Variation in feeding behaviour of Nilaparvata lugens on resistant and susceptible rice varieties

The feeding behaviour of Nilaparavata lugens was monitored on three rice varieties showing different levels of resistance in the Philippines, using a video-assisted observation method. N. lugens made more frequent, shorter probes on the moderately resistant IR46 and resistant IR62 rice varieties than on the susceptible IR22. Honeydew production was significantly lower on the resistant varieties though insect weight gains in 24 h were similar on IR46 and IR22, both being significantly greater than on the highly resistant variety.Population development, growth index and damage ratings were low on IR62 indicating antibiosis and/or non preference. When IR46 plants were infested as seedlings population increase, growth index and damage ratings were similar to those on the susceptible IR22. When infested at a later stage of plant growth the damage rating showed a moderate level of resistance though some population development was maintained, indicating antibiosis and tolerance. N. lugens started probing less frequently after surface exploration on both resistant varieties than on IR22 suggesting the presence of a resistance factor associated with the surface waxes of these varieties.

---

Résumé Le comportement alimentaire de Nilaparvata lugens sur variétés de riz, sensible (IR22), partiellement résistante (IR46) et fortement résistante (IR62), a été contrôlé avec une méthode associant la vidéo à l'observation. N. lugens faisait des piqûres plus fréquentes et plus brèves sur IR46 et IR62, que sur la variété sensible. La production de miellat était significativement plus faible sur les variétés résistantes, bien que les gains de poids des insectes aient été les mêmes en 24 h sur IR46 et IR22, les deux étant significativement supérieurs à celui sur IR62.La croissance de la population, l'indice de croissance et le taux de dégâts étaient tous plus faibles sur IR62, ce qui révèle une antibiose et/ou une absence de préférence. Quand la contamination des IR46 a au lieu au stade semis, la croissance de population, l'indice de croissance et le taux de dégâts étaient semblables à ceux de la variété sensible IR22. Quand la contamination avait lieu à un stade ultérieur, le laux de dégâts révélait un niveau modéré de résistance bien qu'une certaine croissance de population se soit maintenue, ce qui révèle antibiose et tolérance.Après exploration de la surface des feuilles des deux variétés résistantes, N. lugens sondait moins fréquemment que sur IR22, ce qui laisse présumer un facteur de résistance associé aux cires superficielles de ces variétés.

     

Ultrastructural changes in the mitochondria of brown adipose cells during the hibernation cycle of Citellus lateralis

Summary The mitochondrial structure in the brown adipose cells of the golden mantled squirrel, Citellus lateralis, was examined throughout the year in biopsy samples. The mitochondria showed remarkable and apparently reversible changes in size and internal structure related to the physiologic activity of the animal. In the active animal the size of the largest mitochondria was 2.4 m × 1.5 m; during hibernation it increased to 7 m × 2.5 m; and during arousal it reached 11.2m × 5.3 m. The cristae of the mitochondria in the brown adipose cells of the animals in hibernation phase formed loops, whorls and mesh-like interconnections. During the arousal phase they underwent further configurational changes. The most remarkable structure was associated with mitochondria of most unusual proportions which by dissolution gave rise to a new generation. This was a common finding during arousal but did not occur in any other phase of the hibernation cycle. The new mitochondria were virtually indistinguishable from those of brown adipose cells of any active animal.Supported by a grant from the Medical Research Council of CanadaThe author is grateful to colleagues, Dr. G. Dempster and Dr. W.A. Spencer, for many valuable suggestions in the course of the work     

褐家鼠精母细胞中联会复合体的研究Ⅳ.常染色体联会复合体的发育和偶线期节的研究

采用表面铺展-SDS处理、硝酸银和磷钨酸（Phosphotungsticacid,PTA）染色电镜技术,研究了褐家鼠精母细胞中常染色体联会复合体（Synaptonemacomplex,SC）的发育及偶线期节（Zygotenenodule,ZN）。在褐家鼠精母细胞的细线期,常染色体轴心（Axialcores,ACs）已形成,同源轴心在空间上靠近,偶线期SCs开始形成,到粗线期SCs完全形成,于双线期SCs开始解体。在双线期除了个别SCs侧生组分分开外,大多数SCs发生碎片化（fragmentation）．在偶线期未配对的ACs和SCs侧生组分及中央组分上均发现电子密度高的球形或椭圆形的节状结构──偶线期节,ZNss在同源染色体配对过程中起很重要的作用。     

Effect of unilateral surgical denervation of brown adipose tissue on uncoupling protein mRNA level and cytochrom-c-oxidase activity in the Djungarian hamster

The bilateral lobe of interscapular brown adipose tissue of the Djungarian hamster was unilaterally denervated in order to study the role of the sympathetic innervation for maintenance and cold-induced increase of non-shivering thermogenesis. Denervation decreased the noradrenaline content of brown adipose tissue to less than 9% of the intact contralateral pad. This low noradrenaline level was maintained for 1–14 days after denervation. First, to study the role of the sympathetic innervation of brown adipose tissue in the maintenance of the high thermogenic capacity characteristic of the cold acclimated state, brown adipose tissue was denervated in hamsters either kept at thermoneutrality or acclimated to 5°C ambient temperature for 4 weeks. Cold-acclimated hamsters had elevated levels of uncoupling protein messenger ribonucleic acid (8.1-fold) and cytochrom-c oxidase-activity (3-fold). Denervation of brown adipose tissue decreased uncoupling protein-messenger ribonucleic acid level and cytochrom-c-oxidase-activity as compared to the intact pad in thermoneutral and in cold-acclimated hamsters. However, in cold-acclimated hamsters uncoupling protein-messenger ribonucleic acid level and cytochrom-c-oxidase-activity in denervated brown adipose tissue both were maintained on an elevated 6-fold higher levels as compared to thermoneutral controls. Second, to study the role of the sympathetic innervation of brown adipose tissue in the cold-induced increase in thermogenic capacity, hamsters were denervated prior to cold acclimation and responses were measured after 3 and 14 days of cold exposure. Uncoupling protein-messenger ribonucleic acid level and cytochrom-c-oxidase-activity of intact brown adipose tissue increased after 14 days cold acclimation. Denervation did not completely prevent a cold-induced 1.5-fold increase of cytochrom-c-oxidase-activity and a 3.2-fold increase of the uncoupling protein-messenger ribonucleic acid level in denervated brown adipose tissue after 14 days of cold acclimation. In conclusion, high levels of uncoupling protein-messenger ribonucleic acid and cytochrom-c-oxidase activity in brown adipose tissue of cold-acclimated hamsters can partially be maintained without intact sympathetic innervation, suggesting a considerable contribution of trophic factors not requiring sympathetic innervation for maintenance. The cold-induced increase of cytochrom-c-oxidase activity and expression of uncoupling protein-messenger ribonucleic acid largely depends upon sympathetic innervation of brown adipose tissue.Abbreviations ANOVA analysis of variance - BAT brown adipose tissue - COX cytochrom-c-oxidase - HPLC high performance liquid chromatography - mRNA messenger ribonucleie acid - NA noradrenaline - T _a ambient temperature - UCP uncoupling protein     

日本落叶松引种区林地棕壤肥力的多变量分析

本研究从日本落叶松引种区林地棕壤9个主要理化性状及与之配套的17株优势木材料入手,采用多变量分析方法筛选出影响该地区日本落叶松生长的主要肥力因子为氮及磷,並据此将该林地棕壤划分为9个肥力类型。在进行聚类分析时,本研究的创新在于以任意二样本点在各主成份上的坐标值为变量,以各主成份的贡献率为权重,重新定义欧氏距离公式,对主成份坐标值聚类,使其更为合理、直观。同时采用回归分析拟合出理化性状间的多个回归方程。此研究为该林地科学施肥、速生丰产、永续利用提供了可靠的数量依据。     

Light (Blt), a Mutation That Causes Melanocyte Death,Affects Stria Vascularis Function in the Mouse Inner Ear

The Light mutation (B^lt) is a dominant allele of the b-locus on mouse chromosome 4 which causes progressive dilution of coat colour. Melanocytes within the hair follicles of mutant mice develop normally but later degenerate, due to the accumulation of a toxic product, so that the hair becomes lighter with age. Previous studies on W-locus spotting mutants, from which melanocytes are absent, have shown that melanocytes in the stria vascularis of the inner ear are essential for the development and/or maintenance of the endocochlear potential (EP) which is normally around 100 mV. In this study, physiological recordings from the ears of Light mutants were correlated with strial ultrastructure. EPs recorded from all b/b controls and young homozygous and heterozygous mutants (20–22 days old) were normal (77 to 113 mV), but were reduced (19 to 59 mV) in about 30% of ears from older mutants (B^lt/B^lt and B^lt/b). Strial function therefore appears to develop normally but later degenerates in some mutants. This suggests that strial melanocytes are affected by the Light allele and that the continued presence of melanocytes is necessary for strial function. There was no obvious association between the recorded EP value and the ultrastructural appearance of the stria. No structural abnormalities of the stria were noted in control or mutant mice aged 20 days to 4 months including those which had a reduced EP. Strial atrophy was common in old controls and mutants (1–2 years), and appeared to be an age-related process rather than an effect of the Light mutation. Similarly, pigment build-up was common in all strial cells of old mice. However, the accumulations of lipofuscin-like pigment were much larger and more abundant in aged brown non-agouti mice than those observed in old agouti mice, which suggests that this age-related process also has a genetic component.     

The spatial distribution pattern of the brown planthopperNilaparvata lugens Stål (Homoptera: Delphacidae) in west Java,Indonesia

Spatial distribution pattern of the brown planthopper (BPH) was analyzed at 9 experimental fields in the northern part of West Java during two consecutive rice cropping seasons, i.e., wet and dry seasons. The population of each developmental stage and wing form of BPH at each location showed consistent departure from the random (Poisson) distribution, the variances of the densities in most cases exceeding their means. Namely, the distribution pattern of BPH per hill of rice plant was found to have a general tendency to be aggregated or contagious and to fit fairly well to the negative binomial model. The tendency for aggregation was further confirmed by both the β-values of -m regression being larger than unity and the C_A-values being larger than zero for each developmental stage. Although significant variations in the distribution pattern as measured by β- or C_A-value were observed between different developmental stages, between wing forms and among locations, the degree of aggregation for a given developmental stage at each experimental field remained fairly stable throughout the crop period, despite wide temporal changes in population density. Possible factors to explain these characteristics of the spatial distribution pattern of the BPH in West Java were discussed with reference to the process generating it.     

Liquid seaweed extracts identified using <Superscript>1</Superscript>H NMR profiles

Aqueous extracts of Ascophyllum nodosum and several other brown seaweeds are manufactured commercially and widely distributed for use on agricultural crops. The increasingly regulated international trade in such products requires that they be standardized and defined to a degree not previously required. We examined commercially available extracts using quantitative ¹H NMR and principal components analysis (PCA) techniques. Extracts manufactured over a 4-year period using the same process exhibited characteristic profiles that, on PCA, clustered as a discrete group distinct from the other commercial products examined. In addition to recognizing extracts made from different seaweeds, analysis of the ¹H spectra in the 0.35–4.70 ppm region allowed us to distinguish amongst extracts produced from the same algal species by different manufacturers. This result established that the process used to make an extract is an important variable in defining its composition. A comparison of the ¹H NMR integrals for the regions 1.0–3.0 ppm and 3.0–4.38 ppm revealed small but significant changes in the A. nodosum spectra that we attribute to seasonal variation in gross composition of the harvested seaweed. Such changes are reflected in the PCA scores plots and contribute to the scatter observed within the data point cluster observed for Acadian soluble extracts when all data are pooled. Quantitative analysis using ¹H NMR (qNMR) with a certified external standard (caffeine) showed a linear relationship with extract concentration over at least an order of magnitude (2.5–33 mg/mL; R ² > 0.97) for both spectral regions integrated. We conclude that qNMR can be used to profile (or “fingerprint”) commercial seaweed extracts and to quantify the amount of extract present relative to a suitably chosen standard. Issued as NRCC no. 42,652.