Effects of faba bean tannins on the growth and histological structure of the intestinal tract and liver of chicks and rats     

L. T. Ortiz  C. Alzueta  J. Trevino  M. Castano 《British poultry science》1994,35(5):743-754

1. Diets containing a freeze‐dried tannin extract from faba beans (Vicia faba L.) at concentrations of 0, 8 and 16 g/kg were fed to growing chicks and rats.

2. Chicks fed on the tannin‐containing diets exhibited a high mortality and significant decreases in body‐weight as well as lower food intakes and higher food intake:weight gain ratios (P<0.01). In rats there was no mortality but the growth and food intake were adversely affected (P< 0.05).

3. Histological changes occurred in the ileal mucosa of chicks. Atrophy and shortening of villi with distortion of their architecture were observed. Similar histological disorders but less pronounced were also found in rats.

4. Histopathology of the liver of both chicks and rats showed an hydropic degeneration of hepatocytes, clearly more severe in the former than in the latter.  相似文献   

Seasonal changes in bud dormancy in relation to bud morphology, water and starch content, and abscisic acid concentration in adult trees of Betula pubescens     

Rinne P  Tuominen H  Junttila O 《Tree physiology》1994,14(6):549-561

Annual cycles of change in bud morphology, bud burst ability, abscisic acid (ABA) concentration, and starch and water content were studied in mid-crown terminal buds of short shoots and underground basal buds of Betula pubescens Ehrh. In particular, we investigated the roles of ABA and bud water content in the regulation of bud growth. Basal buds differed morphologically from terminal buds of short shoots in that their leaf initials did not develop into embryonic foliage leaves and their total size did not increase significantly during summer. Bud burst ability, measured by forcing detached short shoots and stumps under controlled conditions, was maintained in the basal buds throughout the year, whereas the terminal buds of short shoots remained dormant until October, thereafter their bud burst ability increased gradually and reached a maximum in March-April. The ABA concentration of the basal buds was relatively constant throughout the sampling period (1-3 micro g g(DW) (-1)), whereas that of the terminal buds of short shoots, which was much higher (5-10 micro g g(DW) (-1)), showed a distinct seasonal cycle with a maximum from August to November. Bud ABA concentration decreased during the first 10 days of forcing, especially in basal buds. In both bud types, the amount of starch increased toward the autumn, declined in November, and was negligible in the terminal buds of short shoots between January and March, but in April, the amount was high again in both bud types. Water content varied characteristically in both bud types, although more distinctly in the terminal buds of short shoots, with an increase in spring before bud burst and a decrease during the summer until September. The significant morphological and physiological differences between the mid-crown terminal buds of short shoots and the underground basal buds may partly explain the characteristic growth habit of the basal buds and their development into coppice shoots after cutting the tree. The results also indicate a role for ABA in maintaining dormancy of the terminal buds of short shoots and emphasize the relationship between tissue water status and ABA concentration.  相似文献   

Monofrequency forced oscillation technique for the investigation of pulmonary function in calves: in vitro and in vivo studies     

R. Close  P. Reinhold  P. Lekeux 《Research in veterinary science》1994,56(3):470

Parameters derived from the non-invasive and simple monofrequency forced oscillation technique were compared with classical parameters of ventilatory mechanics in order to assess its usefulness for the investigation of pulmonary function in calves. To facilitate this comparison, theoretical derivations were coupled with in vitro measurements, using an artificial lung model, and with in vivo studies. These studies compared the oscillatory resistance parameters (R_os and Re) and the respiratory system compliance (C_rs) against the classical pulmonary resistance (R_L) and the dynamic compliance (C_dyn), respectively. Ros and Re were highly correlated (r0·87) with R_L and the comparison between Crs and C_dyn gave a similarly high correlation (r0·88). Given its simplicity, its correspondence with classical parameters and its rapidity and reproducibility, monofrequency forced oscillation technique seems well suited for the investigation of pulmonary function under field conditions.  相似文献   

Epidemiology of beet necrotic yellow vein virus in sugar beet at different initial inoculum levels in the presence or absence of irrigation     

G. Tuitert  Y. Hofmeester 《European journal of plant pathology / European Foundation for Plant Pathology》1994,100(1):19-53

A field experiment was set up in 1988 to study the development of rhizomania disease of sugar beet at different inoculum levels of beet necrotic yellow vein virus (BNYVV) in soil. Five, tenfold different, inoculum levels were created by addition of the approximate amounts of 0, 0.5, 5, 50 and 500 kg infested soil per ha (the latter corresponding to 0.01% v/v calculated to the tillage layer). A drip irrigation treatment was applied to study the influence of soil moisture on disease. Susceptible sugar beet, cv. Regina, was grown for three consecutive years.In the first year, root symptoms were not observed, but BNYVV-infected plants were detected by ELISA in low numbers at all inoculum levels at harvest. After late drilling in 1989, high numbers of infected plants, up to 90–100% in plots with the highest inoculum level, were detected already in June. Root symptoms were also observed from June onwards. In both these years disease incidence increased in time and was significantly influenced by the initial inoculum level. In the third year, the whole field was heavily diseased, and only for the non-irrigated plots incidence differed for different initial inoculum levels. The expression of symptoms by BNYVV-infected plants was influenced by initial inoculum level, thus by the amount and timing of primary infection.Root weight at harvest was not affected, but sugar content decreased with increasing inoculum level already in 1988, leading to a reduction in sugar yield of 10% at the highest inoculum level. In 1989, both root weight and sugar content decreased progressively with increasing inoculum level, resulting in sugar yield reductions of 11–66% (down to approximately 3000 kg ha^–1) for low to high inoculum levels compared to the control. As the control plots became contaminated, all yields were low in 1990, still showing a decrease with increasing inoculum level in the non-irrigated plots, but an overall mean sugar yield of 3323 kg ha^–1 for the irrigated ones.Sodium and -amino nitrogen content of the root, additional quality parameters determining extractability of sucrose, showed an increase and decrease, respectively, with increasing initial inoculum level already in the first year. The relative differences in contents compared to those from the control were largest for Na content. A significant negative correlation was found between Na (mmol kg^–1 root) and sugar content (% of fresh weight); linear for 1988, exponential for 1989 and 1990.In spring 1989, the infestation of individual plots was assessed using a quantitative bioassay estimating most probable numbers (MPNs) of infective units of BNYVV per 100 g dry soil. The relationship between the MPns determined and root weight, sugar content and sugar yield at harvest could be described by Gompertz curves. The increase in disease incidence with increasing MPN in 1989 was adequately fitted with a logistic equation.  相似文献   

Effects of temperature,vapour pressure deficit and radiation on infectivity of conidia ofBotrytis cinerea and on susceptibility of gerbera petals     

A. Kerssies 《European journal of plant pathology / European Foundation for Plant Pathology》1994,100(2):123-136

The effect of vapour pressure deficit, temperature and radiation on the postharvest susceptibility of gerbera flowers toB. cinerea, on the water relations of gerbera flowers and on the lesion formation after conidial infection ofB. cinerea was studied. The temperature range in whichB. cinerea could germinate and growin vitro is 5–30 °C. In climate chamber experiments flowers had more lesions ofB. cinerea at temperatures of 20 and 25 °C than at 10 and 15°C. At 15, 20 and 25°C the infectivity ofB. cinerea conidia was negatively affected during a storage-period of 7 days. At a vapour pressure deficit (VPD) of 200 Pa significantly more conidia ofB. cinerea were infective than at 800 Pa. At a VPD of 800 Pa the susceptibility of gerbera flowers forB. cinerea was not significantly different than at 200 Pa. High radiation levels in glasshouses in spring and summer negatively influenced the infectivity of conidia ofB. cinerea on the flower surface, but did not affect the susceptibility of gerbera flowers forB. cinerea. In spring and early summer conidia lost their infectivity at high radiation levels, high temperatures and high levels of VPD. In summer gerbera flowers could be more susceptible toB. cinerea because of high temperatures in glasshouses, but the negative effect of radiation on the conidia ofB. cinerea seemed to overrule the temperature effect. Thus, the numbers of lesions in spring and summer can be low compared with the numbers in other seasons, although the numbers ofB. cinerea colonies on spore traps can be high. The effect of temperature on the susceptibility of gerbera flowers can probably be explained by changes of water status in the petals. At higher temperatures the number of lesions and the turgor (=water potential—osmotic potential) in the petals increased. Temperatures <10°C during lesion formation (RH>95% and VPD<50 Pa) had a temporary negative effect on the number of lesions. After 3 days of incubation the numbers of lesions were about equal (30 lesions/cm²) from 5 to 20°C. At 30°C no lesion formation was observed even after 3 days.  相似文献   

Effects of Neem Seed Derivatives on Brown Planthopper Symbiotes     

S. Raguraman  R. C. Saxena 《Phytoparasitica》1994,22(4):299-307

Populations of intracellular symbiotes declined significantly in brachypterous females of the brown planthopper,Nilaparvata lugens (Stål), which were stressed during nymphal development by caging them on IR20 rice plants treated with 3% neem oil, 5% neem seed kernel aqueous extract, or 10% neem cake aqueous extract. In addition, nymphs grew poorly and symbiote populations in prospective females declined, when reared on rice plants grown in soil treated with neem cake; this indicates systemic action of bioac-tive neem constituents. Addition of custard-apple oil to neem oil did not enhance the inhibitory effects. The effects of neem derivatives on the symbiotes may be either host-mediated — possibly through disturbed neuroendocrine homeostasis, or direct — leading to perturbations of host-symbiote equilibrium.  相似文献   

Fractal dimension estimates of a fragmented landscape: sources of variability   总被引：9，自引：0，他引：9  

Alain Leduc  Yves T. Prairie  Yves Bergeron 《Landscape Ecology》1994,9(4):279-286

Although often seen as a scale-independent measure, we show that the fractal dimension of the forest cover of the Cazaville Region changes with spatial scale. Sources of variability in the estimation of fractal dimensions are multiple. First, the measured phenomenon does not always show the properties of a pure fractal for all scales, but rather exhibits local self-similarity within certain scale ranges. Moreover, some sampling components such as area of sampling unit, the use of a transect in the estimation of the variability of a plane, the location, and the orientation of a transect all affect, to different degrees, the estimation of the fractal dimension. This paper assesses the relative importance of these components in the estimation of the fractal dimension of the spatial distribution of woodlots in a fragmented landscape. Results show that different sources of variability should be considered when comparing fractal dimensions from different studies or regions.  相似文献   

Characterisation of a maize-infecting potyvirus from Spain     

M. Angeles Achon  Vicente Medina  Michael Shanks  Peter Markham  George P. Lomonossoff 《European journal of plant pathology / European Foundation for Plant Pathology》1994,100(2):157-165

In order to characterise and classify an unknown maize-infecting potyvirus isolated from fields in northeast Spain, the entire coat protein gene and the C-terminal twothirds of the large nuclear inclusion protein (NIb) gene were cloned and sequenced. Protein sequencing enabled the cleavage site between the two proteins to be deduced and also revealed that on storage the viral coat protein undergoes a specific degradation in which the N-terminal 39 amino acids are removed. Comparison of the nucleotide sequence of the 3 non-coding region of the viral RNA and the predicted amino acid sequence of the coat protein with the equivalent regions of other members of the potyvirus group revealed that the Spanish virus is closely related to maize dwarf mosaic virus strain A.  相似文献   

Effects of timing and size of daylength change on brown egg laying domestic hens: Plasma luteinising hormone concentration and sexual maturity     

P. D. Lewis  G. C. Perry  T. R. Morris  B. K. Follett 《British poultry science》1994,35(1):25-31

1. Brown egg laying pullets were transferred from an 8‐h photoperiod to an 8‐, 10‐, 13‐ or 16‐h photoperiod at 6, 9, 12, 15, 18 or 20–3 weeks of age. Plasma luteinising hormone (LH) concentrations were measured at transfer and 7 and 14 d afterwards.

2. Significant increases in plasma LH occurred following light stimulations at 6, 9 and 12 weeks of age.

3. Changes in LH concentration 7 d after a light increase from 8 h to 8, 10, 13, 16 h were highly correlated with photoperiod length at 9 and 12 weeks of age.

4. Changes in LH were generally poorly correlated with age at sexual maturity, although the reduced influence on age at first egg of a light increase given close to sexual maturity was reflected in minimal LH responses at 18 and 20.3 weeks.  相似文献   

Peaks of brainstem auditory evoked potentials in dogs     

Y. Kawasaki  S. Inada 《Veterinary research communications》1994,18(5):383-396

The effects of electrode configuration and click polarity on brainstem auditory evoked potentials (BAEP) in dogs were investigated to clarify the inconsistent nomenclature for each peak. Four positive peaks (waves 1, 2, 3 and 4) before a deep negative trough and a fifth positive peak (wave 5) following the trough were the basic components of BAEP in dogs, which were easily identified regardless of recording conditions such as electrode configuration and click polarity. Additional peaks tended to be present when a noncephalic reference electrode and/or single-polarity (rarefaction or condensation) click stimuli were used. The Roman nomenclature for the individual positive peaks of BAEP in dogs is confused owing to variations in the observed waveforms among researchers, but click polarity and/or reference electrode position can explain all the previously reported variations in BAEP waveforms in dogs. When the criteria concerning wave V in the guidelines of BAEP in human beings are applied to avoid further confusion of Roman nomenclature in dogs, it is recommended that the basic five positive peaks (waves 1, 2, 3, 4 and 5 as identified easily with Ai-Vertex configuration and alternating clicks) are designated as waves I, II, III, V and VI, respectively. Wave IV (wave 3b) occurs occasionally before wave V in dogs.Abbreviations BAEP brainstem auditory evoked potentials - dBHL dB hearing level - IPL interpeak latency - Ai the caudodorsal end of the zygomatic arch ipsilateral to the stimulated ear - Nape the neck over the spinous process of the fourth cervical vertebra  相似文献