Modeling the dynamics of Lassa fever in Nigeria

Lassa fever is a zoonotic disease spread by infected rodents known as multimammate rats. The disease has posed a significant and major health challenge in West African countries, including Nigeria. To have a deeper understanding of Lassa fever epidemiology in Nigeria, we present a deterministic dynamical model to study its dynamical transmission behavior in the population. To mimic the disease’s biological history, we divide the population into two groups: humans and rodents. We established the quantity known as reproduction number $${\mathcal {R}}_{0}$$ R 0 . The results show that if $${\mathcal {R}}_{0} <1$$ R 0 < 1 then the system is stable, otherwise it is unstable. The model fitting was performed using the nonlinear least square method on cumulative reported cases from Nigeria between 2018 and 2020 to obtain the best fit that describes the dynamics of this disease in Nigeria. In addition, sensitivity analysis was performed, and the numerical solution of the system was derived using an iterative scheme, the fifth-order Runge–Kutta method. Using different numeric values for each parameter, we investigate the effect of all highest sensitivity indices’ parameters on the population of infected humans and infected rodents. Our findings indicate that any control strategies and methods that reduce rodent populations and the risk of transmission from rodents to humans and rodents would aid in the population’s control of Lassa fever.

Taxonomy of genus Orophyllus Beier, 1954 (Orthoptera: Tettigoniidae: Pseudophyllinae)

Only one species, Orophyllus montanus occurring in southern China is placed in Orophyllus. In this study, we studied samples from Hainan, Guangdong, Guangxi, Guizhou, Sichuan and Zhejiang enabling us to provide new information on this genus. Gene tree was constructed by COI gene. The results showed that there were new taxa other than the type species, namely O. grandivalvatus sp. nov. (巨瓣丽叶螽), O. nigrisartorius sp. nov. (黑缝丽叶螽), O. supeciliarilamellatus sp. nov. (眉板丽叶螽), O. guttatus sp. nov. (腹斑丽叶螽) All materials were deposited in Biological History Museum of East China Normal University (ECNU) and the Shanghai Entomological Museum, Chinese Academy of Sciences (SEM).

Somatic targeted mutation profiling of colorectal cancer precursor lesions

Most colorectal cancers (CRC) arise from precursor lesions. We aimed to characterize the mutation profile of CRC precursor lesions in a Brazilian population. In total, 90 FFPE lesions, including 67 adenomas, 7 sessile serrated lesions, and 16 hyperplastic polyps, were analyzed by next-generation sequencing. The genetic ancestry of the patients was estimated. Somatic driver mutations were identified in 66.7% of cases, including alterations in APC (32.2%), TP53 (20.0%), KRAS (18.9%), BRAF (13.3%) and EGFR (7.8%). Adenomas displayed a higher number of mutations, mainly in APC, compared to serrated polyps (73.1% vs. 47.8%, p = 0.039). Advanced adenomas had a higher frequency of mutation in KRAS and GNAS and a high overall mutation rate than early adenomas (92.9% vs. 59%, p = 0.002). Concerning the serrated pathway, a higher frequency of mutations, mainly in BRAF, was observed in sessile serrated lesions (85.7%) compared to hyperplastic polyps (31.3%, p = 0.027). A high degree of ancestry admixture was observed in the population, with a predominance of European followed by African components. The mutation profile of Brazilian colorectal precursor lesions exhibits a similar landscape to other populations. These results bestow the knowledge of CRC's biological history and may contribute to a molecular screening approach.

Molluscan mitochondrial genomes break the rules

The first animal mitochondrial genomes to be sequenced were of several vertebrates and model organisms, and the consistency of genomic features found has led to a ‘textbook description’. However, a more broad phylogenetic sampling of complete animal mitochondrial genomes has found many cases where these features do not exist, and the phylum Mollusca is especially replete with these exceptions. The characterization of full mollusc mitogenomes required considerable effort involving challenging molecular biology, but has created an enormous catalogue of surprising deviations from that textbook description, including wide variation in size, radical genome rearrangements, gene duplications and losses, the introduction of novel genes, and a complex system of inheritance dubbed ‘doubly uniparental inheritance’. Here, we review the extraordinary variation in architecture, molecular functioning and intergenerational transmission of molluscan mitochondrial genomes. Such features represent a great potential for the discovery of biological history, processes and functions that are novel for animal mitochondrial genomes. This provides a model system for studying the evolution and the manifold roles that mitochondria play in organismal physiology, and many ways that the study of mitochondrial genomes are useful for phylogeny and population biology. This article is part of the Theo Murphy meeting issue ‘Molluscan genomics: broad insights and future directions for a neglected phylum’.

Particle transport in the central Ionian Sea

&lt;p&gt;&lt;span&gt;In the &lt;/span&gt;&lt;span&gt;upper&lt;/span&gt;&lt;span&gt; layers of the Ionian Sea, young Mediterranean Atlantic Waters (MAW) flowing eastward from the Sicily channel meet old MAW. In May 2017, during the PEACETIME cruise, &lt;/span&gt;&lt;span&gt;fluorescence and particle content sampled at high resolution revealed unexpected heterogeneity in the central Ionian. Surface salinity measurements, together with altimetry-derived and hull-mounted ADCP currents, describe a zonal pathway of AW entering the Ionian Sea, consistent with the so-called cyclonic mode in the North Ionian Gyre. The ION-Tr transect, located ~19-20&amp;#176;E- ~36&amp;#176;N turned out to be at the crossroad of three water masses, mostly coming from the west, north and from an isolated anticyclonic eddy northeast of ION-Tr. Using Lagrangian numerical simulations, we suggest that the contrast in particle loads &lt;/span&gt;&lt;span&gt;along &lt;/span&gt;&lt;span&gt;ION-Tr originates from particles transported from these three different water masses. Waters from the west, identified as young AW carried by a strong southwestward jet, were intermediate in particle load, probably originating from the Sicily channel. Water mass originating from the north was carrying abundant particles, probably originating from northern Ionian, or further from the south Adriatic. Waters from the eddy, depleted in particles and Chl-a may originate from south of Peloponnese, where the Pelops eddy forms. &lt;/span&gt;&lt;/p&gt;&lt;p&gt;&lt;span&gt;The central Ionian Sea hence appears as a mosaic area, where waters of contrasted biological history meet. This contrast is particularly clear in spring, when blooming and non-blooming areas co-occur. &lt;/span&gt;&lt;/p&gt;&lt;p&gt;&lt;span&gt;High resolution measurements reveal a high heterogeneity in properties such as particles abundances. To interpret these distributions, &lt;/span&gt;&lt;span&gt;combination of multiparametric &lt;/span&gt;&lt;span&gt;&lt;em&gt;in situ&lt;/em&gt;&lt;/span&gt;&lt;span&gt; measurements with remote sensing and Lagrangian modeling appears &lt;/span&gt;&lt;span&gt;necessary&lt;/span&gt;&lt;span&gt;. &lt;/span&gt;&lt;/p&gt;