Fire ant venom alkaloids: Their contribution to chemosystematics and biochemical evolution

Studies on the chemistry of the 2,6-dialkylpiperidines in the venom of various fire ant species have shown that these alkaloids have practical value as chemotaxonomic characters. In addition, the finding that variations exist in the distribution of the geometric isomers between species and castes has led to a hypothetical construct for the biochemical evolution of these compounds. These various results, obtained previously, are integrated here as a coherent whole.     

Neolignans from an Aniba species

The trunk wood of an Amazonian Aniba (Lauraceae) species contains, besides dillapiol and the benzodioxane-type neolignan eusiderin, four bicyclo(3.2.1)octanoid neolignans. These comprise representatives of the canellin-type: the known methoxycanellin-A and the novel compounds characterized as (1R, 3S, 4S, 5S, 6S, 7R)-1-allyl-4-hydroxy-3, 5-dimethoxy-7-methyl-6-(3′-methoxy-4′, 5′-methylenedioxyphenyl)-8-oxo-bicyclo(3.2.1)octane; (1R, 3S, 4S, 5S, 6S, 7R)-1-allyl-4-hydroxy-3, 5-dimethoxy-7-methyl-6-(3′, 4′, 5′-trimethoxyphenyl)-8-oxobicyclo(3.2.1)octane and (1R, 4R, 5R, 6S, 7R, 8S)-1-allyl-4, 8-dihydroxy-5-methoxy-7-methyl-6-(3′-methoxy-4′,5′-methylenedioxyphenyl)-3-oxobicyclo(3.2.1)octane.     

TIME-DEPENDENT PARTITIONING OF GLUCOSE CARBONS METABOLIZED BY THE SUPERIOR CERVICAL GANGLION FROM CALVES

Abstract— Glucose metabolism in the superior cervical ganglion for calves has been studied by incubating slices with [1-¹⁴C]-, [6-¹⁴C]- and [U-¹⁴C]-labelled glucose at 37°C and pH 7.4. Glucose utilization and the metabolic partitioning of glucose carbon in products during different incubation periods ranging from 5 to 60 min were determined by isotopic methods.
Separation and identification of labelled compounds have been achieved by anion and cation exchange chromatography as well as by TLC and enzymatic analyses.
From the data obtained a carbon balance could be constructed showing lactate to be the major product of glucose metabolism followed by CO₂ and amino acids. Measuring the release of ¹⁴CO₂ from differently ⁴C-labelled glucose, the existence of an active pentose phosphate pathway in the ganglion could be demonstrated although this pathway seems to contribute only to a small extent to glucose metabolism. The marked decrease of the C-U: C-6 and the C-U:C-1 ratios in ¹⁴CO₂ observed in the course of incubation is discussed in terms of a time-dependent change in the rate of synthesis of amino acids which are directly connected with intermediates of the citric acid cycle.     

Dihydroisocoumarins and phthalide from wood samples infested by fungi

Wood samples, infested by fungi during storage, were shown to contain, besides the known 5-methyl-mellein, additional (3R)-8-hydroxy-3-methyl-3,4-dihydroisocoumarins substituted by 7-methyl, 5-formyl, 5-carboxy, 5-hydroxy, 5-methoxy, 6-methoxy-5-methyl and 6,7-dimethoxy-5-methyl groups, as well as 6-formyl-7-hydroxy-5-methoxy-4-methylphthalide. Several 2-methylchromanones were synthesized in order to show that this class of compounds can be distinguished from 3-methyl-3,4-dihydroisocoumarins by MS.     

Neoflavonoids and the cinnamylphenol kuhlmannistyrene from Machaerium kuhlmannii and M. Nictitans

The trunkwood of Machaerium kuhlmannii contains methyl palmitate, 3-O-acetyloleanolic acid and sitosterol; the benzene derivatives 2,3-dimethoxyphenol, 2,6-dimethoxyphenol, 2-hydroxy-3-methoxyphenol, 2,3-dimethoxybenzaldehyde and methyl 3-(2-hydroxy-4-methoxyphenyl)-propionate; the isoflavonoids formononetin and (6aS,11aS)-medicarpin; the neoflavonoids (R)-3,4-dimethoxydalbergione, (R)-3,4-dimethoxydalbergiquinol, kuhlmanniquinol [(R)-3-(4-hydroxyphenyl)-3-(5-hydroxy-2,3,4-trimethoxyphenyl)-propene], dalbergin, kuhlmannin (6-hydroxy-7,8-dimethoxy-4-phenylcoumarin) and kuhlmannene (6-hydroxy-7,8-dimethoxy-4-phenylchrom-3-ene), as well as the cinnamylphenol kuhlmannistyrene [Z-1-(5-hydroxy-2,3,4-trimethoxybenzyl)-2-(2-hydroxyphenyl)-ethylene]. Five of these compounds, in addition to (R)-4′-hydroxy-3,4-dimethoxydalbergione, were also isolated from a trunkwood extract of M. nictitans. Structural assignments were confirmed by chemical interconversion and by the synthesis of (±)-kuhlmanniquinol.     

Genetic transfer of clumping phenotype inAnacystis nidulans

Occasionally a mutation occurs in liquid cultures ofAnacystis nidulans, spreading quickly through the population and causing cells to adhere together in clumps. This phenotype is stable indefinitely and is an inherited characteristic of all cells within a clumping culture. Inoculation with a few living cells from a clumping culture quickly produces the clumping genotype in a majority of cells within a previously non-clumping culture. Killed cells, broken cell extracts, or media from clumping cultures do not produce aggregation in non-clumping cultures. Actively growing cells in clumping cultures do not affect non-clumping cultures when separated by 0.4 μm Millipore filter. Apparently transfer of the clumping trait requires direct contact between living cells. Pili-like projections connect individual cells within clumps, but no slime layer or capsule is seen. Clumps can be dispersed without cell damage; reaggregation requires photosynthesis.     

Control of hepatic mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase during the foetal/neonatal transition, suckling and weaning in the rat.

(1) We assayed active and total (i.e. active plus succinylated) 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) synthase in mitochondria isolated from foetal, neonatal, suckling or weaned rats. (2) HMG-CoA synthase was substantially succinylated and inactivated in mitochondria isolated from term-foetal, (1-h-old, 6-h-old, 1-day-old) neonatal, suckling and high carbohydrate/low-fat (hc)-weaned rats. Succinylation of HMG-CoA synthase was very low in mitochondria isolated from the livers of foetal, 30-min-old neonatal and high-fat/carbohydrate-free (hf)-weaned rats. (3) There was a negative correlation between active HMG-CoA synthase and succinyl-CoA content in mitochondria isolated from term-foetal, suckling and hc-weaned rats. (4) Differences in active enzyme could not be entirely accounted for by differences in succinylation and inactivation of the synthase. Immunoassay confirmed that the absolute amounts of mitochondrial HMG-CoA synthase increased during the foetal/neonatal transition and decreased with hc weaning. The levels remained elevated with hf weaning. (5) From these data we propose that mitochondrial HMG-CoA synthase is controlled by two different mechanisms in young rats. Regulation by succinylation provides a mechanism for rapid modification of existing enzyme in response to changing metabolic states. Changes in the absolute amounts of HMG-CoA synthase provide a more long-term control in response to nutritional changes.     

Differential synthesis by cultured atrial and ventricular rat cardiac myocytes of myosin light chain isoforms

Dissociated cells from neonatal rat atria and ventricles were cultured in monolayers for 3 days. Newly synthesized 35S-methionine labeled myosin light chain isoforms ALC-1, ALC-2 (atrial) and VLC-1, VLC-2 (ventricular) were identified on 2D gels, and their pattern of synthesis was compared to that of myocard fragments immediately after explanation. ALCs were synthesized in 5- to 10-fold excess over VLCs by atrial cultures, whereas the converse was true for ventricular cultures, with two exceptions: one third of the LC-1 synthesized by ventricular fragments was ALC-1, and dissociated atrial cells synthesized very little LC-2 of either isoform. The former finding corresponds to the relatively high proportion of ALC-1 in neonatal ventricular tissue. We conclude that the regional programme of LC isoform expression is basically retained after tissue explantation and even after dissociation and culturing of cardiac myocytes.     

The planktonic rotifers of the estuarine lagunar complex of Suape (Pernambuco,Brazil)

We studied spatial and temporal distribution, abundance, diversity, equitability and species associations of the rotifers of the estuarine area of Suape (Pernambuco-Brazil), based on plankton samples collected according to the tidal regime at 11 fixed stations in Suape Bay and the estuaries of Massangana, Tatuoca and Ipojuca Rivers, during February (dry season) and July (rainy season) of 1978. Concurrent hydrological and climatological data were taken. Eight species groups were established. In general, rotifers dominated in the Ipojuca River estuary and stations subject to its influence. Greatest community similarities were observed among nearby stations, during the same tide and season. Hydrological factors influenced the occurrence and distribution of some species, and a close correlation between phytoplankton and rotifers was observed. Pollution in Ipojuca River contributed to diversity.     

A two-state recurrent stochastic model with time-dependent transition rates.

The two-state recurrent stochastic model with time-independent transition rates is generalized to a model with time-dependent transition rates. The rates can be any general function of external time, that is, any general function of the calendar time in which the process unfolds. Formulas for the state transition probabilities, the proportion of individuals in a particular state at time t, the distribution function, and the expectation of the number of individuals in a particular state at time t are derived.