Metabolism of tritiated and deuterated gibberellins A1, A4 and A9 in Sitka spruce (Picea sitchensis) shoots during the period of cone-bud differentiation

A mixture of tritiated and deuterated gibberellins (GAs) was injected into elongating shoots of Sitka spruce [ Picea sitchensis (Bong.) Carr.] grafts grown under environmental conditions that were either inductive (heat and drought, HD) or non-inductive (cool and wet, CW) for flowering. The metabolites were purified by high performance liquid chromatography (HPLC), detected by liquid scintillation counting of aliquots of collected fractions and identified by gas chromatography–mass spectrometry (GC-MS). Deuterated GA₉ was converted to deuterated GA₄, deuterated GA₃₄, and deuterated GA₁ in both treatments. Deuterated GA₄ was metabolized to deuterated GA₃₄ and deuterated GA₁ in the CW material, but only deuterated GA₁ was detected in the HD material. The amount of detected metabolites was higher in the HD material, caused by a higher rate of metabolism and/or smaller losses of the metabolites during sample purification. GA₁ was converted to a polar unidentified metabolite in both treatments, but to a higher degree in the CW treatment.     

Effectiveness of prostagland in F2α in restoration of HMG-HCG induced ovulation in indomethacin-treated rhesus monkeys

Six mature female rhesus monkeys were treated with HMG-HCG in control cycles at doses adjusted to induce ovulation while avoiding superovulation. Occurrence of ovulation was determined by observation of fresh ovulation points at laparotomy 48 to 120 hours following HCG. In subsequent cycles animals were treated with indomethacin (treatment days 4 through 10) together with the established dose of HMG-HCG. In 8 cycles indomethacin 5 mg/kg was given i.m. once daily; in 9 cycles 10 mg/kg i.m. was administered in 2 divided doses. Following this, PGF₂α (3 mg t.i.d. s.c.) was administered for 3 days together with indomethacin 10 mg/kg and HMG-HCG, beginning on the day prior to HCG. Determinations of progesterone were performed by RIA on treatment days 4, 7, 10, and 11. Eleven of the 13 control cycles were ovulatory. With indomethacin 5 mg/kg/day, 5 of 8 cycles were ovulatory but ovulation was delayed in 2 instances. Of 9 cycles using indomethacin 10 mg/kg/day only 1 was ovulatory. When PGF₂α was administered in subsequent cycles along with indomethacin (10 mg/kg) and HMG-HCG, ovulation occurred in 13 of 19 cycles. These data suggest that local ovarian PGF₂α may be essential in the mechanics of follicle rupture in gonadotropin-treated rhesus monkeys.     

Phospholipid modulation of low-Km cyclic AMP phosphodiesterase activity on rat adipocyte microsomes

The ability of nine phospholipids to alter the activity of low-Km cyclic AMP phosphodiesterase was examined in microsomal fractions of rat adipocytes. The enzyme was activated by phosphatidylserine (21% at 300 microM) and phosphatidylglycerol (36% at 300 microM). The activation was concentration dependent over the range 1-1000 microM. Six other phospholipids were without effect. Phosphatidylinositol 4-phosphate inhibited the activity of the enzyme over the same range of concentrations (26% at 300 microM). Phosphatidylserine also activated a partially purified preparation of the enzyme, whereas phosphatidylinositol 4-phosphate was ineffective. The mechanism of the activation of the enzyme by phosphatidylserine and phosphatidylglycerol involved an increase in the apparent Vmax of the enzyme, while the inhibition by phosphatidylinositol 4-phosphate was associated with an increase in the Km of the enzyme for substrate. The phospholipid modulators of low-Km cyclic AMP phosphodiesterase activity did not alter the activity of high-Km cyclic AMP phosphodiesterase. The ability of phospholipids to alter the activity of low-Km cyclic AMP phosphodiesterase in native membranes suggests a possible role for phospholipids in metabolic regulation.     

Modelling root structure and stability

Summary Seven fully excavated 16 year-old root systems of Sitka spruce were analysed. All roots in excess of 1 cm diameter at their origin on the stumps were analysed, data being collected until root diameter declined to less than 0.5 cm.Root morphology and distribution was identified as a balance between systematic biological mechanisms and their disruption by environmental factors, particularly changes of soil density and soil surface contours. The biological mechanisms have been modelled and the model is capable of simulating root systems in response to a few simple input variablese.g. the number of roots originating at stumps, stem ratius, total number of roots of all ordersetc.Additionally equations have been developed to estimate the distribution of root diameter, and root weight at all distances from tree stems and a similar equation permits the estimation of tree diameter at chosen heights. These latter estimates being utilized to calculate the turning moment of stems when blown by the wind.The influence of the wind on turning moment is explored for simulated root systems of differing strength and gross morphology.     

Electrophoretic techniques for detection of Glypta fumiferanae, an endoparasitoid of western spruce budworm

Parasitoid-free western spruce budworms and western spruce budworm larvae containing the endoparasitoid Glypta fumiferanae (Vier.) (Hymenoptera: Ichneumonidae) were assayed electrophoretically to identify isozyme bands diagnostic for the parasitoid. Bands characteristic of G. fumiferanae were observed with 4 of 15 enzymes tested. These were aconitase, esterase, leucine aminopeptidase and 6-phosphoglucose dehydrogenase. Presence of these isozyme bands is a reliable indication of parasitism by G. fumiferanae. The efficiency of electrophoresis as a tool for routine detection of parasitoids is discussed.

---

Zusammenfassung Raupen von Choristoneura occidentalis ohne und mit dem Endoparasitoiden Glypta fumiferanae (Vier.) (Hymenoptera: Ichneumonidae) wurden elektrophoretisch auf Isoenzymbänder untersucht zum Nachweis des Parasitoiden. Für G. fumiferanae typische Bänder wurden in 4 der untersuchten 15 Enzymen beobachtet. Dies waren Aconitase, Esterase, Leucinaminopeptidase und 6-Phosphoglucose-dehydrogenase. Das Vorkommen dieser Isoenzymbänder ist ein zuverlässiges Zeichen der Parasitierung durch G. fumiferanae. Die Brauchbarkeit der Elektrophorese als Mittel zum Routinenachweis von Parasitoiden wird diskutiert.

     

Comparison of some methods for collecting and analyzing data on aboveground net production and diversity of herbaceous vegetation in a northern Utah subalpine context

Our major objective was to compare methods of collecting and analyzing data on herbaceous aboveground net primary production and plant diversity in sequence of sites inferred to represent a meadow aspen fir spruce-sere in the middle Rocky Mountains. These comparisons should help us better interpret the literature and prepare for monitoring vegetation trends due to global climatic changes. Both absolute and relative values for above net primary production were highly dependent on methods used. The magnitude of differences in community diversity also varied greatly depending on the methods used to express plant richness, equitability, heterogeneity and dominance. We conclude that it is impossible to objectively test differences in production and diversity using data from single sampling dates and arbitrary choices of methods. In communities with great inter and intra-seasonal dynamics, an index of dominance that only measures magnitude (e.g. peak standing crop) was shown to have undesirable properties. We have demonstrated how average seasonal phytomass can overcome these problems by employing a measure of residence time as well as magnitude.Abbreviations ANPP = aboveground net primary production - ASP = average seasonal phytomass - NCSC = net aboveground community standing crop - PCSC = peak community aboveground standing crop     

Mismatches between breeding success and habitat preferences in Hen Harriers Circus cyaneus breeding in forested landscapes

During the past century, the upland breeding areas of Hen Harriers in Ireland have been extensively afforested. There is no evidence that this species avoids breeding in heavily forested landscapes and, indeed, young commercial forests in their second rotation are often selected as nest‐sites. However, Hen Harriers have coexisted with these forested areas for only a few decades and it is possible that such landscapes are suboptimal. We examined the relationship between breeding success and habitat using a dataset spanning three years and four study areas in the south and west of Ireland. We assessed whether nest success and fledged brood size were related to habitat type, both at the nest‐site and in the surrounding landscape. Neither measure of breeding productivity was related to total forest cover or to percentage cover of closed canopy forest in the landscape. However, in a subset of areas, high cover of second‐rotation pre‐thicket (young forests planted on land from which a first rotation has already been harvested) in the surrounding landscape was associated with low levels of breeding success. This may be due to factors related to predation, disturbance or prey availability. The fact that second‐rotation pre‐thicket is a preferred habitat for nesting in Ireland suggests that Hen Harriers may be making suboptimal decisions in the landscapes available to them.     

On the mechanism of apoplastic H<Subscript>2</Subscript>O<Subscript>2</Subscript> production during lignin formation and elicitation in cultured spruce cells—peroxidases after elicitation

A cell culture of Picea abies (L.) Karst. was used for studies of H₂O₂ generation during constitutive extracellular lignin formation and after elicitation by cell wall fragments of a pathogenic fungus, Heterobasidium parviporum. Stable, micromolar levels of H₂O₂ were present in the culture medium during lignin formation. Elicitation induced a burst of H₂O₂, peaking at ca. 90 min after elicitation. Of exogenous reducing substrates that may be responsible for the synthesis of H₂O₂ from O₂, NADH stimulated H₂O₂ production irrespective of elicitation. Cysteine (Cys) and glutathione (GSH) partially scavenged the constitutive H₂O₂, but usually increased or prolonged elicitor-induced H₂O₂ formation. Culture medium peroxidases were not able to generate H₂O₂ in vitro with Cys or GSH as reductants. These thiols, however, generated H₂O₂ non-enzymically at pH 4.5. [³⁵S]Sulphate feeding to spruce cells showed that endogenous sulphur-containing compounds (including GSH, GSSG and cysteic acid) existed in the culture medium. The apoplastic levels of these were, however, undetectable by the monobromobimane method suggesting that their contribution to apoplastic H₂O₂ formation is probably minor. Azide, an inhibitor of haem-containing enzymes, slightly inhibited constitutive H₂O₂ generation but strongly delayed the elicitor-induced H₂O₂ accumulation. Diphenylene iodonium, an inhibitor of flavin-containing enzymes, efficiently inhibited H₂O₂ production irrespective of elicitation. Elicitation led to downregulation of the expression of several peroxidase genes, and peroxidase activity in the culture medium was slightly reduced. Expression of three other peroxidase genes and a respiratory burst oxidase homologue (rboh) gene were upregulated. These data suggest that both peroxidases and rboh may contribute to H₂O₂ generation. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Growth characteristics of Sakhalin spruce (Picea glehnii) planted on the northern Japanese hillsides exposed to strong winds

Sakhalin spruce (Picea glehnii), a native species typically found in northern Japan, has been used in reforestation on hillsides exposed to strong winds. In the reforestation areas, there are south-facing (S-slope) and northwest-facing slopes (NW-slope). Climatic conditions are contrasting between the two slopes, with shallower snow cover on the S-slopes. We compared growth responses of the spruce to micro-environment between the S- and NW-slopes through soil nutrients, needle longevity, water status, photosynthesis, and nutrients in the needles. These parameters were measured in needles exposed above the snow in winter and in lower needles protected by snow cover. High-position needles suffered from drought stress, especially in winter, and needles were shed early in the year on both slopes. Low-position needles did not suffer from drought stress, and maintained a high photosynthetic rate on both slopes. However, needle longevity was reduced on the S-slope, and concentrations of nitrogen, phosphorus, and potassium in the needles decreased with needle age. Soil nutrient concentrations were low on the S-slope, which suggests that the needles on the S-slope may remobilize nutrients from aged needles to younger needles prior to shedding. This characteristic is probably an adaptation in Sakhalin spruce to poor soil conditions.     

The relation among soil microorganism, enzyme activity and soil nutrients under subalpine coniferous forest in Western Sichuan

Soil microorganism and enzymes are important parts of forest ecosystem and sensitive to environmental changes. They have many critical functions in energy conversion and material cycle of forest soil. However, there are few studies about soil biological properties under subalpine coniferous forest, in particular, a serial of spruce plantation chronosequences following clear-cutting of natural coniferous forest in western Sichuan. We measured the quantity of soil microorganism (including bacteria, fungi and actinomyces), enzyme activity and soil nutrients under spruce plantation chronosequences in western Sichuan to investigate soil biological properties and their relationship with soil nutrients. The results showed that soil microorganism, enzyme activity and soil nutrients of the mature spruce plantation were significantly lower than those of the young spruce plantation and secondary broad-leaved forest. Soil fertility degraded greatly with the increasing of spruce plantation age and was mainly affected by forest micro-environment. There were significant correlation between the amounts of soil microorganisms, soil enzyme activities and nutrients (e.g. soil organic matter, total N, total P, alkali-hydrolyzable N and available K). Therefore soil biological indices can be used to evaluate soil fertility. In order to accelerate the course of restoration and rehabilitation of degraded pure plantation, the strategy and measures were put forward, including application of thinning rationally for existing dense plantations and establishment of mixture forest of coniferous and broad-leaved trees for new afforestations, which would create good forest micro-environment for plant growth.