Effect of size on the energy acquired in species of the fish from a neotropical reservoir,Brazil

In this paper we analysed autotrophic sources of the carbon ( ¹³C) and the trophic position ( ¹⁵N) of Leporinus friderici in the influence area of Corumbá Reservoir, Brazil. We collected samples of muscles of fish from different sizes riparian vegetation, C₄ grasses, zooplankton, periphyton and particulate organic carbon (POC). There were significant differences for the carbon isotope proportion found in muscles of L.friderici in the different size groups analysed. The highest values of ¹³C recorded for middle sized individuals is attributed to the large contribution of C₄ plants in their diet. Small individuals sampled upstream also receive similar contribution from C₄ plants. In contrast the same size group sampled downstream from the reservoir, has a much smaller of C₄ plants. The ¹³C negative character of small individuals from downstream is due to the larger contribution of C₃ plants (except periphyton). At larger sizes we found intermediate ¹³C values. The ¹⁵N proportions we found for each size group were not significantly different, however we found decreasing mean values with increasing size. The trophic level calculated from the dietary data was higher than that found with the ¹³C concentration in the muscle, except for small individuals, when the values were equal.     

Spatial and temporal variation in carbon isotope discrimination in prairie graminoids

We present the results of a 5-year examination of variation in the stable carbon isotope composition () of three C₃ graminoid species from a Sandhills prairie: Agropyron smithii, Carex heliophila and Stipa comata. Although consistent species-specific patterns for mean were seen, there was also significant and substantial among-year and within-season variation in . A smaller contribution to variation in came from topographic variation among sampling sites. Effects of species, year, season and topography contribute to variation in in an additive manner. An association between climate and exists that is consistent with previous work suggesting that reflects the interplay between photosynthetic gas exchange and plant water relations. Within the growing season, the time over which integrates plant response to the environment ranges from days to months.     

Comparisons of δ13C values in leaves of aquatic macrophytes from different habitats in Britain and Finland; some implications for photosynthetic processes in aquatic plants

Summary The ¹³C values of submerged aquatic plants from contrasting but relatively defined habitats, and the ¹³C values of emergent, floating and submerged leaves of dimorphic aquatic plants, were measured. In many instances the ¹³C values of dissolved inorganic carbon in the water were also measured. Plant ¹³C values in the vicinity of-40 to-50 were found in rapidly flowing spring waters with carbonate ¹³C values of-16 to-21, consistent with the notion that species such as Fontinalis antipyretica almost exclusively assimilate free CO₂ via RuP₂ carboxylase. Plant ¹³C values in the vicinity of-10 to-15 in sluggish water with carbonate ¹³C values of about-5 were observed, consistent with the notion that boundary layer diffusion and/or HCO₃ ^- uptake may determine the ¹³C value of submerged aquatic plants in these circumstances. Comparisons of ¹³C values of the same or related species growing in waters of similar carbonate ¹³C value but different flow rates confirmed this view; more negative ¹³C values were frequently associated with plants in fast moving water. In Britain, but not in Finland, the ¹³C values of submerged leaves of dimorphic plants were almost invariably more negative than in aerial leaves. The ¹³C value of carbonate from chalk streams and in acid springs indicate substantial inputs of respiratory CO₂, as opposed to atmospheric carbon. The contributions of these variations in ¹³C of the carbon source, and of isotope fractionation in diffusion, to the ¹³C value of submerged parts of dimorphic plants is discussed.     

Carbon isotope composition in relation to leaf gas exchange and environmental conditions in Hawaiian Metrosideros polymorpha populations

Summary Carbon isotope composition, photosynthetic gas exchange, and nitrogen content were measured in leaves of three varieties of Metrosideros polymorpha growing in sites presenting a variety of precipitation, temperature and edaphic regimes. The eight populations studied could be divided into two groups on the basis of their mean foliar ¹³C values, one group consisting of three populations with mean ¹³C values ca.-26 and another group with ¹³C values ca.-28. Less negative ¹³C values appeared to be associated with reduced physiological availability of soil moisture resulting from hypoxic conditions at a poorly drained high elevation bog site and from low precipitation at a welldrained, low elevation leeward site. Gas exchange measurements indicated that foliar ¹³C and intrinsic wateruse efficiency were positively correlated. Maximum photosynthetic rates were nearly constant while maximum stomatal conductance varied substantially in individuals with foliar ¹³C ranging from-29 to-24. In contrast with the patterns of ¹³C observed, leaf nitrogen content appeared to be genetically determined and independent of site characteristics. Photosynthetic nitrogenuse efficiency was nearly constant over the range of ¹³C observed, suggesting that a compromise between intrinsic water- and N-use efficiency did not occur. In one population variations in foliar ¹³C and gas exchange with leaf cohort age, caused the ratio of intercellular to atmospheric partial pressure of CO₂ predicted from gas exchange and that calculated from ¹³C to be in close agreement only in the two youngest cohorts of fully expanded leaves. The results indicated that with suitable precautions concerning measurement protocol, foliar ¹³C and gas exchange measurements were reliable indicators of potential resource use efficiency by M. polymorpha along environmental gradients.     

Keeling plots for hummingbirds: a method to estimate carbon isotope ratios of respired CO<Subscript>2</Subscript> in small vertebrates

The carbon isotope composition of an animals breath reveals the composition of the nutrients that it catabolizes for energy. Here we describe the use of Keeling plots, a method widely applied in ecosystem ecology, to measure the ¹³C of respired CO₂ of small vertebrates. We measured the ¹³C of Rufous Hummingbirds (Selasphorus rufus) in the laboratory and of Mourning (Zenaida macroura) and White-winged (Z. asiatica) Doves in the field. In the laboratory, when hummingbirds were fed a sucrose based C3 diet, the ¹³C of respired CO₂ was not significantly different from that of their diet (¹³C_{C3 diet}). The ¹³C of respired CO₂ for C3 fasted birds was slightly, albeit significantly, depleted in ¹³C relative to ¹³C_{C3 diet}. Six hours after birds were shifted to a sucrose based C4 diet, the isotopic composition of their breath revealed that birds were catabolizing a mixture of nutrients derived from both the C3 and the C4 diet. In the field, the ¹³C of respired CO₂ from Mourning and White-winged Doves reflected that of their diets: the CAM saguaro cactus (Carnegeia gigantea) and C3 seeds, respectively. Keeling plots are an easy, effective and inexpensive method to measure ¹³C of respired CO₂ in the lab and the field.     

Fugu immunoglobulin D: a highly unusual gene with unprecedented duplications in its constant region

We have isolated and characterized the cDNA that encodes IgD of fugu (Takifugu rubripes). Though the splicing of 1 with the 1 domain was similar to those reported for teleost IgDs, highly unusual and unprecedented domain duplications were found in the constant region of the fugu IgD. The structure of the fugu IgD is like VDJ-1-(1-2-3-4-5-6)₂-7-m1-m2. Genomic sequence analysis of the fugu IgD gene supported the results of cDNA sequencing that the first six domains in the constant region are duplicated. Such a novel duplication pattern has not been reported in any other vertebrates. However, IgD secretory domains could not be identified in this study. The deduced amino acid sequence of the fugu IgD constant region showed high identity (35–55%) to the sequences of previously reported teleost IgDs. Gene expression analyses based on RT-PCR demonstrated that the IgD gene is preferentially expressed in presumptive lymphoid tissues; moreover, in situ hybridization showed that IgD-positive cells are distributed throughout the spleen and head kidney. The expression pattern is similar to that of IgM, corroborating the hypothesis that IgD plays an important role in the humoral immune system of this species.The nucleotide sequence data reported in this paper will appear in the DDBJ/EMBL/GenBank nucleotide sequence databases with the accession numbers AB159481 and AB159482.     

Attempt at quantitative analysis of interindividual variability in stress response of leucocyte levels in mice from the viewpoint of control theory

Summary The authors studied the dependence between the ability of systems regulating the level of peripheral leucocytes to damp the fluctuations of this level, occurring under conditions of repeated stressing of the organism by non-specific stress factors (isolation, starvation, handling for blood withdrawal) and the tolerance of the organism to the action of ionizing radiation (summary exposure to X-rays leading to death at repeated irradiation). This regulatory ability was expressed with the aid of the slope (coefficientb) of regression between the leucocytary valuesx _i, fluctuating in time, and the subsequent differences _i ( _i =x _i+1–x _i ). The highest tolerance to lethal action of radiation is correlated to such a regulatory behaviour of the organism at which the time necessary for adaptation of the system is shortest. The authors point out the suitability of the employed regulatory characteristic for the quantitative study of adaptability and resistance of the organism and its relatedness to the damping ratio, used in the automatic control theory.     

Central nervous versus total body thermosensitivity of the duck

Ducks were chronically implanted with thermodes in the POAH region, the lower brainstem or the vertebral canal. At thermoneutral conditions, lowering the temperature of the spinal cord (T_vc) or the lower brainstem (T_mb) stimulated metabolic heat production (M) with a subsequent rise of core temperature (T_c). Lowering the temperature of the POAH region (T_hy) induced a fall of T_c due to paradoxical activation of heat defence and, thus, induced slight to moderate general hypothermia depending on the cooling intensity. When T_hy was normalized, the hypothermia temporarily stimulated metabolic heat production until T_c was normalized. Cold sensitivity of the entire body, as revealed by the metabolic response to the hypothermia induced by preceding POAH cooling, and cold sensitivity of the spinal cord and the lower brainstem, as revealed by the metabolic response to local cooling, were quantified by calculating the quotient M/T from the maximum metabolic response and the experimentally induced drop of T_c, T_mb and T_vc. With lower brainstem cooling M/T_mbdid not exceed –0.4 W/(kg · C). With spinal cord cooling, M/T_vc did not exceed –0.6 W/(kg · C). The mean value of M/T_c after hypothermia induced by POAH cooling was –4.02 W/(kg · C). The results indicate that the cold sensitivity residing in the CNS of ducks represents only a small fraction of the entire cold sensitivity of the body.Presented at the Eighth International Congress of Biometeorology, 9–14 September 1979, Shefayim, Israel.     

Biosynthesis,cDNA and amino acid sequences of a precursor of conglutin δ, a sulphur-rich protein from Lupinus angustifolius

The biosynthesis of conglutin has been studied in developing cotyledons of Lupinus angustifolius L. Precursors of conglutin formed the major sink for [³⁵S]-cysteine incorporated by developing lupin cotyledons, and these precursors were rapidly sequestered into the endoplasmic reticulum. The sequence of a cDNA clone coding for one such precursor of conglutin was determined. The structure of the precursor polypeptide for conglutin predicted from the cDNA sequence contained an N-terminal leader peptide of 22 amino acids directly preceding a subunit polypeptide of M _r 4520, together with a linking region of 13 amino acids and a subunit polypeptide of M _r 9558 at the C-terminus. The amino acid sequence predicted from the cDNA sequence showed minor variations from that established by sequencing of the protein purified from mature dried seeds (Lilley and Inglis, 1986). These were consistent with the existence of a multi-gene family coding for conglutin . Comparison of the sequences of conglutin with those of other 2S storage proteins showed that the cysteines involved in internal disulphide bridges between the mature subunits of conglutin , were maintained throughout this family of proteins but that little else was conserved either at the protein or DNA level.     

Stable oxygen isotopes in<Emphasis Type="Italic"> Porites</Emphasis> corals monitor weekly temperature variations in the northern Gulf of Aqaba,Red Sea

In order to assess the ability of Porites corals to accurately record environmental variations, high-resolution (weekly/biweekly) coral ¹⁸O records were obtained from four coral colonies from the northern Gulf of Aqaba, which grew at depths of 7, 19, 29, and 42 m along one transect. Adjacent to each colony, hourly temperatures, biweekly salinities, and monthly ¹⁸O of seawater were continuously recorded over a period of 14 months (April 1999 to June 2000). Contrary to water temperature, which shows a regular and strong seasonal variation and change with depth, seawater ¹⁸O exhibits a weak seasonality and little change with depth. Positive correlations between seawater ¹⁸O and salinity were observed. The two parameters were related to each other by the equation ¹⁸O _Seawater (, VSMOW) = 0.281 × Salinity – 9.14. The high-resolution coral ¹⁸O records from this study show a regular pattern of seasonality and are able to capture fine details of the weekly average temperature records. They resolve more than 95% of the weekly average temperature range. On the other hand, attenuation and amplification of coral seasonal amplitudes were recorded in deep, slow-growing corals, which were not related to environmental effects (temperature and/or seawater ¹⁸O) or sampling resolution. We propose that these result from a combined effect of subannual variations in extension rate and variable rates of spine thickening of skeletal structures within the tissue layer. However, no smoothing or distortion of the isotopic signals was observed due to calcification within the tissue layer in shallow-water, fast-growing corals. The calculations from coral ¹⁸O calibrations against the in situ measurements show that temperature (T) is related to coral ¹⁸O ( _c ) and seawater ¹⁸O ( _w ) by the equation T (°C) = –5.38 ( _c – _w ) –1.08. Our results demonstrate that coral ¹⁸O from the northern Gulf of Aqaba is a reliable recorder of temperature variations, and that there is a minor contribution of seawater ¹⁸O to this proxy, which could be ignored.     

Conformationally constrained opioid peptide analogs with novel activity profiles

Novel conformationally constrained opioid peptide analogs with antagonist, mixed agonist/ antagonist or agonist properties were developed. TIP(P)-related antagonists showed unprecedented antagonist potency and receptor selectivity, and may have potential for use in analgesia in combination with agonists. A definitive model of their receptor-bound conformation was developed. Three prototype mixed agonist/ antagonists were discovered. They represent the only known compounds with this pharmacological profile and, as expected, one of them was shown to be a potent analgesic and to produce no dependence and less tolerance than morphine. Novel dipeptide derivatives turned out to be potent and selective agonists. Because of their low molecular weight and lipophilic character, these compounds may cross the blood-brain barrier and, thus, may have potential as centrally acting analgesics.     

Sources of nitrate in rivers draining sixteen watersheds in the northeastern U.S.: Isotopic constraints

The feasibility of using nitrogen and oxygenisotope ratios of nitrate (NO₃ ^–) forelucidating sources and transformations ofriverine nitrate was evaluated in a comparativestudy of 16 watersheds in the northeastern U.S.A. Stream water was sampled repeatedly at theoutlets of the watersheds between January andDecember 1999 for determining concentrations,¹⁵N values, and ¹⁸Ovalues of riverine nitrate.In conjunction with information about land useand nitrogen fluxes,¹⁵N_nitrate and¹⁸O_nitrate values providedmainly information about sources of riverinenitrate. In predominantly forested watersheds,riverine nitrate had mean concentrations ofless than 0.4 mg NO₃ ^–-N L^–1,¹⁵N_nitrate values of lessthan +5, and ¹⁸O_nitratevalues between +12 and +19. This indicatesthat riverine nitrate was almost exclusivelyderived from soil nitrification processes withpotentially minor nitrate contributions fromatmospheric deposition in some catchments. Inwatersheds with significant agricultural andurban land use, concentrations of riverinenitrate were as high as 2.6 mg NO₃ ^–-NL^–1 with ¹⁵N_nitratevalues between +5 and +8 and¹⁸O_nitrate values generallybelow +15. Correlations between nitrateconcentrations, ¹⁵N_nitratevalues, and N fluxes suggest that nitrate inwaste water constituted a major, and nitrate inmanure a minor additional source of riverinenitrate. Atmospheric nitrate deposition ornitrate-containing fertilizers were not asignificant source of riverine nitrate inwatersheds with significant agricultural andurban land use. Although complementary studiesindicate that in-stream denitrification wassignificant in all rivers, the isotopiccomposition of riverine nitrate sampled at theoutlet of the 16 watersheds did not provideevidence for denitrification in the form ofelevated ¹⁵N_nitrate and¹⁸O_nitrate values. Relativelylow isotopic enrichment factors for nitrogenand oxygen during in-stream denitrification andcontinuous admixture of nitrate from theabove-described sources are thought to beresponsible for this finding.     

Natural<Superscript>15</Superscript> N Abundance of Plants and Soil N in a Temperate Coniferous Forest

Measurement of nitrogen isotopic composition (¹⁵N) of plants and soil nitrogen might allow the characteristics of N transformation in an ecosystem to be detected. We tested the measurement of ¹⁵N for its ability to provide a picture of N dynamics at the ecosystem level by doing a simple comparison of ¹⁵N between soil N pools and plants, and by using an existing model. ¹⁵N of plants and soil N was measured together with foliar nitrate reductase activity (NRA) and the foliar NO₃^– pool at two sites with different nitrification rates in a temperature forest in Japan. ¹⁵N of plants was similar to that of soil NO₃^– in the high-nitrification site. Because of high foliar NRA and the large foliar NO₃^– pool at this site, we concluded that plant ¹⁵N indicated a great reliance of plants on soil NO₃^– there. However, many ¹⁵N of soil N overlapped each other at the other site, and ¹⁵N could not provide definitive evidence of the N source. The existing model was verified by measured ¹⁵N of soil inorganic N and it explained the variations of plant ¹⁵N between the two sites in the context of relative importance of nitrification, but more information about isotopic fractionations during plant N uptake is required for quantitative discussions about the plant N source. The model applied here can provide a basis to compare ¹⁵N signatures from different ecosystems and to understand N dynamics.     

Primate hemoglobins: Some sequences and some proposals concerning the character of evolution and mutation

During a multipurpose survey we examined electrophoretic mobilities of major (A, i.e., ₂₂) and minor (A₂, i.e., ₂₂) adult hemoglobins from populations of nine primate genera representing a total of 440 New World monkeys and apes. Sequences of hemoglobin chains were inferred from differences in amino acid composition between homologous tryptic peptides supplemented by detailed placement of more than 270 residues. Beta sequences were thus analyzed in five genera (Aotus, Ateles, Hylobates, Saimiri, and Saguinus) and sequences in seven (foregoing plus Gorilla and Pan). In most genera, sequences from several individuals, often from several species, were delineated. Fifteen kinds of intraspecies mutants were detected; 10 of these were precisely characterized. Five of the 15 mutants form electrophoretically detected genetic polymorphisms of ; none such occur in . Six electrophoretically detected mutants, four in and two in , are uncommon. One of these represents the complete absence of minor component. Three kinds of variants, two in and one in , are electrophoretically neutral and chance findings during sequence analysis of the equivalent of 38 allele products. Two of the neutral variants are not especially common; one may have polymorphic frequency. Several general conclusions stem from these and supplementary findings. First, comparisons of sequences suggest that and genes in all primates either arose from a single event in a common ancestor or from two approximately coincident events. Either assumption allows reconstruction of a reasonably accurate archetype sequence that is effectively common to all descendants. Second, there is a pancellular quantitative disproportion between major and minor hemoglobins ranging from 16:1 to 220:1 in species studied. Delta is consequently presumed to be functionally and adaptively less vital than . When these premises are adopted, is expected to be relatively invisible to natural selection, and, where darwinism is the principal arbiter of evolution and polymorphism, is expected to show fewer fixed changes and fewer genetic polymorphisms than . The opposite is observed. Delta exhibits as many or more changes from archetype than . This finding and the comparative abundance of polymorphism are attributed to nonadaptive factors which are thus considered the source of much evolutionary change. Third, particular sequence positions in various species are the site of recurrent mutations in both and . One such area is occupied by the majority of genetic polymorphisms found in man and other primates. The overall distribution of mutations arising in evolution is remarkably nonrandom in , , and a pool of both. These results are quite unlike most other observations in higher organisms. The sources of such nonrandomness are either selection and/or differential mutability. We rely on our prior assumption of relative selective invisibility for and, in part, ascribe the nonrandom distribution of changes to microzones of enhanced mutability. Fourth, the six uncommon electrophoretically detected mutants provide an estimate of heterozygosity (1/73) at hemoglobin loci that is tenfold greater than observed in man. Fifth, the unprecedented chance detection of three kinds of electrophoretically neutral intraspecies mutants among the equivalent of 38 characterized allele products suggests that neutral changes are as common as electrostatically active ones and at least tenfold more common than expected in extrapolation from human variant surveys. Sixth, analyses from three kinds of gibbon (Hylobates) hemoglobin suggest that one of these is a potentially unchanged relict of the ancient archetype and, further, indicate a degree of homozygous diversity within a species that nearly equals the difference between gibbon and man.This investigation received support from grants to S.H.B., HD-02508-04 and K3-GM-6308-03, from the National Institutes of Health.     

Autotrophic carbon sources for heterotrophic bacterioplankton in a floodplain lake of central Amazon

The relative contribution of autotrophic carbon sources (aquatic macrophytes, flooded forest, phytoplankton) for heterotrophic bacterioplankton was evaluated in a floodplain lake of the Central Amazon. Stable carbon isotopes (¹³C) were used as tracers. Values of ¹³C of different autotrophic sources were compared to those of dissolved organic carbon (DOC) and those of bacterially produced CO₂.The percentage of carbon derived from C₄ macrophytes for bacterially produced CO₂ was the highest, on average 89%. The average ¹³C value of CO₂ from bacterial respiration was –18.5 ± 3.3. Considering a fractionation of CO₂ of 3 by bacterial respiration, ¹³C value was –15.5, near C₄ macrophyte ¹³C value (–13.1).The average value of total DOC ¹³C was –26.8 ± 2.4. The percentage of C₄ macrophytes carbon for total DOC was on average 17%. Considering that bacteria consume mainly carbon from macrophytes, the dominance of C₃ plants for total DOC probably reflects a faster consumption of the former source, rather than a major contribution of the latter source.Heterotrophic bacterioplankton in the floodplain may be an important link in the aquatic food web, transferring the carbon from C₄ macrophytes to the consumers.     

Current–voltage–time records of ion translocating enzymes

Membrane currents, as non-linear functions of membrane voltage, V, and time, t, can be recorded quickly by triangular V protocols. From the differences, dI(V,t), of these relationships upon addition of a putative substrate of a charge-translocating membrane protein, the I(V,t) relationships of the transporter itself can be determined. These relationships likely comprise a steady-state component, I_a(V), of the active transporter, and a dynamic component, p_a(V,t), of its V- and time-dependent activity, p_a. Here, the steady-state component is modeled by a central reaction cycle, which senses a fraction _tr of the total V, whereas 1–_tr can be assigned to an inner and outer pore section with _i and _o, respectively (_i+_tr+_o = 1). For the enzymatic cycle, fast binding/debinding is assumed, plus V-sensitive and -insensitive reaction steps which may become rate limiting for charge translocation. At given substrate concentrations, I_a(V) is defined by eight independent system parameters, including a coefficient for the barrier shape of charge translocation. In ordinary cases, the behavior of p_a(V,t) can be described by two rate constants (for activation and inactivation) and their respective V-sensitivity coefficients. Here, the effects of the individual system parameters on I(V,t) from triangular V-clamp experiments are investigated systematically. The results are illustrated by panels of typical curve shapes for non-gated and gated transporters to enable a first classification of mechanisms. We demonstrate that all system parameters can be determined fairly well by fitting the model to experimental data of known origin. Applicability of the model to channels, pumps and cotransporters is discussed.     

Photoinactivation of δ-aminolevulinic acid dehydratase from maize by flavin mononuclotide

The -aminolevulinic acid dehydratase activity was irreversibly inactivated by irradiation of the enzyme in presence of flavin mononucleotide. The loss of enzyme activity was dependent on time of irradiation, concentration of FMN and intensity of irradiance. It required oxygen and was markedly enhanced in heavy water. The presence of levulinic acid (a competitive inhibitor of -ALAD) during irradiation prevented the inactivation considerably indicating photooxidative damage at or near the active site. Superoxide dismutase, sodium benzoate and sodium formate offered no protection, but singlet oxygen quenchers like azide and tryptophan were effective. NADH, electron donor to excited flavins, also prevented the loss of enzyme activity. These results indicate that singlet oxygen produced by light absorption of FMN was responsible for the photooxidative inhibition of the enzyme.Abbreviations ALAD -aminolevulinic acid dehydratase - FMN flavin mononucleotide - O₂ ^- superoxide - H₂O₂ hydrogen peroxide - 10₂ singlet oxygen - LA levulinic acid - PBG porphobilinogen - BSA bovine serum albumin - BME 2-mercaptoethanol - SOD superoxide dismutase - pHMB para-hydroxymercuribenzoate - DTT dithiothreitol - FAD flavin adenine dinucleotide - NADH nicotinamide adenine dinucleotide     

The relationship between the concepts of genetic diversity and differentiation

Summary Diversity as a measure of individual variation within a population is widely agreed to reflect the number of different types in the population, taking into account their frequencies. In contrast, differentiation measures variation between two or more populations, demes or subpopulations. As such, it is based on the relative frequencies of types within these subpopulations and, ideally, measures the average distance of subpopulations from their respective lumped remainders. This concept of subpopulation differentiation can be applied consistently to a single population by regarding each individual as a deme (subpopulation) of its own, and it results in a measure of population differentiation _T which depends on the relative frequencies of the types and the population size. _T corresponds to several indices of variation frequently applied in population genetics and ecology, and it verifies these indices as measures of differentiation rather than diversity. For any particular frequency distribution of types, the diversity is then shown to be the size of a hypothetical population in which each type is represented exactly once, i. e. for which _T =1. Hence, the diversity of a population is its differentiation effective number of types. This uniquely specifies the link between the two concepts. Moreover, again corresponds to known measures of diversity applied in population genetics and ecology. While population differentiation can always be estimated from samples, the diversity of a population, particularly if it is large, may not be. In such cases, it is recommended that population differentiation is estimated and the corresponding sample diversity merely computed. Finally, a solution to the problem of measuring multi-locus diversities is provided.     

Using stable hydrogen and oxygen isotope measurements of feathers to infer geographical origins of migrating European birds

Successful application of stable-hydrogen isotope measurements (D_f) of feathers to track origins of migratory birds and other wildlife requires a fundamental understanding of the correlation between D_f and deuterium patterns in rainfall (D_p) over continental scales. A strong correlation between D_p and D_f has been confirmed for birds and insects in North America, but not yet for other continents. Here, we compare D_f data from resident European birds to new D_p basemaps for Europe. Three maps, representing growing-season and mean annual D_p estimates from an elevation-explicit, detrended interpolation model and growing-season D_p estimates from simple Kriging, all indicate that strong isotope gradients occur across Europe with a general depletion occurring in a northeast direction. The feather data, representing 141 individuals of 25 avian species from 38 sites, ranged from –131 to –38. Regression analysis showed that strong correlations existed between both mean annual and growing-season D_p estimated by detrended interpolation and D_f of non-aquatic and non-corvid birds (r²=0.66 and 0.65, respectively). We also examined mean annual and growing-season ¹⁸O_p vs. ¹⁸O_f for our samples. Both oxygen regressions were similar (r²=0.56 and 0.57, respectively) but poorer than for deuterium. Our study reveals that D measurements of feathers from migratory birds in Europe may be used to track their origin and movements, and so provide a powerful investigative tool for avian migration research in Europe.     

New organisms—novel genetics

This report describes a method for quantifying -endotoxin contents in spray-dried preparations ofBacillus thuringiensis strain GC-91. -Endotoxin is solubilized in the pro-toxin form and separated from other soluble compounds by ion exchange chromatography. The method does not discriminate between the different -endotoxins produced by strain GC-91. It is suitable for quality control, since -endotoxin concentrations found in different preparations correlate inversely with the LC 50 in bioassays on artificial diet against freshly hatched larvae ofSpodoptera littoralis. A typical batch of spray-dried material contains 1.22%±0.08% -endotoxin. The method is most accurate with preparations containing 0.5 to 2.0% toxin, for which triplicate estimations give standard errors close to±0.2%.