Insecticidal fatty acids and triglycerides from Dirca palustris.

Five compounds, 1-5, were isolated from the seed hexane extract of Dirca palustris. Compounds 1-3 were triglycerides, and 4 and 5 were linoleic and oleic acids, respectively. Compounds 1-3 were not biologically active; however, 4 (linoleic acid) and 5 (oleic acid) were insecticidal against fourth instar Aedes aegyptii larvae and exhibited potent feeding deterrent activity against neonate larvae of Helicoverpa zea, Lymantria dispar, Orgyia leucostigma, and Malacosoma disstria.     

Disorder-to-Order Transition in Settling Suspensions of Colloidal Silica: X-ray Measurements

Dispersions of colloidal particles exhibit thermodynamic properties similar to those of molecular systems, including a hard sphere disorder-to-order transition. In experiments with organophilic silica in cyclohexane, gravity settling was used to concentrate the particles. With small particles the slow sedimentation permits rearrangement into the iridescent ordered phase, but larger particles form amorphous sediments instead. Scanning electron microscopy of the crystalline sediment indicates hexagonally closepacked layers. X-ray attenuation measurements reveal a discontinuity coincident with the observed boundary between iridescent and opaque regions. Sediments accumulating faster than the maximum rate of crystallization produce a glass, in accord with the classical theory for crystal growth.     

Investigation into diagnosis and treatment of cobalt deficiency in lambs.

The development of cobalt deficiency was studied in 30 Scottish Blackface lambs grazing pasture on a soil containing 0-17 ppm cobalt. By the end of an eight-week period 50 per cent of lambs were subjectively appraised as showing signs of cobalt deficiency. After a further period lasting four weeks, during which three groups of lambs were studied (one group, least affected by cobalt deficiency, acted as control, the second received a single cobalt bullet and the third received oral doses of 200 mg cobalt chloride at the beginning of the period and three weeks later). Mean urinary formiminoglutamic acid (FIGLU) concentrations were inversely related to serum vitamin B12 concentrations and increased from 0-08 to 0-20 mumole per ml in group 1, and decreased to virtually zero within one week of treatment in groups 2 and 3. The use of serum vitamin B12 and urinary FIGLU concentrations in the diagnosis of cobalt deficiency in sheep are discussed.     

Means of assessing the adequacy of nutrition of pregnant ewesMéthodes d'appréciation de l'état nutritionnel des brebis gestantesMöglichkeiten der Einschätzung einer nicht angemessenen ernährung bei tragenden mutterschafen

The adequacy of nutrition of pregnant ewes can be assessed by means of changes in body condition and live weight, particularly during early (0–30 days) and mid- (30–90 days) pregnancy. In late pregnancy (90–147 days), however, the rapid growth of the foetus makes changes in live weight difficult to interpret, while the time taken to detect meaningful changes in body condition may well be too great to allow any necessary increases in nutrition to be made at the proper time. A means of regulating food inputs according to levels of blood metabolites, such as plasma 3-hydroxybutyrate concentrations, to maintain within prescribed limits the degree of undernutrition known to be consistent with satisfactory lambing results, has been shown to be practicable in both individual feeding and flock situations (1.1 and 0.8 mmol 3-hydroxybutyrate per litre, respectively).     

The technical development of sheep production from hill land in Great Britain

The hill-sheep farming industry in Great Britain, in which the ewe flocks are dependent on grazed pastures throughout the year, is described briefly. Research work on the relationships between nutrition and the various components of hill-sheep production (principally ovulation rate, lamb birth weight, milk production and lamb growth rate) has provided an understanding of the biological reasons for current low levels of output, and has led to the development of a new system of management. This is based on the provision of improved nutrition, from higher quality pasture, at the two stages in the annual cycle when sheep production is most responsive to changes in nutrition, i.e. during lactation and in the pre-mating/mating period. In large field-scale tests of the new management system increases of 130 to 290% in the weight of weaned lamb produced have been achieved as a result of combined increases in output per ewe and in ewe numbers.     

Bioactive compounds and 1,3-Di[(cis)-9-octadecenoyl]-2-[(cis,cis)-9, 12-octadecadienoyl]glycerol from Apium graveolens L. seeds

Bioassay-directed isolation and purification of the hexane extract of Apium graveolens L. seeds led to the characterization of three compounds: beta-selinene (1), 3-n-butyl-4,5-dihydrophthalide (2) and 5-allyl-2-methoxyphenol (3). The structures of these compounds were established by using (1)H and (13)C NMR spectral methods. Compounds, 1-3 demonstrated 100% mortality on fourth-instar Aedes aegyptii larvae at 50, 25, and 200 microg mL(-)(1), respectively, in 24 h. Also, 2 inhibited the growth of Candida albicans and Candida kruseii at 100 microg mL(-)(1). It inhibited both topoisomerase-I and -II enzyme activities at 100 microg mL(-)(1). Compound 2 displayed 100% mortality at 12.5 and 50 microg mL(-)(1), respectively, when tested on nematodes, Panagrellus redivivus and Caenorhabditis elegans. The triglyceride, 1,3-di[(cis)-9-octadecenoyl]-2-[(cis,cis)-9, 12-octadecadienoyl]glycerol (4) and 3 were isolated for the first time from A. graveolens seeds, although 4 was not biologically active.     

The effect on wool production of changes in management designed to increase output of lamb from hill land in the United Kingdom

A system of management designed to increase the economic efficiency of the production of weaned lamb from hill land through the use of pasture improvement and controlled grazing has resulted in considerable increases in the outputs of both lamb and wool. In two examples quoted the weight of weaned lamb produced increased by 51 and 94%; these changes were accompanied by increases in wool output of 31 and 84%, respectively. The additional outputs of both products are attributable to a combination of increased numbers of ewes and higher levels of individual animal performance.The increase in output of wool which may be expected from changes in management directed at increasing lamb production is relatively small, ranging from 4.6 to 6.5 kg per 100 kg increase in weaned lamb in the Scottish Blackface to 11.6 kg per 100 kg increase in weaned lamb in the South Country Cheviot. Evidence is presented to show that the magnitude of the increase in wool production is likely to be determined genetically by the response to improved nutrition of both lamb and wool production.     

Impact of litter species diversity on decomposition processes and communities of soil organisms

The effect of plant species diversity and the C/N ratio of litter on soil processes were analysed in mesocosms in a three year field experiment. Plots 0.5 × 0.5 m with a depth of 15 cm containing sand mixed with loam were used to compare five natural and one artificial litter type (polypropylene string). Natural litters were either monospecific (I: Dactylis glomerata; II: Festuca rubra and III: Trifolium pratense) or were species mixtures (IV: mixture of three species I, II and III; V: mixture of twelve species, IV and nine other meadow plants). Differences among treatments in the litter decomposition rate, humic acid content and nematode density depended on the litter quality (C:N ratio) in most cases. By contrast, most of the differences among treatments found in the substratum below the litter cover resulted from litter diversity. The largest increase of carbon and nitrogen amount during growing season was found under litter mixtures (IV, V) and the highest fulvic acid content under the most diverse litter (V). Similarly, the production of algae in the substratum also significantly increased with litter diversity. Higher taxonomic diversity of Nematoda and Collembola and the most mature community of nematodes were observed under the most complex litter. Epigeic macrofauna, both dwelling in and penetrating the litter, did not differ significantly between experimental treatments. However, the highest share of predators was found in the treatment with the richest plant species diversity. In general, the results suggest that the decomposition of diverse plant litter enhances humus acid accumulation in soils. It is likely that algae participate in the process of humus formation.     

Real-time ultrasonic scanning in the diagnosis of pregnancy and the estimation of gestational age in cattle

Diagnoses of pregnancy were made on 110 Hereford cross Friesian and 69 blue grey (white shorthorn cross Galloway) cows between 92 and 202 days after last service using a real-time ultrasonic scanning instrument with a 3.5 MHz rectal transducer. Of the 174 cows which subsequently calved, one was wrongly diagnosed as non-pregnant. Of the five cows which did not subsequently calve two were diagnosed as pregnant and may in fact have been pregnant at the time of scanning. The overall level of accuracy of pregnancy diagnosis was 98.3 per cent. In further trials with 16 Hereford cross Friesian and 16 blue grey cows scanned at regular intervals between 20 and 140 days of gestation, pregnancy was diagnosed with confidence from 30 days, and relationships were established whereby gestational age could be estimated from measurements of certain uterine and fetal dimensions. Crown-rump length provided the most precise estimate of gestational age (residual sd +/- 4.5 days) and uterine diameter the least (+/- 12.6 days) with head length and the diameters of trunk, head and nose being intermediate (+/- 6.9 to 8.7 days).     

Identification of new limonoids from Swietenia and their biological activity against insects

BACKGROUND: Natural limonoids are one group of compounds being studied for their insecticidal properties. To discover new limonoids with better activities, analogs were prepared via acylation and hydrolysis, and bioassayed. RESULTS: Analogs were identified using one‐ and two‐dimensional (COSY, HMQC and HMBC) ¹H and ¹³C NMR, IR and MS. 3‐O‐Isovalerylswietenolide (13) and 3‐O‐isobutyrylswietenolide (14) showed excellent antifeedant activity, with DC₅₀ values of 0.19 and 0.009 mg L^?1 respectively, compared with the natural limonoid swietenolide (80.6 mg L^?1) against fourth‐instar Spodoptera frugiperda (JE Smith) larvae. CONCLUSION: This work shows that limonoid analogs prepared through semi‐synthesis can be used as lead compounds for the development of new insecticides. Copyright © 2010 Society of Chemical Industry