Pesticide resistance: can we make it a renewable resource?

Negative cross-resistance (NCR) occurs when a mutant allele confers (i) resistance to one toxic chemical and (ii) hyper-susceptibility to another. Sequential deployment of NCR toxins is useful for insect control in few situations (Pittendrigh et al., 2000). Using Monte Carlo simulations, we investigated the concurrent use of a pair of NCR toxins to control a hypothetical insect pest population. When the toxins killed more heterozygotes than homozygotes, the resistance allele became either extremely common or rare depending on starting allelic frequency. If the NCR toxins did not kill the two homozygous groups equally, then the toxin with lesser toxicity eventually played a greater role in the control of the pest population. Based on our results, we present an approach for the systematic development of an NCR toxin after the commercial release of the first toxin. First, large-scale screens are performed to find chemicals that kill the resistant homozygous insects, but not the susceptible ones. Chemicals that preferentially kill resistant insects are then tested for toxicity to the heterozygotes. Those highly toxic to both homo- and heterozygotes are given the highest priority for development. This screen can be adapted to identify compounds useful in controlling antibiotic-, herbicide- or fungicide-resistant organisms.     

Donor vigilance: What are we doing about it?

Donor vigilance is the systematic monitoring of adverse reactions and incidents in blood donor care with a view to improving quality and safety for blood donors. Standard international definitions are available for surveillance purposes. In recent years advances have been made in determining risk factors for vasovagal and other adverse reactions to blood donation as well as in evaluating preventive measures. Blood establishments should record all adverse reactions in blood donors. Besides its use for individual donor care, this information can be reviewed within and between organisations to guide policy decisions and research for improving donor care.     

What does it take to make a heart?

Ever increasing advances are being made in our quest to understand what it takes to direct pluripotent precursor cells to adopt a specific developmental fate. Eventually, the obvious goal is that targeted manipulation of these precursor cells will result in an efficient and reliable production of tissue‐specific cells, which can be safely employed for therapeutic purposes. We have gained an incredible insight as to which molecular pathways are involved in governing neural, skeletal and cardiac muscle fate decisions. However, we still face the challenge of how to direct, for example, a cardiac fate in stem cells in the amounts needed to be employed for regenerative means. Equally importantly, we need to resolve critical questions such as: can the in vitro generated cardiomyocytes actually functionally replace damaged heart tissue? Here I will provide an overview of the molecules and signalling pathways that have first been demonstrated in embryological studies to function in cardiogenesis, and summarize how this knowledge is being applied to differentiate mouse and human embryonic stem cells into cardiomyocytes.     

What are we to make of the concept of race?: Thoughts of a philosopher–scientist

Discussions about the biological bases (or lack thereof) of the concept of race in the human species seem to be never ending. One of the latest rounds is represented by a paper by Neven Sesardic, which attempts to build a strong scientific case for the existence of human races, based on genetic, morphometric and behavioral characteristics, as well as on a thorough critique of opposing positions. In this paper I show that Sesardic’s critique falls far short of the goal, and that his positive case is exceedingly thin. I do this through a combination of analysis of the actual scientific findings invoked by Sesardic and of some philosophical unpacking of his conceptual analysis, drawing on a dual professional background as an evolutionary biologist and a philosopher of science.     

Acanthamoeba: could it be an environmental host of Shigella?

Shigellosis is a serious public health problem in Korea, because large outbreaks of Shigella sonnei infections were recorded in many parts of the country during the period 1998-2000. However, the epidemiological features of shigellosis are not well known. In this study, we devised conditions suitable for the growth and replication of Shigella in an amoebic intracellular environment, and investigate whether medium conditions affect the survival and replication of Shigella within Acanthamoeba. We evaluated the uptake rates of invasive and non invasive S. sonnei strains by three Acanthamoeba species, namely, A. castellanii Neff, A. astronyxis Ray & Hayes, and A. healyi OC-3A. When A. castellanii Neff was infected with S. sonnei 99OBS1 or 80DH248, shigellae was maintained for a longer time in cytoplasms than in other Acanthamoeba species. S. sonnei 99OBS1 strain (a virulent strain) was recovered in higher numbers than the non-virulent S. sonnei 80DH248 strain in all experiments. Moreover, S. sonnei was more easily engulfed by Acanthamoeba at 18 degrees C. The shigellae uptake rates of Neff strain, which was cultured in free-media (less nutrition), were higher (>10-fold) than those observed in original amoeba culture media (PYG medium) in all time points. S. sonnei 99OBS1 was localized, with an intact membrane, to the vacuoles of Acanthamoeba. We conclude that free-living amoebae more likely act as environmental hosts for shigellae, and thus, may have contributed to outbreaks of shigellosis in Korea.     

The genomics of local adaptation in trees: are we out of the woods yet?

There is substantial interest in uncovering the genetic basis of the traits underlying adaptive responses in tree species, as this information will ultimately aid conservation and industrial endeavors across populations, generations, and environments. Fundamentally, the characterization of such genetic bases is within the context of a genetic architecture, which describes the mutlidimensional relationship between genotype and phenotype through the identification of causative variants, their relative location within a genome, expression, pleiotropic effect, environmental influence, and degree of dominance, epistasis, and additivity. Here, we review theory related to polygenic local adaptation and contextualize these expectations with methods often used to uncover the genetic basis of traits important to tree conservation and industry. A broad literature survey suggests that most tree traits generally exhibit considerable heritability, that underlying quantitative genetic variation (Q_ST) is structured more so across populations than neutral expectations (F_ST) in 69% of comparisons across the literature, and that single-locus associations often exhibit small estimated per-locus effects. Together, these results suggest differential selection across populations often acts on tree phenotypes underlain by polygenic architectures consisting of numerous small to moderate effect loci. Using this synthesis, we highlight the limits of using solely single-locus approaches to describe underlying genetic architectures and close by addressing hurdles and promising alternatives towards such goals, remark upon the current state of tree genomics, and identify future directions for this field. Importantly, we argue, the success of future endeavors should not be predicated on the shortcomings of past studies and will instead be dependent upon the application of theory to empiricism, standardized reporting, centralized open-access databases, and continual input and review of the community’s research.     

Predictors and barriers to breastfeeding in north of Jordan: could we do better?

Background

Despite the ongoing recommendations for breastfeeding, we continue to see a decrease in exclusive breastfeeding among Jordanian women during infant follow up visits at the pediatric outpatient clinic. The purpose of our study is to determine the prevalence, predictors and barriers to exclusive breastfeeding in north of Jordan.

Methods

We conducted a cross-sectional survey involving mothers with infants six to twelve months old, at two hospitals in Irbid city in north of Jordan, between December 2016 and March 2017. Questions included demographics, feeding pattern, and reasons for non-exclusive breastfeeding.

Results

Five hundred women were included. Twenty four percent of women were employed and 87% initiated breastfeeding within three hours of birth. The proportion of women with any breastfeeding and exclusive breastfeeding at six months was 76 and 33%. After multivariate logistic regression analysis, predictors of exclusive breastfeeding at six months include the mother’s previous experience (Adjusted Odds Ratio [AOR] 7.9, 95% CI 4.69, 13.36) and multiparity (AOR 2.26, 95% CI 1.2, 4.28), while barriers include maternal employment (AOR 0.4, 95% CI 0.22,0.72), Cesarean delivery (AOR 0.55, 95% CI 0.35, 0.86) and infant’s hospitalization (AOR 0.44, 95% CI 0.23,0.82). Inadequate breastmilk supply and short maternity leave were the main reported reasons for non-exclusive breastfeeding.

Conclusions

In north of Jordan, the majority of women initiate breastfeeding, half practice exclusive breastfeeding after birth while one third continue for six months, particularly those with previous experience. Cesarean delivery and infant’s hospitalization, together with maternal employment are among the main barriers. Implementing educational programs and lactation consultant counselling together with work environment support, should be helpful to improve the breastfeeding practice among Jordanian women.

     

Genetics of Obesity: What have we Learned?

Candidate gene and genome-wide association studies have led to the discovery of nine loci involved in Mendelian forms of obesity and 58 loci contributing to polygenic obesity. These loci explain a small fraction of the heritability for obesity and many genes remain to be discovered. However, efforts in obesity gene identification greatly modified our understanding of this disorder. In this review, we propose an overlook of major lessons learned from 15 years of research in the field of genetics and obesity. We comment on the existence of the genetic continuum between monogenic and polygenic forms of obesity that pinpoints the role of genes involved in the central regulation of food intake and genetic predisposition to obesity. We explain how the identification of novel obesity predisposing genes has clarified unsuspected biological pathways involved in the control of energy balance that have helped to understand past human history and to explore causality in epidemiology. We provide evidence that obesity predisposing genes interact with the environment and influence the response to treatment relevant to disease prediction.     

CoQ10: could it have a role in cancer management?

Coenzyme Q10 or ubiquinone has been shown to have both anti-cancer and immune system enhancing properties when tested in animals. Preliminary results reported here suggest that it might inhibit tumour-associated cytokines. Clinical studies conducted with combination therapies of CoQ10 and other antioxidants are ongoing, but the results are difficult evaluate owing to the lack of proper control groups and of initial randomisation. Also on the basis of some anti-cancer effects of antioxidants reported in literature, further animal studies and a proper clinical trial of coenzyme Q10 in cancer patients are needed.     

What do fish make of mirror images?

Fish act aggressively towards their mirror image suggesting that they consider it another individual, whereas in some mammals behavioural response to mirrors may be an evidence of self-recognition. Since fish cannot self-recognize, we asked whether they could distinguish between fighting a mirror image and fighting a real fish. We compared molecular, physiological and behavioural responses in each condition and found large differences in brain gene expression levels. Although neither levels of aggressive behaviour nor circulating androgens differed between these conditions, males fighting a mirror image had higher immediate early gene (IEG) expression in brain areas homologous to the amygdala and hippocampus than controls. Since amygdalar responses are associated with fear and fear conditioning in other species, higher levels of brain activation when fighting a mirror suggest fish experience fear in response to fights with a mirror image. Clearly, the fish recognize something unusual about the mirror image and the differential brain response may reflect a cognitive distinction.     

The tumorigenic potential of pluripotent stem cells: What can we do to minimize it?

Human pluripotent stem cells (hPSCs) have the potential to fundamentally change the way that we go about treating and understanding human disease. Despite this extraordinary potential, these cells also have an innate capability to form tumors in immunocompromised individuals when they are introduced in their pluripotent state. Although current therapeutic strategies involve transplantation of only differentiated hPSC derivatives, there is still a concern that transplanted cell populations could contain a small percentage of cells that are not fully differentiated. In addition, these cells have been frequently reported to acquire genetic alterations that, in some cases, are associated with certain types of human cancers. Here, we try to separate the panic from reality and rationally evaluate the true tumorigenic potential of these cells. We also discuss a recent study examining the effect of culture conditions on the genetic integrity of hPSCs. Finally, we present a set of sensible guidelines for minimizing the tumorigenic potential of hPSC‐derived cells. © 2016 The Authors. Inside the Cell published by Wiley Periodicals, Inc.     

Examining the developing bone: What do we measure and how do we do it?

The clinical tools available to evaluate bone development in children are often ambiguous, and difficult to interpret. Unfortunately bone densitometry methods (i.e., dual energy X-ray absorptiometry, DXA) which have a relatively straightforward application in adult osteoporosis, are far more difficult to evaluate in the growing skeleton. Even with adequate "adjustment" for bone size or maturity, bone "density" (areal or volumetric) alone often gives an inaccurate assessment of bone strength--especially in children. Ideally, we would like to measure both material and geometric properties of bone to accurately estimate "strength". Mechanically meaningful measures of bone geometry (bone cross-sectional area, cortical thickness) and estimates of bending strength (section modulus, or SSI) are available with non-invasive techniques such as (p)QCT and some DXA software. With new technology it might be possible to also measure bone material properties, which will be especially important in some pediatric disorders. In children, we also need to know something about the loads imposed on a child's bone and consider not only absolute bone strength, but also the strength of bone relative to the physiologic loads. Interpreting bone strength in light of the loads imposed (particularly muscle force) is critical for an accurate diagnosis of the developing bone.     

Joint analysis of demography and selection in population genetics: where do we stand and where could we go?

Teasing apart the effects of selection and demography on genetic polymorphism remains one of the major challenges in the analysis of population genomic data. The traditional approach has been to assume that demography would leave a genome-wide signature, whereas the effect of selection would be local. In the light of recent genomic surveys of sequence polymorphism, several authors have argued that this approach is questionable based on the evidence of the pervasive role of positive selection and that new approaches are needed. In the first part of this review, we give a few empirical and theoretical examples illustrating the difficulty in teasing apart the effects of selection and demography on genomic polymorphism patterns. In the second part, we review recent efforts to detect recent positive selection. Most available methods still rely on an a priori classification of sites in the genome but there are many promising new approaches. These new methods make use of the latest developments in statistics, explore aspects of the data that had been neglected hitherto or take advantage of the emerging population genomic data. A current and promising approach is based on first estimating demographic and genetic parameters, using, e.g., a likelihood or approximate Bayesian computation framework, focusing on extreme outlier regions, and then using an independent method to confirm these. Finally, especially for species where evidence of natural selection has been limited, more experimental and versatile approaches that contrast populations under varied environmental constraints might be more successful compared with species-wide genome scans in search of specific signatures.     

Can we make sense of subjective experience in metabolically situated cognitive processes?

In “Mind, matter and metabolism,” Godfrey-Smith’s objective is to “develop a picture” in which, first, the basis of living activity in physical processes “makes sense,” second, the basis of proto-cognitive activity in living activity “makes sense” and third, “the basis of subjective experience in metabolically situated cognitive processes also makes sense.” show that he fails to attain all three of these objectives, largely owing to the nature and modularization of metabolism.