Measures of economic advantage associated with HPV-positive head and neck cancers among non-Hispanic black and white males identified through the National Cancer Database

BackgroundNational trends show dramatic increases in the incidence of HPV-related head and neck squamous cell carcinomas (HNSCCs) among black and white males. Using cases identified through the National Cancer Data Base, we assessed factors associated with HPV 16- or 16/18 positive HNSCCs among non-Hispanic black and white males diagnosed in the U.S. between 2009 and 2013.MethodsThis sample included 21,524 HNSCCs with known HPV status. Adjusted relative risks (RRs) and 95% confidence intervals (CIs) were estimated using log-binomial regression.ResultsCompared to those with HPV-negative tumors, male patients diagnosed with HPV-positive HNSCCs were non-Hispanic white, younger at diagnosis, lived in zip-code areas with higher median household income and higher educational attainment, had private health insurance and no reported comorbidities at diagnosis. Although the risk of HPV-positive HNSCCs increased with measures of higher area-level socioeconomic status, the effect was stronger for non-Hispanic black males (RR_Adjusted = 1.76, 95% CI 1.49–2.09) than for whites (RR_Adjusted = 1.12, 95% CI 1.08–1.16). The peak age for diagnosis of HPV-positive HNSCCs occurred in those diagnosed at 45–49 years (RR_Adjusted = 1.57, 95% CI 1.42–1.73). Oropharyngeal tumors were strongly associated with HPV-positivity (RR_Adjusted = 4.32, 95% CI 4.03–4.63). In the analysis restricted to oropharyngeal anatomic sites, similar patterns persisted.ConclusionIn our analysis, measures of economic advantage were associated with an increased risk of HPV-positive HNSCCs. In order to develop effective interventions, greater understanding of the risk factors for HPV-positive HNSCCs is needed among both high-risk males and their healthcare providers.     

Potential contributions of root decomposition to the nitrogen cycle in arctic forest and tundra

Plant contributions to the nitrogen (N) cycle from decomposition are likely to be altered by vegetation shifts associated with climate change. Roots account for the majority of soil organic matter input from vegetation, but little is known about differences between vegetation types in their root contributions to nutrient cycling. Here, we examine the potential contribution of fine roots to the N cycle in forest and tundra to gain insight into belowground consequences of the widely observed increase in woody vegetation that accompanies climate change in the Arctic. We combined measurements of root production from minirhizotron images with tissue analysis of roots from differing root diameter and color classes to obtain potential N input following decomposition. In addition, we tested for changes in N concentration of roots during early stages of decomposition, and investigated whether vegetation type (forest or tundra) affected changes in tissue N concentration during decomposition. For completeness, we also present respective measurements of leaves. The potential N input from roots was twofold greater in forest than in tundra, mainly due to greater root production in forest. Potential N input varied with root diameter and color, but this variation tended to be similar in forest and tundra. As for roots, the potential N input from leaves was significantly greater in forest than in tundra. Vegetation type had no effect on changes in root or leaf N concentration after 1 year of decomposition. Our results suggest that shifts in vegetation that accompany climate change in the Arctic will likely increase plant‐associated potential N input both belowground and aboveground. In contrast, shifts in vegetation might not alter changes in tissue N concentration during early stages of decomposition. Overall, differences between forest and tundra in potential contribution of decomposing roots to the N cycle reinforce differences between habitats that occur for leaves.     

Pre-dispersal seed predation reduces the reproductive compensatory advantage of thrum individuals in Erythroxylum havanense (Erythroxylaceae)

Male-sterility mutations in hermaphroditic species represent the first step in the evolution of gender specialization. Male-sterile individuals commonly compensate the loss of the male function by increasing the number or quality of seeds. Because the magnitude of compensation determines the maintenance of females within populations and the evolution of sexual specialization, plant-animal interactions may affect these evolutionary processes if animals are sensitive to such reproductive asymmetries. Here we explore the effect of seed predation on the reproductive compensation of Erythroxylum havanense, a distylous shrub with morph-biased partial male sterility, during two consecutive years. Seed predation reduced the compensatory advantage of thrums in 1987, but not in 1988. Annual differences in the intensity of seed predation seem to be accounted for differences in the onset and synchrony of flowering. Thus, although seed predators may reduce the compensatory advantage of thrums, their impact is modulated by the environmental cues triggering flowering and insect emergence.     

Arbuscular mycorrhizal fungi enhance the growth of the exotic species Ambrosia artemisiifolia

丛枝菌根真菌促进外来植物豚草的生长 丛枝菌根真菌(AMF)可以通过其菌丝增加寄主植物对养分的吸收,从而促进植物生长。丛枝菌根真菌一直与大多数外来植物的成功入侵联系在一起。然而,有关丛枝菌根真菌如何影响植物入侵成功的机制仍然有待研究。豚草(Ambrosia artemisiifolia)是一种外来的菌根植物。通过长期田间实验,我们研究了种间竞争对豚草和狗尾草(Setaria viridis)根系丛枝菌根真菌多样性和组成的影响。此外,在温室实验中探究了摩西球囊霉(Funneliformis mosseae)对这两种植物生长的影响。研究结果表明,豚草入侵改变了本地植物狗尾草根系丛枝菌根真菌的多样性。另外,豚草根系中摩西球囊霉的相对多度显著高于狗尾草根系中。在田间和温室实验中均发现外来种豚草的丛枝菌根真菌侵染率高于本地种狗尾草。温室实验结果表明,丛枝菌根真菌通过影响豚草的光合能力以及磷和钾的吸收而促进豚草生长。这些研究结果揭示了丛枝菌根真菌和豚草成功入侵之间的重要关系。     

Towards an ecological understanding of the killer trait – A reproducible protocol for testing its impact on freshwater ciliates

Paramecium strains with the ability to kill other paramecia often harbour intracellular bacteria belonging to the genera Caedibacter or Caedimonas. Central structures of this killer trait are refractile bodies (R-bodies) produced by the endosymbionts. Once ingested by a sensitive Paramecium, R-bodies presumably act as delivery system for an unidentified toxin which causes the death of endosymbiont-free paramecia while those infected gain resistance from their symbionts. The killer trait is therefore considered as competitive advantage for the hosts of R-body producers. While its effectiveness against paramecia is well documented, the effects on other aquatic ciliates are much less studied.In order to address the broadness of the killer trait, a reproducible killer test assay considering the effects on predatory ciliates (Climacostomum virens and Dileptus jonesi) as well as potential bacterivorous Paramecium competitors (Dexiostoma campyla, Euplotes aediculatus, Euplotes woodruffi, and Spirostomum teres) as possibly susceptible species was established. All used organisms were molecularly characterized to increase traceability and reproducibility. The absence of any lethal effects in both predators and competitors after exposure to killer paramecia strongly suggests a narrow action range for the killer trait. Thus, R-body producing bacteria provide their host with a complex, costly strategy to outcompete symbiont-free congeners only.     

What type of diversity yields synergy during mixed litter decomposition in a natural forest ecosystem?

Investigating the relationship of biodiversity and ecosystem function in natural forests allows incorporation of established feedbacks between long-lived plants and soil processes. We studied forested stands in northern Arizona that vary in dominant species richness across small areas. We examined the effects of natural variation in dominant tree biodiversity on ecosystem parameters, particularly litter decomposition. We determined not only whether plant species decompose in mixture as predicted by their individual decomposition rates but also: (1) how particular species affect the decomposition rate of each other in mixture; and (2) whether litter decomposes more rapidly at its site of origin; i.e. is there a “home field advantage” to decomposition? Over a 2-year period, litter mixtures of functionally similar tree species decomposed more rapidly than expected from rates of the individual species alone. Mixtures of conifer species litter decomposed up to 50% faster than expected, with individual conifer members of those mixtures decomposing up to 85% faster than expected. In contrast, more functionally diverse mixtures of litter, which included a deciduous species, did not show synergistic effects during decomposition. We found no significant “home-field advantage” to decomposition. Our study is the first to demonstrate that litter mixtures from more closely related plant species give rise to the most synergistic effects of biodiversity on litter dynamics, indicating that more taxonomically and functionally diverse plant assemblages do not always drive greater emergent effects on ecosystem function.     

不同光照时长对麋鹿茸生长和繁殖季的溢出效应

光周期可影响鹿角脱落和新茸再生,麋(Elaphurus davidianus)冬至解角,冬季持续的光照时长改变对鹿茸生长速度、角形态发育及夏季的繁殖溢出效应尚未见相关报道。依托北京麋鹿苑2018年出生的同父异母雄性麋鹿12头,于2021年11月-2023年3月进行光照时长处理实验,依次分组为:自然光照(对照组)、缩短光照2h、延长光照3h和6h;记录实验麋鹿解角日期,红外测量新茸再生速度,测定脱落的麋角形态参数,并持续追踪记录翌年发情期等级序位、打斗、交配、繁殖绩效等参数。结果显示:持续缩短2h光照(6L∶18D)使麋鹿解角日期、角主干总长度、单角重量分别较对照组(8L∶16D),提前(8.5±0.4)d、缩短2.93cm(P ＜ 0.01,n=3)、减轻9.81g(P ＜ 0.01,n=3);延长3h光照(10L∶14D)使麋鹿解角日期、角主干总长度、单角重量分别较对照组(8L∶16D),推迟(10.5±0.3)d、增长5.47cm(P ＜ 0.01,n=6)、增加18.64g(P ＜ 0.01,n=6);延长6h光照(12L∶12D)使麋鹿解角日期、角主干总长度、单角重量较对照组(8L∶16D),分别推迟(13.5±0.6)d、增长10.43cm(P ＜ 0.01,n=6)、增加44.31g(P ＜ 0.01,n=6)。光照时长对麋角切片重量的影响差异极显著(P ＜ 0.01,n=6),缩短2h光照(6L∶18D)使麋角切片重量较对照组(8L∶16D)减轻(0.1230±0.0561)g/片;延长光照3h(10L∶14D)、6h(12L∶12D)使麋角切片重量较对照组(8L∶16D)分别增加(0.1200±0.0318)g/片、(0.3133±0.0618)g/片;冬季延长光照可明显增加夏季雄性麋鹿的交配机会和爬跨时长,增加发情持续天数、累积持续时间,增加查验母鹿发情、维护领地和圈群次数,提高交配成功率。综上所述,麋角脱落与光照时长之间密切相关,冬季持续光照时长变化对麋角脱落日期及繁殖产生了溢出效应,其机理仍需进一步研究,结果可为今后开展不同光照对麋角脱落及新茸再生多样化的分子调控机制研究提供理论支撑,可指导鹿科动物鹿茸产量提高、育种、保护与可持续发展。     

Exploring feeding behaviour in deep‐sea dragonfishes (Teleostei: Stomiidae): jaw biomechanics and functional significance of a loosejaw

Deep‐sea dragonfishes (family Stomiidae) possess spectacular morphologies adapted to capturing large prey items in a seascape largely devoid of biomass, including large fang‐like teeth set on extremely long jaws. Perhaps the most intriguing aspect of dragonfish morphology is a lack of a floor to the oral cavity (i.e. there is no skin between the mandibular rami) in species of three dragonfish genera. The present study aimed to investigate the kinematic properties and performance of lower‐jaw adduction in stomiid fishes and to infer what functional advantages or constraints the ‘loosejaw’ confers. A computation model based on dynamic equilibrium predicted very fast jaw adduction for all species at gapes ranging from 90–120° in 66.6–103 ms. Simulations demonstrated that forces resisting lower‐jaw adduction in dragonfishes, and long‐jawed fishes in general, are substantially greater than those in fishes with shorter jaws. These forces constrain inlever length, resulting in relatively high mechanical advantages to attain fast adduction velocities. By reducing the surface area of the lower‐jaw system, loosejaws drastically reduce resistive forces. This has permitted loosejaw dragonfishes to evolve lower mechanical advantages that produce high displacement velocities with an extremely long jaw, a distinct asset in capturing large and scarce resources in the deep‐sea. In addition, loosejaws require a substantially reduced adductor mass to close long jaws at high velocities. These results reveal that the loosejaw condition is an adaptation that expands the morphological boundaries imposed by the dynamic limitations of a long jaw. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 106 , 224–240.     

The emergence and ongoing convergent evolution of the SARS-CoV-2 N501Y lineages

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