Evidence for multiple Pleistocene refugia in the postglacial expansion of the eastern tiger salamander,Ambystoma tigrinum tigrinum

Abstract Pleistocene glaciations were important determinants of historical migration and, hence, current levels of genetic diversity within and among populations. In many cases, these historical migrations led to the existence of disjunct populations of plants and animals. However, the origin and timing of arrival of these disjunct populations is often debated. In the current study, we identify potential refugia and estimate the timing of vicariance events of the eastern tiger salamander, Ambystoma tigrinum tigrinum , using mitochondrial sequence data. The results suggest a vicariant event 0.75–2 million years ago, separating the tiger salamanders to the east and west of the Apalachicola River Basin. East of the Appalachians, there appear to be multiple independent refugia with little migration among the remaining populations. In particular, populations along the Atlantic Coastal Plain were likely isolated in a coastal plain refugium in the Carolinas. Migrants from this refugium were the likely source of colonists for populations occupying previously glaciated areas along the northeastern Atlantic Coast. A second potential refugium occurs in the Blue Ridge Mountains of western Virginia. This refugium contains a disjunct population of the eastern tiger salamander, as well as a community of nearly 70 other disjunct plant and animal species. The tiger salamanders here have been isolated from other populations for 200,000–500,000 years. These results suggest that disjunct mountain populations of Coastal Plain species may have existed in situ throughout the Pleistocene in Appalachian refugia. Therefore, these disjunct populations are not of recent origin, but rather exist as relicts of a warmer, more widespread fauna and flora that is now restricted to the Coastal Plain.     

Isospora viridanae N. Sp., an Intranuclear Coccidian Parasite from the Canarian Skink, Chalcides viridanus (Lacertilia: Scincidae)

A caryotropic species of coccidium, Isospora viridanae n. sp. (Apicomplexa: Eimeriidae). has been found as a parasite in the Canarian skink, Chalcides viridanus Gravenhorst, 1851, from Tenerife, Spain, and is described here as a new species. Fully sporulaled oocysts of Isospora viridanae are spherical and measure 21.6 (1 7.6–23.4) nm in diameter. Mtcropyle, oocyst residuum and polar granule are ali absent. Oocysts of this coccidian, with a smooth bilayered wall, contain 2 ovoid sporocysts 13.2 (11.7–14.0) by 9.5 8.2–10 5) μm. A sporocyst residuum is present as well as a Stieda body and a substieda body. Most oocysts are found to be at the beginning of sporulanon when excreted and show 2 spherical sporoblasts. Sporulation is completed within 24 to 48 h at 23 × 2°C Sporozoites are 13–14 μm long and are about 2.5–3 μ m wide. Endogenous stages of schizogony and gamogony develop in the nuclei of epithelial cells from the small intestine of the skink. Comparisons with other species of the genus found in lacertilian hosts indicate that it is a new species.     

The origin of vertebrates: a hypothesis based on kidney development

The habitat of the earliest vertebrates (craniates) is still being debated. Marine as well as freshwater habitats and anadromous behaviour have been proposed. In contrast, an estuarine origin of vertebrates is suggested here, based on ontogenetic, comparative anatomical and functional data. This approach should resolve inconsistencies between the probable existence of glomeruli in the vertebrate ancestors and the marine habitat of all related extant groups (e.g. urochordates and cephalochordates). The kidney, as the main osmoregulatory organ, must have been developed according to the environmental prerequisites even in stem vertebrates. In the absence of fossil evidence only deductions from contemporary animals are possible. These data indicate that ancestral stem vertebrates probably had well-developed glomeruli, and were capable of at least some ion-exchange between urine and the body. However, they were probably unable to cope with a strong osmotic gradient with respect to their environment. The conclusion is that these animals were osmoconformers at around 300–350 mOsm and therefore were restricted to brackish water.  © 2007 The Linnean Society of London, Zoological Journal of the Linnean Society , 2007, 150 , 435–441.     

Crocodilus affuvelensis Matheron, 1869 from the Late Cretaceous of southern France: a reassessment

Hitherto unpublished crocodylian remains, including four skull fragments, from the lignite-bearing localities of Valdonne and Fuveau (Santonian–Campanian), south-eastern France, are described. They complement the original material of ' Crocodilus affuvelensis ' described by Matheron (1869) and Repelin (1930). Based on overlapping specimens, available elements of the rostrum, the palate, the skull table, the mandible and the pterygoid can be shown to belong to a single taxon, for which a reconstruction is proposed. Designation of a neotype has been proposed to the ICZN committee. A new genus, Massaliasuchus , is proposed here to designate the crocodylian originally described as Crocodilus affuvelensis . This crocodylian presents affinities with basal alligatoroids and complements the picture of crocodylian diversity during the Late Cretaceous in the European archipelago. Massaliasuchus affuvelensis is compared with other European taxa and with basal alligatoroids from North America. The putative basal position of Massaliasuchus as well as its early geological age suggest that the geographical origin of the Alligatoroidea is still uncertain.  © 2008 The Linnean Society of London, Zoological Journal of the Linnean Society , 2008, 152 , 567–580.     

The meticulous phycological investigation of Lake Rudträsket, Central Sweden, 1947–1949, by Heinrichs Skuja

In 1947–1949, studies of water chemistry, aquatic macrophytes, bryophytes and algae were performed in a small lake, L. Rudträsket, near Stockholm, but only a few results concerning water chemistry and macrophytes have so far been published. Heinrichs Skuja (1892–1972) left 62 hand-written pages with the results of his analyses from the lake: a list of taxa, some measurements and several algal sketches. The main part of this material is presented here. Skuja identified about 640 taxa with a majority for desmids, ca. 290, followed by ca. 100 chlorophyceans, 65 euglenophytes and 60 cyanophytes. The species composition gives a fairly reflection of the character of the lake: small, shallow, rich in humus, acid and surrounded by swampy areas with Sphagnum. Dimensions of algae as well as drawings from L. Rudträsket have partly been published in publications by Skuja. In this paper seven plates with about 115 figures have been drawn in Indian ink and printed. Today, the lake has a lower pH value, pH 4.6, than in 1947–1949, pH 5.3–6.1, and would be a stimulating object for comparative studies.     

Influence of Microclimate on the Occurrence of Cyanobacteria in the Phyllosphere in a Premontane Rain Forest of Costa Rica

Abstract: The occurrence of cyanobacteria in the phyllosphere of several understory plants was investigated during a one and a half year study in a primary premontane rain forest in Costa Rica. Altogether, seven species of epiphyllous cyanobacteria were identified and are discussed here. The ecology of the two most frequent species in the understory, Scytonema javanicum and Sc. hofmannii , was studied in further detail. Within the Understory, the relative abundance of these species, as well as of epiphyllous bryophytes, was more influenced by air humidity than by light. The humidity, characterized as potential evaporation, also had influence on the pseudosuccession of the phyllosphere vegetation. While at moist sites bryophytes and both species of Scytonema appeared nearly simultaneously on 6–9-month-old leaves, at dryer sites Sc. javanicum , and especially Sc. hofmannii , appeared 6–9 months after bryophytes had established. On 13–15-month-old leaves bryophytes and Scytoriema were usually well established. On average, 20–30% of the leaf area of 2–5-year old leaves of Spathacanthus hoffmannii (Acan-thaceae, an abundant understory shrub) were covered by bryophytes, 2–3% by Sc. javanicum , and 0.1–0.2% by Sc. hofmannhi . An influence of phorophyte species on the occurrence and abundance of these two species of Scytonema could not be detected. However, Sc. hofmannii was more frequent on leaves with higher bryophyte cover, while Sc. javanicum was independent from bryophytes. A comparison of leaves from the understory and from the canopy showed that the composition and abundance of cyanobacteria species changed with height above forest floor.     

The Storm's Stork Ciconia stormi in Indonesia: breeding biology, population and conservation

Storm's Stork Ciconia stormi is one of the rarest of the storks, regarded as globally endangered and found only in parts of western Indonesia, Malaysia and Brunei. Prior to this study, its breeding biology was unknown and the population status in Indonesia was not well understood. Its breeding habitat, prey, behaviour, voice, eggs and the development of the young are described here for the first time. Breeding biology was studied in 1989 at a nest in south Sumatra, Indonesia. The nest was in the transition zone between mangrove and freshwater swamp forest. Incubation took less than 29 days, and two eggs hatched. Fish 2–7 cm long comprised 67% of the prey for feeding young. The chick was fully feathered at 52–57 days and was seen flying when 57–62 days old. The species is rare in south Sumatra. It occurs in low numbers and flocks of up to seven birds were observed. The density is estimated at 20–40 birds within 110,000 ha of primary swamp forest. At this density, the population would be below 100 birds in south Sumatra and between 100 and 300 in Indonesia. The species is threatened by development and conversion of primary swamp forest.     

On the Origin of Metabolic Pathways

The heterotrophic theory of the origin of life is the only proposal available with experimental support. This comes from the ease of prebiotic synthesis under strongly reducing conditions. The prebiotic synthesis of organic compounds by reduction of CO₂ to monomers used by the first organisms would also be considered an heterotrophic origin. Autotrophy means that the first organisms biosynthesized their cell constituents as well as assembling them. Prebiotic synthetic pathways are all different from the biosynthetic pathways of the last common ancestor (LCA). The steps leading to the origin of the metabolic pathways are closer to prebiotic chemistry than to those in the LCA. There may have been different biosynthetic routes between the prebiotic and the LCAs that played an early role in metabolism but have disappeared from extant organisms. The semienzymatic theory of the origin of metabolism proposed here is similar to the Horowitz hypothesis but includes the use of compounds leaking from preexisting pathways as well as prebiotic compounds from the environment.     

Aspekte zur Herkunft und Verbreitung der Muriden

Wenn es zutrifi, daf3 die typisch afrikanischen, friiher den Muridae zugestellten Gruppen Den- dromurinae, Petromyscinae und Cricetomyinae den Cricetiden viel naher stehen und dafl die bei den Muriden noch verbliebenen afrikanischen Otomyinae - wie hier dargelegt wird - den Muriden mindestens ebenso fern stehen wie die oben genannten, so bleiben von den echten Muriden in Afrika nur die Murinae iibrig. Diese aber sind hochstwahrscheinlich sudostasiati- schen Ursprungs und nach Afrika relativ spat eingewandert. Afrika scheint also keine autochthonen Muriden zu besitzen. Fossilienfunde und tiergeographische Tatsachen stiitzen diese Ansicht.

Summary

Aspects of the Origin and Distribution of the Muridae Importance of the Systematic Position of the Otominae
If it is right that the typical african groups of Dendromurinae, Petromyscinae and Cricetomyinae – formerly all considered as Muridae – are Cricetids and that the African Otomyinae – as stated here – are not Murids, the Murinae are the only remaining "true" Muridae of Africa. These, however are probably of Southeast Asian origin and are relative lately immigrated in Africa. Africa therefore seems to have no autochthonous Muridae. This opinion is supported by fossils and zoogeographical facts.     

Accelerated evolution of early angiosperms: Evidence from ranunculalean phylogeny by integrating living and fossil data

The new discovery of angiosperm remains in the Jehol Biota of northeastern China contributes to our understanding of the origin and early evolution of flowering plants. The earliest eudicot genus with reproductive organs, Leefructus, was recently documented from the Lower Cretaceous Yixian Formation at 125.8–123.0 Ma, and was reconsidered to be close to the extant family Ranunculaceae based on gross morphology. However, this hypothesis has not been tested using a cladistic approach. To determine the possible allies of Leefructus within extant eudicots, we constructed a 66 morphological data matrix. Molecular and morphological analyses of extant Ranunculales combined with the fossil suggest that it has an affinity with the Ranunculaceae. The earliest fossil record of the eudicots is 127–125 Ma based on tricolpate pollen grains. Thus, we suggest a hypothesis that the basal eudicots might have experienced an accelerated evolution and diversification during the latest Barremian and earliest Aptian, leading to the stem groups of at least six extant families or lineages, 10–15 Myr earlier than currently documented. Angiosperms have undergone multiple uneven pulses of radiation since their origin. Many key character innovations occurred in different stages that could have triggered those radiations in concert with various biotic and abiotic factors.     

Enhancement of β-Amyloid Peptide Aβ(1–40)-Mediated Neurotoxicity by Glutamine Synthetase

Abstract: The β-amyloid peptide (Aβ), a main constituent in both senile and diffuse plaques in Alzheimer's disease brains, was previously shown to be neurotoxic and to be able to interact with several macromolecular components of brain tissue. Previous investigations carried out in our laboratory demonstrated free radical species formation in aqueous solutions of Aβ(1–40) and its C-end fragment, Aβ(25–35). Toxic forms of Aβ rapidly inactivate the oxidation-sensitive cytosolic enzyme glutamine synthetase (GS). In this regard, we suggested and subsequently demonstrated that Aβ radicals can cause an oxidative damage of cell proteins and lipids resulting in disruption of membrane functions, enzyme inactivation, and cell death. Because GS can be a substrate for Aβ-derived oxidizing species, the present study was conducted to determine if GS could protect against Aβ neurotoxicity. In contrast to this initial hypothesis, we here report that GS significantly enhances the neurotoxic effects of Aβ(1–40). The Aβ-mediated inactivation of GS was found to be accompanied by the loss of immunoreactive GS and the significant increase of Aβ(1–40) neurotoxicity.     

Whole-genome duplications in South American desert rodents (Octodontidae)

The discovery of tetraploidy in the red viscacha rat, Tympanoctomys barrerae (4 n  = 102) has emphasized the evolutionary role of genome duplication in mammals. The tetraploid status of this species is corroborated here by in situ PCR and Southern blot analysis of a single-copy gene. The species meiotic configuration strongly suggests a hybrid derivation. To investigate the origin of T. barrerae further, the recently described Pipanacoctomys aureus was studied. This 92-chromosome species also has a duplicated genome size, redundant gene copy number and diploid-like meiotic pairing, consistent with an event of allotetraploidization. Phylogenetic analysis of mitochondrial sequences indicates sister-group relationships between these two tetraploid rodents. The new karyotypic data and the phylogenetic relationships suggest the participation of the ancestral lineages of Octomys mimax in the genesis of P. aureus . The high overall DNA similarity and shared band homology revealed by genomic Southern hybridization as well as matching chromosome numbers between O. mimax and the descendant tetraploid species support the notion of introgressive hybridization between these taxa.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 82 , 443–451.     

Swimming out of Africa: mitochondrial DNA evidence for late Pliocene dispersal of a cichlid from Central Africa to the Levant

The rich Levantine fauna and flora were shaped by millions of years of migration across the region, from Africa to Eurasia and vice versa. Most large-scale processes that led to this diversity have been relatively well studied. However, small-scale processes, and details such as the area of origin of particular groups, and the route and time of dispersal are often not as clear. This is the case with the endemic Levantine representatives of the fish family Cichlidae. In this work we combine genetic, palaeontological and geological data in an attempt to understand the dispersal of the cichlid fish Astatotilapia flaviijosephi (Lortet, 1883) from sub-Saharan Africa to the Levant. A. flaviijosephi is unique among the Levantine cichlids in being the only non-tilapiine. It is also the only haplochromine cichlid to be found out of Africa. A partial sequence of the control region of the mitochondrial DNA was used to determine A. flaviijosephi 's phylogenetic relationships with other African haplochromines, and to estimate its time of divergence from this group. Combining our findings with palaeontological and geological data, we suggest that A. flaviijosephi separated from the other haplochromines during the middle to late Pliocene (2.5–3.3 Mya) and probably dispersed from Africa to the Levant via the Nile.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 82 , 103–109.     

Polymorphonuclear granulocyte expression of CD11a/CD18, CD11b/CD18 and L-selectin in normal individuals

Abstract In this study direct immunofluorescence and flow cytometry with calibration using quantitative bead standards were used to enumerate the cell surface receptors CD11a/CD18, CD11b/CD18 and L-selectin. Holding blood at room temperature and fixation of samples prior to staining induced changes in expression, while immediate staining of polymorphonuclear granulocytes (PMN) in whole blood followed by fixation produced accurate values. The ranges of PMN adhesion molecule expression in 10 normal individuals were CD11a/CD18: 14794–28725, CD11b/CD18: 5300–11939 and L-selectin: 35662–61654 receptors per cell. Differences within individuals over 4 h were also observed. Adhesion molecule expression is used as an index of the adhesive function and state of activation of the cell. The data presented here shows that there is inherent variability in the expression of the PMN adhesion molecules between and within individuals, thus direct comparisons of PMN adhesion molecule expression between patients and “normals” must be interpreted with caution.     

Anatomy and systematics of the minute syrnolopsine gastropods from Lake Tanganyika (Caenogastropoda, Cerithioidea, Paludomidae)

The minute syrnolopsine gastropods endemic to Lake Tanganyika have been allied to a number of freshwater, marine and terrestrial groups as a consequence of superficial conchological similarity. Although early anatomical studies confirmed the cerithioid organization of this clade, their close relationship to other lake species was not consistently recognized. In several recent cladistic analyses based on molecular data, the higher taxonomic placement and sister group relationships of syrnolopsines have been unstable. The present analysis confirms that syrnolopsines possess a spermatophore-forming organ – a synapomorphy of the Paludomidae – corroborating their placement in this family. Consistent with the molecular data, syrnolopsine monophyly is supported by two characters that occur exclusively in this group (salivary gland ducts that bypass the nerve ring and a linear albumen gland). Several characters in Martelia tanganyicensis – the most diminutive syrnolopsine – are only evident in the smallest lake species thus far investigated ( Bridouxia , Stormsia ) namely reduction of ctenidial leaflets, sorting area, intestine length and number of statoconia. These features are interpreted as being correlated with reduction in size. Nevertheless, close examination reveals differences in detail that allow more refined hypotheses of homology and are consistent with their independent origin.     

Relationship between allelic state of T-DNA and DNA methylation of chromosomal integration region in transformed <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis> plants

T-DNA insertions are currently used as a tool to introduce, or knock out, specific genes. The expression of the inserted gene is frequently haphazard and up to now, it was proposed that transgene expression depends on the site of insertion within the genome, as well as the number of copies of the transgene. In this paper, we show that the allelic state of a T-DNA insertion can be at the origin of epigenetic silencing. A T-DNA insertional mutant was characterized to explore the function of AtBP80a′, a vacuolar sorting receptor previously associated with germination. Seeds homozygous for the T-DNA do not germinate, but this can be overcome by a cold treatment and maintained by the following generations. The non-germinating phenotype is only observed in homozygous seed produced by heterozygous plants indicating that it is correlated with the allelic state of the T-DNA in parental lines. Analysis of the region between the T-DNA insertion and the ATG codon of atbp80a′ showed that cytosine methylation is highly enhanced in chromatin containing the T-DNA. Data presented here show that an unpaired DNA region during meiosis could be at the origin of a de novo cytosine methylation mechanism.     

Exorhopala ruficeps (Balanophoraceae): morphology and transfer to Helosis

Exorhopala ruficeps is a rare parasitic plant of the family Balanophoraceae, endemic to the north-western part of Peninsular Malaysia. It was originally described in Rhopalocnemis and later placed in a new monotypic genus on the basis of the exogenous origin of its inflorescences. A new collection of material enabled a detailed morphological study, the results of which are presented here. Inter alia, it is documented that the inflorescences originate endogenously as in all other Balanophoraceae. However, no volva is formed and the tuber-tissue covering the emerging inflorescence crumbles into pieces. The inflorescence and flower characters established here are neither in full accordance with Rhopalocnemis nor do they justify a genus of its own, but instead place the species in Helosis , which thus becomes a genus of transpacific distribution. The new combination is Helosis ruficeps (Ridl.) R. K. Eberwein.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 146 , 513–517.     

Where's the glass? Biomarkers,molecular clocks,and microRNAs suggest a 200‐Myr missing Precambrian fossil record of siliceous sponge spicules

The earliest evidence for animal life comes from the fossil record of 24-isopropylcholestane, a sterane found in Cryogenian deposits, and whose precursors are found in modern demosponges, but not choanoflagellates, calcareans, hexactinellids, or eumetazoans. However, many modern demosponges are also characterized by the presence of siliceous spicules, and there are no convincing demosponge spicules in strata older than the Cambrian. This temporal disparity highlights a problem with our understanding of the Precambrian fossil record – either these supposed demosponge-specific biomarkers were derived from the sterols of some other organism and are simply retained in modern demosponges, or spicules do not primitively characterize crown-group demosponges. Resolving this issue requires resolving the phylogenetic placement of another group of sponges, the hexactinellids, which not only make a spicule thought to be homologous to the spicules of demosponges, but also make their first appearance near the Precambrian/Cambrian boundary. Using two independent analytical approaches and data sets – traditional molecular phylogenetic analyses and the presence or absence of specific microRNA genes – we show that demosponges are monophyletic, and that hexactinellids are their sister group (together forming the Silicea). Thus, spicules must have evolved before the last common ancestor of all living siliceans, suggesting the presence of a significant gap in the silicean spicule fossil record. Molecular divergence estimates date the origin of this last common ancestor well within the Cryogenian, consistent with the biomarker record, and strongly suggests that siliceous spicules were present during the Precambrian but were not preserved.     

Quantitative observations on the ability of epiphytic bacteria to contribute to the populations of suspended bacteria in two dissimilar headstreams

SUMMARY. 1. Concentration of suspended bacteria in a calcareous headstream increased linearly from the source to 48 m; this indicated a diffuse origin of bacteria.
2. Drift loss of suspended bacteria and glucose-mineralization capacity from this length of stream were measured, and estimates were also made of the total number and glucose-mineralization capacity of epiphytic bacteria associated with the luxuriant submerged aquatic vegetation.
3. Mean drift loss per day represented 11–12% of total epiphytic bacteria and 8–18% of epiphyte glucose-mineralization capacity, hence the epiphytic population should be well able to sustain the observed downstream losses.
4. In a 90 m length of a contrasting acid, granitic, headstream, in which submerged vegetation was principally a leafy liverwort, there was no downstream change in concentration of suspended bacteria.
5. A substantial population of epiphytic bacteria was found in the acid stream, sufficient for only a 1–2% daily release to produce a doubling in concentration of suspended bacteria; reasons are suggested for the apparent non-release of epiphytes.     

Sgf1p, a New Component of the Sec34p/Sec35p Complex

Here we report the identification of SGF1 as a high-copy suppressor of the sec35–1 mutant. SGF1 encodes an essential hydrophilic protein of ∼ 100 kDa. Using the yeast two-hybrid system and coprecipitation studies, we demonstrate that Sgf1p is a new subunit of the multiprotein Sec34p/Sec35p complex. Reduced levels of Sgf1p lead to the accumulation of a variety of membranes as well as a kinetic block in endoplasmic reticulum to Golgi traffic. Immunofluorescence studies demonstrate that Sec34p is found throughout the Golgi, with a high concentration on early Golgi. Although an earlier study suggested that Sec34p (Grd20p) is not required for protein secretion, we show here that the sec34–2 and sec35–1 mutations lead to a pleiotropic block in the secretion of all proteins into the growth medium.