ON MISSING ENTRIES IN CLADISTIC ANALYSIS

Abstract The exact algorithms of two commonly used parsimony programs, Hennig86 by J. S. Farris and PAUP by D. Swofford, sometimes produce different solutions, and sometimes produce resolutions that are not supported by the data being analysed. The discrepancies apparently involve the treatment of missing entries, which can currently represent unknown data, inapplicable character and/or polymorphic taxa. Each of those potential sources of ambiguity is logically (if not computationally) different; with regard to binary characters, unknown data could be either 0 or 1, inapplicable characters are neither 0 nor 1 and polymorphisms are both 0 and 1. Resolutions that cannot be supported by any possible combination of known state attributions should either be flagged as such or suppressed entirely.     

Antiserum to Nitrogenase Generated from an Amplified DNA Fragment from Natural Populations of Trichodesmium spp

A fragment of the nifH gene was amplified from natural populations of Trichodesmium spp. and cloned into a maltose-binding protein (MBP) expression vector. The peptide product of the amplified 359-bp fragment of nifH was cleaved from the fusion protein, purified, and used to generate a specific antibody to the Fe protein of nitrogenase. The antiserum recognized the MBP-nitrogenase fusion protein and the cleaved nif peptide product but not MBP. The antibody cross-reacted with nitrogenase from natural populations of Trichodesmium spp. from the Caribbean Sea and with a cultured isolate from the Kuroshio waters (Trichodesmium sp. strain NIBB1067). The same nifH fragment was amplified, cloned, and sequenced from Trichodesmium sp. strain NIBB1067 and was found to be 98% identical at both the protein and DNA levels to nifH from the Caribbean populations. Three of the six nucleotide differences between the Trichodesmium sp. strain NIBB1067 and the Trichodesmium spp. nifH sequence had also been found in a second sequence from the natural populations, indicating either that there is more than one strain of Trichodesmium sp. in natural assemblages or that there are multiple copies of nifH in the genome. This DNA fragment, which is easily amplified with the polymerase chain reaction, may provide a good indicator of species relatedness without requiring extensive cloning or sequencing. Furthermore, the use of the polymerase chain reaction in combination with a MBP protein fusion vector provides a rapid method for production of highly specific sera, starting with a small amount of DNA.     

The use of N-methylprotoporphyrin dimethyl ester to inhibit ferrochelatase in Rhodopseudomonas sphaeroides and its effect in promoting biosynthesis of magnesium tetrapyrroles.

N-Methylprotoporphyrin dimethyl ester inhibits ferrochelatase in isolated membranes of Rhodopseudomonas sphaeroides at low concentrations (around 10 nm). Full inhibition developed after a short lag phase. The inhibition was non-competitive with porphyrin substrate. Addition of inhibitor to growing cultures of Rps. sphaeroides caused a decrease (near 40%) in cytochrome content and a severe inhibition of ferrochelatase; the excretion of haem into the medium by cell suspensions was also severely inhibited. The addition of N-methylprotoporphyrin dimethyl ester to suspensions of photosynthetically competent Rps. sphaeroides Ga caused excretion of Mg-protoporphyrin monomethyl ester. When added to mutants V3 and O1, magnesium divinylphaeoporphyrin a5 monomethyl ester and 2-devinyl-2-hydroxyethylphaeophorbide a were excreted, with maximum effect at around 3 microM-inhibitor in the medium. The results are interpreted to suggest that the inhibitor decreases concentration of intracellular haem, which normally controls the activity of 5-aminolaevulinate synthetase. Unregulated activity of this enzyme leads to overproduction of protoporphyrin, which is diverted to the bacteriochlorophyll pathway. Further control operates at magnesium protoporphyrin ester conversion in normal cells.     

Auxin controls Golgi-localized glucan synthetase activity in the maize mesocotyl

Decapitation or red light irradiation (R) inhibited growth and Golgi-localized glucan synthetase (GS I) activity in the mesocotyl of intact maize (Zea mays L.) seedlings. Applied auxin (indole-3-acetic acid) prevented the effects of R and of decapitation on both growth and GS I. Auxin applied several hours after irradiation prevented any further decline in GS I but did not restore it. Mesocotyl segments incubated in solution elongated in response to auxin but lost GS I with time regardless of the presence of exogenous auxin. An attached seed was necessary for maintenance of GS I in the dark-grown mesocotyl.Abbreviations GS glucan synthetase - IAA indole-3-acetic acid - R red light     

Real space refinement of neutron diffraction data from sperm whale carbonmonoxymyoglobin

Neutron diffraction data from crystals of sperm whale carbonmonoxymyoglobin have been refined by the real space refinement technique. Estimates of the neutron occupancies at the end of the refinement show that the mean for each atom type (including hydrogen and deuterium) is close to the expected value and has a standard deviation from the mean of about 5%. Mean neutron occupancies of main-chain atoms involved in deuterium bonds versus those not involved in deuterium bonds demonstrate that the hydrogen/deuterium exchange of the latter group is higher. The oxygen and deuterium co-ordinates for 40 water molecules have been determined: 27 of these water molecules were involved in bridges between protein atoms, and nine were involved in deuterium bonds with main-chain atoms. The deuterium-bond angles in helical regions show significant deviations from linearity. The mean ND … O angle was 154(3) °² and the mean CO … D angle was 145(3) °.     

Effects of Acute and Chronic Denervation on Release of Acetylcholinesterase and Its Molecular Forms in Rat Diaphragms

Abstract: Hemidiaphragms were removed from rats at various times after intrathoracic transection of the left phrenic nerve and were incubated in organ baths containing 1.5 ml of oxygenated, buffered physiologic saline solution, with added glucose and bovine serum albumin. After incubation, the acetylcholinesterase (AChE; EC 3.1.1.7) activities of the bath fluid and of the muscle were determined. Innervated left hemidiaphragms were found to release 107 units of AChE over a 3-h period, corresponding to 1.9% of their total AChE activity. Denervation led to a rapid loss of AChE from the muscle coincident with a transient increase in the outpouring of enzyme activity into the bath fluid. Thus, 1 day after nerve transection the left hemidiaphragm contained only 68% of the control amount of AChE activity, but released 140% as much as control. After 3 or 4 days of denervation, the AChE activity of the diaphragm stabilized at 35% of the control value. Release also fell below control by this time, but not as far. One week after denervation the release, 69 units per 3 hr, corresponded to 3.3% of the reduced content of AChE activity in the muscle, indicating that denervation caused an increase in the proportion of AChE released. Sucrose density gradient ultracentrifugation showed that 10S AChE accounted for more than 80% of the released enzyme activity at all times. The results did not rule out the possibility, however, that the released enzyme originally stemmed from 4S or 16S AChE in the diaphragm.     

Effect of neurotensin on pancreatic function in man

The effect of neurotensin on submaximally-stimulated hepatobiliary and pancreatic secretion was studied in 6 healthy subjects. An intravenous infusion of neurotensin 1.4 ± 0.3 pmol/kg/min, designed to reproduce plasma neurotensin immunoreactivity levels within the physiological range, produced a significant increase in pancreatic bicarbonate output. Plasma concentrations of pancreatic polypeptide rose by 83 ± 16 pmol/l and were associated with a small reduction in trypsin, but no significant change in bilirubin outputs.     

Diterpene carboxylic acids and a heliangolide from Helianthus angustifolius

Two diterpene carboxylic acids, one a new kaurenoid derivative and one the previously characterized labdane, ()-cis-ozic acid, as well as a