Race-centrism: a critique and a research agenda

This article reviews some of the most prominent books in the field of race studies in the USA and identifies their shared assumptions: that racial inequality is the primary principle of stratification in the USA; that is has transformed but not lessened since the civil rights era; that it can be explained by the racist inclinations of the white majority, which operates as a collective, strategic actor to preserve its dominance; and finally, that racial domination plays a similarly crucial role around the world. I explore what kind of questions would need to be answered in order to put these assumptions on firmer empirical and theoretical ground and outline a corresponding research agenda. Some empirical evidence is provided to question the assumption that race plays a dominant role around the world and is associated with more political inequality than ethnic divisions.     

Lipid bilayer tethered inside a nanoporous support: a solid-state nuclear magnetic resonance investigation

(31)P and (1)H solid-state nuclear magnetic resonance (NMR) experiments have been designed with the aim of studying directly the formation of supported bilayers tethered inside nanoporous aluminum oxide supports as a model of biomimetic membranes. The static and magic angle spinning (31)P NMR spectra of the supported bilayers have been compared with the experimental and simulated spectra of a simpler model with cylindrical geometry, namely a phospholipid bilayer adsorbed on an oriented polymer sheet. The broadening observed for the nanoporous model is most likely due to the presence of paramagnetic ions in the aluminum oxide. A phospholipid lateral diffusion coefficient of (2.8 +/- 0.4) x 10(-8) cm(2)/s has been measured for the tethered bilayer on a spherical support, indicating a good fluidity as compared with adsorbed membrane models.     

Skeletal growth in a medieval population from Sudanese Nubia

Long bone growth is analyzed for 180 children from a Medieval population at Kulubnarti in Sudanese Nubia (550–1450 A.D.). A regional interpopulation comparison is made with growth data from Wadi Halfa in Lower Nubia, and an intrapopulation analysis is undertaken to assess diachronic changes in growth at Kulubnarti. Changes in growth patterns are interpreted in the context of mortality and morbidity profiles and relationships between the three variables are discussed. It is suggested that changes in the sociopolitical environment may have been responsible in part for altering levels of biological stress and impacting growth.     

FAD C(4a)-hydroxide stabilized in a naturally fused styrene monooxygenase

StyA2B represents a new class of styrene monooxygenases that integrates flavin-reductase and styrene-epoxidase activities into a single polypeptide. This naturally-occurring fusion protein offers new avenues for studying and engineering biotechnologically relevant enantioselective biochemical epoxidation reactions. Stopped-flow kinetic studies of StyA2B reported here identify reaction intermediates similar to those reported for the separate reductase and epoxidase components of related two-component systems. Our studies identify substrate epoxidation and elimination of water from the FAD C(4a)-hydroxide as rate-limiting steps in the styrene epoxidation reaction. Efforts directed at accelerating these reaction steps are expected to greatly increase catalytic efficiency and the value of StyA2B as biocatalyst.     

Teaching Density with a Little Drama

This article provides an example of an innovative science activity applied in a science methods course for future elementary teachers at a small university in northeastern Turkey. The aim of the activity is to help prospective elementary teachers understand the density concept in a simple way and see an innovative teaching example.     

半红树植物黄槿的生态生物学特性研究

黄槿是一种具有重要生态、药用和观赏价值的半红树植物,在海岸生态系统中发挥重要作用。对其生态及生物学特性进行研究表明:黄槿属典型阳生性植物,具有较高的光合潜能,适于在热带亚热带地区光照充足的环境中生长。其叶绿素荧光的光合电子传递速率-光响应曲线(RLC)显示,黄槿的相对电子传递速率(rETR)随光合有效辐射(PAR)的升高而逐渐增加,并在PAR 2 751μmol.m-2.s-1时达到最大值,说明其光合系统II在强光照下也能保持较高的电子传递效率。黄槿叶绿素荧光参数显示其具有较高的能量利用效率,叶绿素a/b值(2.44∶1)略低于理论值(3∶1)。黄槿对营养元素的利用率较高,植株体内N、P、K、Ca、Na、Mg的加权平均养分含量分别为1.23%、0.23%、1.34%、0.42%、0.24%、0.41%。P含量偏低,在其栽培过程中应及时补充P元素。该研究结果将对黄槿的引种、栽培及开发利用提供重要的理论依据。     

Gibberellin structure and florigenic activity in Lolium temulentum,a long-day plant

Structural requirements for florigenic activity among gibberellins (GAs) and GA derivatives, including several new ones, applied once to leaves of Lolium temulentum, were examined. The compounds were applied to plants kept either in non-inductive short days (SD) or exposed to one inductive long day (LD). Inflorescence initiation and stem-elongation responses were assessed three weeks later. Among the GAs used, the range in effective dose for inflorescence initiation was more than 1000-fold, but substantially less for stem elongation. Some GAs promoted both stem elongation and inflorescence initiation, some promoted one without the other, and some affected neither. The structural features enhancing florigenic activity were often different from those enhancing stem elongation. Except in the case of 2,2-dimethyl GA₄, a double bond in the A ring at either C-1,2 or C-2,3 was essential for high florigenic activity, though not for stem elongation. A free carboxy group was needed for both. Inflorescence initiation in Lolium was enhanced by hydroxylation at C-12, ?13 and ?15, whereas hydroxylation at C-3 reduced the effect on inflorescence initiation but increased that on stem elongation. A 12β-hydroxyl was more effective than the α epimer for inflorescence initiation whereas the reverse was true for stem elongation. Although such differential effectiveness of GAs for inflorescence initiation and for stem elongation could reflect differences in uptake, transport or metabolism, we suggest that it is indicative of specific structural requirements for inflorescence initiation.     

Time budget of caged rhesus monkeys exposed to a companion,a PVC perch,and a piece of wood for an extended time

The present investigation assesses the percentage of time that rhesus monkeys (Macaca mulatta) are kept occupied by a more complex cage environment. Sixty animals were continuously exposed for at least 1.5 years to a compatible companion for social interaction, a suspended plastic pipe for perching, and a branch segment for gnawing. The behavior of the partners of each pair was recorded for 60 minutes when the animals were not distracted by human activities. Individuals spent an average of 23.5% of the time interacting with the companion, but only 10.4% with the plastic pipe and 4.8% with the branch segment. Differences were statistically significant. Females were socially more active than males. Subadult animals (3.5–4 years) used both inanimate objects significantly more than did adult animals (9–30 years). It was concluded that (1) a compatible companion, a suspended plastic pipe, and a loose branch segment remain effective stimuli for caged rhesus monkeys after more than 1 year of exposure and (2) a compatible companion is of greater stimulatory value–particularly for adults–than are inanimate objects.     

Egg maturation strategy and its associated trade-offs: a synthesis focusing on Lepidoptera

Abstract. 1. Insects vary considerably between and within orders, and even within the same genus, in the degree to which the female's lifetime potential egg complement is mature when she emerges as an adult. 2. The ‘ovigeny index’ (OI) – the number of eggs females have ready to lay divided by the lifetime potential fecundity – quantifies variation in the degree of early life concentration of egg production, and also variation in initial reproductive effort. 3. Here, an integrated set of hypotheses is presented, based on a conceptual model of resource allocation and acquisition, concerning trade‐offs at the interspecific level between initial investment in egg production (as measured by OI) and other life‐history traits in holometabolous insects. 4. The evidence supporting each of these hypotheses is reviewed, and particular attention is paid to the Lepidoptera, as relevant life‐history data are rapidly accumulating for this ecologically and economically important group. 5. There is evidence at the interspecific level supporting: (i) a link between OI and a trade‐off between soma and non‐soma in Trichoptera and Hymenoptera (the proportionate allocation to soma decreases with increasing OI); (ii) a negative correlation between OI and dependency on external nutrient inputs (via adult feeding) in Hymenoptera and in Lepidoptera; (iii) a negative correlation between OI and the degree of polyandry (and nuptial gift, i.e. spermatophore, use) in Lepidoptera; (iv) negative correlations between OI and resource re‐allocation capabilities (egg and thoracic musculature resorption) in Hymenoptera and in Lepidoptera; (v) a negative correlation between lifespan and OI in Trichoptera, Hymenoptera, and Lepidoptera, indicating a cost of reproduction; (vi) a link between winglessness and an OI of one in Lepidoptera; (vii) a negative correlation between OI and the degree of female mobility in winged Lepidoptera; and (viii) a negative correlation between OI and larval diet breadth (as mediated by oviposition strategy) in Lepidoptera.     

Spatial heterogeneity as a multiscale characteristic of zooplankton community

Zooplankton spatial heterogeneity has profound effects on understanding and modelling of zooplankton population dynamics and interactions with other planktonic compartments, and consequently, on the structure and function of planktonic ecosystems. On the one hand, zooplankton heterogeneity at spatial and temporal scales of ecological interest is an important focus of aquatic ecology research because of its implications in models of productivity, herbivory, nutrient cycling and trophic interactions in planktonic ecosystems. On the other hand, estimating zooplankton spatial variation at the scale of an ecosystem, is a powerful tool to achieve accurate sampling design. This review concentrates on the spatial heterogeneity of marine and freshwater zooplankton with respect to scale. First to be examined are the concept of spatial heterogeneity, the sampling and statistical methods used to estimate zooplankton heterogeneity, and the scales at which marine and freshwater zooplankton heterogeneity occurs. Then, the most important abiotic and biotic processes driving zooplankton heterogeneity over a range of spatial scales are presented and illustrated by studies conducted over large and fine scales in both oceans and lakes. Coupling between abiotic and biotic processes is finally discussed in the context of the multiple driving forces hypothesis.Studies of zooplankton spatial heterogeneity refer both to the quantification of the degree of heterogeneity (measured heterogeneity) and to the estimation of the heterogeneity resulting from the interactions between the organisms and their environment (functional heterogeneity) (Kolasa & Rollo, 1991). To resolve the problem of measuring zooplankton patchiness on a wide range of spatial scales, advanced technologies (acoustic devices, the Optical Plankton Counter (OPC), and video systems) have been developed and tested in marine and freshwater ecosystems. A comparison of their potential applications and limitations is presented. Furthermore, many statistical tools have been developed to estimate the degree of measured heterogeneity; the three types most commonly used are indices of spatial aggregation, variance: mean ratio, and spatial analysis methods. The variance partitioning method proposed by Borcard et al. (1992) is presented as a promising tool to assess zooplankton functional heterogeneity.Nested patchiness is a common feature of zooplankton communities and spatial heterogeneity occurs on a hierarchical continuum of scales in both marine and freshwater environments. Zooplankton patchiness is the product of many physical processes interacting with many biological processes. In marine systems, patterns of zooplankton patchiness at mega- to macro-scales are mostly linked to large advective vectorial processes whereas at coarse-, fine- and micro-scales, physical turbulence and migratory, reproductive and swarm behaviors act together to structure zooplankton distribution patterns. In freshwater environments, physical advective forces related to currents of various energy levels, and vertical stratification of lake interact with biological processes, especially with vertical migration, to structure zooplankton community over large to fine- and micro-scales. Henceforth, the zooplankton community must be perceived as a spatially well-structured and dynamic system that requires a combination of both abiotic and biotic explanatory factors for a better comprehension and more realistic and reliable predictions of its ecology.     

关于苏北地区某三甲医院进口与国产医疗设备和耗材使用情况及反馈的研究．

目的：初步了解了进口与国产医疗设备与耗材的发展状况和使用反馈情况,并对国内医疗设备与耗材行业的发展提供合理化建议。方法：通过对苏北地区某三级甲等医院设备科工作人员、医生、护士长、患者及患者家属进行调研或访谈,并以调研和访谈的统计结果为依据得出结论并提出建议。结果：技术成熟的中小型医疗设备或耗材,从质量、价格等因素综合考虑,国内产品优于进口产品,一定程度上得到了医务人员和消费者的认可。在高端大中型医疗设备与耗材方面,进口产品具有较大的技术优势。结论：国内医疗设备生产企业应当积极开展研发工作,提高产品的技术含量与质量,巩固自身在中小型医疗设备与耗材方面的优势,并努力在高端大中型医疗设备与耗材方面取得突破。     

The hippocampus and memory: a comparative and ethological perspective

During the past year, considerable progress has been made in our understanding of the wide-ranging functions of the hippocampus. Highlights include the development of new tasks with which to assess spatial/topographic memory in humans and monkeys, novel tests of relational memory in rats, and episodic-like memory tasks in birds. In addition, novel theories of hippocampal function have been developed that are notable for their applicability to both humans and animal models.     

Impacts of urbanization in a biodiversity hotspot: Conservation challenges in Metropolitan Cape Town

The City of Cape Town (City) covers 2460 km² in the southwestern corner of the Cape Floristic Region biodiversity hotspot. Established in 1654, by 1700 there were no animals larger than 50 kg within 200 km of the City. However, apart from an appreciation that timber and firewood were becoming scarce, it was only in the 1930s that the first farm near Cape Point was set aside for conservation. Table Mountain was declared a National Monument in 1958, while it was largely covered by pine and gum plantations. Conservation of the montane areas thereafter expanded, whereas the lowlands were largely ignored, except for a few bird sanctuaries. Only in 1982 was the plight of the lowlands highlighted. Although ad hoc conservation planning was undertaken subsequently, 1997 saw the first priority categorization and conservation plan. The current situation is perilous: a huge effort will be required to meet basic conservation targets for the lowland vegetation types and threatened species. Local and international partners and funders will be key to achieving this. In eight of the City's 19 national vegetation types the minimum conservation targets are not achievable. Of the 3250 plant species estimated to occur in the City, 13 are extinct and 319 are threatened according to the IUCN Red List: this is 18% of the threatened Red List species in South Africa. Now for the first time, implementation is being attempted holistically across the metropole with discussion between internal City and external stakeholders to implement the conservation plan. However, the interim plans towards achieving this — that 60% of the unproclaimed target is secured by 2014, requires that over 40 km² be conserved per annum. This leaves 340 km² that should be secured by 2020 when projections from City spatial growth indicate that the last critical remnants will be urbanized.     

A new chapter for a better Bioscience Reports

As Bioscience Reports enters its fifth decade of continuous multidisciplinary life science publishing, here we present a timely overview of the journal. In addition to introducing ourselves and new Associate Editors for 2021, we reflect on the challenges the new Editorial Board has faced and overcome since we took over the editorial leadership in June of 2020, and detail some key strategies on how we plan to encourage more submissions and broader readership for a better and stronger journal in the coming years.     

Interconversions of Chlorophylls a and b Synthesized from Exogenous Chlorophyllides a and b in Etiolated and Post-Etiolated Rye Seedlings

A comparative study of reciprocal conversions of chlorophylls a and b (Chl aand Chl b) in etiolated and post-etiolated rye seedlings (Secale cereale L.) was performed. The production of these pigments was initiated by infiltration of exogenous chlorophyllides a and b (Chlide a and b). It was shown that Chlide b, when infiltrated into etiolated rye seedlings, was esterified, producing Chl b. A major portion of Chl b (more than 80%) was transformed into Chl aduring long-term seedling dark exposure. The high rate of Chl b conversion into Chl a in the pool of pigments of exogenous origin was also observed during the lag-phase when there was no chlorophyll formation from endogenous precursors. The infiltration of Chlide a resulted in Chl a formation. The efficiency of its conversion into Chl b was low (about 1%) in the etiolated seedlings but increased during their greening. In the post-etiolated seedlings infiltrated with Chlide b, which were preliminary illuminated for 6–12 h, the Chl /Chl a ratio was almost similar in the pools of pigments synthesized from both exogenous and endogenous precursors. The rates of direct and reverse reactions responsible for the interconversion of Chl aand Chl b depended on the stage of the formation of the photosynthetic apparatus during greening of etiolated seedlings, when the particular structural components are formed in a definite sequence.     

关于苏北地区某三甲医院进口与国产医疗设备和耗材使用情况

目的:初步了解了进口与国产医疗设备与耗材的发展状况和使用反馈情况,并对国内医疗设备与耗材行业的发展提供合理化建议。方法:通过对苏北地区某三级甲等医院设备科工作人员、医生、护士长、患者及患者家属进行调研或访谈,并以调研和访谈的统计结果为依据得出结论并提出建议。结果:技术成熟的中小型医疗设备或耗材,从质量、价格等因素综合考虑,国内产品优于进口产品,一定程度上得到了医务人员和消费者的认可。在高端大中型医疗设备与耗材方面,进口产品具有较大的技术优势。结论:国内医疗设备生产企业应当积极开展研发工作,提高产品的技术含量与质量,巩固自身在中小型医疗设备与耗材方面的优势,并努力在高端大中型医疗设备与耗材方面取得突破。     

Catch and release of concanavalin A by a mannose-immobilized photoaffinity PEGA resin coupled with a cleavable disulfide linker

A photoaffinity PEGA resin containing mannose as a ligand and disulfide as a cleavable linker was prepared. The resin was crosslinked to concanavalin A, a binding protein of mannose, by UV irradiation, and the protein was subsequently released by cleavage of the disulfide linker.     

On Characterizing Some Discrete Distributions by a Conditional Distribution and a Regression Function

In this paper we consider characterizations of the binomial, negative binomial, hypergeometric, negative hypergeometric, multinomial and multivariate hypergeometric distributions, by linear regression of one random variable (vector) on the other and the conditional distribution of the other random variable (vector) given the first. It is also indicated how these results can be used in genetics.     

Platelet activating factor-acetylhydrolase in insects: Identification and partial characterization of a 1-alkyl-2-acetyl-sn-glycero-3-phosphocholine acetylhydrolase in a cell-free system of Heliothis

A specific acetylhydrolase that inactivates platelet activating factor (PAF; 1-alkyl-2-acetyl-sn-glycero-3-phosphocholine), a potent cellular mediator in mammalian cells, by removal of the sn-2 acetyl moiety, has been found in the cytosolic fraction of several postembryonic developmental stages and specific tissues of the corn earworm, Heliothis zea (Boddie). Effects of magnesium, calcium, EGTA, deoxycholate, dithiothreitol, diisopropylfluorophosphate, egg phosphatidylcholine, and an acylacetyl-glycerophosphocholine show that hydrolysis of the acetate moiety is due to a specific acetylhydrolase for PAF. The activity does not appear to be due to a typical cellular phospholipase A₂ that utilizes phospholipid substrates with a long-chain acyl group at position sn-2 of glycerol. Specific activities and properties of the acetylhydrolase from this insect match closely with those described from tissues of vertebrate animals.