Leaf chemistry and food selection by common langurs (Presbytis entellus) in Rajaji National Park,Uttar Pradesh,India

Food selection in folivorous primates has been hypothesized to be correlated with leaf chemistry. To test this hypothesis, we conducted a 5-month study on Presbytis entellusin a moist deciduous forest in the Rajaji National Park,Uttar Pradesh, India. The study period covered two seasons, winter and spring. We used the percentage time spent feeding on each food item as an index of food selection, which we estimated from group scan data collected from one study group for 6 days each month. We estimated the selection ratio for each item as the ratio of time spent feeding to availability. We estimated food availability from vegetation sampling and phenological data in the home range of the study group. We estimated crude protein (CP), acid detergent fiber (ADF) and tannins in mature and young leaves of 12 major food species in the laboratory. Food selection is positively correlated with CP in winter and negatively correlated with ADF in both seasons. It also is correlated with CPJADF ratio, but to a lesser extent than the best predictor in winter and spring. Selection ratio is not correlated with CP and ADF in both seasons. It is probable that the inclusion of other factors, such as micronutrients,condensed tannins, and digestibility, might give a better prediction of food selection.     

The biosynthesis of rosmarinic acid in suspension cultures of Coleus blumei

Suspension cultures of Coleus blumei accumulate very high amounts of rosmarinic acid, an ester of caffeic acid and 3,4-dihydroxyphenyllactate, in medium with elevated sucrose concentrations. Since the synthesis of this high level of rosmarinic acid occurs in only five days of the culture period, the activities of the enzymes involved in the biosynthesis are very high. Therefore all the enzymes necessary for the formation of rosmarinic acid from the precursors phenylalanine and tyrosine could be isolated from cell cultures of Coleus blumei: phenylalanine ammonia-lyase, cinnamic acid 4-hydroxylase, hydroxycinnamoyl:CoA ligase, tyrosine aminotransferase, hydroxyphenylpyruvate reductase, rosmarinic acid synthase and two microsomal 3- and 3-hydroxylases. The main characteristics of these enzymes of the proposed biosynthetic pathway of rosmarinic acid will be described.Abbreviations DHPL 3,4-dihydroxyphenyllactate - DHPP 3,4-dihydroxyphenylpyruvate - pHPL 4-hydroxyphenyllactate - pHPP 4-hydroxyphenylpyruvate - RA rosmarinic acid     

Correlation of betacyanin synthesis with cell division in cell suspension cultures of Phytolacca americana

In suspension cultures of Phytolacca americana , betacyanin accumulation was reduced when cell division was inhibited by treatment with various inhibitors of DNA synthesis or anti-microtubule drugs. Aphidicolin (APC), an inhibitor of DNA synthesis, reduced the incorporation of radioactivity from labeled tyrosine into betacyanin, but the incorporation of radioactivity from labeled 3,4-dihydroxyphenylalanine (DOPA) into betacyanin was not affected by similar treatments. Propyzamide, another anti-microtubule drug, reduced incorporation of radioactivity from tyrosine and DOPA into betacyanin. However, the rate of incorporation from DOPA was higher than that from tyrosine. The results suggest that inhibition of betacyanin accumulation in Phytolacca americana cells by APC and propyzamide is due to suppression of the reaction converting tyrosine to DOPA, which may be closely related to cell division.     

Preliminary caged‐field trial,using the fungal pathogen Zoophthora radicans brefeld (zygomycetes: entomophthorales) against the diamondback moth Plutella xylostella L. (lepidoptera: Yponomeutidae) in the UK

Zoophthora radicans Brefeld was tested for control of Plutella xylostella L. in a caged‐field trial. No infection was seen in control cages, but between 36% and 68% of larvae in live samples, and 38% and 55% of larvae at the final harvest, were infected in inoculated cages, suggesting the biological control potential of this fungus.     

Conservation of polyproline II helices in homologous proteins: implications for structure prediction by model building.

Left-handed polyproline II (PPII) helices commonly occur in globular proteins in segments of 4-8 residues. This paper analyzes the structural conservation of PPII-helices in 3 protein families: serine proteinases, aspartic proteinases, and immunoglobulin constant domains. Calculations of the number of conserved segments based on structural alignment of homologous molecules yielded similar results for the PPII-helices, the alpha-helices, and the beta-strands. The PPII-helices are consistently conserved at the level of 100-80% in the proteins with sequence identity above 20% and RMS deviation of structure alignments below 3.0 A. The most structurally important PPII segments are conserved below this level of sequence identity. These results suggest that the PPII-helices, in addition to the other 2 secondary structure classes, should be identified as part of structurally conserved regions in proteins. This is supported by similar values for the local RMS deviations of the aligned segments for the structural classes of PPII-helices, alpha-helices, and beta-strands. The PPII-helices are shown to participate in supersecondary elements such as PPII-helix/alpha-helix. The conservation of PPII-helices depends on the conservation of a supersecondary element as a whole. PPII-helices also form links, possibly flexible, in the interdomain regions. The role of the PPII-helices in model building by homology is 2-fold; they serve as additional conserved elements in the structure allowing improvement of the accuracy of a model and provide correct chain geometry for modeling of the segments equivalenced to them in a target sequence. The improvement in model building is demonstrated in 2 test studies.     

Metabolic engineering of plant secondary products

Plants interact with their environment by producing a diverse array of secondary metabolites. Many of these compounds are valued for their medicinal, industrial or agricultural properties. Other secondary products are toxic or otherwise undesirable and can reduce the commercial value of crops. Gene transfer technology offers new opportunities to modify directly plant secondary product synthesis through metabolic engineering. This article reviews some of the strategies which have been used to increase or decrease the synthesis of specific plant metabolites, as well as methods for expanding the biosynthetic capabilities of individual species.     

Urinary steroid evaluations to monitor ovarian function in exotic ungulates: X. Pregnancy diagnosis in Perissodactyla

Enzymeimmunoassays (EIAs) for estrone conjugates (EC), pregnanediol-3-glucuronide (PDG), and C-19 and C-21 progesterone metabolites (C-19/C-21) were used to analyze urine samples from four nondomestic equid species, four tapir species, and two rhinoceros species in an attempt to identify if these assays could be used for diagnosing and monitoring pregnancy. The same urine samples were also analyzed for the presence of equine chorionic gonadotropin (eCG) activity, using a field dipstick test and a radioimmunoassay (RIA). The EC EIA was validated for three equid species and the Malayan tapir. Neither the PDG nor the C-19/C-21 EIAs were validated in any species evaluated. In equid species, the EC EIA demonstrated a specificity (the percentage of nonpregnant samples identified correctly) of 100% and a sensitivity (the percentage of pregnant samples identified correctly) of ≥ 88%. With the exception of the Grevy's zebra, the C-19/C-21 EIA showed a similar accuracy in identifying pregnant and nonpregnant equids. The PDG EIA was not sufficiently accurate to merit its use in equids or tapirs for pregnancy diagnosis. From the data collected, it appears analysis of a single urine by both the EC EIA and the C-19/C-21 EIA would be the best method of pregnancy detection during the last 2 trimesters of gestation, in equid species. In tapirs, the C-19/C-21 EIA was slightly more accurate for pregnancy diagnosis than the EC EIA. The C-19/C-21 EIA had a specificity of 93%, but a sensitivity of only 73% in tapir species. None of the EIAs evaluated demonstrated a sufficient specificity or sensitivity to be useful, as presently performed, for pregnancy diagnosis from a single sample in the black rhinoceros. The eCG dipstick used in this study did not prove a sufficiently reliable test for routine pregnancy in nondomestic equids. The eCG RIA results in the Przewalski's horses and the Hartman's mountain zebra were positive early in gestation, and indicate that gonadotropin analysis may be useful for pregnancy detection in these species. Only very low amounts of eCG activity was measured by the eCG RIA in the tapir and rhinoceros urine samples. © 1994 Wiley-Liss, Inc.     

Food mixing by generalist grasshoppers: Plant secondary compounds structure the pattern of feeding

Plant secondary compounds can prevent feeding by phytophagous insects or, if ingested, can be poisonous to them. Less attention has been paid to the additional effects they have on feeding behavior when they are only weakly deterrent or not deterrent at all. Experiments were carried out on the generalist grass-hopperSchistocerca americana. Individuals were presented either with two cakes of high-quality artificial food with a single deterrent compound added or with two cakes, each with a different added deterrent compound. The deterrents consisted of single plant secondary compounds that were either marginally or strongly deterrent. There were profound differences in feeding behavior between those individuals given identical and those given different cake types, including longer feeding bouts on single cakes when a choice of different cake types was available. The behavioral effects demonstrate that the presence of secondary compounds in one food can influence the patterns of feeding on other available foods and suggest that such chemicals could impact foraging activities in a complex manner.     

Archiascomycetes: detection of a major new lineage within the Ascomycota

For phylogenetic analysis of the higher fungi, we sequenced the nuclear small subunit rRNA (18S rRNA) gene fromTaphrina populina, the type species of the genusTaphrina, andProtomyces lactucae-debilis. The molecular phylogeny inferred from these 2 sequences and 75 sequences from the DNA data bank divided the Ascomycota into three major lineages: the hemiascomycetes, the euascomycetes, and the archiascomycetes, newly described herein. The former two lineages are monophyletic, whereas the archiascomycetes, which originated first and are comprised ofTaphrina, Protomyces, Saitoella, Schizosaccharomyces, andPneumocystis, may not be monophyletic. Among the archiascomycetes, theTaphrina/Protomyces branch is monophyletic. Confirmation of the archiascomycetes as a monophyletic taxonomic class will require comparison of additional genetically defined characters.This work was supported in part by grants 05454030 from the Ministry of Education, Science, and Culture of Japan (to J. S.) and 4369 from the Japan Society for the Promotion of Science Fellowship Programs (to H. N.).     

Generation of hydrogen peroxide,superoxide anion and the hydroxyl free radical from polyphenols and active benzene metabolites: Their possible role in mutagenesis

Benzene is strongly suspected of being an animal and human carcinogen, but the mechanisms by which it induces tumors of lymphoid and hematopoietic organs are unknown. Production of active oxygen species from benzene metabolites [hydroquinone (HQ), catechol and 1,2,4-benzenetriol (1,2,4-BT) and related polyphenols (resorcinol, pyrogallol and phloroglucinol) are investigated. Pyrogallol and 1,2,4-BT can produce H₂O₂, O ₂ ^– and^·OH simultaneously, and have powerful mutagenic potential. Resorcinol and phloroglucinol cannot produce all of the active oxygen species, and show no mutagenic effects. Catechol can produce H₂O₂, but cannot produce O ₂ ^– and^·OH, and has no mutagenic activity. These data strongly support the hypothesis that benzene metabolites can cause mutagenicity via the generation of oxygen radicals. Although HQ produces H₂O₂ only, and less than produced by pyrogallol and 1,2,4-BT, the mutagenicity of HQ is higher. The results indicate that HQ may act via another mechanism to cause mutagenicity. In the presence of trace metal ions, the reactivity of polyphenols is increased. The biological significance of these phenomena are investigated and discussed.