Beyond the “The ‘diaspora’ diaspora”: a response to Rogers Brubaker

In this short reflection, I revisit Rogers Brubaker’s influential 2005 article on “The ‘diaspora’ diaspora”. I consider the key arguments of this important intervention, before addressing three key conceptual issues in diaspora studies: (i) the role of place, origin and scale; (ii) diaspora, race and difference; (iii) sociological and historical approaches to diaspora. In the concluding section, I briefly consider some new directions in diaspora studies.     

The cytotoxic T-lymphocyte response to HTLV-I: the main determinant of disease?

There is a powerful, chronically activated cytotoxic T-lymphocyte (CTL) response to the Tax protein of human T-cell leukaemia virus type I (HTLV-I) in most people infected with the virus. The CTL select variant sequences of Tax which escape immune recognition and interfere with recognition of the wild-type protein. This positive selection process is more efficient in healthy HTLV-I carriers than in patients with tropical spastic paraparesis, an inflammatory neurological disease associated with HTLV-I. The mean virus load is more than 10-fold greater in patients with this neurological disease than in healthy carriers of HTLV-I. We conclude that anti-Tax CTL play an important part in limiting the rate of replication of HTLV-I. We suggest that the outcome of infection with HTLV-I is primarily determined by the CTL response of the individual: low CTL responders to HTLV-I develop a high virus load, resulting in widespread chronic activation of T cells. The activated T cells then invade the tissues and cause bystander tissue damage, probably by releasing cytokines and other soluble substances. An efficient CTL response to HTLV-I limits the equilibrium virus load, and so reduces the chance of developing inflammatory disease.     

The role of autophagy in neonatal tissues: just a response to amino acid starvation?

Autophagy is activated soon after birth in neonatal tissues and is essential for survival because mice deficient in Atg5 or Atg7 autophagy genes die within 1 day after birth. Amino acid starvation has been considered as a major deleterious effect of autophagy deficiency, since the concentration of amino acids in plasma was decreased by 20% in the two knockout models, whereas blood glucose and fatty acid levels were apparently not affected. However, autophagy may have other important functions in neonatal physiology, including glycogen degradation, programmed cell remodeling and response to oxidative stress.     

Is the response of aphids to alarm pheromone stable?

Aphid taxa are characterized by a number of biological features, such as their feeding behaviour and host selection, which it is generally accepted are affected by keeping them for several generations under standard conditions in a laboratory. Analyses of three strains of the green pea aphid, Acyrthosiphon pisum (Harris, 1776), reared in culture for long periods, indicate that other characters are also affected. For example, the response of these aphids to alarm pheromone is dramatically reduced. This raises an interesting question regarding the mechanism by which it occurs and has consequences when aphids from laboratory cultures are used for studies in ecology and applied biology and especially the long‐term effectiveness of crop plants genetically engineered to produce EBF as a means of controlling aphids.     

The immune response of allophenic mice to the synthetic polymer GLΦ

The immune response of allophenic mice of type C57BL/6(A × SJL) F₁ to GL administered in complete Freund's adjuvant was tested. Control mice of the three strains C57BL/6, A, and SJL are all nonresponders to this antigen. However, the F₁ generations of C57BL/6 × A, C57BL/6 × SJL, and A × SJL were all responders to the antigen, so that the complementarity of at least two genes is confirmed. The allophenic mice showed no further complementation beyond the F₁ generation, a result which may argue against the possibility that more than two genes control the response to GL in these mouse strains. Characterization of the allophenic mice over several months showed that they exhibit chimeric drift, both in their coat color and in peripheral white blood cell population. There is no apparent correlation of coat color to the lymphocyte composition of the mice at any one time. The mice are true chimeras, since killing of the two populations of white blood cells with two different anti-H-2 sera produced a 100 percent killing. The immune response of individual allophenic mice to GL showed a good correlation to the number of A × SJL lympho-cytes in the animal.Abbreviations used in this paper are GL an amino acid polymer of 57 %l-glutamic acid, 38%l-lysine, and 5%l-phenylalanine - GLT¹⁵ an amino acid polymer ofl-glutamic acid,l-lysine, and 15 %l-tyrosine - (T,G)-A-L an amino acid polymer having a polylysine backbone with side chains of polyd-l-alanine, terminating in short sequences of tyrosine and glutamic acid - GAT₁₀ an amino acid polymer of 60%l-glutamic acid, 30%l-alanine, and 10%l-tyrosine - GLA₅ an amino acid polymer of 57%l-glutamic acid, 38%l-lysine, and 5%l-alanine - DNP 2,4 dinitrophenyl - BGG bovine gamma globulin - FCS fetal calf serum - PWBC peripheral white blood cell - SWBC spleen white blood cell - T cell thymus-derived lymphocyte - B cell bone marrow-derived lymphocyte     

The Extraterrestrial Origin of the Homochirality of Biomolecules – Rebuttal to a Critique

Having concluded that abiotic terrestrial mechanisms would have been ineffectual for the origin of terrestrial homochirality, we have proposed an alternative extraterrestrial scenario involving stereoselective ultraviolet photolysis of the racemic constituents of interstellar grain mantles by circularly polarized synchrotron radiation from neutron stars, followed by terrestrial accretion of the resulting chiral molecules via cometary impact. Recently L. Keszthelyi (1995) has reviewed a number of our arguments and advanced several erroneous calculations and conclusions purporting to negate them. We offer here points of rebuttal to Keszthelyi's criticisms, and support our inferences with recent data regarding indigenous enantiomeric excesses of L-amino acids in the Murchison meteorite.     

Rehabilitating a biological notion of race? A response to Sesardic

The point Sesardic (Biol Philos 25: 143–162, 2010) makes about the possibility of distinguishing groups for which there is a lot of within-group variation is not sufficient to rehabilitate a biological concept of race. In this note, I sketch a number of issues that quickly arise once we delve more deeply into the relevant scientific knowledge, concepts, methods, and questions for inquiry.     

Metabolic depression: a response of cancer cells to hypoxia?

Hypoxic tumours have the worst prognosis because they are the most aggressive and the most likely to metastasize. This may be because these aggressive cancers have a hypoxic core which generates signals that activate angiogenesis which enables the supply of nutrients and oxygen to a rapidly growing outer oxidative shell. The hypoxic core is a crucial element of this hypothesis, as is the fact that the cells in the hypoxic core are inherently adapted to survive hypoxia. We reasoned therefore that cancer cells exposed to hypoxia/anoxia should show the hallmarks of adaptation to hypoxia/anoxia, i.e. a down-regulation of protein synthesis and a reverse Pasteur effect. We tested this hypothesis in transformed (MCF-7) and normal (HME) human mammary epithelial cells, by exposing both cell types to a range of oxygen concentrations, including anoxia. We find that indeed protein synthesis is down-regulated in the MCF-7, but not in the HME cells in response to anoxia. The data on glycolysis are not as clear-cut, but in the light of similar previous measurements on hypoxia-tolerant animals, is still consistent with the hypothesis.     

The Angiomotins – From discovery to function

Angiomotins were originally identified as angiostatin binding proteins and implicated in the regulation of endothelial cell migration. Recent studies have shed light on the role of Angiomotins and other members of the Motin protein family in epithelial cells and in pathways directly linked to the pathogenesis of cancer. In particular, Motins have been shown to play a role in signaling pathways regulated by small G-proteins and the Hippo–YAP pathway. In this review the role of the Motin protein family in these signaling pathways will be described and open questions will be discussed.     

Is the response of coral calcification to seawater acidification related to nutrient loading?

The effect of decreasing aragonite saturation state (Ω_Arag) of seawater (elevated pCO₂) on calcification rates of Acropora muricata was studied using nubbins prepared from parent colonies located at two sites of La Saline reef (La Réunion Island, western Indian Ocean): a back-reef site (BR) affected by nutrient-enriched groundwater discharge (mainly nitrate), and a reef flat site (RF) with low terrigenous inputs. Protein and chlorophyll a content of the nubbins, as well as zooxanthellae abundance, were lower at RF than BR. Nubbins were incubated at ~27°C over 2 h under sunlight, in filtered seawater manipulated to get differing initial pCO₂ (1,440–340 μatm), Ω_Arag (1.4–4.0), and dissolved inorganic carbon (DIC) concentrations (2,100–1,850 μmol kg⁻¹). Increasing DIC concentrations at constant total alkalinity (A_T) resulted in a decrease in Ω_Arag and an increase in pCO₂. A_T at the beginning of the incubations was kept at a natural level of 2,193 ± 6 μmol kg⁻¹ (mean ± SD). Net photosynthesis (NP) and calcification were calculated from changes in pH and A_T during the incubations. Calcification decrease in response to doubling pCO₂ relative to preindustrial level was 22% for RF nubbins. When normalized to surface area of the nubbins, (1) NP and calcification were higher at BR than RF, (2) NP increased in high pCO₂ treatments at BR compared to low pCO₂ treatments, and (3) calcification was not related to Ω_Arag at BR. When normalized to NP, calcification was linearly related to Ω_Arag at both sites, and the slopes of the relationships were not significantly different. The increase in NP at BR in the high pCO₂ treatments may have increased calcification and thus masked the negative effect of low Ω_Arag on calcification. Removing the effect of NP variations at BR showed that calcification declined in a similar manner with decreased Ω_Arag (increased pCO₂) whatever the nutrient loading.     

The response of Puccinellia maritima to burial: A key to understanding its role in salt‐marsh dynamics?

Abstract. The plant and sediment dynamics in salt marshes are strongly interrelated, but few data are available to document their interaction. Puccinellia maritima is a perennial grass that occurs widely in salt marshes and this study examines its role in the stabilization or trapping of sediment in the pioneer zone and its response to burial, a characteristic phenomenon in accreting salt marshes. Puccinellia not only appears to limit erosion but also to significantly enhance accretion. The functional role of this species is largely dependent on the local disturbance regime. The response of Puccinellia to burial was studied in a series of burial treatments. Growth performance of Puccinellia was stimulated by burial of 4 mm sediment and reduced by burial of 8 mm/month. Burial under 12 mm of sediment led to high mortality of up to 97%. Response was determined by the instantaneous thickness of sediment rather than by the total quantity. Morphological response to burial consisted mainly of stem elongation. Plants collected from accretion zones in the field also produced tillers with adventitious roots at successive soil layers. The range of burial tolerances found for Puccinellia fits well with its occurrence in locations with up to 8 mm sediment accretion per tidal cycle, a common situation in the salt marsh studied.     

Nitrogen isotopes of individual tree-ring series – The validity of middle- to long-term trends

Although requiring laborious analytical treatment, tree-ring series of nitrogen isotopes (δ¹⁵N) have gained popularity amongst researchers for their potential as environmental indicators as anthropogenic emissions increase globally with potential effects on forest N cycles. Previous studies suggested that tree-ring series correlate with climatic and air quality parameters. However, none discussed the level of replication required for expressing the population signals of specific species of trees. In this investigation, we studied 27 white spruce trees from two sites under distinct environmental conditions to evaluate the appropriate protocol for preparing consistent tree-ring δ¹⁵N series.The produced series indicate that high frequency (short-term, <7 years) δ¹⁵N changes at a replication as high as 10 trees cannot serve environmental purposes. Conversely, the low frequency (middle-, 7–15 years, to long-term, > 15 years) δ¹⁵N trends show coherence between arithmetic means of individual series at replication levels as low as three trees, whereas middle-term pooled trends do not perform as coherently. The low frequency mean trends of individual series obtained for the two sites suggest that local biogeochemical soil conditions modified by anthropogenic emissions modulate the δ¹⁵N responses in trees. Hence, we propose that long-term tree-ring δ¹⁵N series constitute reliable environmental indicators.     

The divinyl-chlorophyll a/b-protein complexes of two strains of the oxyphototrophic marine prokaryote Prochlorococcus – characterization and response to changes in growth irradiance

Apoproteins of the antenna complexes of Prochlorococcus marinus clone SS120 (= CCMP 1375) and Prochlorococcus sp. clone MED4 (= CCMP 1378) cross-reacted with an antibody against the 30 kDa CP 5 complex of Prochlorothrix hollandica antenna. For the MED4 strain, which has a high divinyl-chlorophyll a to divinyl-chlorophyll b (DV-Chl a/b) ratio ranging from 11.4 to 15.0 (w/w), the major antenna proteins had an apparent molecular mass of 32.5 kDa. In contrast for the SS120 strain, which has a low DV-Chl a/b ratio ranging from 1.1 to 2.2, antenna apoproteins were observed in the range 34–38 kDa. For both strains, these apoproteins decreased at high growth irradiance but more markedly in the latter. Partially purified antenna fractions had a DV-Chl a/b ratio ca. 7-fold lower for SS120 than for MED4 at 30 mol photons m-2 s-1. For both strains, the 77 K fluorescence emission spectra of whole thylakoids displayed a major peak at 685 nm and a broad but very low shoulder above 700 nm. Energetic coupling of the antenna to both PS II and PSI reaction centers was demonstrated for SS120 by the strong contribution of DV-Chl b in both the 77 K excitation fluorescence spectra and the oxidized minus reduced absorption difference spectra of P700. The PS I to PS II ratio of Prochlorococcus SS120 was determined as being 0.7 ± 0.1 at low light.     

Science – or not? The status and dynamics of biotechnology

This review traces the emergence of biotechnology as a new scientific discipline since the 1980s, when it became a major economic force. Significant changes in theoretical perception, research strategies, aims, and experimental methods, mainly in genetic engineering techniques, occurred during this period. The article is based on an analysis of its scientific status over four decades: the 60s and 70s when work in the field proceeded in different disciplines with a low level of coherence and little integration, then a significant change during the 80s and 90s when common approaches and the merging of molecular biology and biochemical engineering created a new discipline. The analysis covers scientific highlights and outstanding technical progress, presenting two studies undertaken by scientific and governmental agencies in Germany and the USA, as well as results of interviews and a questionnaire dealing with the scientific status of biotechnology. Answers to the questionnaire were obtained from internationally known scientists and from young scientists with biotechnology degrees. The results collected trace the transition of biotechnology from heterogeneous specialties and approaches towards a scientific discipline of its own. A hypothesis is put forward suggesting a new common paradigm allowing for a coherent perception the of phenomena observed.     

The ventilatory response to incremental exercise: is it one or two breakpoints?

The primary objective of this study was to determine if the ventilatory (&OV0312;E) breakpoint during incremental exercise to fatigue is best represented by a single breakpoint (BP1), double breakpoint (BP2), or an exponential function (EXP) exhibiting no BP. A secondary objective was to determine if visual assessment of the BP was valid and reliable. Subjects (n = 49) were both men (n = 12) and women (n = 37) who identified either running (n = 31) or triathlon (n = 18) as their primary sport. Subjects completed a maximal oxygen test on a motor-driven treadmill according to a modified Bruce protocol. The difference in mean square error (MSE) for BP1 (4.91 ± 3.35 L) was slightly but significantly (p < 0.05) greater than in MSE for BP2 (2.75 ± 1.7 L) for VE. Mean square error for EXP (7.85 ± 5.1 L) was significantly greater (p < 0.05) than BP1 and BP2. Visual assessment of VE on scatterplots produced poor validity, with a mean of 71.7% being misclassified compared to the computer model. Both interevaluator reliability (30.6% agreement) and intraevaluator reliability (59.7% agreement) were low. From the results of this study, it is concluded that (a) VE exhibits a BP2 model rather than BP1 or EXP and (b) visual assessment of BP is both invalid and unreliable.     

The Patentability of Biomolecules – Does Online Bioinformatics Compromise Novelty?

Researchers are becoming increasingly concerned that the confidentiality of their novel biomolecule sequences is being jeopardised, particularly when these sequences are either submitted to sequence databases or uploaded as query terms onto internet-based bioinformatic software suites. The researcher's fears stem from the fact that the actual uploading of their sequences acts as a novelty destroying prior disclosure or publication, and that this may subsequently preclude valid patent protection for the sequences. This article addresses the key issues involved in the analyses of biomolecules, highlighting potential risks taken by many researchers in regard to patent protection and suggests possible ways in which these risks may be mitigated.