Immunodominant Francisella tularensis antigens identified using proteome microarray

Stimulation of protective immune responses against intracellular pathogens is difficult to achieve using non-replicating vaccines. BALB/c mice immunized by intramuscular injection with killed Francisella tularensis (live vaccine strain) adjuvanted with preformed immune stimulating complexes admixed with CpG, were protected when systemically challenged with a highly virulent strain of F. tularensis (Schu S4). Serum from immunized mice was used to probe a whole proteome microarray in order to identify immunodominant antigens. Eleven out of the top 12 immunodominant antigens have been previously described as immunoreactive in F. tularensis. However, 31 previously unreported immunoreactive antigens were revealed using this approach. Twenty four (50%) of the ORFs on the immunodominant hit list belonged to the category of surface or membrane associated proteins compared to only 22% of the entire proteome. There were eight hypothetical protein hits and eight hits from proteins associated with different aspects of metabolism. The chip also allowed us to readily determine the IgG subclass bias, towards individual or multiple antigens, in protected and unprotected animals. These data give insight into the protective immune response and have potentially important implications for the rational design of non-living vaccines for tularemia and other intracellular pathogens.     

The conjugating green alga Zygnema sp. (Zygnematophyceae) from the Arctic shows high frost tolerance in mature cells (pre-akinetes)

Protoplasma - Green algae of the genus Zygnema form extensive mats and produce large amounts of biomass in shallow freshwater habitats. Environmental stresses including freezing may perturb these...     

Mitochondrial DNA Analyses of Cercopithecus Monkeys Reveal a Localized Hybrid Origin for C. mitis doggetti in Gombe National Park,Tanzania

International Journal of Primatology - In recent years, hybridization has gained recognition as an important creative force in primate evolution. The exchange of genetic material between species...     

Learning from the COVID-19 pandemic to strengthen routine immunization systems

Kate Causey and Jonathan F Mosser discuss what can be learnt from the observed impacts of the COVID-19 pandemic on routine immunisation systems.

In the final months of 2021, deaths due to the Coronavirus Disease 2019 (COVID-19) surpassed 5 million globally [1]. Available data suggest that even this staggering figure may be a substantial underestimate of the true toll of the pandemic [2]. Beyond mortality, it may take years to fully quantify the direct and indirect impacts of the COVID-19 pandemic such as disruptions in preventive care services. In an accompanying research study in PLOS Medicine, McQuaid and colleagues report on the uptake of routine childhood immunizations in 2020 in Scotland and England during major pandemic-related lockdowns [3]. This adds to a growing body of literature quantifying the impact of the COVID-19 pandemic on routine health services and childhood immunization [4,5], which provides important opportunities to learn from early pandemic experiences as immunization systems face ongoing challenges.McQuaid and colleagues compared weekly or monthly data on vaccine uptake in Scotland and England from January to December of 2020 to the rates observed in 2019 to estimate the changes in uptake before, during, and after COVID-19 pandemic lockdowns in each country. The authors included 2 different preschool immunizations, each with multiple doses. They found significantly increased uptake within 4 weeks of eligibility during the lockdown and postlockdown periods in Scotland for all 5 vaccine dose combinations examined: During lockdown, percentage point increases ranged from 1.3% to 14.3%. In England, there were significant declines in uptake during the prelockdown, lockdown, and postlockdown periods for all 4 vaccine dose combinations examined. However, declines during lockdown were small, with percentage point decreases ranging from −0.5% to −2.1%. Due to the nature of the data available, the authors were unable to account for possible seasonal variation in vaccine delivery, control for important individual-level confounders or effect modifiers such as child sex and parental educational attainment, or directly compare outcomes across the 2 countries.These findings stand in contrast to the documented experience of many other countries, where available data suggest historic disruptions in routine childhood vaccination coverage, particularly during the first months of pandemic-related lockdowns [5,6]. Supply side limitations such as delayed shipments of vaccines and supplies [7], inadequate personal protective equipment [8], staff shortages [9], and delayed or canceled campaigns and introductions [9] threatened vaccine delivery. Furthermore, fear of exposure to COVID-19 at vaccination centers [10], misinformation about vaccine safety [8], and lockdown-related limitations on travel to facilities [9,10] reduced demand. In polls of country experts conducted by WHO, UNICEF, and Gavi, the Vaccine Alliance throughout the second quarter of 2020, 126 of 170 countries reported at least some disruption to routine immunization programs [10,11]. Global estimates suggest that millions more children missed doses of important vaccines than would have in the absence of the COVID-19 pandemic [5,6]. While many vaccine programs showed remarkable resilience in the second half of 2020, with rates of vaccination returning to or even exceeding prepandemic levels [5,6], disruptions to immunization services persisted into 2021 in many countries [12].As the authors discuss, it is critical to pinpoint the specific program policies and strategies that contributed to increased uptake in Scotland and only small declines in England and, more broadly, to the rapid recovery of vaccination rates observed in many other countries. McQuaid and colleagues cite work suggesting that increased flexibility in parental working patterns during lockdowns, providing mobile services or public transport to vaccine centers, and sending phone- and mail-based reminders are strategies that may have improved uptake of timely vaccination in Scotland during this period [13]. Similarly, immunization programs around the world have employed a broad range of strategies to maintain or increase vaccination during the pandemic. Leaders in Senegal, Paraguay, and Sri Lanka designed and conducted media campaigns to emphasize the importance of childhood immunization even during lockdown [8,14,15]. Although many programs delayed mass campaigns in the spring of 2020, multiple countries were able to implement campaigns by the summer of 2020 [8,16–20]. In each of these examples, leaders responded quickly to meet the unique challenges presented by the COVID-19 pandemic in their communities.Increased data collection and tracking systems are essential for efficient and effective responses as delivery programs face challenges. When concern arose for pandemic-related disruptions to immunization services, public health decision-makers in Scotland and England responded by increasing the frequency and level of detail in reports of vaccine uptake and by making these data available for planning and research. The potential for robust data systems to inform real-time decision-making is not limited to high-income countries. For instance, the Nigerian National Health Management Information System released an extensive online dashboard shortly after the onset of the pandemic, documenting the impact of COVID-19 on dozens of indicators of health service uptake, including 16 related to immunization [21]. Vaccination data systems that track individual children and doses, such as the reminder system in Scotland, allow for highly targeted responses. Similarly, in Senegal, Ghana, and in Karachi, Pakistan, healthcare workers have relied on existing or newly implemented tracking systems to identify children who have missed doses and provide text message and/or phone call reminders [8,22,23]. Investing in robust routine data systems allows for rapid scale-up of data collection, targeted services to those who miss doses, and a more informed response when vaccine delivery challenges arise.Policy and program decision-makers must learn from the observed impacts of the COVID-19 pandemic on health systems and vaccine delivery. The study by McQuaid and colleagues provides further evidence that vaccination programs in England and Scotland leveraged existing strengths and identified novel strategies to mitigate disruptions and deliver vaccines in the early stages of the pandemic. However, the challenges posed by the pandemic to routine immunization services continue. To mitigate the risk of outbreaks of measles and other vaccine-preventable diseases, strategies are needed to maintain and increase coverage, while ensuring that children who missed vaccines during the pandemic are quickly caught up. The accompanying research study provides important insights into 2 countries where services were preserved—and even increased—in the early pandemic. To meet present and future challenges, we must learn from early pandemic successes such as those in Scotland and England, tailor solutions to improve vaccine uptake, and strengthen data systems to support improved decision-making.     

Genetic diversity of Typha latifolia (Typhaceae) and the impact of pollutants examined with tandem-repetitive DNA probes

Genetic diversity at variable-number-tandem-repeat (VNTR) loci was examined in the common cattail, Typha latifolia (Typhaceae), using three synthetic DNA probes composed of tandemly repeated “core” sequences (GACA, GATA, and GCAC). The principal objectives of this investigation were to determine whether: (1) the previously reported almost complete lack of polymorphism at allozyme loci in this species was indicative of a reduced amount of genetic diversity at VNTR loci as well; (2) VNTR markers were informative about possible clonal propagation; and (3) significant differences in genetic structure of sampling sites were associated with differences in environmental levels of pollutants at those sites. Previously, widespread sampling across the eastern United States, surveying across ten allozyme loci, has detected only two genotypes, involving a difference at a single locus, among 104 populations. In this study, the amount of genetic diversity detected at VNTR loci: (1) among ramets (N = 40; 40 genotypes detected) collected at ∼8-km intervals along a 320-km transect; (2) among ramets (N = 220; 117 genotypes detected) from five study sites separated by 50–3000 m; and (3) even among ramets within each study site [N = 44 per site; from 13 to 34 genotypes detected per site (270 m²)] exceeds that previously found in those more geographically widespread allozyme surveys. Among the 260 ramets analyzed here, the mean number of bands scored per individual was 48.61 (SD = 2.80). Mean genetic similarity among ramets collected along the 320-km transect was 0.91, which was within the range of mean genetic similarity within the five study sites (range: 0.89–0.95). Among the five study sites, 61% of the samples analyzed appeared to be clonal ramets, with up to 12 clones detected for 44 ramets sampled within a site. Clones grew intermingled and ranged up to 39 m in extent. Permutation tests of genetic similarity revealed significant genetic differentiation between each of the five study sites. Consistent with the previous allozyme studies, T. latifolia was characterized by extremely low genetic variation relative to levels of polymorphism detected at VNTR loci in other plant species. Estimated heterozygosity among ramets along the 320-km transect ranged from 0.11 to 0.13, while that within the five study sites ranged from 0.05 to 0.12. Estimates of F_st (0.32–0.41) also indicated considerable genetic subdivision among these stands. Significantly higher genetic diversity was detected at the two study sites that chemistry and toxicity data indicate to be the most severely impacted by pollutants. Although this correlation does not establish cause and effect, the results of this study indicate that the analysis of genetic diversity at VNTR loci may be a useful tool for monitoring anthropogenic-induced changes in the genetic structure of natural populations of plants.     

Application of morphometric techniques to postnatal rat testes in organ culture: insights into testis growth

The extent of Sertoli cell proliferation during fetal and neonatal development determines the final adult testis size and potential for sperm output. To gain further knowledge of the factors that regulate Sertoli cell proliferation, the present study used a new approach to analyse changes in morphology and proliferation in the postnatal testis by combining organ culture with morphometric analysis. Fragments of rat testes from days 0 to 10 postpartum were cultured in contact with DMEM for 6 h or 72 h and fixed. The effects of ovine follicle-stimulating hormone (FSH) and activin were studied in an additional 72-h organ culture experiment using day 9 testes. Bromodeoxyuridine (BrdU) was added for the last 6 h of culture to mark proliferating cells. Two-microm sections of the fragments were analysed for morphological changes of the seminiferous cords, and the proportion of BrdU-labelled Sertoli and germ cells was determined. Assessment of 6-h samples revealed growth characteristics consistent with those observed in vivo during days 1-10 of postnatal development. From day 2 onwards, the volume fraction of seminiferous cords began to increase, while significant growth in cross-sectional area of the cords occurred only after day 6. In these culture conditions, germ cell proliferation and testicular architecture was consistent with that expected for the age of the tissue at time of explant. The proportion of dividing Sertoli cells declined from 15-20% at days 0-4 postpartum to below % at day 10 postpartum in the 6-h culture, and it was low or abolished in the 3-day culture at all time points. Activin and FSH together, but not singly, stimulated Sertoli cell proliferation in the 72-h culture. This paper presents a new approach to analysis of in vitro testis development. The combination of fragment culture and stereological analysis permits rigorous and detailed assessment of developmental changes in the postnatal testis.     

Breeding system in a population of Trigonella balansae (Leguminosae)

BACKGROUND AND AIMS: Although some taxonomic studies in the genus Trigonella have been conducted, there has been no concerted effort to study the breeding system. This paper examines the floral structure and pollination system in a population of T. balansae, an annual pasture legume. METHODS: Floral morphology, hand and vector pollination, stigma receptivity, pollen tube growth, using scanning electron and fluorescence microscopy, were conducted. KEY RESULTS: Measurements of floral structure from before to after anthesis indicates an inability for T. balansae to self-pollinate and a requirement for an external vector to effectively transfer pollen from the anthers onto the stigmas of this species. Seed set can be obtained by hand or honeybee manipulation of T. balansae flowers. CONCLUSIONS: Trigonella balansae is a self-compatible species, but which requires vectors such as honeybees to bring about pollination.     

Melatonin, melatonin receptors and melanophores: a moving story

Melatonin (5-methoxy N-acetyltryptamine) is a hormone synthesized and released from the pineal gland at night, which acts on specific high affinity G-protein coupled receptors to regulate various aspects of physiology and behaviour, including circadian and seasonal responses, and some retinal, cardiovascular and immunological functions. In amphibians, such as Xenopus laevis, another role of melatonin is in the control of skin coloration through an action on melanin-containing pigment granules (melanosomes) in melanophores. In these cells, very low concentrations of melatonin activate the Mel(1c) receptor subtype triggering movement of granules toward the cell centre thus lightening skin colour. Mel(1c) receptor activation reduces intracellular cAMP via a pertussis toxin-sensitive inhibitory G-protein (Gi), but how this and other intracellular signals regulate pigment movement is not yet fully understood. However, melanophores have proven an excellent model for the study of the molecular mechanisms which coordinate intracellular transport. Melanosome transport is reversible and involves both actin- (myosin V) and microtubule-dependent (kinesin II and dynein) motors. Melanosomes retain both kinesin and dynein during anterograde and retrograde transport, but the myosin V motor seems to be recruited to melanosomes during dispersion, where it assists kinesin II in dominating dynein thus driving net dispersion. Recent work suggests an important role for dynactin in coordinating the activity of the opposing microtubule motors. The melanophore pigment aggregation response has also played a vital role in the ongoing effort to devise specific melatonin receptor antagonists. Much of what has been learnt about the parts of the melatonin molecule required for receptor binding and activation has come from detailed structure-activity data using novel melatonin ligands. Work aiming to devise ligands specific for the distinct melatonin receptor subtypes stands poised to deliver selective agonists and antagonists which will be valuable tools in understanding the role of this enigmatic hormone in health and disease.