Rural-to-Urban Labor Migration,Household Livelihoods,and the Rural Environment in Chongqing Municipality,Southwest China

Rural migration and its relationship to the rural environment have attracted increasing research interest in recent decades. Rural migration constitutes a key component of human population movement, while rural areas contain most of the world’s natural resources such as land and forests. This study empirically evaluates a conceptual framework incorporating rural household livelihoods as an integrative mediating factor between rural migration and the rural environment in the context of rural-to-urban labor migration in Chongqing Municipality, Southwest China. The analysis draws on data collected through household surveys and key informant interviews from four villages. Results confirm the hypothesis that labor-migrant and non-labor-migrant households differ significantly in livelihood activities including agricultural production, agricultural technology use, income and consumption, and resource use and management. Implications for the subsequent environmental outcomes of rural labor out-migration and corresponding natural resource management and policy in rural origin areas are discussed.     

Projection of the Mexican National Labor Force, 1980–2005

Abstract

Mexico has a large and rapidly growing labor force. This paper projects the Mexican national labor force from 1980 to 2005, with varying assumptions of vital rates, economic activity, and international migration. Projections are also made for the urban and rural components of the Mexican population, assuming inter‐component migration flows. Results indicate that the Mexican labor force will grow over the projection period at an average annual rate of 907,000 to 1,183,000 workers; will age slightly; and will have a much higher proportion female. Implications are discussed in terms of Mexican‐U.S. migration, possible agreements on free trade, and global trends in workforce.     

Dissecting the Factors Involved in the Locomotion Mode of Neuronal Migration in the Developing Cerebral Cortex

Neuronal migration is essential for proper cortical layer formation and brain function, because migration defects result in neurological disorders such as mental retardation and epilepsy. Neuronal migration is divided into several contiguous steps: early phase (multipolar mode), locomotion mode, and terminal translocation mode. The locomotion mode covers most of the migration route and thereby is the main contributor to cortical layer formation. However, analysis of the molecular mechanisms regulating this mode is difficult due to the secondary effects of defects at the early phase of migration. In this study, we established an ex vivo chemical inhibitor screening, allowing us to directly analyze the locomotion mode of migration. Roscovitine and PP2, inhibitors for Cdk5 and Src family kinases, respectively, suppressed the locomotion mode of migration. In line with this, a small percentage of Cdk5- or Src family kinase (Fyn)-knockdown cells exhibited locomoting morphology but retarded migration, although the majority of cells were stalled at the early phase of migration. We also showed that rottlerin, widely used as a specific inhibitor for protein kinase Cδ (PKCδ), suppressed the locomotion mode. Unexpectedly, however, the dominant-negative form as well as RNA interference for PKCδ hardly affected the locomotion, whereas they may disturb terminal translocation. In addition, we found JNK to be a potential downstream target of rottlerin. Taken together, our novel chemical inhibitor screening provides evidence that Cdk5 and Src family kinases regulate the locomotion mode of neuronal migration. It also uncovered roles for Fyn and PKCδ in the early and final phases of migration, respectively.     

陕北小流域退耕农户剖面特征的土地利用决策响应

采用基于GIS的空间分析、数理统计(Mathematical Statistics)与Multi-logistic回归模型相结合的方法(GMM),探讨退耕前后陕北燕沟流域土地利用及其关键的社会经济驱动因素的变化,揭示农村劳动力转移在土地利用决策中的重要性,了解农村土地利用变化的驱动机制。结果表明:(1)1990—2013年,流域土地利用变化特征总体上与延安市的土地利用变化趋势一致,即坡耕地减少和林草地增加显著;(2)1990—2001年,农业劳动力转移对农户土地利用决策的影响不明显,农户家庭基本特征与资源禀赋等对农户土地利用决策的影响显著。2001—2013年,劳动力转移和交通条件对农户土地利用决策有显著影响,退耕还林政策对农村劳动力的再分配产生了较大影响。     

Rho family GTPases: Making it to the third dimension

The role of Rho family GTPases in controlling the actin cytoskeleton and thereby regulating cell migration has been well studied for cells migrating on 2D surfaces. In vivo, cell migration occurs within three-dimensional matrices and along aligned collagen fibers with rather different spatial requirements. Recently, a handful of studies coupled with new approaches have demonstrated that Rho GTPases have unique regulation and roles during cell migration within 3D matrices, along collagen fibers, and in vivo. Here we propose that migration on aligned matrices facilitates spatial organization of Rho family GTPases to restrict and stabilize protrusions in the principle direction of alignment, thereby maintaining persistent migration. The result is coordinated cell movement that ultimately leads to higher rates of metastasis in vivo.     

Shodagor Family Strategies

The Shodagor of Matlab, Bangladesh, are a seminomadic community of people who live and work on small wooden boats, within the extensive system of rivers and canals that traverse the country. This unique ecology places particular constraints on family and economic life and leads to Shodagor parents employing one of four distinct strategies to balance childcare and provisioning needs. The purpose of this paper is to understand the conditions that lead a family to choose one strategy over another by testing predictions about socioecological factors that impact the sexual division of labor, including a family’s stage in the domestic cycle, aspects of the local ecology, and the availability of alloparents. Results show that although each factor has an impact on the division of labor individually, a confluence of these factors best explains within-group, between-family differences in how mothers and fathers divide subsistence and childcare labor. These factors also interact in particular ways for Shodagor families, and it appears that families choose their economic strategies based on the constellation of constraints that they face. The results of these analyses have implications for theory regarding the sexual division of labor across cultures and inform how Shodagor family economic and parenting strategies should be contextualized in future studies.     

Informational returnees: deportation,digital media,and the making of a transnational cybertariat in the Mexican call center industry

In recent years, the US government has intensified the deportation of undocumented Mexican migrants, some of them with long life trajectories in the USA. With weak family networks in their communities of origin and sometimes none at all, many deportees choose to stay in cities along the US-Mexico border, joining the army of underpaid, low-skilled, and informal urban workers. Some take advantage of their transnational experience to earn a better income; within this context, the call center industry is an economic sector that profits from the language facility and sociocultural skills deported populations bring with them from their years spent living in the USA. This paper addresses the working conditions among call center workers in Mexico, with a focus in Tijuana City in the Mexican Northwest. In particular, I explore how migration, deportation, and call center labor produces what I call informational return, a process in which the convergence of culture, deportation, and digital media plays a key role in the constitution of a transnational digital worker.     

Unemployment and labor migration in rural Galicia (Spain)

This article focuses on the difficulty of entering into—and literally getting back and forth to—the waged labor market for adolescent and young adult workers from rural parts of Galicia, a region that has experienced a prolonged history of persistently high levels of unemployment. Unemployment is one of the most serious issues facing Spain, other countries of the EU, and states all over the world. In Spain, for the population of workers under 30, this problem is at staggeringly high levels that have reached 50 % plus in the last few years of the current crisis but has been longstanding. So, too, has labor migration to and from rural Galician households. This article takes a broad approach to the analysis of labor mobility, including daily commuting as well as longer distance and longer duration labor migration. It considers the role of state and EU policies over time in instituting, supporting, or discouraging different geographical trajectories and forms of movement for young adult “wage seekers” from rural Galician households.     

Export agriculture,transnational farmworkers,and labor resistance in the Mexico–US borderlands

This article discusses the system of export agriculture in northern Mexico and its impact on transnational farmworkers employed in both sides of the US–Mexico border. Since the late 1990s, a transnational industry producing fresh produce for consumer markers in the USA has taken hold in the San Quintin Valley in Baja California, transforming the economic and social fabric of this border region. This industry has generated a new labor regime predicated upon the employment of a flexible and cheap source of indigenous workers from the poorest states in southern Mexico. I examine the contours of this regime, the forms of labor resistance it has elicited, and the new types of labor migration it has generated by Mexican workers to the USA. As I show, indigenous farm laborers engage in novel forms of labor and political protests to claim for their rights. These developments, I argue, speak of the class formation of transnational farmworkers who, mobilizing local and transnationally, combine traditional labor demands with wider claims for their civil and political rights.     

Biphasic functions of the kinase-defective Ephb6 receptor in cell adhesion and migration

EphB6 is a unique member in the Eph family of receptor tyrosine kinases in that its kinase domain contains several alterations in conserved amino acids and is catalytically inactive. Although EphB6 is expressed both in a variety of embryonic and adult tissues, biological functions of this receptor are largely unknown. In the present study, we examined the function of EphB6 in cell adhesion and migration. We demonstrated that EphB6 exerted biphasic effects in response to different concentrations of the ephrin-B2 ligand; EphB6 promoted cell adhesion and migration when stimulated with low concentrations of ephrin-B2, whereas it induced repulsion and inhibited migration upon stimulation with high concentrations of ephrin-B2. A truncated EphB6 receptor lacking the cytoplasmic domain showed monophasic-positive effects on cell adhesion and migration, indicating that the cytoplasmic domain is essential for the negative effects. EphB6 is constitutively associated with the Src family kinase Fyn. High concentrations of ephrin-B2 induced tyrosine phosphorylation of EphB6 through an Src family kinase activity. These results indicate that EphB6 can both positively and negatively regulate cell adhesion and migration, and suggest that tyrosine phosphorylation of the receptor by an Src family kinase acts as the molecular switch for the functional transition.     

Plasma membrane receptor mediated MAPK signaling pathways are activated in human uterine cervix at parturition

Background  

Cervical ripening resembles an inflammatory reaction. Estrogens induce leukocyte migration into tissue and factors promoting cervical remodeling and labor, although the mechanisms are only partially known. The aim of this study was to investigate whether plasma membrane receptor mediated pathways, known to be activated by estrogens and proinflammatory compounds, are involved in cervical ripening before labor.     

Demand for labor and population growth in colonial Java

Population growth in Java paralleled the development of a colonial economy based on the production of export crops using Javanese land and labor. The increase in population may be interpreted as a demographic response to demand for labor within the family, created by the need to intensify subsistence production in the face of colonial demands on land, labor, and produce.     

重点生态功能区农户生计对环境资源的依赖性——以甘南高原为例

重点生态功能区承担着重要的生态系统服务供给功能,农户作为该区主要的经济活动主体,其对环境资源过度依赖会严重影响该区的生态环境质量,从而使生态系统服务功能受损。当前亟需深入探索重点生态功能区农户生计对环境资源的依赖性及其影响因素,为制定环境友好型区域发展政策提供借鉴。本研究以甘南高原为例,基于581份农户调查数据,分析了农户生计对环境资源的依赖度,并利用有序多分类Logistic回归模型识别了影响农户环境资源依赖度的因素。结果表明: 甘南高原农户生计对环境资源的依赖度较高,其主要体现在食物自给、生活用能、收入来源3个方面,依赖度分别为57.3%、56.9%和37.4%;不同类型农户生计对环境资源的依赖性存在显著差异,劳动力受教育水平较高及非农化水平较高的农户,对环境资源的依赖度较低,而抚养比系数较高的农户对环境资源的依赖度较高;家庭抚养比、劳动力受教育水平、家庭成员领导能力、外出打工人数占劳动力比重、生态政策、海拔等因素均对农户的环境资源依赖度有显著影响。其中,家庭抚养比、海拔对其具有正向影响,而外出打工人数占劳动力比重、劳动力受教育水平、家庭成员领导能力、生态政策等因素对其表现为负向影响。     

Woman of the house: gender, architecture, and ideology in Dorset prehistory

The role of women in Paleoeskimo households has rarely been examined. Careful application of analogies to Inuit culture reveal that there are both similarities and differences in how Late Dorset and Inuit gender roles are expressed in household organization. On an ideological level, Late Dorset women probably had a similar role to that of women in Inuit society, as the soul of the house and an important intermediary between hunters and the souls of the animals they hunted. On a day-to-day basis, however, Late Dorset women seem to have shared more of their labor as members of dual family households than did Inuit women, as members of nuclear family units. The increased importance of small, trapped game such as foxes and rabbits during Late Dorset times (Darwent 2001) may have contributed to the need for shared labor. Finally, women, in their role as keepers of the hearth, were important in maintaining community ties at seasonal aggregation sites dominated by long houses and external hearth rows.     

Role of nm23 in the regulation of cell shape and migration via Rho family GTPase signals

Rho family small GTPase plays a key role in the regulation of cell shape and migration in mammalian cells. Constitutive activation of Rho GTPase leads to the aberrant cell morphology and migration. We identified nm23-H2 as a binding partner of Lbc proto-oncogene product, which specifically activates RhoA, and revealed that nm23-H2 could act as a negative regulator of Rho activity. Furthermore, we found that Lbc, nm23-H2 and ICAP1-α could form tertial complex in cells, and this complex formation was thought to be critical for cell migration stimulated by integrin. It is reported that nm23-H1 bound to Tiam1 and Dbl, which activates Rac and Cdc42 small GTPase, respectively. We discuss the role of nm23 in the regulation of cell morphology and cell migration via Rho family GTPases.     

ArgBP2 and the SoHo family of adapter proteins in oncogenic diseases

ArgBP2, a member of the SoHo family of adapter proteins, is a regulator of actin-dependent processes such as cell adhesion and migration. Recent data from our lab revealed that by regulating adhesion and migration of pancreatic cancer cells, ArgBP2 is endowed with an anti-tumoral function. We could show that part of the molecular mechanism involved the interaction of ArgBP2 with the Arp2/3 activator WAVE1, the tyrosine phosphatase PTP-PEST, and the tyrosine kinase c-Abl. As ArgBP2 shares common structural organization and overlapping functions with the two other members of this protein family, CAP and Vinexin, it raises the question whether these two other proteins could also be involved in cancer diseases. The control of cell migration being an important issue in tumor treatment, these recent findings suggest that ArgBP2 family-dependent signaling pathways represents potential targets for the development of therapeutic strategies, and highlight the importance of elucidating their molecular mechanisms of cytoskeletal regulation.Key words: ArgBP2, pancreatic cancer, SoHo family of proteins, adapter protein, CAP/ponsin, vinexin, cell signaling, actin cytoskeleton, adhesion, migrationAcquisition of migration properties by cancerous cells is a crucial feature for cancer cell invasion and metastasis and, therefore, the control of cell migration is an important issue in tumor treatment.¹ As molecular mechanisms governing cell motility are common to non-neoplasic cells and cancer cells, the elucidation of these mechanisms is crucial in order to better understand how the loss of control of cell adhesion, migration and cytoskeletal organization participate to tumorigenesis.     

Regulation of microtubules in cell migration

Directional cell migration is a fundamental process in all organisms that is stringently regulated during tissue development, chemotaxis and wound healing. Migrating cells have a polarized morphology with an asymmetrical distribution of signaling molecules and the cytoskeleton. Microtubules are indispensable for the directional migration of certain cells. Recent studies have shown that Rho family GTPases, which are key regulators of cell migration, affect microtubules, in addition to the actin cytoskeleton and adhesion. Rho family GTPases capture and stabilize microtubules through their effectors at the cell cortex, leading to a polarized microtubule array; in turn, microtubules modulate the activities of Rho family GTPases. In this article, we discuss how a polarized microtubule array is established and how microtubules facilitate cell migration.     

The biogeography of Nothofagus and Trigonobalanus and the origin of the Fagaceae

The suggestion that Trigonobalanus excelsa reached Colombia by migration from south-east Asia via the Bering land-bridge is criticized. The distribution of Trigonobalanus can be more simply explained by the disruption and drift of the former Pacific continent and the peninsula of West Gondwanaland. All but the New Guinea species of Nothofagus remain on the drifted fragments of the Gondwana peninsula, the original home of the family. Drift accounts for the present disjunct distribution of related Nothofagus species in the Southern hemisphere, but topoclines in characters of the fructifications and of the leaves linking New Zealand, New Caledonia and New Guinea indicate the overland migration route into the Pacific continent. Diversification of the family occurred in Pacifica before that continent was disrupted in the late Jurassic. With the formation of Eurasia, a topocline in leaf characters developed in Fagus along the migration route from China to Western Europe. Absence of topoclines involving the Bering land-bridge indicate that this bridge played no significant part in the dispersal of the Fagaceae. Shedding of the fruits of Glossopteris before the development of an embryo draws attention to the primitive character of delay in fertilization found in Nothofagus.     

Members of the Zyxin family of LIM proteins interact with members of the p130Cas family of signal transducers.

Integrin binding to extracellular matrix proteins induces formation of signaling complexes at focal adhesions. Zyxin co-localizes with integrins at sites of cell-substratum adhesion and is postulated to serve as a docking site for the assembly of multimeric protein complexes involved in regulating cell motility. Recently, we identified a new member of the zyxin family called TRIP6. TRIP6 is localized at focal adhesions and overexpression of TRIP6 slows cell migration. In an effort to define the molecular mechanism by which TRIP6 affects cell migration, the yeast two-hybrid assay was employed to identify proteins that directly bind to TRIP6. This assay revealed that both TRIP6 and zyxin interact with CasL/HEF1, a member of the Cas family. This association is mediated by the LIM region of the zyxin family members and the SH2 domain-binding region of CasL/HEF1. Furthermore, the association between p130(Cas) and the two zyxin family members was demonstrated to occur in vivo by co-immunoprecipitation. Zyxin and Cas family members may cooperate to regulate cell motility.