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1.
Popul Stud (Camb) ; 75(3): 381-401, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-32990142

RESUMO

Adult stature has become a widely used indicator of childhood nutritional status in historical populations and may provide insights into health inequalities that are not discernible in mortality rates. However, most pre-twentieth-century British data on heights suffer from selection biases. Here we present unique evidence on heights of adult males by occupation from an unbiased sample of adult males in Dorset in 1798-99. The mean height of fully grown (married) men was very similar to that of older military recruits, and our sample therefore confirms the taller stature of English males relative to males of other European countries in the same period. In contrast to previous evidence of negligible or U-shaped socio-economic gradients in mortality in this period, we found a fairly linear gradient in height by socio-economic status, that is similar in magnitude to class differences in adult height among English males born in the mid-twentieth century.Supplementary material for this article is available at: https://doi.org/10.1080/00324728.2020.1823011.


Assuntos
Estatura , Classe Social , Adulto , Inglaterra , Europa (Continente) , Humanos , Masculino , Casamento , Fatores Socioeconômicos
2.
Hist Fam ; 24(1): 174-206, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31058272

RESUMO

Anecdotal evidence indicates that high-status women in England generally did not breastfeed their children in the seventeenth and early eighteenth centuries. Metropolitan families of varied social status also often sent their children out of London for wet-nursing. However, anecdotal sources and rural burial registers also suggest that these practices declined rapidly from the mid-eighteenth century, and were replaced by a culture of maternal breastfeeding in all social classes. These changes in infant-feeding practices have been argued to explain much of the dramatic improvement in infant mortality rates in London in this period. Here we used quantitative evidence from a partial family reconstitution of the London parish of St. Martin in the Fields to test these claims. Using birth interval analysis to infer breastfeeding patterns in families by four categories of wealth, we found that birth intervals were close to the national average in pauper and poor families, but much shorter in wealthier families, in the period 1752-74. We also found evidence that many infants especially in wealthier families were missing from observation, consistent with high levels of rural wet-nursing. Both these phenomena declined between 1775 and 1812, suggesting a convergence in breastfeeding practices to the national norm. We used event history analysis, with corrections to aggregate rates for missing infants, to compare mortality rates over time and by wealth category. We found that infant mortality was initially higher in wealthier families, but declined in all groups over the period 1752-1812. We conclude that increases in maternal breastfeeding were probably important in improving survival of infants from wealthier families, however changes in breastfeeding patterns were insufficient to account for the ubiquitous improvements in mortality of urban-born infants in this period.

3.
Hist Fam ; 24(2): 404-438, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31274973

RESUMO

The malign contribution of northern industrial cities to the stagnation of national life expectancy over the period 1820-1870 forms part of one of the most long-running debates in English economic history, regarding the impact of early industrialisation on living standards. The deteriorating quality of urban water supplies often features in these arguments as the key driver of worsening mortality in this period. Here we use mortality reported from cholera in the epidemic years 1831-1832 and 1848-1849 as an indicator of the extent of sewage contamination of water in English and Welsh towns in this period. Surprisingly, the geography of reported mortality did not indicate that northern manufacturing and industrial towns were especially deficient in this respect. However, logistic regression analyses identified a number of risk factors for high cholera mortality, including location on coal-bearing strata, which was a feature of many industrial towns. Notably, however, textile-manufacturing towns, although often located in coal-rich districts, were associated with low levels of cholera mortality, and high population growth rates did not influence the risk of cholera. Reductions in cholera mortality after 1849 raise the possibility of widespread improvements in water quality after mid-century, rather earlier than is often assumed. However, in contrast to cholera, infant and diarrhoeal mortality remained high especially in northern towns until at least 1900. Several lines of evidence suggest that infants were relatively protected from waterborne diseases such as cholera and typhoid, and therefore did not benefit greatly from improvements in water quality. We conclude (1) that any worsening of water quality in urban areas c.1800-1850 was not confined to new͛ or rapidly growing industrial or manufacturing towns; and (2) infants probably rarely drank untreated water, so high infant or diarrhoeal mortality rates should not be read as indicators of poor water quality, in the English context.

4.
Local Popul Stud ; 96: 28-49, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27489393

RESUMO

Family reconstitutions have been undertaken only rarely in urban settings due to the high mobility of historical urban populations, in both life and death. Recently Gill Newton has outlined a methodology for the reconstitution of urban populations and we applied a modified version of this method to the large Westminster parish of St. Martin in the Fields between 1752 and 1812, a period that posed particular difficulties for family reconstitution because of the rapid lengthening of the interval between birth and baptism.1 The extraordinary richness of the records for St. Martin in the Fields made it possible to investigate burial and baptismal practices in great detail, and the extent and impact of residential mobility. We found that short-range, inter-parochial movement was so frequent that it was necessary to confine the reconstitution sample to windows in which families registered events at a single street address. Using birth interval analysis and the frequencies of twin births it was possible to demonstrate that the registration of birth events was fairly complete, but that many infant and child burials were missed. These missing burials probably resulted from the unreported export of corpses for burial in other parishes, a phenomenon for which we had considerable evidence. The limitations of family reconstitution in this highly mobile and heterogeneous urban population is discussed and we demonstrate some checks and corrections that can be used to improve the quality of such reconstitutions.

5.
Local Popul Stud ; (96): 28-49, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-29939514

RESUMO

Family reconstitutions have been undertaken only rarely in urban settings due to the high mobility of historical urban populations, in both life and death. Recently Gill Newton has outlined a methodology for the reconstitution of urban populations and we applied a modified version of this method to the large Westminster parish of St. Martin in the Fields between 1752 and 1812, a period that posed particular difficulties for family reconstitution because of the rapid lengthening of the interval between birth and baptism. The extraordinary richness of the records for St. Martin in the Fields made it possible to investigate burial and baptismal practices in great detail, and the extent and impact of residential mobility. We found that short-range, inter-parochial movement was so frequent that it was necessary to confine the reconstitution sample to windows in which families registered events at a single street address. Using birth interval analysis and the frequencies of twin births it was possible to demonstrate that the registration of birth events was fairly complete, but that many infant and child burials were missed. These missing burials probably resulted from the unreported export of corpses for burial in other parishes, a phenomenon for which we had considerable evidence. The limitations of family reconstitution in this highly mobile and heterogeneous urban population is discussed and we demonstrate some checks and corrections that can be used to improve the quality of such reconstitutions.


Assuntos
Intervalo entre Nascimentos , Sepultamento/história , Parto , Dinâmica Populacional/história , População Urbana/história , Intervalo entre Nascimentos/estatística & dados numéricos , Inglaterra , História do Século XVIII , História do Século XIX , Humanos , Dinâmica Populacional/estatística & dados numéricos , População Urbana/estatística & dados numéricos
6.
Local Popul Stud ; (94): 28-47, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26536752

RESUMO

The evident lengthening of the interval between birth and baptism over the eighteenth century has often been assumed to have increased the risk that young infants died before baptism. Using burial records that include burials of unbaptised infants and give age at death we demonstrate that very few infants who survived the first few days of life escaped baptism in the parish of St. Martin in the Fields, despite a very profound lengthening of the delay between birth and baptism over the second half of the eighteenth century. Examination of baptism fee books indicates that perhaps a third of all infants were baptized privately in the parish and a pamphlet dispute between the vicar and one of his clerks provides extraordinary evidence of the extent to which baptism was a process rather than a single event. Our analysis suggests that it was the registration of baptism that was delayed, with no affect on the risk of death before baptism.


Assuntos
Clero , Mortalidade/história , Parto , Políticas , Inglaterra , História do Século XVIII , História do Século XIX , Humanos
7.
Econ Hist Rev ; 76(2): 624-660, 2023 May.
Artigo em Inglês | MEDLINE | ID: mdl-38516251

RESUMO

Health improved in English cities in the last third of the nineteenth century, in tandem with substantial increases in public spending on water supplies and sanitation. However, previous efforts to measure the contribution of public expenditures to mortality improvements have been hampered by difficulties in quantifying public health investments and the lack of mortality data for specifically urban populations. We improve upon the existing evidence base by (1) creating measures of the stock of urban district sanitary capital, by type, on the basis of capital expenditure flows, rather than loan stocks; (2) using mortality and capital stock data that relate to the same administrative units (urban districts), and (3) studying the period 1880-1909 as well as the earlier period from 1845. The stock of sewerage capital was robustly related to improvements in all-cause mortality after 1880. The size of this effect varied with the extent of public investment in water supplies, suggesting complementarity between the two assets. For the period 1845-84, investments in water were associated with declines in infant and child mortality but the effect was much smaller and less precisely estimated in later decades. Our results suggest that improvements in water and sewerage targeted different transmission pathways for faecal-oral diseases.

8.
Int J Paleopathol ; 34: 37-49, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34146819

RESUMO

OBJECTIVE: This study tests the argument that industrialisation was accompanied by a dramatic worsening of urban health in England. MATERIALS: Family reconstitutions derived from baptism, marriage and burial records for the period before 1837, and from civil registration of deaths and census populations between 1837 and 1900. METHODS: Age-specific mortality rates are used as indicators of population health. RESULTS: The available evidence indicates a decline in urban mortality in the period c.1750-1820, especially amongst infants and (probably) rural-urban migrants. Mortality at ages 1-4 years demonstrated a more complex pattern, falling between 1750 and 1830 before rising abruptly in the mid-nineteenth century. CONCLUSIONS: These patterns are better explained by changes in breastfeeding practices and the prevalence or virulence of particular pathogens than by changes in sanitary conditions or poverty. Mortality patterns amongst young adult migrants were affected by a shift from acute to chronic infectious diseases over the period. SIGNIFICANCE: Pathogen evolution, infant care and migration exerted major influences on mortality trends and should be given greater attention in studies of the health impacts of British industrialisation. LIMITATIONS: Evidence of urban mortality rates is very limited before 1837 and may not be fully representative of industrialising populations. Mortality also provides only a partial picture of the health of urban populations and may be distorted by migration patterns. FURTHER RESEARCH: There is enormous scope for collaboration between archaeologists and historians to investigate the health of industrial populations, through the triangulation and contextualisation of diverse sources of evidence.


Assuntos
População Rural , Pré-Escolar , Cidades , Inglaterra/epidemiologia , Humanos , Lactente , Prevalência , População Urbana , Adulto Jovem
9.
Econ Hist Rev ; 73(2): 455-485, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32355360

RESUMO

In the long-running debate over standards of living during the industrial revolution, pessimists have identified deteriorating health conditions in towns as undermining the positive effects of rising real incomes on the 'biological standard of living'. This article reviews long-run historical relationships between urbanization and epidemiological trends in England, and then addresses the specific question: did mortality rise especially in rapidly growing industrial and manufacturing towns in the period c. 1830-50? Using comparative data for British, European, and American cities and selected rural populations, this study finds good evidence for widespread increases in mortality in the second quarter of the nineteenth century. However, this phenomenon was not confined to 'new' or industrial towns. Instead, mortality rose in the 1830s especially among young children (aged one to four years) in a wide range of populations and environments. This pattern of heightened mortality extended between c. 1830 and c. 1870, and coincided with a well-established rise and decline in scarlet fever virulence and mortality. The evidence presented here therefore supports claims that mortality worsened for young children in the middle decades of the nineteenth century, but also indicates that this phenomenon was more geographically ubiquitous, less severe, and less chronologically concentrated than previously argued.

10.
Annu Rev Plant Biol ; 53: 67-107, 2002.
Artigo em Inglês | MEDLINE | ID: mdl-12221989

RESUMO

Nonselective cation channels are a diverse group of ion channels characterized by their low discrimination between many essential and toxic cations. They are ubiquitous in plant tissues and are active in the plasma membrane, tonoplast, and other endomembranes. Members of this group are likely to function in low-affinity nutrient uptake, in distribution of cations within and between cells, and as plant Ca2+ channels. They are gated by diverse mechanisms, which can include voltage, cyclic nucleotides, glutamate, reactive oxygen species, and stretch. These channels dominate tonoplast cation transport, and the selectivity and gating mechanisms of tonoplast nonselective cation channels are comprehensively reviewed here. This review presents the first classification of plant nonselective cation channels and the first full description of nonselective cation channel candidate sequences in the Arabidopsis genome.


Assuntos
Canais Iônicos/fisiologia , Fenômenos Fisiológicos Vegetais , Sequência de Aminoácidos , Cátions , Canais Iônicos/química , Canais Iônicos/metabolismo , Dados de Sequência Molecular , Homologia de Sequência de Aminoácidos , Frações Subcelulares/metabolismo
11.
Soc Sci Med ; 206: 75-85, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29684651

RESUMO

Smallpox is regarded as an ancient and lethal disease of humans, however very little is known about the prevalence and impact of smallpox before the advent of vaccination (c.1800). Here we use evidence from English burial records covering the period 1650-1799 to confirm a striking geography to smallpox patterns. Smallpox apparently circulated as a childhood disease in northern England and Sweden, even where population densities were low and settlement patterns dispersed. However, smallpox was a relatively rare epidemic disease in southern England outside the largest cities, despite its commercialised economy and the growing spatial interconnectedness of its settlements. We investigated a number of factors hypothesised to influence the regional circulation of smallpox, including exposure to naturally occurring orthopox viruses, settlement patterns, and deliberate preventative measures. We concluded that transmission was controlled in southern England by local practices of avoidance and mass inoculation that arose in the seventeenth and eighteenth centuries. Avoidance measures included isolation of victims in pest houses and private homes, as well as cancellation of markets and other public gatherings, and pre-dated the widespread use of inoculation. The historical pattern of smallpox in England supports phylogenetic evidence for a relatively recent origin of the variola strains that circulated in the twentieth century, and provides evidence for the efficacy of preventative strategies complementary to immunisation.


Assuntos
Varíola/epidemiologia , Varíola/história , Inglaterra/epidemiologia , Geografia , História do Século XVII , História do Século XVIII , Humanos
12.
Econ Hist Rev ; 69(1): 188-214, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26900169

RESUMO

Smallpox was probably the single most lethal disease in eighteenth-century Britain but was reduced to a minor cause of death by the mid-nineteenth century due to vaccination programmes post-1798. While the success of vaccination is unquestionable, it remains disputed to what extent the prophylactic precursor of vaccination, inoculation, reduced smallpox mortality in the eighteenth century. Smallpox was most lethal in urban populations, but most researchers have judged inoculation to have been unpopular in large towns. Recently, however, Razzell argued that inoculation significantly reduced smallpox mortality of adults and older children in London in the last third of the eighteenth century. This article uses demographic evidence from London and Manchester to confirm previous findings of a sudden fall in adult smallpox mortality and a rise in the importance of smallpox in early childhood c. 1770. The nature of these changes is consistent with an increase in smallpox transmission in London and Manchester after 1770 and indicates that smallpox inoculation was insufficient to reduce smallpox mortality in large towns. It remains unclear whether inoculation could have operated to enhance smallpox transmission or whether changes in the properties of the smallpox virus drove the intensification of smallpox mortality among young children post-1770.

14.
PLoS One ; 8(12): e81797, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-24349130

RESUMO

Birth cohort patterns in mortality are often used to infer long-lasting impacts of early life conditions. One of the most widely accepted examples of a birth cohort effect is that of tuberculosis mortality before the late 1940s. However the evidential basis for claims of cohort-specific declines in tuberculosis mortality is very slight. Reanalysis of original or enhanced versions of datasets used previously to support claims of cohort effects in tuberculosis mortality indicated that: 1. where the initial decline in tuberculosis mortality occurred within the period of observation, onset of decline occurred simultaneously in many age groups, in a pattern indicative of 'period' not cohort-dependent effects. 2. there was little evidence of 'proportional hazard'-type cohort patterns in tuberculosis mortality for any female population studied. Therefore any mechanisms proposed to underlie this type of cohort pattern in male mortality must be sex-specific. 3. sex ratios of tuberculosis mortality at older ages peaked in cohorts born around 1900, and resembled cohort sex ratios of lung cancer mortality. This analysis indicates that age-specific patterns in the decline in tuberculosis mortality before 1950 are unlikely to reflect improvements in early life conditions. The patterns observed are generally more consistent with the influence of factors that reduced mortality simultaneously in most age groups. Additional influences, possibly smoking habits, impeded the decline of tuberculosis in older adult males, and produced the sex-specific shifts in age distributions of mortality that were previously interpreted as evidence of cohort-dependent mortality decline.


Assuntos
Tuberculose/epidemiologia , Adolescente , Adulto , Distribuição por Idade , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Criança , Pré-Escolar , Efeito de Coortes , Estudos de Coortes , Europa (Continente)/epidemiologia , Feminino , Humanos , Lactente , Recém-Nascido , Japão/epidemiologia , Masculino , Pessoa de Meia-Idade , Razão de Masculinidade , Fumar , Análise de Sobrevida , Tuberculose/mortalidade , Estados Unidos/epidemiologia
15.
Econ Hist Rev ; 64(4): 1289-314, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-22171404

RESUMO

Smallpox was probably the single most lethal disease in eighteenth-century Britain, but was a minor cause of death by the mid-nineteenth century. Although vaccination was crucial to the decline of smallpox, especially in urban areas, from the beginning of the nineteenth century, it remains disputed the extent to which smallpox mortality declined before vaccination. Analysis of age-specific changes in smallpox burials within the large west London parish of St Martin-in-the-Fields revealed a precipitous reduction in adult smallpox risk from the 1770s, and this pattern was duplicated in the east London parish of St Dunstan's. Most adult smallpox victims were rural migrants, and such a drop in their susceptibility is consistent with a sudden increase in exposure to smallpox in rural areas. We investigated whether this was due to the spread of inoculation, or an increase in smallpox transmission, using changes in the age patterns of child smallpox burials. Smallpox mortality rose among infants, and smallpox burials became concentrated at the youngest ages, suggesting a sudden increase in infectiousness of the smallpox virus. Such a change intensified the process of smallpox endemicization in the English population, but also made cities substantially safer for young adult migrants.


Assuntos
Transmissão de Doença Infecciosa , Mortalidade , Grupos Populacionais , Saúde Pública , Vacina Antivariólica , Varíola , Antropologia Cultural/educação , Antropologia Cultural/história , Transmissão de Doença Infecciosa/economia , Transmissão de Doença Infecciosa/história , História do Século XVIII , História do Século XIX , Humanos , Londres/etnologia , Mortalidade/etnologia , Mortalidade/história , Grupos Populacionais/educação , Grupos Populacionais/etnologia , Grupos Populacionais/história , Grupos Populacionais/legislação & jurisprudência , Grupos Populacionais/psicologia , Serviços Preventivos de Saúde/economia , Serviços Preventivos de Saúde/história , Saúde Pública/economia , Saúde Pública/educação , Saúde Pública/história , Varíola/etnologia , Varíola/história , Vacina Antivariólica/história
16.
Plant Cell Environ ; 30(4): 497-507, 2007 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-17324235

RESUMO

HKT-type transporters appear to play key roles in Na(+) accumulation and salt sensitivity in plants. In Arabidopsis HKT1;1 has been proposed to influx Na(+) into roots, recirculate Na(+) in the phloem and control root : shoot allocation of Na(+). We tested these hypotheses using (22)Na(+) flux measurements and ion accumulation assays in an hkt1;1 mutant and demonstrated that AtHKT1;1 contributes to the control of both root accumulation of Na(+) and retrieval of Na(+) from the xylem, but is not involved in root influx or recirculation in the phloem. Mathematical modelling indicated that the effects of the hkt1;1 mutation on root accumulation and xylem retrieval were independent. Although AtHKT1;1 has been implicated in regulation of K(+) transport and the hkt1;1 mutant showed altered net K(+) accumulation, (86)Rb(+) uptake was unaffected by the hkt1;1 mutation. The hkt1;1 mutation has been shown previously to rescue growth of the sos1 mutant on low K(+); however, HKT1;1 knockout did not alter K(+) or (86)Rb(+) accumulation in sos1.


Assuntos
Proteínas de Arabidopsis/fisiologia , Arabidopsis/metabolismo , Proteínas de Transporte de Cátions/fisiologia , Transporte de Íons/fisiologia , Sódio/metabolismo , Simportadores/fisiologia , Xilema/metabolismo , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Proteínas de Transporte de Cátions/genética , Hidroponia , Modelos Biológicos , Mutação , Raízes de Plantas/metabolismo , Potássio/metabolismo , Trocadores de Sódio-Hidrogênio/fisiologia , Simportadores/genética , Vacúolos/metabolismo
17.
J Exp Bot ; 57(5): 1161-70, 2006.
Artigo em Inglês | MEDLINE | ID: mdl-16510514

RESUMO

Thellungiella halophila is a useful model species for research into plant salt tolerance. It is closely related to Arabidopsis thaliana, but shows considerably higher salt tolerance. Comparative analysis of ion homeostasis in the two species allows the identification of ion transport pathways that are critical for salt tolerance and provides the basis for future studies into their molecular features. Previous studies indicated that salt tolerance in T. halophila is accompanied by low accumulation of Na in the leaves. Kinetic analysis of net ion uptake over three days confirmed lower Na uptake and K loss in T. halophila compared with A. thaliana. Differential net Na uptake rates were still apparent after 6 weeks of salt treatment. To assess the contribution of unidirectional Na fluxes to net Na uptake, kinetic studies of (22)Na fluxes were carried out in both species. The results show that unidirectional root Na influx is significantly lower in salt-grown T. halophila plants than in A. thaliana exposed to the same level of salinity (100 mM). Quantitative comparison of unidirectional influx and net Na accumulation suggests that both species operate efficient Na efflux, which partly compensates for Na influx. Kinetic analysis of (22)Na efflux indicated higher root Na efflux in A. thaliana than in T. halophila. Thus A. thaliana appears to spend more energy on Na export while nevertheless accumulating more Na than T. halophila. It is proposed that limitation of Na influx is the main mechanism by which T. halophila secures low net Na accumulation in saline conditions. This strategy provides the basis for a positive balance between growth and net Na uptake rates, which is essential for survival in high salt.


Assuntos
Brassicaceae/metabolismo , Sódio/metabolismo , Arabidopsis/efeitos dos fármacos , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/metabolismo , Brassicaceae/efeitos dos fármacos , Brassicaceae/crescimento & desenvolvimento , Cálcio/metabolismo , Cátions/metabolismo , Césio/farmacologia , Transporte de Íons/efeitos dos fármacos , Cinética , Raízes de Plantas/citologia , Raízes de Plantas/genética , Raízes de Plantas/metabolismo , Bloqueadores dos Canais de Sódio/farmacologia , Canais de Sódio/fisiologia , Tetraetilamônio/farmacologia
18.
Plant Physiol ; 142(4): 1537-47, 2006 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-17028150

RESUMO

Durum wheat (Triticum turgidum L. subsp. durum Desf.) Line 149 contains two novel major genes for excluding Na(+) from leaf blades, named Nax1 and Nax2. The genes were separated into families containing a single gene and near-isogenic homozygous lines were selected. Lines containing either Nax1 or Nax2 had lower rates of Na(+) transport from roots to shoots than their near-isogenic pairs due to lower rates of net loading of the xylem, not to lower rates of net uptake from the soil or higher rates of retranslocation in the phloem. Nax1 and Nax2 lines also had higher rates of K(+) transport from root to shoot, resulting in an enhanced discrimination of K(+) over Na(+). Lines containing Nax1 differed from those containing Nax2 by unloading Na(+) from the xylem as it entered the shoot so that Na(+) was retained in the base of the leaf, leading to a high sheath to blade ratio of Na(+) concentration. Gradients in tissue concentrations of Na(+) along the leaf suggested that Na(+) was continually removed from the xylem. The Nax2 line did not retain Na(+) in the base of the leaf, suggesting that it functioned only in the root. The Nax2 gene therefore has a similar function to Kna1 in bread wheat (Triticum aestivum).


Assuntos
Proteínas de Plantas/genética , Sódio/metabolismo , Triticum/genética , Transporte de Íons/genética , Folhas de Planta/metabolismo , Proteínas de Plantas/metabolismo , Raízes de Plantas/metabolismo , Brotos de Planta/metabolismo , Potássio/metabolismo , Triticum/metabolismo , Xilema/metabolismo
19.
Plant Physiol ; 137(3): 807-18, 2005 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-15734907

RESUMO

In many species, salt sensitivity is associated with the accumulation of sodium (Na(+)) in photosynthetic tissues. Na(+) uptake to leaves involves a series of transport steps and so far very few candidate genes have been implicated in the control of these processes. In this study, Na(+) transport was compared in two varieties of durum wheat (Triticum turgidum) L. subsp. durum known to differ in salt tolerance and Na(+) accumulation; the relatively salt tolerant landrace line 149 and the salt sensitive cultivar Tamaroi. Genetic studies indicated that these genotypes differed at two major loci controlling leaf blade Na(+) accumulation (R. Munns, G.J. Rebetzke, S. Husain, R.A. James, R.A. Hare [2003] Aust J Agric Res 54: 627-635). The physiological traits determined by these genetic differences were investigated using measurements of unidirectional (22)Na(+) transport and net Na(+) accumulation. The major differences in Na(+) transport between the genotypes were (1) the rate of transfer from the root to the shoot (xylem loading), which was much lower in the salt tolerant genotype, and (2) the capacity of the leaf sheath to extract and sequester Na(+) as it entered the leaf. The genotypes did not differ significantly in unidirectional root uptake of Na(+) and there was no evidence for recirculation of Na(+) from shoots to roots. It is likely that xylem loading and leaf sheath sequestration are separate genetic traits that interact to control leaf blade Na(+).


Assuntos
Sódio/metabolismo , Triticum/metabolismo , Transporte Biológico Ativo , Genótipo , Folhas de Planta/metabolismo , Raízes de Plantas/metabolismo , Cloreto de Sódio/metabolismo , Fatores de Tempo , Triticum/genética
20.
Ann Bot ; 90(5): 549-57, 2002 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-12466095

RESUMO

Ionotropic glutamate receptors function in animals as glutamate-gated non-selective cation channels. Numerous glutamate receptor-like (GLR) genes have been identified in plant genomes, and plant GLRs are predicted, on the basis of sequence homology, to retain ligand-binding and ion channel activity. Non-selective cation channels are ubiquitous in plant membranes and may function in nutrient uptake, signalling and intra-plant transport. However, there is little evidence for amino acid gating of plant ion channels. Recent evidence suggests that plant GLRs do encode non-selective cation channels, but that these channels are not gated by amino acids. The functional properties of these proteins and their roles in plant physiology remain a mystery. The problems surrounding characterization and assignation of function to plant GLRs are discussed in this Botanical Briefing, and potential roles for GLR proteins as non-selective cation channels involved in metabolic signalling are described.


Assuntos
Plantas/metabolismo , Receptores de Glutamato/metabolismo , Sequência de Aminoácidos , Animais , Arabidopsis/genética , Arabidopsis/metabolismo , Evolução Molecular , Dados de Sequência Molecular , Plantas/genética , Receptores de Glutamato/química , Receptores de Glutamato/genética , Transdução de Sinais
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