Levels of genetic diversity at different stages of the domestication cycle of interior spruce in British Columbia

Concerns over the reductionist nature of the domestication of forest-tree species focus on the possibility of potential genetic erosion during this process. To address these concerns, genetic diversity assessments in a breeding zone the Province of British Columbia “interior” spruce (Picea glauca×engelmanni) program was conducted using allozyme markers. Genetic-variation comparisons were made between natural and production (seed orchard) populations as well as seed and seedling crops produced from the same breeding zone’s seed orchard. The natural population sample consisted of a total of 360 trees representing three stands within each of three watersheds present in the Shuswap-Adams low-elevation zone of interior British Columbia. Small amounts of genetic differentiation were observed among the nine natural populations (4%) and this was attributable to extensive gene flow Consequently, the sum of these nine populations was considered as a baseline for the genetic variation present in the breeding zone. The comparisons between the seed orchard and the breeding zone produced a similar percentage of polymorphic loci while the expected hetrozygosity (0.207 vs 0.210) and the average number of alleles per locus (2.7 vs 2.4) were slightly lower in the seed orchard. A total of seven natural populations’ rare alleles were not present in the orchard population, while one allele was unique to the orchard. The %P increased to 70.6% in the seedlot, but dropped to the natural populations level (64.7%) in the plantation. The observed increase in %P was a result of pollen contamination in the orchard. It is suspected that the reduction in the plantation was caused by an unintentional selection in the nursery. Simulated roguing in the orchard did not drastically reduce even if up to 50% of the orchard’s clones were rogued. However, roguing was associated with a reduction in the average number of alleles per locus (i.e., sampling effect). Received: 2 January 1996 / Accepted: 24 May 1996     

The formation of flavonoids in cell suspension cultures ofPrunus x yedoensis matsum

Two lines of the red and pale yellow cell suspension cultures, prepared fromPrunus x yedoensis Matsum. callus induced by Murashige and Skoog's (1962) basal medium supplemented with 2, 4-dichlorophenoxyacetic acid (2, 4-D, 1.0 mg/l), kinetin (0.1 mg/l) and sucrose (30 g/l), were maintained on Schenk and Hildebrandt medium as modified by Mitchell and Gildow (1975). The red cell suspension culture produced cyanidin 3-monoglucoside, 5, 4′-dihydroxy-7-methoxyisoflavone 4′-glucoside (prunetrin), isoquercitrin, catechin, epicatechin, and procyanidin B-1, B-2, B-3 and B-4, while the pale yellow cells produced only a small amount of catechin and epicatechin as main flavonoids. These flavonoid compounds found in the red cell culture were present also in maturePrunus leaves. Maximum growth and maximum amount of total phenol and proanthocyanidin (procyanidins) were obtained with 0.3 mg/l of both 2,4-D and kinetin. Maximum concentration of anthocyanin was also obtained with 0.3 mg/l 2, 4-D regardless of kinetin concentration. Accumulation of proanthocyanidin was markedly stimulated by low concentrations of phosphate, which reduced growth by about half, and also by high concentrations of inorganic nitrogen. Production of both anthocyanin and proanthocyanidin was reduced by lowered nitrogen levels. Cell growth and production of all phenolics were inhibited when ammonium ion replaced nitrate in the medium.     

Nutrients and mass in litter and top soil of ten tropical tree plantations

The importance of litter to nutrient and organic matter storage and the possible influence of species selection on soil fertility in ten stands each consisting of a separate tree species were examined in this study. The plantations had been grown under similar conditions in an arboretum in the Luquillo Experimental Forest, Puerto Rico. The species involved were: Anthocephalus chinensis, Eucalyptus × patentinervis, E. saligna, Hernandia sonora, Hibiscus elatus, Khaya nyasica, Pinus caribaea var. hondurensis, P. elliottii var. densa, Swietenia macrophylla, and Terminalia ivorensis. After 26 yr, litter mass ranged from 5 mg ha^-1 in the H. sonora stand to 27.2 Mg ha^-1 in the P. caribaea stand. Nutrients in the litter (N, P, K, Ca, and Mg) also varied widely, but stands were ranked in different order when ranked by nutrients in the litter than then ranked according to accumulation of mass. Only E. saligna and A. chinensis stands were ranked similarly in accumulation of both nutrients and mass, and the stand of H. elatus was ranked higher with respect to nutrient accumulation than to accumulation of mass. The nutrient concentration in standing leaf litter generally increased in the order of recently fallen <old intact< fragmented. Nutrient concentration of standing leaf litter appears to increase with age and depth in the litter layer. The amount of nutrients stored in the litter compartment of these plantations was in the same order of magnitude as the quantity of available nutrients in the top 10-cm of mineral soil. Total litter mass was negatively correlated with the mass-weighted concentration of N, K, and Mg. The same relationship was found for Ca in the leaf litter and N in the fine wood litter compartments. In some stands (notably P. caribaea, P. elliottii, and E. saligna), leaf litter derived from species other than the species planted in that particular stand had higher nutrient concentration than leaf litter from the planted species. Soils of the 10 stands were classified in the same soil series and had similar texture (clay soils). However, significantly different chemical characteristics were found. Results obtained by analysis of covariance and by limiting comparisons to adjacent stands with similar soil texture, indicate that different species have had different influences on the concentration of available nutrients in soil.     

Tri-Calciphor (16,16-dimethyl-15-dehydroprostagalndin B1 trimer)-mediated mitochondrial Ca2+ movements: modulation by phosphate

The trimeric derivative of 16,16-dimethyl-15-dehydroprostaglandin B₁ (termed tri-Calciphor), which protects tissues against ischemic damage, induced Ca²⁺ efflux and swelling in mitochondria in the absence of phosphate, Mg²⁺ and ATP. When glutamate/malate rather than succinate was the substrate, higher tri-Calciphor concentrations were required for the ionophoretic activity. Ca²⁺ efflux and mitochondrial swelling induced by tri-Calciphor were completely inhibited by ATP, phopsphate and Mg²⁺ added together, and partially inhibited with phosphate plus either ATP or Mg²⁺. Between 0 and 7 μM added Ca²⁺ and in the presence of phosphate, ATP and Mg²⁺, tri-Calciphor stimulated the uptake of Ca²⁺ by mitochondria and increased the efficiency of buffering of extramitochondrial Ca²⁺. Thus depending on the assay conditions, two different effects involving Ca²⁺ movements and mitochondria are observed with tri-Calciphor.     

Modulation of platelet responsiveness through selective phosphorylation of plasma membrane proteins: Antagonistic eeffects of cyclic AMP and cyclic GMP

³²P phosphorylation of plasma membranes from human blood platelets, under conditions that closely resemble physiological ones (endogeneous phosphate donors and intact platelets in homologous plasma), result in the incorporation of the label mainly in a membrane glycoprotein of apparently high molecular weight (greater than 400 000). Dibutyryl cyclic AMP, an inhibitor of platelet aggregation, specifically increases the degree of phosphorylation of this glycoprotein. Moreover, it has been found that prostaglandin E₁ one of the most potent inhibitors of platelet aggregation which also increases phosphorylation of the same glycoprotein, is significantly more effective than cyclic AMP.Cyclic GMP does not have any apparent effect on platelet aggregation. However, incubation of platelet-rich plasma with both cyclic GMP and cyclic AMP results in a partial recovery of the platelet responsiveness towards ADP-induced aggregation. Coincidently, the degree of phosphorylation of the high molecular weight glycoprotein under these conditions, although still higher than in controls (no nucleotides added), is significantly decreased as compared with cyclic AMP-treated cells. Furthermore, cyclic GMP inhibits the cyclic AMP-dependent protein kinase activity in isolated platelet plasma membranes.These results suggest a central role for this membrane phosphoglycoprotein in the triggering of platelet aggregation and, furthermore, suggest that modulation of its degree of phosphorylation may be exerted through some cyclic AMP/cyclic GMP relationship, which in the basal state might be critical for platelet responsiveness.     

Rat and human embryo and post-natal sera contain a potent endogenous competitor of estrogen-rat alpha-fetoprotein interactions

A highly active inhibitor of the binding of estrone and estradiol-17β to rat alpha-fetoprotein is demonstrated for the first time in embryo, immature and adult rat sera as well as in fetal and adult human sera. The competitive character and the narrow specificity of this inhibition effect is shown. The major compound responsible for this activity is isolated by successive column Sephadex LH₂₀ and thin layer chromatography : it is characterized as a nonpolar, nonphenolic, dialysable and thermostable substance, unreactive towards anti-estrone and anti-estradiol-17β anti-bodies. The possible biological role of an endogenous non-estrogen ligand of rodent fetoproteins is discussed.     

九连山常绿阔叶林乔木优势种群的种间关联性分析

九连山国家级自然保护区分布着原生的典型常绿阔叶林, 且已形成不同的优势群落, 目前尚不清楚群落乔木层中优势物种之间的作用关系。采用2×2联列表, 通过方差分析, χ²检验、Pearson相关系数和Spearman秩相关系数检验, 对九连山常绿阔叶林乔木层中重要值较高的28个优势种群、378个种对间的关联性进行定量研究。方差分析表明: 28个优势种群的总体种间关联性呈显著的正关联, 反映该群落处于较稳定的顶极阶段。不同检验结果表明: χ²检验结果有140个种对呈正相关, 238个种对呈负相关, 正负关联比为0.588; Pearson相关系数检验有104个种对呈正相关, 274个种对呈负相关, 正负关联比为0.380; Spearman秩相关系数检验有144个种对呈正相关, 234个种对呈负相关, 正负关联比为0.615; 与Pearson相关系数检验方法相比, Spearman秩相关系数检验具有较高的灵敏度。378个种对中, 绝大多数种对的联结关系未达到显著水平, 种对间的独立性相对较强, 这种种间联结的松散性可能与群落目前的发展阶段及物种本身的生态学特性有关, 各群落正处于稳定的顶极阶段。根据28个优势种群对环境的适应方式和主导生态因素, 可将它们划分为阳生植物和阴生植物两大生态种组。     

植物激素对草莓叶片不定芽形成的影响

用试管内生长的草莓幼嫩叶片作外植体,培养在MS基本培养基上附加1.5—2.5毫克/升6—BA和0.1毫克/升NAA,可直接诱导成不定芽,诱导率可达20%。如果不定芽继代培养在同样浓度的培养基上,继而可形成大量的丛生芽。能使叶外植体形成不定芽的植物激素组合而不能使其愈伤组织分化成芽。IAA与6—BA的不同浓度组合对不定芽形成效果不明显。