Physiological and life history changes associated with seasonal adaptation in the cactophilic Drosophila mojavensis

Many insects inhabiting temperate climates are faced with changing environmental conditions throughout the year. Depending on the species, these environmental fluctuations can be experienced within a single generation or across multiple generations. Strategies for dealing with these seasonal changes vary across populations. Drosophila mojavensis is a cactophilic Drosophila species endemic to the Sonoran Desert. The Sonoran Desert regularly reaches temperatures of 50°C in the summer months. As individuals of this population are rare to collect in the summer months, we therefore simulated in a temperature and light controlled chamber the cycling temperatures experienced by D. mojavensis in the Sonoran Desert from April to July (four generations) to understand the physiological and life history changes that allow this population to withstand these conditions. In contrast to our hypothesis of a summer aestivation, we found that D. mojavensis continue to reproduce during the summer months, albeit with lower viability, but the longevity of the population is highly reduced during this period. As expected, stress resistance increased during the summer months in both the adult and the larval stages. This study examines several strategies for withstanding the Sonoran Desert summer conditions which may be informative in the study of other desert endemic species.

Beneficial cumulative effects of old parental age on offspring fitness

Old parental age is commonly associated with negative effects on offspring life-history traits. Such parental senescence effects are predicted to have a cumulative detrimental effect over successive generations. However, old parents may benefit from producing higher quality offspring when these compete for seasonal resources. Thus, old parents may choose to increase investment in their offspring, thereby producing fewer but larger and more competitive progeny. We show that Caenorhabditis elegans hermaphrodites increase parental investment with advancing age, resulting in fitter offspring who reach their reproductive peak earlier. Remarkably, these effects increased over six successive generations of breeding from old parents and were subsequently reversed following a single generation of breeding from a young parent. Our findings support the hypothesis that offspring of old parents receive more resources and convert them into increasingly faster life histories. These results contradict the theory that old parents transfer a cumulative detrimental ‘ageing factor’ to their offspring.

Identification of maternal-effect genes in zebrafish using maternal crispants

In animals, early development is dependent on a pool of maternal factors, both RNA and proteins, which are required for basic cellular process and cell differentiation until zygotic genome activation. The role of a majority of these maternally expressed factors is not fully understood. By exploiting the biallelic editing ability of CRISPR-Cas9, we identify and characterize maternal-effect genes in a single generation, using a maternal crispant technique. We validated the ability to generate biallelic mutations in the germline by creating maternal crispants that phenocopied previously characterized maternal-effect genes: motley/birc5b, tmi/prc1l, and aura/mid1ip1. Additionally, by targeting maternally expressed genes of unknown function in zebrafish, we identified two new maternal-effect zebrafish genes, kpna7 and fhdc3. The genetic identity of these maternal crispants was confirmed by sequencing haploid progeny from F0 females, which allowed the analysis of newly induced lesions in the maternal germ line. Our studies show that maternal crispants allow for the effective identification and primary characterization of maternal-effect genes in a single generation, facilitating the reverse genetics analysis of maternal factors that drive embryonic development.

On “Dynastic” Inequality

This chapter investigates whether the replication of inequality is, other things being equal, morally objectionable in ways not applicable to inequality that remains confined to a single generation or “birth cohort.” The focus is both theoretical and practical. The chapter considers the philosophical foundations that might lie behind an objection to dynastic inequality, negotiating the diversity of egalitarian views supporting this position and the complexity around the causal mechanisms at work in cases where inequality has a dynastic tendency. It then discusses the policy reforms that might target inequalities that replicate old distributive trends while leaving newly produced trends more intact, with a focus on tax policy. Current tax rules in most developed economies do not make a distinction between new and old influences on the material distribution. Accordingly, it is likely that the tax reforms implied could be quite extensive.

A genotype independent DMP-HI system in dicot crops

Doubled haploid (DH) technology is used to obtain homozygous lines in a single generation, which significantly accelerates the crop breeding trajectory. Traditionally, in vitro culture is used to generate DHs, but is limited by species and genotype recalcitrance. In vivo haploid induction (HI) through seed is been widely and efficiently used in maize and was recently extended to several monocot crops. However, a similar generic and efficient HI system is still lacking in dicot crops. Here we show that genotype-independent in vivo HI can be triggered by mutation of DMP genes in tomato, rapeseed and tobacco with HI rates of ~1.9%, 2.4% and 1.2%, respectively. The DMP-HI system offers a robust DH technology to facilitate variety improvement in these crops. The success of this approach and the conservation of DMP genes paves the way for a generic and efficient genotype-independent HI system in other dicot crops.

Association of family structure with gain and loss of household headship among older adults in India: Analysis of panel data

Background Despite huge changes in demographic behaviors, the family continues to be the major source of psychosocial support for older adults in India. The loss of household headship can be a cause of disregard for the aged and is associated in a very fundamental way with other status losses. Our study used the two rounds of the India Human Development Survey to understand the association of family structure on the gain or loss status of household headship among 10,527 older adults. Method Bivariate analysis was done using the chi-square test for association. Equivalently, the multivariate analysis involved estimating multivariable logistic regression models. Multicollinearity did not affect the estimates from the regression models. For examining headship transition, we performed two complete sets of analysis, by taking gain in headship and loss in headship as the outcome variable respectively. Results Across two rounds, a major shift in family structure was noticed as 6.8% of households moved from extended to a single generation. Results indicate that family structure was significantly associated with gaining and losing headship among older adults. Headship loss was more common among nuclear [OR: 2.16; CI: 1.28, 3.65] and extended [OR: 2.76; CI: 1.64, 4.66] family structures. Moreover, gaining headship was found to be significantly associated with married, educated, and working older adults. Conclusion Since living in single generation household may preferably be encouraged among older adults than their living in a complex household without headship and value they deserve, the public intervention may support the independent living within the older population through housing policies that create additional choices presented to older adults making residential decisions.

ENVIRONMENTAL DISASTER: COOPERATION OF UZBEKISTAN WITH REPUBLIC OF KOREA ON THE ARAL SEA PROBLEMS

The article analyzes the causes, and consequences of the Aral Sea catastrophe and considers initial results of regional and international cooperation aimed at cushioning urgent problems, especially those emerging in the Aral Sea Basin disaster zone. The Aral, one of the world’s largest lakes, to dried up and almost disappeared within the lifespan of a single generation. Mismanagement of water resources and cotton monoculture led the Aral to a point of irreversibility by the FSU’s break-up. After dissolution of the FSU, the problem took on an international character, with multifaceted implications for keeping negative effects on sustainable human development as attempts were made to preserve at least some fragments of the Aral. Joint national, regional and international efforts initiated by new Uzbekistan situation in recent 4 years has been step by step improving. Cooperation of Uzbekistan with Republic of Korea on the Aral Sea Problems also serves for this purpose.

Fraternal households of the Saratov province at the end of the XIX century: Historical and demographic analysis

Fraternal households belong to the category of specific complex households consisting of cohabiting single-generation couples. As a rule, their appearance is the result of an unfulfilled family section for one reason or another. Due to their structural exoticism, fraternal families are easily identified and compared. At the same time, by virtue of their peculiarity, fraternal families are more likely unstable collectives, prone to disintegration. Within the framework of this article, an analysis of fraternal households recorded in the materials of zemstvo courtyard censuses of the province of the late XIX century will be made.

Inherently confinable split-drive systems in Drosophila

CRISPR-based gene-drive systems, which copy themselves via gene conversion mediated by the homology-directed repair (HDR) pathway, have the potential to revolutionize vector control. However, mutant alleles generated by the competing non-homologous end-joining (NHEJ) pathway, resistant to Cas9 cleavage, can interrupt the spread of gene-drive elements. We hypothesized that drives targeting genes essential for viability or reproduction also carrying recoded sequences that restore endogenous gene functionality should benefit from dominantly-acting maternal clearance of NHEJ alleles combined with recessive Mendelian culling processes. Here, we test split gene-drive (sGD) systems in Drosophila melanogaster that are inserted into essential genes required for viability (rab5, rab11, prosalpha2) or fertility (spo11). In single generation crosses, sGDs copy with variable efficiencies and display sex-biased transmission. In multigenerational cage trials, sGDs follow distinct drive trajectories reflecting their differential tendencies to induce target chromosome damage and/or lethal/sterile mosaic Cas9-dependent phenotypes, leading to inherently confinable drive outcomes.

Identification of Maternal-Effect Genes in Zebrafish using Maternal Crispants

In animals, early development is dependent on a pool of maternal factors, both RNA and proteins, which are required for basic cellular process and cell differentiation until zygotic genome activation. The role of a majority of these maternally expressed factors in adult fertility and early development is not fully understood. By exploiting the biallelic editing ability of CRISPR-Cas9 and the benefits of the zebrafish model, we identify and characterize maternal-effect genes in a single generation, using a maternal crispant technique. We validated the ability to generate biallelic mutations in the germline by creating maternal crispants that phenocopied previously characterized maternal-effect genes: motley/birc5b, tmi/prc1l, and aura/mid1ip1. Additionally, by targeting maternally expressed genes of unknown function in zebrafish, we identified two new maternal-effect zebrafish genes, kpna7 and fhcd3. The genetic identity of these maternal crispants was confirmed by sequencing haploid progeny from F0 females, which allowed the sequence analysis of newly induced lesions in the maternal germ line. Analysis of the induced lesions shows minimal genetic variation within a clutch, with an average of two edited alleles per clutch. These findings are consistent with biallelic editing events occurring in germ cells or their precursors of early CRISPR-Cas9-injected embryos, leading to maternal-effect phenotypes in the offspring. Our studies show that maternal crispants allow for the effective identification and primary characterization of maternal-effect genes in a single generation, facilitating the reverse genetics analysis of maternal factors that drive embryonic development.