Inherent differences in response of douglas fir families to nitrogen and phosphorus supply levels     

R. van den Driessche  Y. A. El-Kassaby 《Water, air, and soil pollution》1990,54(4):657-663

Douglas fir (Pseudotsuga menziessi [Mirb.] Franco) seedlings from a half diallel mating design showed significant family by nutrient interactions when grown in a 3N × 3P × 15 family factorial experiment for 2 yr. Differences in response of these families to N and P treatment levels were related to nutrient productivity (dry matter production nutrient⁻¹ time⁻¹), but unrelated to the proportion of dry matter allocated to root growth, or to nutrient net uptake rate. Significance of general combining ability for N and K productivity showed clonal control of these characters. Evidence for genetic control of tissue N% and K%, shoot:root ratio and N uptake rate were also shown.  相似文献   

Incorporation of glucose-14C and NH4 + in microbial biomass of alkaline saline soil     

E. Ramírez-Fuentes  M. Luna-Guido  A. Ponce-Mendoza  E. Van den Broeck  L. Dendooven 《Biology and Fertility of Soils》2002,36(4):269-275

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Tentative assignment of the potato serine protease inhibitor group as beta-II proteins based on their spectroscopic characteristics     

Pouvreau L  Gruppen H  van Koningsveld GA  van den Broek LA  Voragen AG 《Journal of agricultural and food chemistry》2004,52(25):7704-7710

Potato serine protease inhibitor (PSPI) is the most abundant protease inhibitor group in potato tuber. The investigated PSPI isoforms have a highly similar structure at both the secondary and the tertiary level. From the results described, PSPI is classified as a beta-II protein based on (1) the presence in the near-UV spectra of sharp peaks, indicating a rigid and compact protein; (2) the sharp transition from the native to the unfolded state upon heating (only 6 degrees C) monitored by a circular dichroism signal at 222 nm; and (3) the similarity in secondary structure to soybean trypsin inhibitor, a known beta-II protein, as indicated by a similar far-UV CD spectrum and a similar amide I band in the IR spectrum. The conformation of PSPI was shown also to be stable at ambient temperature in the pH range 4-7.5. Upon lowering the pH to 3.0, some minor changes in the protein core occur, as observed from the increase of the intensity of the phenylalanine peak in the near-UV CD spectrum.  相似文献   

A subsoil compaction database: its development, structure and content     

A. Trautner  J. J. H. van den Akker  H. Fleige  J. Arvidsson  R. Horn 《Soil & Tillage Research》2003,73(1-2):9-13

A database which holds results of field and laboratory experiments on the impact of subsoil compaction on physical and mechanical soil parameters and on crop yields and environmental impact is being developed within the EU sponsored concerted action (CA) project “Experiences with the impact of subsoil compaction on soil, crop growth and environment and ways to prevent subsoil compaction”. The database accumulates and can provide all available data from the participants of the European Union countries, and is compatible with the European Soil Database and other related databases.

More than 600 sets of data (Excel workbooks) from participants from the European Union, plus Poland, Switzerland and Norway are included in the database. Through a similar EU sponsored CA, Eastern European countries are expected to deliver 260 sets of data thus bringing the total number of Excel workbooks to approximately 860. In total, the database will contain approximately 13,500 data spreadsheets.

The objective of the database is to collect data on subsoil compaction, to store it in a structured format and to make it available for analysis and use. Thereby it will enable elucidation of the impact of subsoil compaction on soil properties, crop yields and environment and evaluate the vulnerability of soils to compaction.  相似文献   

Erratum     

W Van den Broeck  M D'haeseleer  M Coryn  P Simoens 《Reproduction in domestic animals》2002,37(5):314-320

This study describes the localization of progesterone receptors (PR) in the bovine ovary. Ovaries were obtained from 11 non‐pregnant and two pregnant cows. Progesterone receptors were visualized by immunohistochemistry on paraffin sections. Nuclear staining for PR was observed in cells of the follicles, corpora lutea, theca layers, surface epithelium, tunica albuginea, and in superficial and deep stroma cells. No staining was noticed in apoptotic bodies of atretic follicles. Expression of PR in follicle cells indicates an intrafollicular role of progesterone. The higher expression in thecal cells compared with follicle cells indicates that thecal cells mediate some effects of progesterone on the follicular development. Superficial stroma cells showing high expression might have a similar influence on primordial and primary follicles. In general, luteal cells had a lower expression than follicle cells, which may be explained by the down‐regulatory effect of locally produced progesterone. The lower expression in luteal cells during pregnancy can be due to the longer life span of this corpus luteum and concomitant degeneration of its PR. The high and rather constant expression of PR in cells of the surface epithelium remains to be elucidated.  相似文献   

Predator-prey interactions in continuous culture     

van den Ende P 《Science (New York, N.Y.)》1973,181(4099):562-564

The exploitation of a bacterial food supply by a protozoan predator does not necessarily lead to the extinction of either species. Even a "homogeneous" experimental system contains sufficient heterogeneity (the boundaries) for avoidance strategies to evolve, which allow the populations to presist.  相似文献   

Assessment of glomerular filtration rate in dogs with renal insufficiency: analysis of the 51Cr-EDTA clearance and its relation to the plasma concentrations of urea and creatinine     

W J Biewenga  W E van den Brom 《Research in veterinary science》1981,30(2):158-160

The glomerular filtration rate (GFR) was determined with the single injection 51Cr-EDTA clearance in 48 dogs with renal disease and the results were compared with the plasma Creatinine (PC) and plasma urea (PU) levels. The superiority of PC values over PU values for the assessment of the GFR is represented by the power functions PC = 78.2 CR(-0.67) mmol per litre and PU = 10.3 Cr(-0.52) mmol per litre, in which Cr is the relative glomerular filtration rate. The higher correlation between PC and Cr (r = 0.834) than between PU and Cr (r = 0.693) also demonstrates this superiority. An extended two compartment analysis of the 51Cr-EDTA plasma disappearance curve is not essential for diagnostic purposes.  相似文献   

Experimental induction of fasting hypoglycaemia and fatty liver syndrome in three Yorkshire terrier pups     

A J van Toor  J S van der Linde-Sipman  T S van den Ingh  T Wensing  J A Mol 《The Veterinary quarterly》1991,13(1):16-23

Eight hours fasting in Yorkshire terrier pups resulted in marked variation of blood glucose, showing both hypo- en hyperglycaemia. Prolonged fasting in three Yorkshire terrier pups resulted in hypoglycaemia with concomitant ketosis and steatosis of the liver. The hypoglycaemia was associated with decreasing insulin and increasing glucagon and cortisol levels. This is in contrast to fasting adult dogs, which maintain glucohomeostasis and show only slightly decreased insulin levels, normal glucagon levels and a moderate increase of plasma ketone bodies. The reaction to an eight hour fasting period in the Yorkshire terrier pups is thought to be related to inadequate gluconeogenesis and diminished insulin production and/or release. The different reaction to prolonged fasting, compared to adult dogs and pups of larger breeds, seems related to inadequate gluconeogenesis and results in hypoglycaemia, a ketogenic hormonal setting and steatosis of the liver. Frequent feeding of a high-energy, protein-rich diet to both mother and pups may prevent toy-breed pups from developing hypoglycaemia and may help them to overcome periods with a decreased intake of energy.  相似文献   

Influence of androgens on the genital tract of cyclic heifers     

M J Groot  J M den Hartog  E Gruys 《The Veterinary quarterly》1989,11(4):198-209

Cyclic heifers were implanted with the synthetic androgen trenbolone acetate (TBA = 17 beta-hydroxy-19-norandrosta-4, 9, 11-trien-3-on-17 beta-acetate, C2OH2403) (for formulas see Fig. 1). The influence of this androgen on the macroscopic and microscopic morphology of the genital tract was studied. The most striking result was the induction of polycystic ovaries. The clitoris was markedly enlarged and the cervix showed an increased amount of mucus. Microscopically, extensive folding of the cervical epithelium, consisting of tall swollen columnar cells with basal nuclei was seen. The vagina showed an increase of PAS-positive granules in the superficial layer of the epithelium, while there was no increase in the height of the epithelium. These effects are due to androgenic influence on the female genital tract and are in no case specific to one particular product. They could be of help in the detection of the illegal use of agents with androgenic activity.  相似文献   

Role of navicular bone shape in the pathogenesis of navicular disease: a radiological study     

K. J. DIK  J. van den BROEK 《Equine veterinary journal》1995,27(5):390-393

From progeny lists of 30 Dutch Warmblood sires, 586 3-year-old females by these stallions were randomly selected, each progeny group aimed at 20 animals for statistical reasons. The front feet of the sires and female progeny were examined radiographically using lateromedial and dorsopalmar upright pedal projections. The radiological features associated with navicular disease were classified 0–4 using a standardised classification, grades 3 and 4 representing the more severe changes. The shape of the proximal articular border of the navicular bone outlined on the dorsopalmar view was classified 1–4: l=concave; 2=undulating; 3=straight; 4=convex. A significant shape-grade association was found, the highest grades 3 and 4 incidence associated with shape 1 and the lowest grades 3 and 4 incidence demonstrated by shape 4. In shapes 1 and 2, navicular bones grades 3 and 4 features were mainly characterised by inverted flask-shaped channels. In shape 3, navicular bones grades 3 and 4 were dominated by enthesiophytes. These findings indicate an apparent shape predisposition to radiological changes associated with navicular disease. The shape of the navicular bone in the offspring was on average the same as the sire, indicating an hereditary element in navicular bone shape.  相似文献