13C spin relaxation measurements in RNA: Sensitivity and resolution improvement using spin-state selective correlation experiments

A set of new NMR pulse sequences has been designed for the measurement of ¹³C relaxation rate constants in RNA and DNA bases: the spin-lattice relaxation rate constant R(C_z), the spin-spin relaxation rate constant R(C₊), and the CSA-dipolar cross-correlated relaxation rate constant . The use of spin-state selective correlation techniques provides increased sensitivity and spectral resolution. Sensitivity optimised C-C filters are included in the pulse schemes for the suppression of signals originating from undesired carbon isotopomers. The experiments are applied to a 15% ¹³C-labelled 33-mer RNA–theophylline complex. The measured ratios indicate that ¹³C CSA tensors do not vary significantly for the same type of carbon (C₂, C₆, C₈), but that they differ from one type to another. In addition, conformational exchange effects in the RNA bases are detected as a change in the relaxation decay of the narrow ¹³C doublet component when varying the spacing of a CPMG pulse train. This new approach allows the detection of small exchange effects with a higher precision compared to conventional techniques.     

A bias correction for estimates of effective population size based on linkage disequilibrium at unlinked gene loci*

Analysis of linkage disequilibrium (=mean squared correlation of allele frequencies at different gene loci) provides a means of estimating effective population size (N _e) from a single sample, but this method has seen much less use than the temporal method (which requires at least two samples). It is shown that for realistic numbers of loci and alleles, the linkage disequilibrium method can provide precision comparable to that of the temporal method. However, computer simulations show that estimates of N _e based on for unlinked, diallelic gene loci are sharply biased downwards ( in some cases) if sample size (S) is less than true N _e. The bias is shown to arise from inaccuracies in published formula for when S and/or N _e are small. Empirically derived modifications to for two mating systems (random mating and lifetime monogamy) effectively eliminate the bias (residual bias in % in most cases). The modified method also performs well in estimating N _e in non-ideal populations with skewed sex ratio or non-random variance in reproductive success. Recent population declines are not likely to seriously affect , but if N has recently increased from a bottleneck can be biased downwards for a few generations. These results should facilitate application of the disequilibrium method for estimating contemporary N _e in natural populations. However, a comprehensive assessment of performance of with highly polymorphic markers such as microsatellites is needed.The US Governmentȁ9s right to retain a non-exclusive, royalty-free license in and to any copyright is acknowledged.     

Interaction-induced electric (hyper)polarizability in the dihydrogen–neon pair: basis set and electron correlation effects

We investigated the interaction (hyper)polarizability of neon–dihydrogen pairs by performing high-level ab initio calculations with atom/molecule-specific, purpose-oriented Gaussian basis sets. We obtained interaction-induced electric properties at the SCF, MP2, and CCSD levels of theory. At the CCSD level, for the T-shaped configuration, around the respective potential minimum of 6.437 a₀, the interaction-induced mean first hyperpolarizability varies for 5?<? R/a₀?<?10 as

$$ \left[{\overline{\beta}}_{\mathrm{int}}(R)\hbox{-} {\overline{\beta}}_{\mathrm{int}}\left({R}_{\mathrm{e}}\right)\right]/{e}^3{a_0}^3{E_{\mathrm{h}}}^{-2}=-0.91\left(R\hbox{-} {R}_{\mathrm{e}}\right)+0.50{\left(R\hbox{-} {R}_{\mathrm{e}}\right)}^2\hbox{--} 0.13{\left(R\hbox{-} {R}_{\mathrm{e}}\right)}^3+0.01{\left(R\hbox{-} {R}_{\mathrm{e}}\right)}^4. $$

Again, at the CCSD level, but for the L-shaped configuration around the respective potential minimum of 6.572 a₀, this property varies for 5?<? R/a₀?<?10 as

$$ \left[{\overline{\beta}}_{\mathrm{int}}(R)\hbox{-} {\overline{\beta}}_{\mathrm{int}}\left({R}_{\mathrm{e}}\right)\right]/{e}^3{a_0}^3{E_{\mathrm{h}}}^{-2}=-1.33\left(R\hbox{-} {R}_{\mathrm{e}}\right)+0.75{\left(R\hbox{-} {R}_{\mathrm{e}}\right)}^2-0.20{\left(R\hbox{-} {R}_{\mathrm{e}}\right)}^3+0.02{\left(R\hbox{-} {R}_{\mathrm{e}}\right)}^4. $$

Open image in new window

Graphical Abstract Interaction-induced mean dipole polarizability (\( \overline{a} \)) for the T-shaped configuration of H₂–Ne calculated at the SCF, MP2, and CCSD levels of theory

     

Root biomass fraction as a function of growth degree days in wheat

Root, underground and above-ground biomass were measured on various wheat cultivars from 1986 to 1988 in the south-east of France. The results are expressed as root: total (f _r) or underground: total (f _u) biomass fractions. Observed f _r and f _u values are in good agreement with previous results. f _r and f _u decrease steadily from emergence to maturity, with an exponential tendency. When using cumulative growth degree days since emergence relative to cumulative growth degree days until ear emergence () as time scale, f _r and f _u can be expressed as simple functions of % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGceaqabeaacaWGMb% addaWgaaqaaiaadkhaaeqaamaabmaabaGccqaH4oqCdaahaaWcbeqa% aiaacQcaaaaamiaawIcacaGLPaaakiabg2da9iaaicdacaGGUaGaaG% imaiaaiwdacqGHRaWkcaaIWaGaaiOlaiaaiwdacaaI4aGaamyzamaa% CaaaleqabaGaeyOeI0IaaGymaiaac6cacaaI0aGaaGioaiabeI7aXn% aaCaaameqabaGaaiOkaaaaaaaakeaacaWGMbaddaWgaaqaaiaadwha% aeqaamaabmaabaGccqaH4oqCdaahaaWcbeqaaiaacQcaaaaamiaawI% cacaGLPaaakiabg2da9iaaicdacaGGUaGaaGymaiaaikdacqGHRaWk% caaIWaGaaiOlaiaaiIdacaaI4aGaamyzamaaCaaaleqabaGaeyOeI0% IaaGOmaiaac6cacaaIYaGaaGioaiabeI7aXnaaCaaameqabaGaaiOk% aaaaaaaaaaa!610D!\[\begin{gathered} f_r \left( {\theta ^* } \right) = 0.05 + 0.58e^{ - 1.48\theta ^* } \hfill \\ f_u \left( {\theta ^* } \right) = 0.12 + 0.88e^{ - 2.28\theta ^* } \hfill \\ \end{gathered} \]The incremental root biomass partitioning coefficient, % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeqySde2aaS% baaSqaaiaadkhaaeqaaOGaeyypa0JaaiikaiaadsgacaWGxbWaaSba% aSqaaiaadkhaaeqaaOGaai4laiaadsgacaWG0bGaaiykaiaac+caca% GGOaGaamizaiaadEfadaWgaaWcbaGaamiDaaqabaGccaGGVaGaamiz% aiaadshacaGGPaaaaa!4834!\[\alpha _r = (dW_r /dt)/(dW_t /dt)\], which describes the net increase in root biomass dW _r over time dt relative to the increase in total biomass (dW _r) over the same time period, has been derived from f and the relative growth rate. Its time course is accurately represented by% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeqySdegdda% WgaaqaaiaadkhaaeqaamaabmaabaGccqaH4oqCdaahaaWcbeqaaiaa% cQcaaaaamiaawIcacaGLPaaakiabg2da9iabgkHiTiaaicdacaGGUa% GaaGymaiaaiwdacqGHRaWkcaaIWaGaaiOlaiaaiAdacaaIZaGaamyz% amaaCaaaleqabaGaeyOeI0IaaGimaiaac6cacaaI5aGaaGioaiabeI% 7aXnaaCaaameqabaGaaiOkaaaaaaaaaa!4D15!\[\alpha _r \left( {\theta ^* } \right) = - 0.15 + 0.63e^{ - 0.98\theta ^* } \]Under our experimental conditions, with no severe water stresses or nutrient deficiencies, and for our sampling frequency, around 2 weeks, the development scale , is the main factor governing the time courses of f _r, f _u and _r.     

The mechanism and kinetics of decomposition of 5-aminotetrazole

The pathway and ab initio direct kinetics of the decomposition 5-aminotetrazole (5-ATZ) to HN₃ and NH₂CN was investigated. Reactant, products and transition state were optimized with MP2 and B3LYP methods using 6–311G** and aug-cc-pVDZ basis sets. The intrinsic reaction coordinate curve of the reaction was calculated using the MP2 method with 6–311G** basis set. The energies were refined using CCSD(T)/6–311G**. Rate constants were evaluated by conventional transition-state theory (CVT) and canonical variational transition-state theory (TST), with tunneling effect over 300 to 2,500 K. The results indicated that the tunneling effect and the variational effect are small for the calculated rate constants. The fitted three-parameter expression calculated using the CVT and TST methods are and , respectively. Figure The mechanism of the decomposition process of 5-ATZ to HN₃ and NH₂CN     

Pace of diffusion through membranes

Summary Although membranes are often viewed as barriers to diffusing particles, in many cases their presence does not slow down diffusion. Investigations of the transit time (mean diffusion time) for cases where the source and the target of diffusing particles are separated by various arrangements of membranes reveal the following facts: (i) The transit time is composed of the sum of the times to diffuse each of the membrane and aqueous regions separately and terms representing the time spent at the vicinity of the interfaces between these regions. (ii) In cases of one dimensional diffusion between aqueous and membranal phases, the transit time is governed by the parameter whereD _m andD _w are the diffusion coefficients in the membrane and water, respectively, and is the membrane/water partition coefficient of the particles. While the former ratio depends mostly on the viscosities of the two phases, the latter parameter is very strongly dependent on the identity of the particles. The diffusion from water to the membrane is faster than from the membrane to water whenever 1$$ " align="middle" border="0"> . The opposite is true when this parameter is smaller than 1. (iii) In case of one dimensional transmembranal diffusion, the transit time shows a minimum when wherel _w1 andl _w2 are the net diffusion distances in the aqueous phases on both sides of the membrane. In this case, if the diffusion proceeds through pores in the membrane, represents the fraction of membrane area that is occupied by the pores.The transit times for three dimensional diffusion into and from a spherical cell are also presented in a simple form. In addition, some of the relations between transit times and other measurable time parameters, such as the course of the decay of gradients and the time lag to establish steady states, are discussed briefly.The conclusions emerging from this analysis, together with the simple expressions for the transit times can make these investigation useful for the understanding of diffusion in systems containing natural or artificial membranes.     

Energy requirements of Adélie penguin (Pygoscelis adeliae) chicks

Summary The energy requirements of Adélie penguin (Pygoscelis adeliae) chicks were analysed with respect to body mass (W, 0.145–3.35 kg, n=36) and various forms of activity (lying, standing, minor activity, locomotion, walking on a treadmill). Direct respirometry was used to measure O₂ consumption ( ) and CO₂ production. Heart rate (HR, bpm) was recorded from the ECG obtained by both externally attached electrodes and implantable HR-transmitters. The parameters measured were not affected by hand-rearing of the chicks or by implanting transmitters. HR measured in the laboratory and in the field were comparable. Oxygen uptake ranged from in lying chicks to at maximal activity, RQ=0.76. Metabolic rate in small wild chicks (0.14–0.38 kg) was not affected by time of day, nor was their feeding frequency in the colony (Dec 20–21). Regressions of HR on were highly significant (p< 0.0001) in transmitter implanted chicks (n=4), and two relationships are proposed for the pooled data, one for minor activities ( ), and one for walking ( ). Oxygen consumption, mass of the chick (2–3 kg), and duration of walking (T, s) were related as , whereas mass-specific O₂ consumption was related to walking speed (S, m·s^-1) as .Abbreviations bpm beats per minute - D distance walked (m) - ECG electrocardiogram - HR heart rate (bpm) - ns number of steps - RQ respiratory quotient - S walking speed (m·s^-1) - T time walked (s) - W body mass (kg)     

Structural analysis of novel rhamnose-branched oligosaccharides from the glycophosphosphingolipids ofLeptomonas samueli

Mild alkaline hydrolysis of the glycophosphosphingolipids of the protozoanLeptomonas samueli liberated several phosphoinositol-containing oligosaccharides (PI-oligosaccharides), which were purified by high performance anion exchange chromatography. The oligosaccharides in the resulting four fractions were characterized by methylation analysis, fast atom bombardment mass spectrometry and two-dimensional nuclear magnetic resonance spectroscopy. The oligosaccharides contain the core structure Man(1–4)GlcN(1–6)-myo-inositol-1-OPO₃, and are substituted with 2mol of 2-aminoethylphosphonate per mol of oligosaccharide. The nonreducing ends of the oligosaccharides were terminated by rhamnose branched neutral and acidic xylose-containing penta-, hexa-, hepta- and octasaccharides, of which the three most abundant were shown to have the structures:

Topological research on diamagnetic susceptibilities of organic compounds

A novel molecular connectivity index, , based on the adjacency matrix of molecular graphs and novel atomic valence connectivities, , for predicting the molar diamagnetic susceptibilities of organic compounds is proposed. The is defined as: , where and E_i are the atomic valence connectivity and the valence orbital energy of atom i, respectively. A good QSPR model for molar diamagnetic susceptibilities can be constructed from and using multivariate linear regression (MLR). The correlation coefficient r, standard error, and average absolute deviation of the MLR model are 0.9918, 5.56 cgs, and 4.26 cgs, respectively, for the 721 organic compounds tested (training set). Cross-validation using the leave-one-out method demonstrates that the MLR model is highly reliable statistically. Using the MLR model, the average absolute deviations of the predicted values of molar diamagnetic susceptibility of another 360 organic compounds (test set) is 4.34 cgs. The results show that the current method is more effective than literature methods for estimating the molar diamagnetic susceptibility of an organic compound. The MLR method thus provides an acceptable model for the prediction of molar diamagnetic susceptibilities of organic compounds. Figure Plot of calculated vs experimental values of molar diamagnetic susceptibilities using the multivariate linear regression (MLR) model (Eq. 8)     

Energetics of the growth of Methanobacterium thermoautotrophicum and Methanococcus thermolithotrophicus on ammonium chloride and dinitrogen

Methanobacterium thermoautotrophicum was grown in continuous culture in a fermenter gassed with H₂ and CO₂ as sole carbon and energy sources, and in a medium which contained either NH₄Cl or gaseous N₂ as nitrogen source. Growth was possible with N₂. Steady states were obtained at various gas flow rates with NH₄Cl and with and the maintenance coefficient varied with the gas input and with the nitrogen source. Growth of Methanococcus thermolithotrophicus in continuous culture in a fermenter gassed with H₂, CO₂ as nitrogen, carbon and energy sources was also examined.Abbreviations molecular growth yield (g dry weight of cells per mol of CH₄ evolved) - growth rate (h^-1) - D dilution rate (h^-1) - rate (h_-1); relation of Neijssel and Tempest and of Stouthamer and Bettenhaussen - energy     

The threshold of perception of angular acceleration as a function of duration

The threshold for rotation about the yaw axis was determined for constant acceleration stimuli as a function of their duration in the range from 3 to 25 s. From the torsion-swing model the following theoretical equation can be derived: 1 $$a_{{\text{thr}}} = {C \mathord{\left/ {\vphantom {C {\left[ {1 - \exp \left( { - {{t_s } \mathord{\left/ {\vphantom {{t_s } {\tau _1 }}} \right. \kern-\nulldelimiterspace} {\tau _1 }}} \right)} \right]}}} \right. \kern-\nulldelimiterspace} {\left[ {1 - \exp \left( { - {{t_s } \mathord{\left/ {\vphantom {{t_s } {\tau _1 }}} \right. \kern-\nulldelimiterspace} {\tau _1 }}} \right)} \right]}}$$ , where a _thr=acceleration amplitude at threshold, t _s =duration of the acceleration, τ₁=time constant, C=threshold for very long stimuli. According to this formula the Mulder product (i.e. the product of the threshold acceleration amplitude and the duration of the stimulus) is constant for durations up to 0.3 τ₁. The best fit of this theoretical function to the somatosensory data is found for τ₁=14.5 s, and C=0.22⁰/s ². The time within the Mulder product is constant (about 5s) is doubtless due to the mechanics of the semicircular canals. For the oculogyral data a lower value of τ₁ is found. We do not have any explanation for this lower value.     

Effects of common soil anions and pH on the uptake and accumulation of perchlorate in lettuce

A mechanistic understanding of perchlorate () entry into plants is important for establishing the human health risk associated with consumption of contaminated produce and for assessing the effectiveness of phytoremediation. To determine whether common soil anions affect uptake and accumulation in higher plants, a series of competition experiments using lettuce (Lactuca sativa L.) were conducted between (50 nM) and (4–12 mM), (1–10 mM), or Cl⁻ (5–15 mM) in hydroponic solution. The effects of (0–5 mM) and pH (5.5–7.5) on uptake were also examined. Increasing in solution significantly reduced the amount of taken up by green leaf, butter head, and crisphead lettuces. Sulfate and Cl⁻ had no significant effects on uptake in lettuce over the concentrations tested. Increasing pH significantly reduced the amount of taken up by crisphead and green leaf lettuces, whereas increasing significantly reduced uptake in butter head lettuce. The inhibition by across all lettuce genotypes suggests that may share an ion carrier with , and the decrease in uptake with increasing pH or provides macroscopic evidence for cotransport across the plasma membrane.     

Modification of the data-processing method for the turbidimetric bioassay of nisin

The data processing method of the turbidimetric bioassay of nisin was modified to facilitate its industrial application. The influence of the initial indicator concentration was minimized by a redefined specific dose of the bacteriocin as the quotient between the titer of the added bacteriocin and the initial population density of the indicator in the suspension. It was found that d _c = 0.125 μg ml⁻¹ was the critical dose of nisin that can cause a complete inhibition of the indicator, Pediococcus acidilactici UL5, with an initial OD of 0.135. To eliminate the interference of the cell debris, an equation, , exploiting d _c, was formulated to obtain the intrinsic survival proportion. The use of the specific dose of the bacteriocin and the intrinsic survival proportion as parameters of the dose/response curve greatly enhanced its repeatability and feasibility. A dual-dosage approach was developed to further simplify the conventional standard dose/response curve method.     

Compensatory changes in Photosystem II electron turnover rates protect photosynthesis from photoinhibition

Exposure of algae or higher plants to bright light can result in a photoinhibitory reduction in the number of functional PS II reaction centers (n) and a consequential decrease in the maximum quantum yield of photosynthesis. However, we found that light-saturated photosynthetic rates (P_max) in natural phytoplankton assemblages sampled from the south Pacific ocean were not reduced despite photoinhibitory decreases in n of up to 52%. This striking insensitivity of P_max to photoinhibition resulted from reciprocal increases in electron turnover ( )through the remaining functional PS II centers. Similar insensitivity of P_max was also observed in low light adapted cultures of Thalassiosira weissflogii (a marine diatom), but not in high light adapted cells where P_max decreased in proportion to n. This differential sensitivity to decreases in n occurred because was close to the maximum achievable rate in the high light adapted cells, whereas was initially low in the low light adapted cells and could thus increase in response to decreases in n. Our results indicate that decreases in plant productivity are not necessarily commensurate with photoinhibition, but rather will only occur if decreases in n are sufficient to maximize or incident irradiance becomes subsaturating.     

Theoretical study of the reaction of CH2XO (X = F, Cl, Br) radicals with the NO radical

In this paper, we focus on the multiple-channel reactions of CH₂XO (X = F, Cl, Br) radicals with the NO radical by means of direct dynamic methods. All structures of the stationary points were obtained at the MP2/6-311+G(d,p) level and vibrational frequency analysis was also performed at this level of theory. The minimum energy path (MEP) was obtained via the intrinsic reaction coordinate (IRC) theory at the MP2/6-311+G(d,p) level, and higher-level energetic information was refined by the MC-QCISD method. The rate constants for the three hydrogen abstraction reaction channels over the temperature range 200–1,500 K were calculated by the improved canonical variational transition state theory (ICVT) with a correction for small-curvature tunneling (SCT). The rate constants calculated in this manner were in good agreement with the available experimental data, and the three-parameter rate–temperature formulae for the temperature range 200–1,500 K were $ {k_{1{\text{a}} }}(T)=0.32\times {10^{-18 }}{T^{1.83 }}\exp \left( {1748.54/T} \right) $ , $ {k_{2{\text{a}} }}(T)=0.22\times {10^{-19 }}{T^{2.19 }}\exp \left( {1770.19/T} \right) $ , $ {k_{3{\text{a}} }}(T)=0.88\times {10^{-20 }}{T^{2.20 }}\exp \left( {1513.82/T} \right) $ (in units of cm³ molecule^?1?s^?1).     

Topography of nucleic acid helices in solutions. 3. Interactions of spermine and spermidine derivatives with polyadenylic-polyuridylic and polyinosinic-polycytidylic acid helices

The synthesis of spermine derivatives (II), \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm R}_1 {\rm R}_{\rm 2} {\rm R}_{\rm 3} \mathop {\rm N}\limits^ + \left( {{\rm CH}_2 } \right)_3 \mathop {\rm N}\limits^ + {\rm R}_{\rm 1} {\rm R}_{\rm 2} \left( {{\rm CH}_2 } \right)_2 ]_2 \cdot 4{\rm X}^ - $\end{document}, and spermidine derivatives (III), \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm R}_1 {\rm R}_{\rm 2} {\rm R}_{\rm 3} \mathop {\rm N}\limits^ + \left( {{\rm CH}_2 } \right)_4 \mathop {\rm N}\limits^ + {\rm R}_{\rm 1} {\rm R}_{\rm 2} \left( {{\rm CH}_2 } \right)_3 \mathop {\rm N}\limits^ + {\rm R}_{\rm 1} {\rm R}_{\rm 2} {\rm R}_3 \cdot 3{\rm X}^ - $\end{document}, are reported. The effects of these salts on the helix–coil transition of rA–rU and rI–rC helices were examined. Increasing the size of the hydrophobic substituents, R¹, R², and R³ lowers the degree of stabilization of the helical structure. The disproportionation reaction, 2rA–rU→rA–rU₂ + rA occurs readily with salts II and III, especially when the substituents, R₁, R₂, and R₃ are small, i.e., H or Me. Spermine is found to stabilize the rA–rU² and rI–rC helices to approximately the same extent; however, large differences between the degree of stabilization of rA–rU₂ and rI-rC helices are observed when the substituents R₁, R₂, and R₃ are large hydrophobic groups. Similar results are also obtained for the spermidine series. Finally, differences in the interactions of the salts II and III with rA–rU₂ and rI–rC helices suggest that the latter helix is denser.     

Seagrass habitat complexity and macroinvertebrate abundance in Lakshadweep coral reef lagoons,Arabian Sea

Macrofauna of seagrass community in the five Lakshadweep atolls were studied and compared. The associated epifaunal and infaunal taxa comprising nine major taxonomic groups, showed significant differences in the total number of individuals (1041–8411 m^–2) among sites and habitats. The density of macrofauna was directly related to mean macrophytic biomass (405–895 g wet wt. m^–2). The fauna was dominated by epifaunal polychaetes, amphipods and isopods in the vegetated areas. When compared with the density of nearby unvegetated areas , seagrass meadows harbour a denser and richer macroinvertebrate assemblage .     

Proposal for a scoring of the quality of the banding of chromosomes

Summary We propose an objective scoring of the quality of the banding of mitoses based on the number of bands (B), the length (L), and the width (W) of chromosome 7 in metaphase as used in the formula . When no figure shows the quality of mitoses from which a breakpoint is described, this scoring could give information about it. It could be applied in cytogenetic cancer studies as well as for preparations with high resolution banding.