Seasonal changes in the pigments, carbohydrates and growth of red spruce as affected by ozone

Two-year-old red spruce seedlings were exposed to various levels ot ozone, from 0.4 to 3 times ambient levels, in open-top chambers in Ithaca, NY, USA. Exposures, which varied with changes in day length, commenced on May 30, 1987 and continued until December 14, 1987. Seedling biomass, carbohydrate contents, pigment contents, and rate of electron transport were assessed twice monthly during the fumigation period. Orthogonal quadratic or cubic polynomials were used to model the response through time each variable measured. A one-way analysis of variance model was fitted to every regression coefficient in each polynomial model to test for ozone effects on seasonal physiological patterns. Ozone did not influence growth, foliar pigment content, foliar starch content, root carbohydrate content, or rate of electron transport. The seasonal change of needle raffinose content differed between exposed to low (0.4 ×, 1×) and high (2×, 3×) ozone levels. There was also a trend towards reduced total soluble sugar content foliage during late autumn in higher ozone treatments.     

Vertical distribution and abundance of invertebrates within the sandy substrate of a low-gradient headwater stream

SUMMARY. 1 The vertical distribution of invertebrates (>0.053 mm) was studied in a sandy-bottomed, first-order stream on the Coastal Plain of Virginia, U.S.A. Invertebrate species composition, abundance and bio-mass were determined monthly over one year at sediment depth intervals of 0–1, 1–5, 5–15,15–30 and 30–40 cm.
2. The subsurface community was numerically dominated by species of Chironomidae, Nematoda and Crustacea, while much of the biomass was due to early instars of several species of Trichoptera.
3. Invertebrate density and biomass decreased significantly with depth in the substrate (ANOVA; P <0.05). Annual mean density decreased from 1,346,844 individuals m⁻³ at the surface to 13,578 individuals m⁻³ at 15–30 cm. Annual mean biomass decreased from 66.30 g m⁻³ at the surface to 0.44 g m⁻³ at 15–30 cm.
4. Dissolved oxygen decreased markedly from the surface to the 5 cm depth in the substrate, anaerobic conditions often occurring below 10 cm. Density and biomass both showed a significant positive relationship with dissolved oxygen concentration (Linear regression; P <0.05).
5. Physical forces were important in structuring the subsurface invertebrate community. Besides low dissolved oxygen concentration, sediment scouring resulting from storm discharge dramatically reduced density and biomass     

Biocontrol of Rhizoctonia crown and root rot of sugar beet by binucleate Rhizoctonia spp. and Laetisaria arvalis

Two isolates of Laetisaria arvalis and 10 of binucleate Rhizoctonia spp. (BNR) from the Ohio sugar beet production area, were tested in the greenhouse and field for biocontrol of Rhizoctonia crown and root rot of sugar beet, caused by Rhizoctonia solani anastomosis group 2, type 2. L. arvalis was ineffective in standard greenhouse tests, and the single isolate used in the field was generally ineffective. Seven of 10 BNR isolates effectively controlled crown and root rot in greenhouse tests. Delayed application of biocontrol agents to plants 5 – 10 wk old was generally more effective than applications made at planting. A BNR isolate significantly reduced % plant loss and disease ratings and increased yield in a 1985 field test as compared with the control infested with R. solani alone. Two BNR isolates were effective in a 1986 field test and increased yields c. 22% in comparison to a L. arvalis treatment, which did not differ from the R. solani-infested control. The Ohio binucleate Rhizoctonia isolates appear to have considerable potential as applied biocontrol agents and may play a role in the natural ecology of R. solani in the sugar beet production area of Ohio.     

Basicranial axis length v. skull length in analysis of carnivore skull shape

Skull length is the measurement most commonly used as a standard against which other aspects of cranial morphology are compared to derive an index of relative size or proportions. However, skull length is composed of two different functional components, facial skull and cerebral skull, which vary independently and have different scaling relationships with body size. An analysis of carnivore skull shape with measurements standardized against basicranium length produced very different results than an analysis using skull length as the standard. For example, expressions of relative size of cranial measurements were reduced by 13% in mustelids and increased by 20% in canids, reflecting removal of jaw length (short in mustelids and long in canids) from the comparative standard (basicranial axis length). Cranial measurements scale with higher allometric exponents against basicranial axis length than against skull length.     

Relationships between metal concentrations and organism size in aquatic insects

SUMMARY.

• 1 The influence of organism size on whole-body metal concentrations of eight metals was examined in aquatic insects in field and laboratory studies. Information on the partitioning of metals between adsorbed, absorbed and gut content material was also obtained.
• 2 For Co, Cr, Fe, Sb and Sc, an exponential decrease in concentration with increasing organism size was observed, indicating surface adsorption as an important mode of metal accumulation.
• 3 No, or only a slight, concentration-size relationship was found for K, Mn and Na. This is expected for metals with high absorption efficiencies and a low capacity to be adsorbed.
• 4 Clearing of the gut of the mayfly Stenonema modestum (Ephemeroptera: Heptageniidae) did not significantly after the concentration size relationship for any of the metals studied.
• 5 Studies of Cr uptake with Stenacron interpunctatum (Ephemeroptera: Heptageniidae) indicate that the concentration-size relationship is not affected by variability in the concentration of available Cr.
• 6 About 52% of the whole-body burden of Cr in S. interpunctatum was associated with gut material while at least 33% was adsorbed to the organism's exoskeleton and at most 15% was internally absorbed.

     

Structure of the “Peroxy-Y Base” from Liver tRNA<Superscript>Phe</Superscript>

WE wish to report that reconstituted sperm whale myoglobin prepared by the method of Breslow¹ (except that pH 2 was found sufficient to remove all the haem) (I) crystallizes² in a different habit from those prepared by the method of Rossi-Fanelli et al.³ (II) using haemin of Sigma lot 77B-0220 and our own ⁵⁷Fe photoporphyrin preparation and the native myoglobin (III). Although all three form type A³ monoclinic prisms, the best developed plane is [001] for II and III, it is [100] for I. There seems to be great interest in reconstituted haemoproteins^4,5, so it is important that crystallization habit may be a sensitive test for subtle changes in protein structures.