Tracer studies with 32P on the distribution of functional roots of Arabica coffee in Kenya

Seven experiments were done over a period of 21 months at Ruiru, Kenya, using 4 mCi/tree of ³²P tracer to study the distribution of functional roots of mature Arabica coffee trees. Tracer was placed at sixteen equally spaced sites around individual trees at one of five depths (to 180 cm) and three distances (to 135 cm = mid-row). Thereafter, samples of three-leaf shoot tips were collected at 14-day intervals for up to seven occasions and the radioactivity assessed after drying and ashing. There was negligible activity at any time at 180 cm depth but at other depths, and at all three distances, the relative level of activity changed markedly with season. After prolonged drought relatively high root activity was found at mid-depth, near to the trunk; after the soil was re-wetted by rain most root activity occurred in the topsoil at the quarter-row distance; after the soil profile had been wet for some time there was a more general distribution of functional roots. Some departures from this general scheme are discussed as are practical implications and the need for further investigations.     

Investigations on a Metabolite from Lactobacillus bulgaricus which Neutralizes the Effect of Enterotoxin from Escherichia coli Pathogenic for Pigs

Eleven species of lactic acid bacteria when grown on a milk-based medium reduced the pH value to < 4.7. The cells of nine of these species inhibited the growth of Escherichia coli on agar in Petri dishes. However, only Streptococcus faecium and Lactobacillus bulgaricus gave significant cell free anti- E. coli activity. Activity against E. coli enterotoxin was also found only in two species. L. bulgaricus and S. faecalis . Part of the activity in the former species was cell free. Further investigation of the cell-free anti-enterotoxic activity from L. bulgaricus showed that it had a low molecular weight probably < 10³, was not very stable and was independent of the anti- E. coli activity. Broths containing L. bulgaricus fermented to produce high levels of antienterotoxin were beneficial when added to diets for early weaned pigs. It was inferred that this effect was likely to be caused by the anti-enterotoxic activity.     

Double-stranded RNA analysis of strawberry plants affected by June yellows

Using an improved method for extraction of dsRNA from strawberry leaf tissue, small quantities of several dsRNA species with mol. wt greater than 1.0 × 10⁶were detected in strawberry plants free from known strawberry viruses but affected by June yellows (JY). No such dsRNA species were detected in plants of Fragaria vesca or seven strawberry cultivars known to be free from JY. Neither JY symptoms nor these dsRNA species were detected in healthy strawberry and F. vesca plants graft-inoculated with tissue from JY-affected plants. It is not known whether the JY-associated dsRNA species are those of a causal agent of JY or are a consequence of the JY condition. Nevertheless, the detection of such dsRNA species in plants affected by JY may offer a possible objective method for detecting the incipient condition in symptomless strawberry plants. However, the concentrations of dsRNA in JY-affected plants are very low and dsRNA analysis is thought not to be sufficiently reliable for routine testing of plants. The occurrence of anomalous dsRNA species in extracts from some strawberry plants was caused by dsRNA from two-spotted spider mites (Tetranychus urticae) infesting the plants.     

Stable-isotope and amino acid profiles of the New Zealand giant Pliocene oyster Crussostreu ingens

Mitchell, L., Curry, G.B. & Fallick, A.E. 1995 11 30: Stable-isotope and amino acid profiles of the New Zealand giant Pliocene oyster Crassostrea ingens .
Oxygen and carbon stable-isotope profiles and intracrystalline amino acid profiles (free and total) were determined for the New Zealand giant Pliocene oyster Crassostrea ingens by sampling annual growth increments along a sagittal section. These profiles reflect both ontogenetic and environmental change over the life-time of the oyster (approximately 20 years). There is a gradual increase in δ¹⁸O from the umbo towards the shell margin and a subsequent levelling-off about halfway along the shell. This pattern probably reflects a decrease in the growth rate of the oyster rather than a temperature effect. The δ¹³C profile initially increases sharply at the umbo and then gradually decreases towards the shell margin. This may be due to kinetic or metabolic effects associated with the development of a fast-growing juvenile into a slower-growing, sexually mature adult, or it may be due to the influence of ¹³C-depleted carbon derived from the oxidation of organic matter in the surrounding sediment. The amino acid profile reveals a gradual decrease in abundance from the umbo to the shell margin, indicative of a progressive increase in the relative amounts of inorganic carbonate to protein over the life of the oyster, that may also be a consequence of decreasing growth rate. Glycine and alanine are the two most common amino acids in both the free and total amino acid profiles: free (i.e. naturally hydrolysed) amino acids account for about three quarters of the total amino acids present. □ Biogeochemistiy, stable isotopes, amino acids, environment, ontogeny .     

Insights into the Evolution of Nuclear Dualism in the Ciliates Revealed by Phylogenetic Analysis of rRNA Sequences

The small subunit rRNA gene sequences of the karyorelictean ciliates, Loxodes striatus and Protocruzia sp., and the heterotrichian ciliates, Climacostomum virens and Eufolliculina uhligi , were used to test the evolution of nuclear dualism in the Phylum Ciliophora. Phylogenies derived using a least squares distance method, neighbour joining, and maximum parsimony demonstrate that the karyorelictean ciliates sensu Small and Lynn, 1985 do not form a monophyletic group. However, Loxodes and the heterotrich ciliates form the first branch in the ciliate lineage, and Protocruzia branches, in distance methods, basal to the spirotrich lineage. It is proposed that Protocruzia be removed from the Class Karyorelictea, and placed in closer taxonomic association with the spirotrich lineage. The distribution of nuclear division types along the phylogenetic tree is consistent with the notion that macronuclei incapable of division represent a derived rather than a primitive or "karyorelictid" character trait.