The effect of a political crisis on performance of community forests and protected areas in Madagascar

Understanding the effectiveness of conservation interventions during times of political instability is important given how much of the world's biodiversity is concentrated in politically fragile nations. Here, we investigate the effect of a political crisis on the relative performance of community managed forests versus protected areas in terms of reducing deforestation in Madagascar, a biodiversity hotspot. We use remotely sensed data and statistical matching within an event study design to isolate the effect of the crisis and post-crisis period on performance. Annual rates of deforestation accelerated at the end of the crisis and were higher in community forests than in protected areas. After controlling for differences in location and other confounding variables, we find no difference in performance during the crisis, but community-managed forests performed worse in post-crisis years. These findings suggest that, as a political crisis subsides and deforestation pressures intensify, community-based conservation may be less resilient than state protection.

A planetary health innovation for disease, food and water challenges in Africa

Many communities in low- and middle-income countries globally lack sustainable, cost-effective and mutually beneficial solutions for infectious disease, food, water and poverty challenges, despite their inherent interdependence^1-7. Here we provide support for the hypothesis that agricultural development and fertilizer use in West Africa increase the burden of the parasitic disease schistosomiasis by fuelling the growth of submerged aquatic vegetation that chokes out water access points and serves as habitat for freshwater snails that transmit Schistosoma parasites to more than 200 million people globally^8-10. In a cluster randomized controlled trial (ClinicalTrials.gov: NCT03187366) in which we removed invasive submerged vegetation from water points at 8 of 16 villages (that is, clusters), control sites had 1.46 times higher intestinal Schistosoma infection rates in schoolchildren and lower open water access than removal sites. Vegetation removal did not have any detectable long-term adverse effects on local water quality or freshwater biodiversity. In feeding trials, the removed vegetation was as effective as traditional livestock feed but 41 to 179 times cheaper and converting the vegetation to compost provided private crop production and total (public health plus crop production benefits) benefit-to-cost ratios as high as 4.0 and 8.8, respectively. Thus, the approach yielded an economic incentive-with important public health co-benefits-to maintain cleared waterways and return nutrients captured in aquatic plants back to agriculture with promise of breaking poverty-disease traps. To facilitate targeting and scaling of the intervention, we lay the foundation for using remote sensing technology to detect snail habitats. By offering a rare, profitable, win-win approach to addressing food and water access, poverty alleviation, infectious disease control and environmental sustainability, we hope to inspire the interdisciplinary search for planetary health solutions¹¹ to the many and formidable, co-dependent global grand challenges of the twenty-first century.

From remotely sensed solar-induced chlorophyll fluorescence to ecosystem structure, function, and service: Part I-Harnessing theory

Solar-induced chlorophyll fluorescence (SIF) is a remotely sensed optical signal emitted during the light reactions of photosynthesis. The past two decades have witnessed an explosion in availability of SIF data at increasingly higher spatial and temporal resolutions, sparking applications in diverse research sectors (e.g., ecology, agriculture, hydrology, climate, and socioeconomics). These applications must deal with complexities caused by tremendous variations in scale and the impacts of interacting and superimposing plant physiology and three-dimensional vegetation structure on the emission and scattering of SIF. At present, these complexities have not been overcome. To advance future research, the two companion reviews aim to (1) develop an analytical framework for inferring terrestrial vegetation structures and function that are tied to SIF emission, (2) synthesize progress and identify challenges in SIF research via the lens of multi-sector applications, and (3) map out actionable solutions to tackle these challenges and offer our vision for research priorities over the next 5-10 years based on the proposed analytical framework. This paper is the first of the two companion reviews, and theory oriented. It introduces a theoretically rigorous yet practically applicable analytical framework. Guided by this framework, we offer theoretical perspectives on three overarching questions: (1) The forward (mechanism) question-How are the dynamics of SIF affected by terrestrial ecosystem structure and function? (2) The inference question: What aspects of terrestrial ecosystem structure, function, and service can be reliably inferred from remotely sensed SIF and how? (3) The innovation question: What innovations are needed to realize the full potential of SIF remote sensing for real-world applications under climate change? The analytical framework elucidates that process complexity must be appreciated in inferring ecosystem structure and function from the observed SIF; this framework can serve as a diagnosis and inference tool for versatile applications across diverse spatial and temporal scales.

From remotely-sensed solar-induced chlorophyll fluorescence to ecosystem structure, function, and service: Part II-Harnessing data

Although our observing capabilities of solar-induced chlorophyll fluorescence (SIF) have been growing rapidly, the quality and consistency of SIF datasets are still in an active stage of research and development. As a result, there are considerable inconsistencies among diverse SIF datasets at all scales and the widespread applications of them have led to contradictory findings. The present review is the second of the two companion reviews, and data oriented. It aims to (1) synthesize the variety, scale, and uncertainty of existing SIF datasets, (2) synthesize the diverse applications in the sector of ecology, agriculture, hydrology, climate, and socioeconomics, and (3) clarify how such data inconsistency superimposed with the theoretical complexities laid out in (Sun et al., 2023) may impact process interpretation of various applications and contribute to inconsistent findings. We emphasize that accurate interpretation of the functional relationships between SIF and other ecological indicators is contingent upon complete understanding of SIF data quality and uncertainty. Biases and uncertainties in SIF observations can significantly confound interpretation of their relationships and how such relationships respond to environmental variations. Built upon our syntheses, we summarize existing gaps and uncertainties in current SIF observations. Further, we offer our perspectives on innovations needed to help improve informing ecosystem structure, function, and service under climate change, including enhancing in-situ SIF observing capability especially in "data desert" regions, improving cross-instrument data standardization and network coordination, and advancing applications by fully harnessing theory and data.

Journal submissions, review and editorial decision patterns during initial COVID-19 restrictions

We use the full administrative records from four leading agricultural economics journals to study the impacts of the COVID-19 pandemic on manuscript submission, editorial desk rejection and reviewer acceptance rates, and time to editorial decision. We also test for gender differences in these impacts. Manuscript submissions increased sharply and equi-proportionately by gender. Desk rejection rates remained stable, leading to increased demand for reviews. Female reviewers became eight percentage points more likely to decline a review invitation during the early stage of the pandemic. First editorial decisions for papers sent out for peer review occurred significantly faster after pandemic lockdowns began. Overall, the initial effects of the pandemic on journal editorial tasks and review patterns appear relatively modest, despite the increased number of submissions handled by editors and reviewers. We find no evidence in agricultural economics of a generalized disruption to near-term, peer-reviewed publication.

Building a Global Food Systems Typology: A New Tool for Reducing Complexity in Food Systems Analysis

Food systems have a profound impact on diets, nutrition, health, economic development, and environmental sustainability. Yet their complexity poses a persistent challenge in identifying the policy actions that are needed to improve human and planetary health outcomes. Typologies are a useful classification tool to identify similarities and differences among food systems, while reducing this analytical complexity. This study presents a new food system typology, implemented at the country level using parsimonious data that characterize food supply chains, food environments, consumer-related factors, and key outcomes, including dietary intake, nutritional status, health, and environmental impacts. Five food system types are identified: rural and traditional; informal and expanding; emerging and diversifying; modernizing and formalizing; and industrial and consolidated. Patterns across the five system types in key outcome variables align with narratives provided by the food systems and nutrition transition literature, demonstrating the usefulness of this classification method. Substantial heterogeneity nonetheless still exists within individual food system types. Therefore, the recommended use of the typology is in early stages of hypothesis generation, to identify potential risk factors or constraints in the food system that can be explored further at national and sub-national levels.

Sustainability standards in global agrifood supply chains

Agrifood supply chains contribute to many environmental and social problems. Sustainability standards-rules that supply chain actors may follow to demonstrate their commitment to social equity and/or environmental protection-aim to mitigate such problems. We provide a narrative review of the effects of many distinct sustainability standards on different supply chain actors spanning multiple crops. Furthermore, we discuss five emerging questions-causality, exclusion, compliance and monitoring, excess supply and emerging country markets-and identify directions for future research. We find that, while sustainability standards can help improve the sustainability of production processes in certain situations, they are insufficient to ensure food system sustainability at scale, nor do they advance equity objectives in agrifood supply chains.

Post-farmgate food value chains make up most of consumer food expenditures globally

Progress towards many United Nations Sustainable Development Goals depends on interventions in food value chains, yet data and methods have thus far limited the production of cross-nationally comparable estimates of food value chains' magnitudes. Here we develop a standardized method and data series to estimate the distribution of consumer food expenditures between value-added activities on farms and in the post-farmgate value chain. Using data from 61 countries over 2005-2015, representing 90% of the global economy, we show that farmers receive, on average, 27% of consumer expenditure on foods consumed at home and a far lower percentage of food consumed away from home. That figure consistently falls in the 16-38% range for middle- and high-income countries and falls significantly as incomes rise. The large and growing post-farmgate food value chain merits greater attention as the world grapples with the economic, environmental and social impacts of food systems.

Fishers' response to temperature change reveals the importance of integrating human behavior in climate change analysis

Climate change will reshape ecological dynamics. Yet, how temperature increases alter the behavior and resource use of people reliant on natural resources remains underexplored. Consequent behavior shifts have the potential to mitigate or accelerate climate impacts on livelihoods and food security. Particularly within the small-scale inland fisheries that support approximately 10% of the global population, temperature changes likely affect both fish and fishers. To analyze how changing temperatures alter households' fishing behavior, we examined fishing effort and fish catch in a major inland fishery. We used longitudinal observational data from households in Cambodia, which has the highest per-capita consumption of inland fish in the world. Higher temperatures caused households to reduce their participation in fishing but had limited net effects on fish catch. Incorporating human behavioral responses to changing environmental conditions will be fundamental to determining how climate change affects rural livelihoods, food production, and food access.

Articulating the effect of food systems innovation on the Sustainable Development Goals

Food system innovations will be instrumental to achieving multiple Sustainable Development Goals (SDGs). However, major innovation breakthroughs can trigger profound and disruptive changes, leading to simultaneous and interlinked reconfigurations of multiple parts of the global food system. The emergence of new technologies or social solutions, therefore, have very different impact profiles, with favourable consequences for some SDGs and unintended adverse side-effects for others. Stand-alone innovations seldom achieve positive outcomes over multiple sustainability dimensions. Instead, they should be embedded as part of systemic changes that facilitate the implementation of the SDGs. Emerging trade-offs need to be intentionally addressed to achieve true sustainability, particularly those involving social aspects like inequality in its many forms, social justice, and strong institutions, which remain challenging. Trade-offs with undesirable consequences are manageable through the development of well planned transition pathways, careful monitoring of key indicators, and through the implementation of transparent science targets at the local level.

The intertemporal evolution of agriculture and labor over a rapid structural transformation: Lessons from Vietnam

We combine nationally representative household and labor force survey data from 1992 to 2016 to provide a detailed description of rural labor market evolution and how it relates to the structural transformation of rural Vietnam, especially within the agricultural sector. Our study adds to the emerging literature on structural transformation in low-income countries using micro-level data and helps to answer several policy-related questions. We find limited employment creation potential of agriculture, especially for youth. Rural-urban real wage convergence has gone hand-in-hand with increased diversification of the rural economy into the non-farm sector nationwide and rapid advances in educational attainment in all sectors' and regions' workforce. Minimum wage laws seem to have played no significant role in increasing agricultural wages. This enhanced integration also manifests in steady attenuation of the longstanding inverse farm size-yield relationship. Farming has remained securely household-based and the family farmland distribution has remained largely unchanged. Small farm sizes have not obstructed mechanization nor the uptake of labor-saving pesticides, consistent with factor substitution induced by rising real wage rates. As rural households rely more heavily on the labor market, human capital accumulation (rather than land endowments) have become the key correlate of improvements in rural household well-being.

Cohort Description of the Madagascar Health and Environmental Research-Antongil (MAHERY-Antongil) Study in Madagascar

The Madagascar Health and Environmental Research-Antongil (MAHERY-Antongil) study cohort was set up in September 2015 to assess the nutritional value of seafood for the coastal Malagasy population living along Antongil Bay in northeastern Madagascar. Over 28 months of surveillance, we aimed to understand the relationships among different marine resource governance models, local people's fish catch, the consumption of seafood, and nutritional status. In the Antongil Bay, fisheries governance takes three general forms: traditional management, marine national parks, and co-management. Traditional management involves little to no involvement by the national government or non-governmental organizations, and focuses on culturally accepted Malagasy community practices. Co-management and marine national parks involve management support from either an non-govermental organization (NGO) or the national government. Five communities of varying governance strategies were enrolled into the study including 225 households and 1031 individuals whose diets, resource acquisition strategies, fisheries and agricultural practices, and other social, demographic and economic indicators were measured over the span of 3 years. Clinical visits with each individual were conducted at two points during the study to measure disease and nutritional status. By analyzing differences in fish catch arising from variation in governance (in addition to intra-annual seasonal changes and minor inter-annual changes), the project will allow us to calculate the public health value of sustainable fisheries management approaches for local populations. There is hope that coastal zones that are managed sustainably can increase the productivity of fisheries, increasing the catch of seafood products for poor, undernourished populations.

Emerging human infectious diseases and the links to global food production

Infectious diseases are emerging globally at an unprecedented rate while global food demand is projected to increase sharply by 2100. Here, we synthesize the pathways by which projected agricultural expansion and intensification will influence human infectious diseases and how human infectious diseases might likewise affect food production and distribution. Feeding 11 billion people will require substantial increases in crop and animal production that will expand agricultural use of antibiotics, water, pesticides and fertilizer, and contact rates between humans and both wild and domestic animals, all with consequences for the emergence and spread of infectious agents. Indeed, our synthesis of the literature suggests that, since 1940, agricultural drivers were associated with >25% of all - and >50% of zoonotic - infectious diseases that emerged in humans, proportions that will likely increase as agriculture expands and intensifies. We identify agricultural and disease management and policy actions, and additional research, needed to address the public health challenge posed by feeding 11 billion people.

Review: Food loss and waste in Sub-Saharan Africa

The research, development practitioner, and donor community has begun to focus on food loss and waste - often referred to as post-harvest losses (PHL) - in Sub-Saharan Africa. This article reviews the current state of the literature on PHL mitigation. First, we identify explicitly the varied objectives underlying efforts to reduce PHL levels. Second, we summarize the estimated magnitudes of losses, evaluate the methodologies used to generate those estimates, and explore the dearth of thoughtful assessment around "optimal" PHL levels. Third, we synthesize and critique the impact evaluation literature around on-farm and off-farm interventions expected to deliver PHL reduction. Fourth, we suggest a suite of other approaches to advancing these same objectives, some of which may prove more cost-effective. Finally, we conclude with a summary of main points.

Agricultural factor markets in Sub-Saharan Africa: An updated view with formal tests for market failure

This paper uses the recently collected Living Standard Measurement Study-Integrated Surveys on Agriculture Initiative data sets from five countries in Sub-Saharan Africa to provide a comprehensive overview of factor market participation by agrarian households and to formally test for failures in rural markets. Under complete and competitive markets, households can solve their consumption and production problems separately, so that household factor endowments do not predict input demand. This paper implements a simple, theoretically grounded test of this separation hypothesis, which can be interpreted as a reduced form test of market failure. In all five study countries, the analysis finds strong evidence of factor market failure. Moreover, those failures appear general and structural, not specific to subpopulations defined by gender, geography, human capital, or land quality. However, we show that rural markets are not generally missing in an absolute sense, suggesting that market existence is less of a problem than market function.

Ten striking facts about agricultural input use in Sub-Saharan Africa

Conventional wisdom holds that Sub-Saharan African farmers use few modern inputs despite the fact that most poverty-reducing agricultural growth in the region is expected to come largely from expanded use of inputs that embody improved technologies, particularly improved seed, fertilizers and other agro-chemicals, machinery, and irrigation. Yet following several years of high food prices, concerted policy efforts to intensify fertilizer and hybrid seed use, and increased public and private investment in agriculture, how low is modern input use in Africa really? This article revisits Africa's agricultural input landscape, exploiting the unique, recently collected, nationally representative, agriculturally intensive, and cross-country comparable Living Standard Measurement Study-Integrated Surveys on Agriculture (LSMS-ISA) covering six countries in the region (Ethiopia, Malawi, Niger, Nigeria, Tanzania, and Uganda). Using data from over 22,000 households and 62,000 agricultural plots, we offer ten potentially surprising facts about modern input use in Africa today.

Assessing the Impact of U.S. Food Assistance Delivery Policies on Child Mortality in Northern Kenya

The U.S. is the main country in the world that delivers its food assistance primarily via transoceanic shipments of commodity-based in-kind food. This approach is costlier and less timely than cash-based assistance, which includes cash transfers, food vouchers, and local and regional procurement, where food is bought in or nearby the recipient country. The U.S.’s approach is exacerbated by a requirement that half of its transoceanic food shipments need to be sent on U.S.-flag vessels. We estimate the effect of these U.S. food assistance distribution policies on child mortality in northern Kenya by formulating and optimizing a supply chain model. In our model, monthly orders of transoceanic shipments and cash-based interventions are chosen to minimize child mortality subject to an annual budget constraint and to policy constraints on the allowable proportions of cash-based interventions and non-US-flag shipments. By varying the restrictiveness of these policy constraints, we assess the impact of possible changes in U.S. food aid policies on child mortality. The model includes an existing regression model that uses household survey data and geospatial data to forecast the mean mid-upper-arm circumference Z scores among children in a community, and allows food assistance to increase Z scores, and Z scores to influence mortality rates. We find that cash-based interventions are a much more powerful policy lever than the U.S.-flag vessel requirement: switching to cash-based interventions reduces child mortality from 4.4% to 3.7% (a 16.2% relative reduction) in our model, whereas eliminating the U.S.-flag vessel restriction without increasing the use of cash-based interventions generates a relative reduction in child mortality of only 1.1%. The great majority of the gains achieved by cash-based interventions are due to their reduced cost, not their reduced delivery lead times; i.e., the reduction of shipping expenses allows for more food to be delivered, which reduces child mortality.

Socioenvironmental threats to pastoral livelihoods: risk perceptions in the Altay and Tianshan Mountains of Xinjiang, China

Subjective risk perceptions give rise to unique policy implications as they reflect both the expectation of risk exposure and the ability to mitigate or cope with the adverse impacts. Based on data collected from semistructured interviews and iterative ranking exercises with 159 households in the Altay and Tianshan Mountains of Xinjiang, China, this study investigates and explains the risks with respect to a seriously understudied population and location. Using both geostatistical and econometric methods, we show that although fear of environmental crisis is prevalent among our respondents, recently implemented pastoral conservation, sedentarization, and development projects are more likely to be ranked as the top concerns among affected households. In order to reduce these concerns, future pastoral policy must be built on the livestock economy, and intervention priority should be given to the geographic areas identified as risk hot spots. In cases where pastoralists have to give up their pastures, the transition to other comparable livelihood strategies must be enabled by creating new opportunities and training pastoralists to acquire the needed skills.

Poverty, disease, and the ecology of complex systems

Understanding why some human populations remain persistently poor remains a significant challenge for both the social and natural sciences. The extremely poor are generally reliant on their immediate natural resource base for subsistence and suffer high rates of mortality due to parasitic and infectious diseases. Economists have developed a range of models to explain persistent poverty, often characterized as poverty traps, but these rarely account for complex biophysical processes. In this Essay, we argue that by coupling insights from ecology and economics, we can begin to model and understand the complex dynamics that underlie the generation and maintenance of poverty traps, which can then be used to inform analyses and possible intervention policies. To illustrate the utility of this approach, we present a simple coupled model of infectious diseases and economic growth, where poverty traps emerge from nonlinear relationships determined by the number of pathogens in the system. These nonlinearities are comparable to those often incorporated into poverty trap models in the economics literature, but, importantly, here the mechanism is anchored in core ecological principles. Coupled models of this sort could be usefully developed in many economically important biophysical systems--such as agriculture, fisheries, nutrition, and land use change--to serve as foundations for deeper explorations of how fundamental ecological processes influence structural poverty and economic development.

Risk-taking behavior in the presence of nonconvex asset dynamics

The growing literature on poverty traps emphasizes the links between multiple equilibria and risk avoidance. However, multiple equilibria may also foster risk-taking behavior by some poor people. We illustrate this idea with a simple analytical model in which people with different wealth and ability endowments make investment and risky activity choices in the presence of known nonconvex asset dynamics. This model underscores a crucial distinction between familiar static concepts of risk aversion and forward-looking dynamic risk responses to nonconvex asset dynamics. Even when unobservable preferences exhibit decreasing absolute risk aversion, observed behavior may suggest that risk aversion actually increases with wealth near perceived dynamic asset thresholds. Although high ability individuals are not immune from poverty traps, they can leverage their capital endowments more effectively than lower ability types and are therefore less likely to take seemingly excessive risks. In general, linkages between behavioral responses and wealth dynamics often seem to run in both directions. Both theoretical and empirical poverty trap research could benefit from making this two-way linkage more explicit.

Measuring food insecurity

Food security is a growing concern worldwide. More than 1 billion people are estimated to lack sufficient dietary energy availability, and at least twice that number suffer micronutrient deficiencies. Because indicators inform action, much current research focuses on improving food insecurity measurement. Yet estimated prevalence rates and patterns remain tenuous because measuring food security, an elusive concept, remains difficult.

The complex links between governance and biodiversity

We argue that two problems weaken the claims of those who link corruption and the exploitation of natural resources. The first is conceptual and the second is methodological. Studies that use national-level indicators of corruption fail to note that corruption comes in many forms, at multiple levels, that may affect resource use quite differently: negatively, positively, or not at all. Without a clear causal model of the mechanism by which corruption affects resources, one should treat with caution any estimated relationship between corruption and the state of natural resources. Simple, atheoretical models linking corruption measures and natural resource use typically do not account for other important control variables pivotal to the relationship between humans and natural resources. By way of illustration of these two general concerns, we used statistical methods to demonstrate that the findings of a recent, well-known study that posits a link between corruption and decreases in forests and elephants are not robust to simple conceptual and methodological refinements. In particular, once we controlled for a few plausible anthropogenic and biophysical conditioning factors, estimated the effects in changes rather than levels so as not to confound cross-sectional and longitudinal variation, and incorporated additional observations from the same data sources, corruption levels no longer had any explanatory power.

The sperm stress test: a novel test that predicts pregnancy in assisted reproductive technologies

OBJECTIVE

To develop a reliable sperm test that would predict pregnancy rate in assisted reproductive technologies.

DESIGN

Blind prospective cohort study.

SETTING

Tertiary-care, university hospital-affiliated IVF program.

PATIENTS

One hundred nineteen sperm samples were obtained from 110 males from couples undergoing IVF or GIFT (ART). Sperm samples were washed by Percoll, incubated at 24 degrees C for 4 hours, and an aliquot of the same sperm suspension was used for ART incubated at 40 degrees C for 4 hours (stress test). Stress test scores are expressed as the ratio of final to initial motility.

RESULTS

Of 119 ART cycles, 24 resulted in pregnancy. Of 24 pregnancies, 23 occurred in cycles that used sperm samples with stress test scores > or = 0.75 and only one with a stress test score < 0.75. The negative predictive value of the test, defined as the absence of pregnancy with scores < 0.75, was 98% and the positive predictive value, defined as the occurrence of pregnancy with scores > or = 0.75, was 36%. Logistic regression analysis indicated that the stress test score alone was correlated significantly with pregnancy after ART.

CONCLUSION

These results indicate that stress test scores < 0.75 are predictive of poor pregnancy outcome in ART.

Progestins inhibit murine oocyte meiotic maturation in vitro

The in vitro culture of fully grown mammalian oocytes results in spontaneous meiotic maturation from prophase arrest to metaphase II. This maturation can be inhibited by steroid hormones in both murine and porcine oocytes. Using selected steroids, we have examined the structure-activity relationships of steroids and oocyte inhibition. Experiments with androgens, estrogens, glucocorticoids, and progesterone revealed that at least one steroid from each class was inhibitory. Progesterone, however, was two to three times more effective than steroids from other classes. Examination of a variety of progestins showed that most substitutions decreased or abolished the inhibitory activity. Hydroxy group substitutions at different carbon atoms and substitutions at the 4-ene group lessened the inhibitory effectiveness, with the exception of 5 beta-dihydroprogesterone, which was as effective as progesterone. However, several steroids with substitutions at the C17 acetyl group were more active than progesterone, including 20 beta-dihydroprogesterone which was the most inhibitory steroid tested (ID50 = 5 microM). The progesterone agonist R5020 was also very active (ID50 = 8 microM). This is the first report of a detailed examination of the steroid-induced inhibition of murine oocytes. A comparison between the results reported here and previous reports of steroid-induced inhibition in porcine oocytes reveals differences in the response of oocytes from the two families. The structure-activity relationships of the inhibitory steroids examined here suggest that the steroids are acting via a receptor-mediated system.

A purified S6 kinase kinase from Xenopus eggs activates S6 kinase II and autophosphorylates on serine, threonine, and tyrosine residues

S6 kinases I and II have been purified previously from Xenopus eggs and shown to be activated by phosphorylation on serine and threonine residues. An S6 kinase clone, closely related to S6 kinase II, was subsequently identified and the protein product was expressed in a baculovirus system. Using this protein, termed "rsk" for Ribosomal Protein S6 Kinase, as a substrate, we have purified to homogeneity from unfertilized Xenopus eggs a 41-kDa serine/threonine kinase termed rsk kinase. Both microtubule-associated protein-2 and myelin basic protein are good substrates for rsk kinase, whereas alpha-casein, histone H1, protamine, and phosvitin are not. rsk kinase is inhibited by low concentrations of heparin as well as by beta-glycerophosphate and calcium. Activation of rsk kinase during Xenopus oocyte maturation is correlated with phosphorylation on threonine and tyrosine residues. However, in vitro, rsk kinase undergoes autophosphorylation on serine, threonine, and tyrosine residues, identifying it as a "dual specificity" enzyme. Purified rsk kinase can be inactivated in vitro by either a 37-kDa T-cell protein-tyrosine phosphatase or the serine/threonine protein phosphatase 2A. Phosphatase-treated S6KII can be reactivated by rsk kinase, and S6 kinase activity in resting oocyte extracts increases significantly when purified rsk kinase is added. The availability of purified rsk kinase will enhance study of the signal transduction pathway(s) regulating phosphorylation of ribosomal protein S6 in Xenopus oocytes.

Efficacy and safety field trials of a recombinant DNA vaccine against feline leukemia virus infection

A new recombinant gp70 vaccine was found to be safe and effective for prevention of infection by FeLV. The vaccine incorporates a unique purified saponin adjuvant with the recombinant antigen. Serious systemic reactions were not observed during the efficacy trial. Local reactions were transient and mild. More than 2,000 doses were administered to a cross section of household cats in a field safety trial. Only 1 cat had hypersensitivity reaction, which resolved. Among veterinarians who used the vaccine and the cat owners, the vaccine was judged satisfactory and safe. After rigorous intraperitoneal challenge exposure without use of immunosuppressants, 100% of the controls in the efficacy trial became infected, 70% of which remained persistently infected with FeLV. Among vaccinates, 45% were never viremic and 40% cleared transient infection within 12 weeks after challenge exposure. Of the 20 vaccinated cats, 3 were persistently infected. Overall, 85% of cats vaccinated with this recombinant DNA FeLV vaccine resisted persistent FeLV infection after stringent challenge exposure, which translates to preventable fraction of 78.6%.

Ha-rasVal-12,Thr-59 activates S6 kinase and p34cdc2 kinase in Xenopus oocytes: evidence for c-mosxe-dependent and -independent pathways

Treatment with insulin or progesterone or microinjection of the transforming protein product of Ha-rasVal-12,Thr-59 (p21) is known to induce germinal vesicle breakdown in Xenopus oocytes. We have investigated the effect of p21 on S6 kinase and the H1 histone kinase of maturation-promoting factor in the presence and absence of antisense oligonucleotides against the c-mosxe proto-oncogene. Injection of p21 led to a rapid increase in S6 phosphorylation, with kinetics similar to those previously observed with insulin. Microinjection of c-mosxe antisense oligonucleotides inhibited germinal vesicle breakdown induced by p21 and totally abolished S6 kinase activation by insulin or progesterone but only partially inhibited activation by p21. However, the activation of p34cdc2 protein kinase by all three stimuli was blocked by antisense oligonucleotides. The results suggest that in oocyte maturation c-mosxe functions downstream of p21 but upstream of p34cdc2 and S6 kinase activation, although not all p21-induced events require c-mosxe.