Ecological theories and Dutch nature conservation

This paper aims to achieve insight into various ecological theories in the Netherlands which have different, and sometimes opposing, views on the conservation of nature. Interviews, publications and archival research brought to light four separate theories: vitalistic/holistic, dynamic, cybernetic and chaos. Diversity is reached through stability according to vitalistic/holistic and cybernetic theories, but through change and instablility according to the dynamic and chaos theories. These two groups are working apart, and continue to have their own ideas. Prediction of the future is only possible with the vitalistic/holistic and cybernetic theories. Ecologists who adhere to these theories feel responsible and able in different ways to change ecological nature towards desirable end goals. The other two theories, dynamic and chaos, appear to be less activist.     

Evaluation of an exotic maize population adapted to a locality

Summary An exotic Zea mays L. population (Tuxpeno) was adapted to North Carolina conditions by first introducing genes for adaptability from two North Carolina varieties ([(Jarvis X Indian Chief)Tuxpeno]Tuxpeno) including four generations of intermating, and then selecting for adaptability using maturity as the primary measure. The study evaluated selection for adaptability and the diversity available between adapted Tuxpeno and the local varieties, Jarvis and Indian Chief. Analytical procedures were developed to quantify the diversity between populations and the complementation of local varieties by introduced germ plasms. The analyses utilized the specific effects available from the diallel mating design.Three replicate selections responded similarly under simple recurrent mass selection (1/10) for the earliest disease-free plants initially and additionally for plant types (primarily height) in the final generation. The 1/4 local germ plasm permitted rapid adaptation of Tuxpeno gene pool to local conditions. The adapted Tuxpeno populations yielded similarly to the local populations with an average heterosis for grain yield of 28% when crossed to the local populations used as source of genes for adaptability. The diversity found between adapted Tuxpeno lines and these local varieties based on genes affecting grain yield was 1.5 to 2.5 times that measured between the local varieties (Jarvis and Indian Chief). Diversity lost through intergradation with local material was a reasonable investment. Yield genes introduced from Tuxpeno complemented local gene pools through nonadditive, primarily dominance-associated, gene effects. Reassortment of major gene blocks apparently occurred leading to significant divergence among replicate selections involving both additive-associated and dominance-associated gene effects.Paper No. 6355 of the North Carolina Agri. Res. Ser., Raleigh, NC. Research supported in collaboration with the Rockefeller Foundation and CIMMYT, D.F. (Mexico)     

Factors influencing the isotopically exchangeable phosphate in soils

Summary The labile phosphate in a non-calcareous and a slightly calcareous soil was determined by isotopic exchange in the presence and absence of 0.001 molar solutions of a chelating and a non-chelating organic anion. The rate of isotopic exchange curves were analyzed graphically to sub-divide the labile phosphate into 3 or 4 fractions. The half-lives of exchange for the rapid, medium and slow fractions were between 0.3 to 1.6 hours, 1.8 to 8.6 hours and 25.8 to 46.1 hours respectively. In addition, an instantaneously-exchanging component was sometimes observed.In the presence of the citrate ion, the total labile phosphate was increased in the non-calcareous soil and decreased in the calcareous soil, whereas the diethyl barbiturate ion (DEB) anions decreased the total labile phosphate in both soils. In general, the citrate ion increased the rapid and the medium fractions whereas the DEB anion either did not affect them or decreased them. Again, whereas citrate always increased the phosphate in solution, the effect of DEB anions depended on the soil. The major effect of the organic anions was to greatly decrease the slowly-exchanging fraction in both soils.The half-lives of exchange for the rapid, medium and slow fractions were in the order no organic anion > citrate > barbiturate and the rate constants for a first-order mechanism were in the order no organic anion < barbiturate < citrate.Small but significant differences were observed between the two soils.     

Genetic diversity in relation to heterosis and combining ability in spring wheat

Summary Genetic diversity among ten varieties of spring wheat used as parents in a diallel cross was assessed through multivariate analysis (D²-statistics) and then related to heterosis and SCA effects of their hybrids. The parents fell into three groups. Group I contained the varieties, Nobre, Girua and Carazinho; group II contained Sonalika, Lyallpur and Pitic 62 and group III contained Indus 66, Balaka, Sonora 64rs and MSl. The varieties of group I were good general combiners, while the varieties of group III were poor combiners. Significant heterotic and SCA effects for yield and yield components were observed in the hybrids of the parents belonging to different groups but not in the same group. Genetic divergence between the parents had a positive relationship with heterosis and SCA effects of the hybrids.     

Variation in the karyotype of three cultivars of Narcissus tazetta L. (Amaryllidaceae)

Three cultivated varieties of Narcissus tazetta, Grand Soleil d'Or, Chinese Sacred Lily and Cypri, are triploid (2n = 3x+30) with the basic number 10. Grand Soleil d'Or has three homomorphic sets, each comprising 2 long submetacentrics, 4 long acrocentrics and 4 short acrocentrics. Karyotypes of the other two varieties are heteromorphic. Both possess one telocentric satellited chromosome. In addition, Cypri shows translocation between two chromosomes belonging to the seventh and eighth triplets. The number of secondary constrictions varies between 3 (Chinese Sacred Lily) and 4 (Grand Soleil d'Or and Cypri) which is also the number of nucleoli observed in the respective varieties.     

Molecular mapping of a new gene Rrs4 CI 11549 for resistance to barley scald (Rhynchosporium secalis)

Doubled haploid (DH) progeny from a cross between the scald susceptible barley (Hordeum vulgare L.) cultivar Ingrid and the resistant accession CI 11549 (Nigrinudum) was evaluated for resistance in the pathogen Rhynchosporium secalis (Oudem) J.J. Davis. Two linked and incompletely dominant loci confer resistance CI 11549 against isolate 4004. One is an allele at the complex Rrs1 locus on chromosome 3H close to the centromere; the other is located 22 cM distally on the long arm. The latter locus is designated Rrs4. In BC₃-lines into Ingrid from CI 2222 (another Nigrinudum) resistance seems governed by one locus close to the telomeric region of chromosome 7H, probably allelic to Rrs2. In neither case did we find any trace of the recessive gene rh8 reported to be present in Nigrinudum. Various resistance donors of Ethiopian origin designated as Nigrinudum, Jet or Abyssinian were identical to a great extent with respect to markers, but differed in resistance to different isolates of scald or in barley yellow dwarf virus (BYDV) resistance. The implications for their use as differentials in scald tests and screening of germplasm collections are discussed.     

Monitoring watercourse vegetation, a synecological approach to dynamic gradients

Changes in vegetation under reduced control measures over 3 to 5 years in watercourses in a rural environment in The Netherlands were evaluated. A method to deal with slow changes on a steep gradient is presented. The gradient with various vegetation types between the middle of the watercourse and the bank-top was split up into zones. Species composition of each zone was evaluated using literature on syntaxonomy. Cover of character species, multiplied by the width of the zones, was used to quantify the contribution of various syntaxa in the vegetation. Changes in these contribution data were used to evaluate changes over the years. The method was applied to two experiments in which cleaning frequency was reduced. Submerged vegetation of Callitriche-Ranunculetum penicillati in one and of Potamogetonetalia pectinati in the other case, hardly changed. Emergent vegetation of Nasturtio-Glycerietalia or Sparganio-Glycerietum fluitans tended to expand into the submerged zone. Bank vegetation began to show signs of development into ruderal vegetation, as a shift from Molinio-Arrhenatheretea into Artemisietea was detected. The method allowed the conclusion that conditions were too eutrophic in both experiments for a diverse brook vegetation development without additional habitat improvement.     

Immunofluorescence localization of the epidermolytic toxin target in mouse epidermal cells and tissue

Summary An epidermolytic toxin target was observed in keratohyalin granules of sectioned epidermis by a direct fluorescence procedure using FTC-toxin, but not by an indirect procedure using sequential reaction with toxin, anti-toxin and FTC-secondary antibody. The investigation of the two procedures was extended to keratinocytes. A dispase digestion procedure yielded three fractions which corresponded to basal, spinous and granular cells according to biochemical and morphological criteria. It was shown that the direct and indirect procedures both detected the toxin target in the keratohyalin granules of granular cells, but that the indirect procedure was very insensitive. In control experiments, the profilaggrin of keratohyalin granules was detected readily in cells by a direct procedure using FTC-antiprofilaggrin but only weakly by an indirect double antibody procedure. Insensitivity to indirect procedures thus appears to be a particular property of the keratohyalin granule site. It was shown that the toxin target was readily accessible in permeable (trypsin-isolated) granular cells but inaccessible in impermeable (dispase-isolated) cells.     

The assignment of a Thinopyrum distichum (Thunb.) Löve-derived translocation to the long arm of wheat chromosome 7D using endopeptidase polymorphisms

Summary Endopeptidase zymograms of the translocation line Indis revealed the presence of several major and minor bands that had differential expression in coleoptile and seed tissues. While Indis lacks Ep-D1a, which is present in the parental cultivar Inia 66, it also may not express any of the Th. distichum bands. The Indis zymogram was found to be identical to that of an isogenic line of Inia 66 possessing Lr19. Since the absence of an Ep-D1a product appears to be linked to the 7DL translocation, it is possible to use the null condition as a marker for both the Lr19 or Indis translocations. The Indis translocation also did not show recombination with the cn-D1 chlorophyl mutant on 7DL, confirming that a part of 7D was involved. The results of a telocentric mapping experiment involving the 7D telosomes indicated that in Indis a chromosome segment from Th. distichum replaced a large section of 7DL of Inia 66.     

Wheat chromosome 2D carries genes controlling the activity of two DNA-degrading enzymes

DNA-degrading enzymes of 24.0 kDa and 27.0 kDa were observed to have different activities in two common wheat (Triticum aestivum L.) cultivars, Wichita and Cheyenne. A substrate-based SDS-PAGE assay revealed that these two enzymes were much more active in Wichita than in Cheyenne. Genes controlling the activities of these two enzymes were localized on chromosome 2D by testing DNA-degrading activities in reciprocal chromosome substitution lines between Wichita and Cheyenne. While the allele on Wichita chromosome 2D stimulated the activities of the 24.0- and 27.0-kDa enzymes in Cheyenne, the allele on Cheyenne chromosome 2D did not reduce the activities of the 24-kDa and 27-kDa enzymes in Wichita. Whether these genes code for the DNA-degrading enzymes themselves or for factors that regulate the enzyme activities remains unknown.This work was supported in part by USDA-Competitive Research Grants Office grant No. 90-37140-5426 to P.S.B. Contribution from Agricultural Research Division, University of Nebraska. Journal Series Number 10304     

Nuclear and cytoplasmic gene control of resistance to loose smut (Ustilago tritici (Pers.) Rostr.) in wheat (Triticum aestivum L.)

Summary Using disomic chromosome substitution lines based on the susceptible wheat cultivar Chinese Spring, loose smut resistance of wheat cultivars Hope and Thatcher was shown to be conferred in each case by a single dominant major gene carried on chromosome 7 A (Hope) or 7 B (Thatcher). Partial resistance was determined by genes on an additional eight Hope or seven Thatcher chromosomes, and similarities were evident between the partial resistance genotypes ofHope and Thatcher. Chinese Spring exhibited a mean infection value of approximately 50%, indicating a significant level of partial resistance, which was found to be due, in part, to genes on the homoeologous chromosome arms 1 As, 1 Es and 1 Ds, and to cytoplasmic genes. Substitution of the Chinese Spring nucleus into the cytoplasm of Aegilops squarrosa, Ae. variabilis or Ae. mutica resulted in increased susceptibility to Ustilago tritici. Several alloplasmic lines of the resistant wheat cultivars Selkirk and Chris exhibited race-specific susceptibility to U. tritici.     

Light and electron microscopic study of adenosine triphosphatase activity of anuran tadpole musculature

Summary The histochemical activities of succinic dehydrogenase (SDH) and Ca⁺⁺-activated ATPase (pHs 7.4 and 9.4) were studied in the larval tail musculature of Rana japonica, Rana catesbeiana and Rana ornativentris. The ATPase reaction product was detected by both light and electron microscopy. Red and white muscle fibres, as distinguished by SDH, showed high and low Ca⁺⁺-ATPase reaction, respectively, at pHs 7.4, 9.4 and following preincubation in cold K₂-EDTA solution. The ultrastructural investigation of CA⁺⁺-ATPase reaction at pH 7.4 by the Ca⁺⁺-citrophosphate technique demonstrated electron-dense reaction product in association with A, I and Z bands, intermyofibrillar (SR) compartment and the mitochondrial inner chamber. However, Pb⁺⁺ precipitation technique demonstrated Mg⁺⁺-activated myosin ATPase activity at pH 9.2 ultrastructurally. The present histochemical data suggest that the anuran larval tail red muscle fibres are possible slow, and emphasize a possible lack of correlation between the speed of contraction with their ATPase activity. Moreover, red muscle fibres of the anuran tail musculature are not equivalent to Type I fibres of higher chordates.     

An explication of ‘wind illness’ in Northern Thailand

Wind illness is a very common complaint among the Northern Thai, yet is rarely recognized by Thai physicians trained in biomedicine. Persons most susceptible to wind illness are adult women who have ever borne a child. Consequently, data were obtained from 415 everparous women, 43% of whom reported ever having had wind illness and 57%, never having had it. In addition, 20 individuals who had ever had the syndrome were followed for case study, and 13 indigenous healers who traditionally treat clients suffering wind illness were interviewed. Their perceptions of the etiology, symptomatology and treatment of wind illness are reported in Part I. Part II is an attempt to define wind illness in terms of biomedicine and as a consequence of fertility. Part III synthesizes the emic and etic accounts with explanations for the perdurance of wind illness despite the advances of biomedicine and the recent fertility decline in Northern Thailand.     

The nutritional status of Picea abies (L.) Karst. across Europe,and implications for ‘forest decline’

Summary During the summer of 1986, three year-classes of foliage were sampled from approximately 30-year-old Norway spruce [Picea abies (L.) Karst.] trees at 12 sites from S. W. Germany to N. Scotland. At sites in Germany, where trees were showing symptoms of decline, samples were taken from trees with good crown condition and poor crown conditon. The distinction between good and poor was made on the basis of international protocols for defining crown density and foliar discoloration. There was a wide range in nutrient content (percent dry weight) in apparently healthy trees. Current year foliage had ranges of mean values per site: S(0.07–0.13%), N(0.9–1.4%), K(0.5–0.9%), Ca(0.2–0.7%), and Mg (0.05–0.1%). Ranges were greater for 2-year-old foliage: S(0.09–0.18%), N(1.0–1.8%), K(0.4–0.7%), Ca(0.2–1.4%), and Mg(0.03–0.09%). At sites with trees having poor crown condition, there were significantly smaller concentrations of Mg and Ca, and larger concentrations of K in 2-year-old foliage from poor trees, compared with adjacent good trees. Ratios of nutrient content were more significantly related to crown condition within sites than individual nutrients, especially in older needles. Poor crowns were associated with larger ratios of NMg, KMg, SMg, KCa and smaller ratios of SK and NK. A risk index is defined for trees showing no visible decline symptoms, based upon nutrient content and nutrient ratios, which may be useful in identifying sites liable to experience deterioration in crown condition.With the exception of one German site, where few poor trees were observed, the index increases from Scottish sites to English sites to Dutch sites to German sites. The index is empirical, and not necessarily related to potential effects of air pollution. The time dependence of foliar nutrient content may also be useful in diagnosis. At sites with trees having poor crown condition, even apparently healthy trees showed a lack of increase in calcium content with needle age, decreases in nitrogen content and very large decreases in magnesium content with needle age. The results show the importance of sampling several year classes of foliage from Norway spruce trees in determining the nutrient status of the tree.     

Comparisons of a new triazole retardant PP 333 with ancymidol and other compounds on pot-grown tulips

PP 333 was compared with ancymidol, CGA 65993, dikegulac-sodium (as Atrinal) and maleic hydrazide for its ability to restrict stem extension in tulip cvs Paul Richter, Apeldoorn and Trance. Single, 300 ml compost drenches were applied one day after housing fully cooled bulbs grown in a sphagnum peat/sand compost (3:1 v/v).Experiments in 1979/1980 and 1980/1981 with mid- and late-season crops showed that PP 333, like ancymidol, could reduce stem extension without deleterious responses. However, higher amounts of PP 333 (0.8–33.3 mg a.i./pot) were required than of ancymidol (0.625–2.5 mg a.i./pot). Cv. Paul Richter was much less responsive to PP 333 and ancymidol than Apeldoorn, particularly when grown as a late-season crop. Dikegulac was the most effective chemical in the latter situation, especially as it restricted post-flowering extension growth. PP 333 and ancymidol were better able to control such growth in the mid-season crops. Other than for the above purpose, dikegulac proved unsuitable because it increased flower bud blasting and gave rise to abnormally coloured perianth segments. Similarly, marked reductions in stem length of Apeldoorn and Paul Richter with CGA 65993 were associated with unacceptable side-effects, namely, smaller flowers (both cvs) and more bud blasting in Apeldoorn. Maleic hydrazide (5–500 mg a.i./pot) had little influence on stem length in any of the three cultivars.The trials indicated the need to test each cultivar/retardant combination, as well as to take into account the time of forcing because, whereas Paul Richter and Apeldoorn were adequately dwarfed by PP 333 and ancymidol without adverse effects, both compounds caused about 50% of Trance flowers to blast. No treatment influenced flowering date in cv. Paul Richter but PP 333 delayed flowering by two days in Apeldoorn and Trance, as did the higher doses of ancymidol in Apeldoorn.     

Possible chromosomal location of genes determining the osmoregulation of wheat

Summary Stress-induced free amino acid accumulation in the presence of 0.7 M mannitol has been compared in tissue cultures of moderately stress-tolerant Chinese Spring and stress-sensitive Cappelle Desprez cultivars and in disomic chromosome substitution lines of Cappelle Desprez into Chinese Spring. The profile of amino acid accumulation was different in the two parents. The amino acid concentration of the substitution lines belonging to the A, B and D genomes, respectively, altered characteristically under stress condition. The Cappelle Desprez chromosomes associated with non-ionic osmotic stress-induced free amino acid accumulation were 5A and 5D.     

Diallel analysis of submergence tolerance in rice,Oryza sativa L.

Summary The genetics of submergence tolerance in rice was studied in a 10 × 10 half-diallel cross set involving 10 lowland rice varieties, four of which were tolerant (FR13A, FR43B, Kurkaruppan, and Goda Heenati) and the remaining six were nontolerant (RD19, IR42, IR17494-32-1, IR19672-24-3, Jagannath, and CR1009). Estimates of genetic parameters following Hayman's method showed significant additive and nonadditive gene action and the latter appeared to be solely due to dominance. Narrow sense heritability (0.70) indicated that additive gene effects were more important in the inheritance of the trait. Tolerance was dominant over nontolerance and the average dominance was within the range of incomplete dominance. Dominant alleles were more concentrated in the three tolerant parents, FR13A, Kurkaruppan, and FR43B in that order. Wr/Vr graphic analysis suggested the involvement of both major and minor genes. Combining ability analysis by Griffing's method also indicated significance of both additive and nonadditive effects, and the former appeared to be more important than the latter. The hybrids involving FR13A with RD19, IR42, and IR17494-32-1, and those of Kurkaruppan with RD19 and CR1009 appeared to be promising for incorporating an adequate level of tolerance to submergence into lowland rice cultivars.     

Regulation of guanylate cyclase activity by atrial natriuretic factor and protein kinase C

Summary The putative second messenger of certain atrial natriuretic factor (ANF) signal transductions is cyclic GMP. Recently, we purified a 180-kDa protein, apparently containing both ANF receptor and guanylate cyclase activities, and hypothesized that this is one of the cyclic GMP transmembrane signal transducers. The enzyme is ubiquitous and appears to be conserved. Utilizing the 180-kDa membrane guanylate cyclase, we now show that the 180-kDa guanylate cyclase is regulated in opposing fashions by two receptor signals—ANF stimulating it and protein kinase C inhibiting it. Furthermore, protein kinase C phosphorylates the 180-kDa enzyme. This suggests a novel switch on and switch off mechanism of the cyclic GMP signal transduction. Switch off represents the phosphorylation while switch on the dephosphorylation of the enzyme.     

Genetic analysis of certain in vitro and in vivo parameters in pigeonpea (Cajanus cajan L.)

Summary Studies on callus growth and shoots/cotyledon, using seven different genotypes of pigeonpea and their hybrid progenies, revealed continuous variation for these traits. Hence, the type of gene action influencing in vitro cell proliferation and differentiation has been investigated in a diallel analysis of seven pigeonpea genotypes. Highly significant average heterosis was recorded for callus growth and seed yield/plant. In general, the F₁ hybrids which showed heterosis for callus growth also exceeded their better parent for yield/ plant. Combining ability analysis revealed both additive and non-additive gene effects for callus growth, while number of shoots/cotyledon was mostly governed by non-additive gene effects. The genotype, ICP 7035, was the best general combiner for callus growth and shoot forming capacity of cotyledons. Two cross combinations, 7186×6974 and 7035×T-21, showed maximum SCA effects for callus growth and shoots/cotyledon. Callus dry weight was positively correlated with seed yield/plant and seedling weight. The strong positive association of callus growth with seed yield indicates the possibility of using this system for mass screening and selection of superior hybrids.     

Genetic analysis of brown planthopper resistance in twenty varieties of rice,Oryza saliva L.

Summary The inheritance of resistance to brown planthopper, Nilaparvata lugens (Stol.), of 20 rice cultivars was studied. Single dominant genes that are allelic to Bph 3 condition the resistance in cultivars Ptb 19, Gangala (Acc. 7733), Gangala (Acc. 15207), Horana Mawee, Kuruhondarwala, Mudu Kiriyal and Muthumanikam. Single recessive genes that are allelic to bph 4 govern the resistance in cultivars Gambada Samba, Heenhoranamawee, Hotel Samba, Kahata Samba, Kalukuruwee, Lekam Samba, Senawee, Sulai, Thirissa and Vellai Illankali. The resistance in Ptb 33, Sudu Hondarwala, and Sinna Sivappu is governed by one dominant and one recessive gene which segregate independently of each other. The dominant resistance genes in these cultivars appear allelic to either Bph 1 or Bph 3. Similarly, the recessive genes in these cultivars seem allelic to either bph 2 or bph 4. Further investigations are needed to conclusively determine the allelic relationships of resistance genes in Ptb 33, Sudu Hondarwala and Sinna Sivappu.