Cuticle hydrolysis in four medically important fly species by enzymes of the entomopathogenic fungus Conidiobolus coronatus

Entomopathogenic fungi infect insects via penetration through the cuticle, which varies remarkably in chemical composition across species and life stages. Fungal infection involves the production of enzymes that hydrolyse cuticular proteins, chitin and lipids. Host specificity is associated with fungus–cuticle interactions related to substrate utilization and resistance to host‐specific inhibitors. The soil fungus Conidiobolus coronatus (Constantin) (Entomophthorales: Ancylistaceae) shows virulence against susceptible species. The larvae and pupae of Calliphora vicina (Robineau‐Desvoidy) (Diptera: Calliphoridae), Calliphora vomitoria (Linnaeus), Lucilia sericata (Meigen) (Diptera: Calliphoridae) and Musca domestica (Linnaeus) (Diptera: Muscidae) are resistant, but adults exposed to C. coronatus quickly perish. Fungus was cultivated for 3 weeks in a minimal medium. Cell‐free filtrate, for which activity of elastase, N‐acetylglucosaminidase, chitobiosidase and lipase was determined, was used for in vitro hydrolysis of the cuticle from larvae, puparia and adults. Amounts of amino acids, N‐glucosamine and fatty acids released were measured after 8 h of incubation. The effectiveness of fungal enzymes was correlated with concentrations of compounds detected in the cuticles of tested insects. Positive correlations suggest compounds used by the fungus as nutrients, whereas negative correlations may indicate compounds responsible for insect resistance. Adult deaths result from the ingestion of conidia or fungal excretions.     

Harmful cyanobacteria and their cyanotoxins in Egyptian fresh waters – state of knowledge and research needs

Cyanobacterial blooms have increased in freshwater ecosystems worldwide in the last century, mostly resulting from eutrophication and climate change. These blooms represent serious threats to environmental and human health because of the production of harmful metabolites, called cyanotoxins. Like many countries, Egypt has been plagued with cyanobacterial blooms in most water sources, including the Nile River, irrigation canals, lakes and fishponds. However, the data about cyanotoxins produced in these blooms are limited. Only two types of cyanotoxins, microcystins and cylindrospermopsin, have been identified and characterised, mainly from Microcystis and Cylindrospermopsis blooms. The data revealed the presence of microcystins in raw and treated drinking waters at concentrations (0.05–3.8 µg l^?1), exceeding the WHO limit (1 µg l^?1) in some drinking water treatment plants. In addition, Nile tilapia Oreochromis niloticus caught from ponds containing heavy cyanobacterial blooms have accumulated considerable amounts of cyanotoxins in their edible tissues. The data presented here could be the catalyst for the establishment of a monitoring and management programme for harmful cyanobacteria and their cyanotoxins in Egyptian fresh waters. This review also elucidates the important research gaps and possible avenues for future research on cyanobacterial blooms and cyanotoxins in Egypt.     

Focus: Health Equity: The Social Value of Implementing the Ten Steps to Successful Breastfeeding in an Indonesian Hospital: A Case Study

Background: Despite the known importance of breastfeeding for women’s and children’s health, global exclusive prevalence among infants under 6 months old is estimated at only 41%. In 2018, Indonesia had a lower exclusive breastfeeding rate of 37% at 6 months postpartum; ranging from 20% to 56%, showing unequal breastfeeding support throughout the country. The World Health Organization (WHO) launched the Ten Steps to Successful Breastfeeding (Ten Steps) in 1989, later embedded in UNICEF’s Baby-Friendly Hospital Initiative (BFHI) program in 1991. The BFHI aims to encourage maternity facilities worldwide to ensure adequate education and support for breastfeeding mothers by adhering to the Ten Steps and complying with the International Code of Marketing of Breastmilk Substitutes. An Indonesian survey in 2011 found that less than one in 10 government hospitals implemented the Ten Steps. It has been common for Indonesian health services to collaborate with infant formula companies. While no Indonesian hospitals are currently BFHI-accredited, the WHO/UNICEF Ten Steps (updated in 2018) have been adopted in Indonesia’s national regulation of maternity facilities since 2012. Internationally, implementation of the Ten Steps individually and as a package has been associated with benefits to breastfeeding rates and maternal and infant health. However, to date, few studies have examined the impact of implementing the Ten Steps in economic terms. This study aims to measure the economic benefit of Ten Steps implementation in an Indonesian hospital. Methods: The study was conducted in January 2020 in Airlangga University Hospital, Surabaya, Indonesia, which has implemented the Ten Steps since it was established in 2012. To understand and generate evidence on the social value of the Ten Steps, we conducted a “Social Return on Investment (SROI)” study of implementing the Ten Steps in this maternity facility. To estimate the costs relating to the Ten Steps we interviewed the financial and nursing managers, a senior pediatrician, and senior midwife due to their detailed understanding of the implementation of the Ten Steps in the hospital. The interview was guided by a questionnaire which we developed based on the 2018 WHO/UNICEF Ten Steps to Successful Breastfeeding. The analysis was supported with peer-reviewed literature on the benefits of Ten Steps breastfeeding outcomes. Results: The total per annum value of investment (cost) required to implement Ten Steps in Airlangga University Hospital was US$ 972,303. The estimate yearly benefit was US$ 22,642,661. The social return on the investment in implementing Ten Steps in this facility was calculated to be US$ 49 (sensitivity analysis: US$ 18-65). Thus, for every US$ 1 invested in Ten Steps implementation by Airlangga Hospital could be expected to generate approximately US$ 49 of benefit. Conclusions: Investment in the Ten Steps implementation in this Surabaya maternity facility produced a social value 49 times greater than the cost of investment. This provides novel evidence of breastfeeding as a public health tool, demonstrating the value of the investment, in terms of social impact for mothers, babies, families, communities, and countries. Breastfeeding has the potential to help address inequity throughout the lifetime by providing the equal best start to all infants regardless of their background. Indonesia’s initial moves towards implementing the WHO/UNICEF Ten Steps can be strengthened by integrating all elements into the national regulation and health care system.     

Discovery of Influenza A Virus Sequence Pairs and Their Combinations for Simultaneous Heterosubtypic Targeting that Hedge against Antiviral Resistance

The multiple circulating human influenza A virus subtypes coupled with the perpetual genomic mutations and segment reassortment events challenge the development of effective therapeutics. The capacity to drug most RNAs motivates the investigation on viral RNA targets. 123,060 segment sequences from 35,938 strains of the most prevalent subtypes also infecting humans–H1N1, 2009 pandemic H1N1, H3N2, H5N1 and H7N9, were used to identify 1,183 conserved RNA target sequences (≥15-mer) in the internal segments. 100% theoretical coverage in simultaneous heterosubtypic targeting is achieved by pairing specific sequences from the same segment (“Duals”) or from two segments (“Doubles”); 1,662 Duals and 28,463 Doubles identified. By combining specific Duals and/or Doubles to form a target graph wherein an edge connecting two vertices (target sequences) represents a Dual or Double, it is possible to hedge against antiviral resistance besides maintaining 100% heterosubtypic coverage. To evaluate the hedging potential, we define the hedge-factor as the minimum number of resistant target sequences that will render the graph to become resistant i.e. eliminate all the edges therein; a target sequence or a graph is considered resistant when it cannot achieve 100% heterosubtypic coverage. In an n-vertices graph (n ≥ 3), the hedge-factor is maximal (= n– 1) when it is a complete graph i.e. every distinct pair in a graph is either a Dual or Double. Computational analyses uncover an extensive number of complete graphs of different sizes. Monte Carlo simulations show that the mutation counts and time elapsed for a target graph to become resistant increase with the hedge-factor. Incidentally, target sequences which were reported to reduce virus titre in experiments are included in our target graphs. The identity of target sequence pairs for heterosubtypic targeting and their combinations for hedging antiviral resistance are useful toolkits to construct target graphs for different therapeutic objectives.     

Individual optimization: Mechanisms shaping the optimal reaction norm

In general, optimal reaction norms in heterogeneous populations can be obtained only by iterative numerical procedures (McNamara, 1991; Kawecki and Stearns, 1993). We consider two particular, but biologically plausible and analytically tractable cases of individual optimization to gain insight into the mechanisms which shape the optimal reaction norm of fecundity in relation to an environmental variable or an individual trait. In the first case, we assume that the quality of the environment (e.g. food abundance) or the quality of the individual (e.g. body size) is fixed during its entire life; it may also be a heritable individual trait. In the second case, individual quality is assumed to change randomly such that the probability distribution of quality in the next year is the same for the parent and for her offspring. For these two cases, we obtain analytical expressions for the shape of the optimal reaction norm, which are heuristically interpretable in terms of underlying selective mechanisms. It is shown that better quality may reduce the optimal fecundity. This outcome is particularly likely if better quality increases a fecundity-independent factor of parental survival in a long-lived species with fixed quality. This revised version was published online in July 2006 with corrections to the Cover Date.