Showing papers by "University of Hertfordshire published in 1968"

Taxonomy of Meloidogyne (Nematodea: Heteroderidae) with descriptions of four new species.

Abstract: A review of the literature on Meloidogyne Goeldi, 1887 (endoparasitic gall-forming nematodes in roots of higher plants) emphasised the need for a detailed morphological study of the genus to provide an adequate basis for the identification of its species. The taxonomic study reported here confirmed the morphological distinctness of 23 species, including four new ones–M. decalineata sp. n., M. ethiopica sp. n. and M. megadora sp. n. from Africa and M. indica sp. n. from India. M. inornata Lordello, 1956a and M. tadshikistanica Kiryanova & Ivanova, 1965 may also be distinct species but M. poghossianae Kiryanova, 1963 is regarded as a species inquirenda. Meloidogyne spp. can be identified by the posterior cuticular pattern of the females and the morphology of the water-hatched, fixed larvae and of the males. Measurements, especially of water-hatched, fixed larvae are also useful in the differentiation of species. An improved technique for identification of Meloidogyne spp. is proposed and keys based on adults and on larvae are presented. Types are designated for M. exigua Goeldi, 1887, M. arenaria (Neal, 1889) Chitwood, 1949, M. hapla Chitwood, 1949, M. incognita (Kofoid & White, 1919) Chitwood, 1949, M. javanica (Treub, 1885) Chitwood, 1949 and M. thamesi Chitwood in Chitwood, Specht & Havis, 1952 (Goodey, T., 1963). The genus Hypsoperine Sledge & Golden, 1964 is rejected and two of its species renamed M. graminis (Sledge & Golden, 1964) comb. n. and M. spartinae (Rau & Fassuliotis, 1965) comb, n., while H. acronea (Coetzee, 1956) Sledge & Golden, 1964 is returned to M. acronea Coetzee, 1956.

α-[( t -Butylamino)methyl]-4-hydroxy- m -xylene-α 1 , α 3 -diol (AH.3365): a Selective β-Adrenergic Stimulant

Abstract: α-[(t-Butylaraino)methyl]-4-hydroxy-m-xylene- α1, α3-diol (AH.3365), one of a new series of β-adrenergic stimulants described in the preceding communication, when tested on animals has been found to have a considerably greater action on bronchial smooth muscle than on other smooth muscles affected by β-stimulants. Relative potencies found for AH.3365, isoprenaline and orciprenaline in preventing bronchospasm induced by acetylcholine in guinea-pigs are given in Table 1 together with their potencies in relaxing spontaneous tone of isolated tracheal chain preparations. In the Konzett–Rossler preparation, similar orders of potency were found when the spasmogen used was histamine, 5-hydroxytryptamine or bradykinin. At equi-effective doses AH.3365 and orciprenaline had a similar duration of action and both were longer acting than isoprenaline in the in vivo tests. The ratios found on the tracheal chain preparation are different from those obtained in any in vivo experiment designed to measure airflow or airways resistance in any species tested so far. Thus in vitro tests may give a poor estimate of the real bronchodilator activity of β-stimulants.

Isolation of Ammonia‐oxidizing Autotrophic Bacteria

Abstract: SUMMARY Procedures are described for isolating ammonia-oxidizing autotrophic bacteria in pure culture, using solid media made from purified agar and appropriate micromanipulations.

New Class of Selective Stimulants of β-Adrenergic Receptors

Abstract: THE duration of the bronchodilator action of isoprenaline (I, R1 = R2 = OH, R3 = Pri) is limited by metabolism by catechol-0-methyl transferase (COMT) to the inactive ether (I, R1 =OH, R2 = OMe, R3 = Pri) (ref. 1).

Mucopolysaccharides in the anuran defence against desiccation

Abstract: In addition to those usually mentioned in textbooks on comparative anatomy, the anuran skin contains, in many species, a layer situated between the stratum compactum and the stratum spongiosum which is acellular and which has a selective tinctorial affinity for Alizarine, haematoxylin, Alcian Blue and ionized iron. The indications are that this layer consists of acid mucopolysaccharides and calcium. This layer is most prominently developed in the more differentiated anuran families. It is almost entirely absent in the aquatic species but predominantly present in the terrestrial forms. Presumably this layer plays an important part in the defence mechanism of the Anura against desiccation.

Recovery of helminth eggs from archaeological excavations, and their possible usefulness in providing evidence for the purpose of an occupation.

Abstract: HELMINTH eggs vary widely in their structure and, consequently, in their ability to resist desiccation and destruction. But usually theirs is the most resistant stage in the life-cycle of the worm and any conclusions to be made, concerning early helminthic infections, are most likely to come from recognition of these eggs. These have been recovered from three sources: mummified or otherwise preserved bodies, formed stools and soil from cesspits or similar structures. While the first two sources can provide more positive identification of the origin of the eggs, it is from the third source that the greatest variety of species has been obtained, presumably because they accumulate over a period of time. Here is reported an investigation in which soil from a Roman Age occupation at Owlesbury, near Winchester, was examined in the hope that positive identification of eggs might provide some clue to the nature of the occupation, to supplement the archaeological evidence. I have reviewed the literature on similar investigations1.

Fractionation and comparison of purothionin and globulin components of wheat

Abstract: Purothionin, an unusual wheat protein and the ‘fast-moving wheat globulins’ have been separated into two components. Earlier evidence of the close similarity of purothionin and these ‘globulins’ is strengthened by amino acid analyses, ‘fingerprints’ (peptide mapping) and C-terminal end group determination of the individual components. A preparation similar to the crude ‘lipoprotein’ precursor of purothionin previously reported in the literature and stated to contain ‘lecithin’ on the basis of the presence of lipid phosphorus has been partially resolved into six components, and the presence of phosphatidyl choline, amino phospholipids and two glycolipids has been demonstrated in fractions containing purothionin.

A comparison of some cardiovascular properties of propranolol, MJ 1999 and quinidine in relation to their effects in hypertensive animals

Abstract: 1. A comparison of some cardiovascular effects of propranolol, MJ 1999 and quinidine has been made in rats and dogs.2. After intravenous, subcutaneous or oral administration to rats and dogs, propranolol was found to be 2-4 times more potent than MJ 1999 in blocking the chronotropic and vasodepressor responses to intravenously administered isoprenaline.3. Propranolol and quinidine affected the e.c.g. of rats and dogs in a similar manner.4. At dose-levels causing effective blockade of beta-receptors propranolol and MJ 1999 had no hypotensive effect after short- or long-term administration to conscious hypertensive rats and dogs.5. At very high dose-levels propranolol and quinidine, but not MJ 1999, lowered blood pressure in the hypertensive rat. This effect of propranolol is probably related to one or more of the properties that propranolol and quinidine have in common rather than to a blockade of beta-receptors.6. The possible relevance of these results to the use of propranolol as a hypotensive agent in man is discussed.

Methods of measuring the prevalence of pathogenic fungi on potato tubers

Abstract: SUMMARY Methods are described whereby the prevalence of pathogenic fungi on seed potato tubers can be measured quickly and quantitatively. Eye-bearing plugs of tuber tissue, 8 mm diameter by 10 mm long, are excised, incubated over water at 15 °C for 5 days and then examined microscopically. The occurrence of fungi and macroscopic tuber symptoms are recorded directly on punched tape and tabulated by computer.

The response of human cultured lymphocytes to cytochalasin B.

Abstract: The cytochalasins are a new group of compounds which have been recently isolated from moulds. Some of their properties are of interest in the study of cytoplasmic and nuclear division since they have been shown to inhibit motility, produce nuclear extrusion and prevent cytoplasmic cleavage with the production of multinucleated cells. The present study is a report of the effects of cytochalasin B on cultured human lymphocytes. After exposure to cytochalasin B, a proportion of the cultured human lymphocytes became multinucleate. The magnitude of this effect was related to the concentration and the length of time of exposure to the compound. Cells with from one to eight nuclei were identified. Progressive variation in nuclear morphology became apparent as the number of nuclei in a cell increased. Examination of the chromosomes showed only diploid, tetraploid and a few octaploid cells. No obvious chromosomal abnormalities were detected, except in octaploid cells. It is suggested that in multinucleated cells there may be a failure of mitotic control leading to variations in size and shape of interphase nuclei.

Leaf injury and food consumption by larvae of phaedon cochleariae (coleoptera; chrysomelidae) and plutella maculipennis (lepidoptera plutellidae) feeding on turnip and radish

Abstract: Larvae of Plutella maculipennis (Lepidoptera; Plutellidae) and Phaedon cochleariae (Coleoptera; Chrysomelidae) were fed on the leaves of both turnip Brassica rapa and radish Raphanus sativus. Both the weight of the food eaten and the area of leaf injured were measured. The weight eaten depended on the nutritive value of the food, whereas the area of leaf injured depended on the leaf thickness and the method of feeding of the insect. Both species developed fastest on young plants, which contained the most protein. They ate a greater weight of old than of young leaves, and injured a greater area of radish than of turnip leaf, which had more dry matter/unit area. The area of leaf injured by P. maculipennis was equivalent to the weight eaten, but P. cochleariae which had a different method of feeding destroyed much more leaf area than was expected from the weight of food eaten. ZUSAMMENFASSUNG BLATTSCHADEN UND NAHRUNGSVERBRAUCH DER LARVEN VON PHAEDON COCHLEARIAE (COLEOPTERA: CHRYSOMELIDAE) UND PLUTELLA MACULIPENNIS (LEPIDOPTERA: PLUTELLIDAE) BEIM FRASS AN RUBSEN UND RETTICH Larven des Meerrettichkafers, Phaedon cochleariae Fab., und der Kohlschabe, Plutella maculipennis Curtis, wurden an intakten Pflanzen von Rettich (Rhaphanus sativus L., var. French Breakfast) und Rubsen (Brassica rapa L., var. Early Milan White) gehalten. Grose und Trockengewicht der verzehrten Nahrung wurden wahrend der gesamten Larvalentwicklung ermittelt. Die Versuche verliefen bei einer konstanten Raumtemperatur von 20°. Beide Insekten frasen eine grosere Gewiohtsmenge von Rubsen- als von Rettichblattern und von alten mehr als von jungen Blattern. Die mittlere Umsatzrate von P. maculipennis betrug fur Rubsen und Rettich 0,41 und der Ausnutzungskoeffizient war an jungeren Pflanzen sowohl bei Rettich wie Rubsen groser als an alteren. Die Umsatzrate von P. cochleariae variierte zwischen 0,11 und 0,27 in Abhangigkeit von Art und Alter der Nahrpflanze, aber es war nicht moglich, den Ausnutzungskoeffizienten zu messen, weil der Kot nicht gesammelt werden konnte. Das Trockengewicht der von P. maculipennis gefressenen Nahrung auf den jungsten und altesten Pflanzen variierte bei Rubsen zwischen 10,52 und 23,77 mg und bei Rettich zwischen 9,45 und 15,28 mg; und bei P. cochleariae zwischen 12,24 und 15,70 fur Rubsen und 9,79 und 12,29 fur Rettich. Beide Insekten frasen von Rettich eine grosere Blattflache als von Rubsen, wahrscheinlich weil Rubsen einen groseren Gehalt an Trockensubstanz pro Flacheneinheit enthalt. Die von P. maculipennis beschadigte Blattflache entsprach dem Gewicht der gefressenen Nahrung, da sie sauber durch das Blatt hindurch frist und die Blattadern meidet. P. cochleariae beschadigte eine grosere Blattflache als erwartet wurde, da er die untere Blattoberflache beschabt, oft nicht eindringt, aber die Blattadern durchnagt, so das das Gewebe infolge Austrocknung und Ernahrungsstorungen abstirbt.

Effects of feeding by larvae of Phaedon cochleariae (F.) and Plutella maculipennis (Curt.) on the yield of radish and turnip plants

Abstract: SUMMARY Different numbers of larvae of the beetle Phaedon cochleariae (F.) and the moth Plutella maculipennis (Curt.) were fed on the leaves of turnip plants (variety Early Milan White) and radish (variety French Breakfast) growing in a constant-environment room. Turnips grew more slowly than radish, were less affected by insect feeding and were affected more by Phaedon than by Plutella. Phaedon larvae severed leaf veins and rasped the leaf surface, thus killing more leaf tissue by desiccation than they ate. They remained on and greatly damaged the older leaves and their feeding reduced yield. Plutella larvae fed on leaves of all ages, which they ate cleanly, leaving the veins. They pupated sooner than Phaedon and did less damage to older leaves, which grew larger and lived longer than corresponding leaves on intact plants. This compensatory growth by turnip prevented loss of yield and may have increased it, as indicated by dry weight of the roots. Both species of insect decreased the yield of radish similarly. Loss of yield of turnip caused by Phaedon or of radish caused by both species of insects was negatively and linearly proportional to the number of larvae that fed on the leaves.

Laboratory studies on the acute contact and oral toxicities of insecticides to honeybees.

Abstract: SUMMARY Standard procedures for determining acute oral and contact toxicities of insecticides to worker honeybees were developed and used to find the median lethal doses (LD50) of twenty-one compounds. The test procedures can be simplified to give less precise results and can be applied with little modification to other species of bee.

A simple method for recording the electrocardiogram and heart rate from conscious animals.

Abstract: The small bioelectrical signals of the heart detected at the body surface of animals are usually relayed to the initial amplifier stage of the electrocardiograph by the use of plate, needle or clip electrodes (Clark, Szabuniewicz & McCrady, 1966). In a series of experiments in which rapid and repeated measurements of the electrocardiogram (e.c.g.) and resting heart rate from conscious, unrestrained guinea-pigs were required none of the standard methods proved suitable and a modification was therefore developed in which the animals stand on plate electrodes. This method has been used to obtain recordings from conscious mice, rats, cats and dogs, and some applications of the method are illustrated in the experiments described in this article.

Mongolism and duration of marriage.

Abstract: In 1968 J.L. German suggested that the occurrence of mongolism was linked to delayed fertilization which in turn was related to marriage duration. In light of Germans contention the hypothesis that the occurrence of mongolism is positively related to the duration of parental marriage was tested using data on parental marriage duration for a sample of 988 mongols and a control sample of 1146 non-mongols who were mentally retarded. Mean parental marriage duration at the time of the birth of the mongols was significantly longer than the mean marriage duration of the parents at the birth of the control group. The respective mean marriage ages were 9.54 years and 5.82 years. However when maternal age was controlled for the difference between mean marriage duration for the sample group and for the control group was insignificant. Although these findings do not disprove Germans theory they do not lend support to the theory.

The effect of a low‐viscosity swelling liquid on the tensile strength of rubber

Abstract: The paper examines the effect of swelling on a number of different gum rubbers and rubbers filled with different types and concentrations of black. The observed decrease in strength with decreasing rubber fraction Vr (increasing swelling ratio) is, in the case of gum rubbers, associated with a decrease in internal friction. The incorporation of a black filler is shown to increase strength by hydrodynamic stiffening and by an increase in internal friction of the rubber network, and a simple reduction scheme of the data shows a close analogy between the strength as a function of Vr and the dynamic modulus of a rubber solution as a function of concentration. The results lead to a failure criterion, which describes the energy density at break as a simple function of the hysteresis near break.

Adsorption and desorption of simazine by some rothamsted soils

Abstract: Summary. The adsorption of simazine from, and subsequent desorption into, 0–01 M calcium chloride solution was investigated using twenty-three Rothamsted soil samples from sites differing greatly in cropping history and manurial treatment. Organic carbon content was the only factor related to the ability of the soils to sorb simazine; this accounted for 90% or more of the variation between soils Equilibrium was attained during adsorption in from fewer than 2 to more than 24 hr. Equilibrium during desorption was only occasionally attained within 24 hr. Differences between theoretically predicted and measured concentrations of simazine in solution following desorption were least for soils that attained equilibrium fastest during adsorption. Differences in adsorption and desorption kinetics between soils could not be related to soil pH, organic carbon content or cropping and manuring history. Comparisons of unlimed and limed soils suggested that no simnazine was lost by acid hydrolysis during the experiments. Adsorption et desorption de la simazine par quelques sols de Rothamsted Resume. L'adsorption et la desorption de la simazine, en utilisant une solution de 0,01 M de chlorure de calcium, aeteetudiee dans vingttrois echantillons de sol de Rothamsted, de differentes provenances et presentant des differences importantes quant e leurs antecedents culturaux et a leur fumure. La teneur en carbone organique fut le seul facteur en liaison avec la propriete des sols d'adsorber la simazine; ceci entrait pour 90% ou plus de la variation entre les sols. L'equilibre etait atteint durant l'adsorption dans un temps allant de moins de deux heures a plus de 24 heures. Les differences entre les concentrations theoriquement prevues et les concentrations mcsurEes de simazine dans la solution apr i-s desorption furent moindres pour lea sols qui atteignaient l'equilibre au cours d'une adsorption plus rapide. Les differences entre les cinetiques d'adsorption et de desorption entre les sols ne purent etre reliees au pH du sol, a sa teneur en carbone organique, a ses antecedents culturaux ni a sa fumure au cours du temps. Des comparaisons entre sols chauies et non chauies suggererent que la simazine n'etait pas perdue par hydrolyse acide au cours des experiences. Zusammenfassung. Die Adsorption von Simazin durch 23 Bodenproben von verschiedenen Feldern in Rothamsted, die sich in Bezug auf langjiihrige Fruchtfolge und Dungung sehr stark untcrschicden, wurde ebenso wie die Desorption des Simazins aus diesen Boden an 0,01 M Calciumchloridlosung untersucht. Der Gehalt an organischem Kohlenstoff war allein verantwortlich fiir die Fahigkeit dec Boden, das Simazin zu sorbieren; mehr als 90% des Unterschieds zwischen diesen Biiden war hierauf zuruckzufuhren. Wahrend der Adsorption wurde ein Gleichgewicht innerhalb von weniger als 2 bis zu mehr als 24 Stunden erreicht. Bei der Desorption wurde nur selten ein Gleichgewicht innerhalb von 24 Stunden erreicht. Die Unterschiede zwischen theoretisch errechneten und tatsachhch gemessenen Simazinkonzentrationen in der Losung nach Desorption waren am geringsten in Boden, die das Adsorptionsgleichgewicht am schnellsten erreicht hatten. Die Unterschiede in dem Adsorption-und Dcsorptionsverhalten zwischen den einzelnen Boden konnten nicht mit dem Boden-pH, dem Gehalt des Bodens an organischem Kohlenstoff oder der Fruchtfolge bzw. Dungung in Verbindung gebracht werden. Der Vergleich von gekalkten und ungekalkten Boden legt die Vermutung nahe, dass kein Simazin durch Saurehydrolyse wahrend der Versuche verloren gegangen war.

Pesticides residues in foodstuffs in Great Britain. VI. Mercury residues in rice.

Abstract: Analyses of samples of rice from United Kingdom importers and from retail sources show that levels of mercury are often negligible, although they may rise to 0.01 ppm and occasionally to 0.015 ppm.

The behaviour of a cotton stainer dysdercus intermedius (heteroptera, pyrrhocoridae) in a temperature gradient and the effect of temperature on aggregation

Abstract: Problems relating to the distribution of insects in artificial temperature gradients are discussed and the meanings of terms defined. The distribution of insects in a temperature gradient can be expressed as the mean of the preferred range of positions taken and as the standard deviation about this mean. Experiments with Dysdercus intermedius showed that with ten individuals in the gradient apparatus, distributions were unimodal but with more insects than ten, distributions were bimodal with one peak in the “preferred temperature” range and another at the cold end of the apparatus. When there was no gradient of temperature, aggregations formed at temperatures below 30°, but above 30° insects began to scatter and at 43° they did not aggregate. Zusammenfassung DAS VERHALTEN EINER BAUMWOLL-FARBER-WANZE, DYSDERCUS INTERMEDIUS (HETEROPTERA, PYRRHOCORIDAE), IN EINEM TEMPERATURGEFALE UND DIE WIRKUNG DER TEMPERATUR AUF DIE GRUPPENBILDUNG 1. In einem Temperaturgefalle von 18, 2–35, 0° lag das durch die Standardabweichung gekennzeichnete Vorzugstemperaturgebiet der Larven und Imagines von Dysdercus intermedius zwischen 19, 3 und 31, 6°. Die mittlere Vorzugstemperatur betrug 23, 8–27, 5°. 2. Die Verteilungen waren bei bis zu 10 Tieren unimodal im Gradientbereich, bei mehreren Insekten (z.B. 25 oder 50) waren sie bimodal mit einer Haufung im Vorzugstemperatur-bereich und einer anderen am kalten Ende des Temperaturgefalles. Je dichter die Insekten gehalten wurden, um so mchr samm***elten sich am kalten Ende. 3. Obwohl sich die Insekten manchmal strong zwischen 18 und 20° ansammelten, bestand sehr wenig Unterschied im Verhaltnis der Wanzen, die sich bei verschiedenen Temperaturen zwischen 20 und 30° zusammenscharten. Wenn die Temperatur uber 30° anstieg, begannen sich die Insekten zu zerstreuen und bei 43° scharten sie sich nicht mchr zusammen.

Nature of the Complementation Products Formed by a Complementing Mutant of Neurospora crassa

Abstract: The mutant am-14 produces no active nicotinamide adenine dinucleotide phosphate-linked glutamate dehydrogenase (GDH) and no protein showing immunological cross-reaction with the enzyme. Nevertheless, it shows complementation with several other am mutants in heterokaryons. Active GDH can be extracted from heterokaryons formed from am-14 and other mutants which, by themselves, produce more or less inactive varieties of the enzyme. The enzyme from am-14 + am-3 heterokaryons can be partially separated from am-3 mutant GDH on a diethylaminoethyl cellulose column. It is characterized by abnormally high thermolability and by a capacity for activation by glutamate. By the same procedure as brings about hybridization between mutant GDH proteins, it has been possible to recover enzyme with the properties of pure am-3 GDH from a partially purified am-14 + am-3 GDH preparation which was initially substantially free of unhybridized am-3 enzyme. This is interpreted as evidence that the active complementation product is a hybrid oligomer containing am-3 monomers and also am-14 monomers, the latter being unable to aggregate by themselves. Heterokaryons formed from am-14 and wild type produce GDH of abnormally high thermolability, presumably due to the formation of am-14 + am+ hybrids.

Schizophrenic Birth Order: the Last but One Position

Abstract: RESULTS of birth order studies on schizophrenics from the United States, Canada and Britain suggest an increased incidence of patients born late in the family1–7.