showing leukaemic cell differentiation and drug-induced apoptosis have reciprocal, interdependent and a highly schedule-dependent relationship. We have addressed this relationship in terms of a widely-used model for apoptosis induced by cytotoxic drugs: namely the effect of etoposide on CEM cells. In respect of commitment toward differentiation, we assessed changes in expression of marker genes and the level of CD3 antigenicity. Changes in these parameters following exposure of CEM cells to etoposide was similar to that observed following treatment of the same cells with phorbol 12-myristate 13-acetate (PMA), though this latter treatment did not cause cell death. Similarities in response to etoposide and PMA also included generation of 50 kilobase fragmentation of DNA and convolution of nuclei as assessed by transmission electron microscopy. However, condensation of chromatin and externalization of phosphatidylserine were only recorded in response to the cytotoxic drug and not in response to PMA. The data are consistent with apoptosis in these lymphoblastoid cells being accompanied by activation of specific markers of T-cell differentiation, but ultimately involving processes unequivocally associated with cell death.     

Female choice in Drosophila: evidence from Hawaii and implications for evolutionary biology

Details of female choice of mate in Drosophila silvestris of Hawaii strikingly parallels epigamic behavioral systems in many other animals and may be common in other species of Drosophilidae. Females respond selectively to male circling, wing displays, songs and tactile stimulation with foreleg cilia, a quantitative character that is highly variable in some populations. I hypothesize that the female can exert choice based on these cues from individual males that differ genetically by quantitative trait loci. Laboratory tests show that one third of courting males are repeatedly rejected in favor of a minority of alpha males. This result imposes non-random mating at the local population level. Past multiple-choice lab tests, widely used to measure isolation between pairs of populations or species of Drosophila may be flawed, since random mating has been assumed in the interpretation of results. Pre-mating sexual selection is clearly a powerful intrapopulation force in population biology. This view creates difficulties for discerning any proposed simultaneous interpopulation selective events in the presence of strong female choice. The long-held theory assuming that there is significant selection for pre-mating isolation between groups is questionable.     

An evolutionary model explaining the Neolithic transition from egalitarianism to leadership and despotism

The Neolithic was marked by a transition from small and relatively egalitarian groups to much larger groups with increased stratification. But, the dynamics of this remain poorly understood. It is hard to see how despotism can arise without coercion, yet coercion could not easily have occurred in an egalitarian setting. Using a quantitative model of evolution in a patch-structured population, we demonstrate that the interaction between demographic and ecological factors can overcome this conundrum. We model the coevolution of individual preferences for hierarchy alongside the degree of despotism of leaders, and the dispersal preferences of followers. We show that voluntary leadership without coercion can evolve in small groups, when leaders help to solve coordination problems related to resource production. An example is coordinating construction of an irrigation system. Our model predicts that the transition to larger despotic groups will then occur when: (i) surplus resources lead to demographic expansion of groups, removing the viability of an acephalous niche in the same area and so locking individuals into hierarchy; (ii) high dispersal costs limit followers'' ability to escape a despot. Empirical evidence suggests that these conditions were probably met, for the first time, during the subsistence intensification of the Neolithic.