Surface areas,lengths and volumes of Picea abies (L.) Karst. needles: determination,biological variability and effect of environmental factors

Summary A method for the rapid determination of the lengths and surface areas of very large samples of needles of Picea abies (L.) Karst. using a computer-aided image analysis system was developed. Two independent methods for measuring non-destructively the volumes of individual needles and of all needles attached to a twig were devised. The surface areas and lengths of about 38000 needles sampled from the three youngest needle age-classes (1986, 1985, 1984) of 48 trees approximately 130 years old at four sites in the Fichtelgebirge mountains (N. E. Bavaria, FRG) were measured. The frequency distributions of lengths and areas for each site and age-class are given. Variability of needle size was fairly large. Even though the sites differed in climate, soil, and air pollution levels no consistent effect of these factors on needle size could be detected. Needle lengths and surface areas did not correlate with either the total chlorophyll content of the needles or the degree of crown thinning. The needle surface area (in mm²) of fully developed P. abies needles can be estimated by the empirical equation surface area = 4.440 x needle length -24.8 (r = 0.937), and the needle volume (in mm³) by needle volume = 0.208 x projected needle area ^1.353 (r = 0.969).     

In vivo ionizing irradiations produce deletions in the hprt gene of human T-lymphocytes

The hprt T-lymphocyte cloning assay, which detects mutations occurring in vivo in humans, has been used to examine mutants induced in patients receiving radioimmunoglobulin therapy (RIT) for cancer. Samples from 13 patients before treatment (controls) and 15 samples from 12 patients after treatment were studied for both mutant frequencies and molecular changes in the hprt mutant T-cell clones. Patients were studied up to 48 months after treatment. Post-RIT patients showed increased mutant frequencies as compared to pre-treatment values. T-cell receptor (TCR) gene analysis of mutant T-cell clones demonstrated that 84% arose independently, both pre- and post-treatment, which is the same proportion as seen in normal individuals. However, several individuals did show large sets of mutants with the same TCR gene rearrangement patterns. Molecular analysis of mutants demonstrated a greater proportion of mutations with hprt gene changes on Southern blots after RIT treatment than before (40% versus 20%). RIT increases the proportion of mutations with total rather than partial gene deletions or other gross structural changes compared to normal individuals or pre-treatment patients. These studies are defining the spectrum for radiation-induced hprt gene mutations in vivo in human T-lymphocytes.     

THE SEPARATION OF DIFFERENT CELL CLASSES FROM LYMPHOID ORGANS : III. The Purification of Erythroid Cells by pH-Induced Density Changes

1. Mammalian erythrocytes swell as the pH of the isotonic suspending medium is lowered, as a direct consequence of the specialized permeability properties of the erythrocyte membrane. Lymphocytes and granulocytes from a variety of sources did not exhibit this property. 2. The behaviour of mouse bone marrow erythroid cells at various stages of differentiation was studied by using a change in buoyant density with pH as an index of swelling. The ability to swell with a pH drop was acquired while the cell was still nucleated. All non-nucleated cells showed swelling. Most small erythroblasts shared this property, whereas most large erythroblasts did not. 3. The density shift with pH was used to provide a purification scheme specific for erythroid cells. The bone marrow cells were first centrifuged to equilibrium in an isotonic albumin density gradient at neutral pH. Regions of the gradient containing the erythroid cells were collected, and the cells were recovered and redistributed in an albumin gradient at acid pH. The erythroid cells showed a specific density shift which removed them from contaminants. Preparations containing 90–97% erythroblasts were obtained by this technique. 4. Differentiation within the erythroid series was accompanied by a general increase in cell buoyant density at neutral pH. This density increase may have been a discontinuous process, since erythroid cells appeared to form a number of density peaks. 5. The pH shift technique, in association with established density distribution and sedimentation velocity procedures, provides a range of cell separation techniques for biological or biochemical studies of erythroid cell differentiation in the complex cell mixtures in bone marrow or spleen.     

Interstrand cross-linking reaction in triplexes containing a monofunctional transplatin-adduct.

Our aim was to determine whether a single transplatin monofunctional adduct, either trans-[Pt(NH3)2(dC)Cl]+ or trans-[Pt(NH3)2(dG)Cl]+ within a homopyrimidine oligonucleotide, could further react and form an interstrand cross-link once the platinated oligonucleotide was bound to the complementary duplex. The single monofunctional adduct was located at either the 5' end or in the middle of the platinated oligonucleotide. In all the triplexes, specific interstrand cross-links were formed between the platinated Hoogsteen strand and the complementary purine-rich strand. No interstrand cross-links were detected between the platinated oligonucleotides and non-complementary DNA. The yield and the rate of the cross-linking reaction depend upon the nature and location of the monofunctional adducts. Half-lives of the monofunctional adducts within the triplexes were in the range 2-6 h. The potential use of the platinated oligonucleotides to modulate gene expression is discussed.     

The unusual social organization of the antPachycondyla tridentata (Formicidae,ponerinae)

Colonies of the ponerine antPachycondyla tridentata from Malaysia occur with and without queens. In a total of 7 colonies we found more than 80% of the workers to be mated, irrespective of the presence or absence of queens. This is a hitherto unknown social organisation in ants. Queens and workers competed equally for reproduction. In the colonies investigated several ants were laying eggs. Behavioral observations revealed persistent dominance interactions between colony members. A few ants, but not necessarily a queen, occupied top positions. Removal of the most dominant ants led to a new hierarchy in which subordinate ants with developed ovaries were attacked significantly more frequently than non-reproductive ants. On the average, callows were more aggressive than older subordinate ants, displacing most of the older laying workers in one colony. Nestmate recognition tests revealed that non-reproductive ants were much more aggressive towards foreign ants than were ants with developed ovaries.     

Accumulation of hexoses in leaf vacuoles: Studies with transgenic tobacco plants expressing yeast-derived invertase in the cytosol,vacuole or apoplasm

The subcellular distribution of hexoses, sucrose and amino acids among the stromal, cytosolic and vacuolar compartments was analysed by a nonaqueous fractionation technique in leaves of tobacco (Nicotiana tabaccum L.) wild-type and transgenic plants expressing a yeast-derived invertase in the cytosolic, vacuolar or apoplasmic compartment. In the wild-type plants the amino acids were found to be located in the stroma and in the cytosol, sucrose mainly in the cytosol and up to 98% of the hexoses in the vacuole. In the leaves of the various transformants, where the contents of hexoses were greater than in wild-type plants, again 97–98% of these hexoses were found in the vacuoles. It is concluded that leaf vacuoles contain transporters for the active uptake of glucose and fructose against a high concentration gradient. A comparison of estimated metabolite concentrations in the subcellular compartments of wild-type and transformant plants indicated that the decreased photosynthetic capacity of the transformants is not due to an osmotic effect on photosynthesis, as was shown earlier to be the case in transformed potato leaves, but is the result of a long-term dedifferentiation of tobacco leaf cells to heterotrophic cells.Abbreviations apo-inv tobacco plant with yeast invertase in the apoplasm - Chl chlorophyll - cy-inv tobacco plant with yeast invertase in the cytosol - vac-inv tobacco plant with yeast invertase in the vacuole - WT wild-type tobacco plant The authors thank A. Großpietsch for her able technical assistance. This work has been supported by the Bundesminister für Forschung und Technologie.     

Preparation, X-ray structure and solution behavior of [Ag(9-EtGH-N7)2]NO3·H2O (9-EtGH=9-ethylguanine)

The preparation and X-ray structure of [Ag(9-EtGH-N7)₂]NO₃·H₂O(9-EtGH=neutral 9-ethylguanine) is reported. The compound crystallizes in the triclinic system, space group P with a=7.063(6), b=7.153(3), c=11.306(10) Å, α=83.36(6), β=76.66(7), γ=81.44(6)°. The cation is centrosymmetric with Ag(I) coordinated via two N7 positions and Ag---N7 bond lengths of 2.11(1) Å. Applying ¹⁰⁹Ag NMR spectroscopy, complex formation constants for both the 1:1 complex (log β₁=0.6) and the title compound (log β₂=1.6) in Me₂SO have been determined.     

Assessing the impact of ozone on photosynthesis of European beech (Fergus sylvatica L.) in environmental chambers

An exposure — response study with proportionalto-ambient ozone levels was conducted in closed chambers on 3-year-old European beech (Fagus sylvatica L.) of montane origin. The fumigation started in April 1990 and lasted for a single growing season. Climate data and ozone concentrations monitored at an experimental station of the Institute for Applied Plant Biology, Schönenbuch, Switzerland were simulated in the exposure chambers 12 days later (1*O₃). To test exposure-response relations three additional treatments were applied, subambient (0.2*O₃) and two proportionally increased ozone treatments (1.5*O₃ and 2*O₃). The photosynthetic behaviour of the trees in August revealed the light reactions to be less affected than parameters which are related to the dark reactions of photosynthesis. Assimilation (A₃₅₀), apparent carboxylation efficiency (CE), and maximum photosynthetic capacity (A₂₅₀₀) were reduced with increasing ozone concentration. For the ozone response of CE and A₂₅₀₀ Critical Levels were calculated.