Majority-rule (+) consensus trees

The construction of a consensus tree to summarize the information of a given set of phylogenetic trees is now routinely a part of many studies in systematic biology. One popular method is the majority-rule consensus tree. In this paper we introduce and characterize a new consensus method that refines the majority-rule tree by adding certain compatible clusters satisfying a simple criterion.     

A test of Rensch's rule in varanid lizards

In a model group of giant reptiles, we explored the allometric relationships between male and female body size and compared the effects of sexual and fecundity selection, as well as some proximate causes, on macroevolutionary patterns of sexual size dimorphism (SSD). Monitor lizards are a morphologically homogeneous group that has been affected by extreme changes in body size during their evolutionary history, resulting in 14‐fold differences among the body sizes of recent species. Here, we analysed data concerning the maximum and/or mean male and female snout–vent lengths in 42 species of monitor lizard from literary sources and supplemented these data with measurements made in zoos. There was a wide scale of SSD from nearly monomorphic species belonging mostly to the subgenus Odatria and Prasinus group of the Euprepriosaurus to apparently male‐larger taxa. The variable best explaining SSD was the body size itself; the larger the species, the higher the SSD. This pattern agrees with the currently discussed Rensch's rule, claiming that the relationship between male and female body size is hyperallometric, i.e. the allometric exponent of this relationship exceeds unity and thus SSD increases with body size in the case of male‐larger taxa. All our estimates of the reduced major axis regression slopes of this relationship ranged from 1.132 to 1.155. These estimates are significantly higher than unity, and thus unequivocally corroborate the validity of Rensch's rule in this reptilian group. In spite of our expectation that the variation in SSD can be alternatively explained by variables reflecting the strength of sexual selection (presence of male combat), fecundity selection (e.g. clutch size and mass) and/or proximate ecological factors (habitat type), none of these variables had consistent effects on SSD, especially when the data were adjusted to phylogenetic dependence and/or body size. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100 , 293–306.     

Macromolecular composition of Palaeozoic scolecodonts: insights into the molecular taphonomy of zoomorphs

Dutta, S., Hartkopf‐Fröder, C., Mann, U., Wilkes, H., Brocke, R. & Bertram, N. 2010: Macromolecular composition of Palaeozoic scolecodonts: insights into the molecular taphonomy of zoomorphs. Lethaia, Vol. 43, pp. 334–343. Biogeochemistry and molecular taphonomy of biopolymers of marine zoomorphs are poorly known. In order to obtain insights into this issue we report on the biogeomacromolecular composition of hand‐picked, well‐preserved scolecodonts of Ordovician, Silurian and Devonian age using micro‐Fourier transform infrared (micro‐FTIR) spectroscopy, Curie point pyrolysis‐gas chromatography‐mass spectrometry (Cupy‐GC‐MS) and tetramethylammonium hydroxide (TMAH)‐assisted thermochemolysis‐GC‐MS. The present study reveals that scolecodonts are composed of both aliphatic and aromatic moieties. The micro‐FTIR spectra of scolecodonts are characterized by aliphatic CH_x (3000–2800 and 1460–1450/cm) and CH₃ (1375/cm) absorptions and aromatic C=C (1560–1610/cm) and CH (3050/cm and 700–900/cm) absorptions. The major pyrolysis products from the scolecodonts include aromatic hydrocarbons such as alkylbenzenes, alkylnaphthalenes and alkylphenols. Aliphatic hydrocarbons are represented by a homologous series of n‐alkenes and n‐alkanes. The compounds released upon thermochemolysis with TMAH are saturated and unsaturated fatty acids (as their methyl esters), n‐alkenes/alkanes and aromatic acids (as their methyl esters). No protein/amino acid‐derived compounds have been recognized in the pyrolysates or in the thermochemolysates, and it is concluded that protein/amino acid‐related compounds, which are commonly found in the jaws of extant polychaetes, were destroyed due to diagenetic processes. Obviously, excellent morphological preservation and low thermal alteration are not paralleled by a similar degree of chemical preservation. □Biogeomacromolecules, micro‐FTIR, pyrolysis‐GC‐MS, scolecodonts, thermochemolysis‐GC‐MS.     

Natural occurrence of aflatoxins and ochratoxin a in corn and barley from mazandaran and golestan in north provinces of I. R. Iran

Fourteen barley and nine corn samples, destined for animal feed, collected from Golestan and Mazandaran provinces in the north of Islamic Republic of Iran (I. R. Iran) were analysed for aflatoxins (AF) and ochratoxin A (OA) by high performance liquid chromatography. In corn samples, aflatoxin B₁ (AFB₁) and aflatoxin B₂ (AFB₂) were detected in 8 (88.8%) and 6 (66.6%) samples at a mean level of 15.83 and 2.99 ppb (median 1.72 and 1 ppb), respectively. None of the corn samples contained detectable amounts of aflatoxin G₁ (AFG₁) and aflatoxin G₂ (AFG₂). Only one of the AF-contaminated samples was co-contaminated with OA at a concentration of 0.35 ppb. This is the first report concerning natural occurrence of OA and co-occurrence with AF in corn samples of north of I. R. Iran.     

Pseudoguaianolides from the flowers of Parthenium hysterophorus

Chemical investigation on the flowers of Parthenium hysterophorus has resulted in the isolation of four new pseudoguaianolides, hysterones A-D along with the known compounds, parthenin, coronopilin, 2beta-hydroxycoronopilin and tetraneurin-A. The structures of the new compounds were established by interpretation of their spectral (1D and 2D NMR) data. The X-ray crystallographic analysis of hysterones A and C was also carried out.     

A Monoclonal Antibody Raised to Corpus Callosum Extract Reacts with 2'',3''-Cyclic Nucleotide 3''-Phosphohydrolase

Monoclonal antibody against 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNP) was generated by fusing mouse myeloma cells with spleen cells from BALB/c mice immunized with delipidated white matter from rat corpus callosum. The antibody was characterized by solid-phase radioimmunoassay, immunoblot of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), immunoprecipitation from C6 glioma cells, and indirect immunofluorescence staining of monolayer cultures containing oligodendrocytes. The monoclonal antibody bound specifically to an intracellular antigen of oligodendrocytes, but not to Schwann cells, astrocytes, neurons, or fibroblast cytoplasm. The immunoblot of SDS-PAGE of CNS myelin showed that the antibody identified two protein bands at 48,000 and 50,000 molecular weight. These proteins were not identified in peripheral nervous system myelin. The monoclonal antibody immunoprecipitated CNP enzyme activity from extracts of C6 glioma cells. This monoclonal antibody should prove useful in further study of this myelin-specific enzyme in CNS myelin and in cells responsible for myelin production.     

Cyclic AMP regulates the rate of differentiation of oligodendrocytes without changing the lineage commitment of their progenitors

Oligodendrocytes differentiate in primary cultures of rat brain cells on a specific schedule similar to that observed in vivo. We show that the pace of this developmental schedule is accelerated by the addition of the cyclic AMP analogs dibutyryl cAMP (dbcAMP) or 8-bromo cAMP. Dibutyryl cAMP also inhibits DNA synthesis in A2B5-positive oligodendrocyte-type 2 astrocyte (O-2A) progenitor cells, consistent with the relationship between cessation of proliferation and onset of differentiation observed in vivo and in vitro. Treatment of cultures with dbcAMP has no effect on the proportion of O-2A progenitors that become oligodendrocytes rather than type 2 astrocytes and thus does not affect progenitor lineage decisions. Thus, cyclic AMP analogs accelerate the differentiation of cells apparently already determined to become oligodendrocytes.     

Normal Myelin Composition and Phospholipid Synthesis in Adrenalectomized Rats with Reduced Brain Myelin and Glycerol 3-Phosphate Dehydrogenase Activity

The composition of CNS myelin was investigated in rats adrenalectomized at day 14 and killed 7 days later, previously shown to result in a 25% reduction in the amount of bulk-isolated myelin and a 40% decrease in brain glycerol 3-phosphate dehydrogenase activity. The proportions of the major myelin proteins, as well as the specific activity of 2',3'-cyclic nucleotide 3'-phosphohydrolase, were the same in the myelin from both adrenalectomized and control animals. The amount of total phospholipid and the proportions of individual phospholipids were also normal in myelin from the adrenalectomized animals. The amount of nonmyelin phospholipid in whole brain was unchanged by adrenalectomy. Labeling studies carried out 4 days after adrenalectomy of 14-day-old animals showed no change in the synthesis rates of the major myelin phospholipids as compared with the synthesis rate of nonmyelin phospholipids. Furthermore, incorporation of [1,(3)-14C]glycerol into the glycerol moiety of ethanolamine plasmalogen, which requires glycerol 3-phosphate dehydrogenase, was also normal, showing that the reduced oligodendroglial glycerol 3-phosphate dehydrogenase activity following adrenalectomy was not rate-limiting for myelin phospholipid synthesis.