title: PeerJ description: Articles published in PeerJ link: https://peerj.com/articles/index.rss3?journal=peerj&page=659 creator: info@peerj.com PeerJ errorsTo: info@peerj.com PeerJ language: en title: Evolution of Helicobacter spp: variability of virulence factors and their relationship to pathogenicity link: https://peerj.com/articles/13120 last-modified: 2022-08-29 description: BackgroundVirulence factors (VF) are bacteria-associated molecules that assist to colonize the host at the cellular level. Bacterial virulence is highly dynamic and specific pathogens have a broad array of VFs. The genus Helicobacter is gram-negative, microaerobic, flagellated, and mucus-inhabiting bacteria associated with gastrointestinal inflammation. To investigate about their pathogenicity, several Helicobacter species have been characterized and sequenced. Since the variability and possible origin of VF in the genus are not clear, our goal was to perform a comparative analysis of Helicobacter species in order to investigate VF variability and their evolutionary origin.MethodsThe complete genomes of 22 Helicobacter species available in NCBI were analyzed, using computational tools. We identifyed gain and loss events in VF genes, which were categorized in seven functional groups to determine their most parsimonious evolutionary origin. After verifying the annotation of all VF genes, a phylogeny from conserved VF organized by Helicobacter species according to gastric Helicobacter species (GHS) or enterohepatic (EHS) classification was obtained.ResultsGain and loss analysis of VF orthologous in Helicobacter ssp revealed the most possible evolutionary origin for each gene set. Microevolutionary events in urease and flagella genes were detected during the evolution of the genus. Our results pointed that acquisition of ureases and adherence genes and deletion of cytotoxins in some lineages, as well as variation in VF genes copy number, would be related to host adaptation during evolution of the Helicobacter genus. Our findings provided new insights about the genetic differences between GHS and EHS and their relationship with pathogenicity. creator: Carlos F. Prada creator: Maria A. Casadiego creator: Caio CM Freire uri: https://doi.org/10.7717/peerj.13120 license: https://creativecommons.org/licenses/by/4.0/ rights: © 2022 Prada et al. title: Accelerating the discovery of rare tree species in Amazonian forests: integrating long monitoring tree plot data with metabolomics and phylogenetics for the description of a new species in the hyperdiverse genus Inga Mill link: https://peerj.com/articles/13767 last-modified: 2022-08-29 description: In species-rich regions and highly speciose genera, the need for species identification and taxonomic recognition has led to the development of emergent technologies. Here, we combine long-term plot data with untargated metabolomics, and morphological and phylogenetic data to describe a new rare species in the hyperdiverse genus of trees Inga Mill. Our combined data show that Inga coleyana is a new lineage splitting from their closest relatives I. coruscans and I. cylindrica. Moreover, analyses of the chemical defensive profile demonstrate that I. coleyana has a very distinctive chemistry from their closest relatives, with I. coleyana having a chemistry based on saponins and I. cylindrica and I. coruscans producing a series of dihydroflavonols in addition to saponins. Finally, data from our network of plots suggest that I. coleyana is a rare and probably endemic taxon in the hyper-diverse genus Inga. Thus, the synergy produced by different approaches, such as long-term plot data and metabolomics, could accelerate taxonomic recognition in challenging tropical biomes. creator: Juan Ernesto Guevara Andino creator: Consuelo Hernández creator: Renato Valencia creator: Dale Forrister creator: María-José Endara uri: https://doi.org/10.7717/peerj.13767 license: https://creativecommons.org/licenses/by/4.0/ rights: ©2022 Guevara Andino et al. title: Genetic structure of the small yellow croaker (Larimichthys polyactis) across the Yellow Sea and the East China Sea by microsatellite DNA variation: implications for the division of management units link: https://peerj.com/articles/13789 last-modified: 2022-08-29 description: The small yellow croaker, Larimichthys polyactis, is a commercial fish of the order Perciformes that mainly inhabit estuaries and coastal waters.In recent years, the resources and catch of L. polyactis have undergone huge fluctuations. To detect genetic variations caused by the fluctuation of resources, genetic diversity of L. polyactis in the coastal waters of China were analyzed in this study using microsatellite DNA marker. The results revealed high genetic diversity of this species. The STRUCTURE, DAPC and FST results all indicated that there was no genetic structure consistent with the distribution pattern. Overall, our main findings are in agreement with previous studies, indicating that L. polyactis showed high genetic diversity and low genetic differentiation. Our results for high genetic connectivity among L. polyactis localities provide insights into the development of management strategies, that is, to manage this species as a single management unit. creator: Jian Zheng creator: Yunrong Yan creator: Zhonglu Li creator: Na Song uri: https://doi.org/10.7717/peerj.13789 license: https://creativecommons.org/licenses/by/4.0/ rights: ©2022 Zheng et al. title: TRIM38 protects H9c2 cells from hypoxia/reoxygenation injury via the TRAF6/TAK1/NF-κB signalling pathway link: https://peerj.com/articles/13815 last-modified: 2022-08-29 description: Tripartite motif (TRIM) 38 is a ubiquitin E3 protein ligase that is involved in various intracellular physiological processes. However, the role of TRIM38 in myocardial ischaemia/reperfusion (I/R) injury remains to be elucidated. We aimed to establish an in vitro cellular hypoxia/reperfusion (H/R) model to explore the role and potential mechanisms of TRIM38 in H9c2, a rat cardiomyoblast cell line. Recombinant adenoviruses for silencing or overexpressing TRIM38 were constructed and transfected into H9c2 cells. Western blotanalysisshowed that TRIM38 expression was significantly decreased after H/R injury. Functionally, TRIM38 expression relieved inflammatory responses and oxidative stress, and inhibited H/R-induced apoptosis in H9c2 cells. Mechanistically, TRIM38 overexpression inhibited H/R-induced transforming growth factor beta-activated kinase 1 (TAK1)/nuclear factor-kappa B (NF-κB) pathway activity in H9c2 cells. The opposite results were observed after TRIM38 knockdown. Furthermore, H/R-induced injury aggravated by TRIM38 deficiency in H9c2 cells was reversed upon treatment with 5Z-7-oxozeaenol, a TAK1 inhibitor. Therefore, TRIM38 reduction attenuated the anti-apoptotic capacity and anti-inflammatory potential of H/R-stimulated H9c2 cells by activating the TAK1/NF-κB signalling pathway. Specifically, TRIM38 alleviated H/R-induced H9c2 cell injury by promoting TNF receptor-associated factor 6 degradation, which led to the inactivation of the TAK1/NF-κB signalling pathway. Thus, our study provides new insights into the molecular mechanisms underlying H/R-induced myocardial injuries. creator: Zhengri Lu creator: Mengen Deng creator: Genshan Ma creator: Lijuan Chen uri: https://doi.org/10.7717/peerj.13815 license: https://creativecommons.org/licenses/by/4.0/ rights: ©2022 Lu et al. title: Multiple propane gas burn rates procedure to determine accuracy and linearity of indirect calorimetry systems: an experimental assessment of a method link: https://peerj.com/articles/13882 last-modified: 2022-08-29 description: ObjectiveIndirect calorimetry (IC) systems measure the fractions of expired carbon dioxide (FeCO2), and oxygen (FeO2) recorded at the mouth to estimate whole-body energy production. The fundamental principle of IC relates to the catabolism of high-energy substrates such as carbohydrates and lipids to meet the body’s energy needs through the oxidative process, which are reflected in the measured oxygen uptake rates (V̇O2) and carbon dioxide production rates (V̇CO2). Accordingly, it is important to know the accuracy and validity of V̇O2and V̇CO2 measurements when estimating energy production and substrate partitioning for research and clinical purposes. Although several techniques are readily available to assess the accuracy of IC systems at a single point for V̇CO2 and V̇O2, the validity of such procedures is limited when used in testing protocols that incorporate a wide range of energy production (e.g., basal metabolic rate and maximal exercise testing). Accordingly, we built an apparatus that allowed us to manipulate propane burn rates in such a way as to assess the linearity of IC systems. This technical report aimed to assess the accuracy and linearity of three IC systems using our in-house built validation procedure.ApproachA series of trials at different propane burn rates (PBR) (i.e., 200, 300, 400, 500, and 600 mL min−1) were run on three IC systems: Sable, Moxus, and Oxycon Pro. The experimental values for V̇O2 and V̇CO2 measured on the three IC systems were compared to theoretical stoichiometry values.ResultsA linear relationship was observed between increasing PBR and measured values for V̇O2and V̇CO2 (99.6%, 99.2%, 94.8% for the Sable, Moxus, and Jaeger IC systems, respectively). In terms of system error, the Jaeger system had significantly (p < 0.001) greater V̇O2(mean difference (M) = −0.057, standard error (SE) = 0.004), and V̇CO2(M = −0.048, SE = 0.002) error compared to either the Sable (V̇O2, M = 0.044, SE = 0.004; V̇CO2, M = 0.024, SE = 0.002) or the Moxus (V̇O2, M = 0.046, SE = 0.004; V̇CO2, M = 0.025, SE = 0.002) IC systems. There were no significant differences between the Sable or Moxus IC systems.ConclusionThe multiple PBR approach permitted the assessment of linearity of IC systems in addition to determining the accuracy of fractions of expired gases. creator: Mohammad Ismail creator: Sanaa A. Alsubheen creator: Angela Loucks-Atkinson creator: Matthew Atkinson creator: Thamir Alkanani creator: Liam P. Kelly creator: Fabien Basset uri: https://doi.org/10.7717/peerj.13882 license: https://creativecommons.org/licenses/by/4.0/ rights: ©2022 Ismail et al. title: Morphology and cytochemical patterns of peripheral blood cells of tiger frog (Rana rugulosa) link: https://peerj.com/articles/13915 last-modified: 2022-08-29 description: BackgroundTiger frog (Rana rugulosa) is a national second-class protected amphibian species in China with an important ecological and economic value. In recent years, due to excessive human hunting, pollution and habitat loss, the wild population of tiger frog has declined sharply. To protect wildlife resources, the artificial breeding of tiger frogs has rapidly developed in China. Diseases are increasing and spreading among tiger frogs due to the increasing scale of artificial farming. The blood examination is the most straightforward and less invasive technique to evaluate the animal health condition. Thus, it is essential to obtain the normal hematological indicators of tiger frogs. The objective of this study was to investigate the morphometry, microstructure and cytochemical patterns of peripheral blood cells in tiger frogs.MethodsThe number of blood cells in tiger frogs was counted on a blood count board, and the cell sizes were measured by a micrometer under light microscope. The morphology and classification of blood cells were studied by Wright-Giemsa staining, and the cytochemical pateerns was investigated by various cytochemical staining including periodic acid-Schiff (PAS), Sudan black B (SBB), peroxidase (POX), alkaline phosphatase (AKP), acid phosphatase (ACP), chloroacetic acid AS-D naphthol esterase (CAE) and α-naphthol acetate esterase (ANAE) staining.ResultsBesides erythrocytes and thrombocytes, five types of leukocytes were identified in tiger frogs: neutrophils, eosinophils, basophils, lymphocytes and monocytes. The mean erythrocyte, leukocyte and thrombocyte counts were 1.33 ± 0.15 million/mm3, 3.73 ± 0.04 × 104/mm3 and 1.7 ± 0.01 × 104/mm3, respectively. Small lymphocytes were the most abundant leukocytes, followed by large lymphocytes, Neutrophils, eosinophils and monocytes, basophils were the fewest. Eosinophils were strongly positive for PAS, positive for SBB, POX, ACP, CAE, ANAE, while weakly positive for AKP staining; basophils were strongly positive for PAS, ACP, positive for SBB, CAE, weakly positive for ANAE, negative for AKP, POX staining; neutrophils were strongly positive for ACP, SBB, positive for PAS, POX, weakly positive for AKP, CAE and ANAE staining; monocytes were positive for PAS, SBB, ANAE, weakly positive for ACP, AKP, POX, CAE staining; large lymphocytes and thrombocytes were positive for PAS, ACP, weakly positive for ANAE, while negative for SBB, POX, AKP, CAE; small lymphocytes were similar to large lymphocytes, except for strongly positive for PAS and ACP staining.ConclusionsThe blood cell types and morphology of tiger frogs were generally similar to those of other amphibians, while their cytochemical patterns had some notable species specificity.Our study could enrich the knowledge of peripheral blood cell morphology and cytochemistry in amphibians, and provide baseline data for health condition evaluation and disease diagnosis of tiger frogs. creator: Xianxian Chen creator: Yu Wu creator: Lixin Huang creator: Xue Cao creator: Misbah Hanif creator: Fei Peng creator: Xiaobing Wu creator: Shengzhou Zhang uri: https://doi.org/10.7717/peerj.13915 license: https://creativecommons.org/licenses/by/4.0/ rights: ©2022 Chen et al. title: COVID-19 onset reduced the sex ratio at birth in South Africa link: https://peerj.com/articles/13985 last-modified: 2022-08-29 description: BackgroundThe sex ratio at birth (defined as male/(male+female) live births) is anticipated to approximate 0.510 with a slight male excess. This ratio has been observed to decrease transiently around 3–5 months following sudden unexpected stressful events. We hypothesised that stress engendered by the onset of the COVID-19 pandemic may have caused such a decrease in South Africa 3–5 months after March 2020 since in this month, South Africa reported its first COVID-19 case, death and nationwide lockdown restrictions were instituted.MethodsWe used publicly available, recorded monthly live birth data from Statistics South Africa. The most recent month for which data was available publicly was December 2020. We analysed live births for a 100-month period from September 2012 to December 2020, taking seasonality into account. Chi-squared tests were applied.ResultsOver this 100-month period, there were 8,151,364 live births. The lowest recorded monthly sex ratio at birth of 0.499 was in June 2020, 3 months after March 2020. This June was the only month during this period where the sex ratio inverted i.e., fewer male live births occurred. The predicted June 2020 ratio was 0.504. The observed June 2020 decrease was statistically significant p = 0.045.ConclusionsThe sex ratio at birth decreased and inverted in South Africa in June 2020, for the first time, during the most recent 100-month period. This decline occurred 3 months after the March 2020 onset of COVID-19 in South Africa. As June 2020 is within the critical window when population stressors are known to impact the sex ratio at birth, these findings suggest that the onset of the COVID-19 pandemic engendered population stress with notable effects on pregnancy and public health in South Africa. These findings have implications for future pandemic preparedness and social policy. creator: Gwinyai Masukume creator: Margaret Ryan creator: Rumbidzai Masukume creator: Dorota Zammit creator: Victor Grech creator: Witness Mapanga uri: https://doi.org/10.7717/peerj.13985 license: https://creativecommons.org/licenses/by/4.0/ rights: ©2022 Masukume et al. title: Effects of exogenous calcium on the drought response of the tea plant (Camellia sinensis (L.) Kuntze) link: https://peerj.com/articles/13997 last-modified: 2022-08-29 description: BackgroundDrought is one of the major factors reducing the yield of many crops worldwide, including the tea crop (Camellia sinensis (L.) Kuntze). Calcium participates in most of cellular signaling processes, and its important role in stress detection and triggering a response has been shown in many crops. The aim of this study was to evaluate possible effects of calcium on the tea plant response to drought.MethodsExperiments were conducted using 3-year-old potted tea plants of the best local cultivar Kolkhida. Application of ammonium nitrate (control treatment) or calcium nitrate (Ca treatment) to the soil was performed before drought induction. Next, a 7-day drought was induced in both groups of plants. The following physiological parameters were measured: relative electrical conductivity, pH of cell sap, and concentrations of cations, sugars, and amino acids. In addition, relative expression levels of 40 stress-related and crop quality–related genes were analyzed.ResultsUnder drought stress, leaf electrolyte leakage differed significantly, indicating greater damage to cell membranes in control plants than in Ca-treated plants. Calcium application resulted in greater pH of cell sap; higher accumulation of tyrosine, methionine, and valine; and a greater Mg2+ content as compared to control plants. Drought stress downregulated most of the quality-related genes in both groups of tea plants. By contrast, significant upregulation of some genes was observed, namely CRK45, NAC26, TPS11, LOX1, LOX6, Hydrolase22, DREB26, SWEET2, GS, ADC, DHN2, GOLS1, GOLS3, and RHL41. Among them, three genes (LOX1, RHL41, and GOLS1) showed 2–3 times greater expression in Ca-treated plants than in control plants. Based on these results, it can be speculated that calcium affects galactinol biosynthesis and participates in the regulation of stomatal aperture not only through activation of abscisic-acid signaling but also through jasmonic-acid pathway activation. These findings clarify calcium-mediated mechanisms of drought defense in tree crops. Thus, calcium improves the drought response in the tea tree. creator: Lyudmila S. Malyukova creator: Natalia G. Koninskaya creator: Yuriy L. Orlov creator: Lidiia S. Samarina uri: https://doi.org/10.7717/peerj.13997 license: https://creativecommons.org/licenses/by/4.0/ rights: © 2022 Malyukova et al. title: The redescription of the holotype of Nothosaurus mirabilis (Diapsida, Eosauropterygia)—a historical skeleton from the Muschelkalk (Middle Triassic, Anisian) near Bayreuth (southern Germany) link: https://peerj.com/articles/13818 last-modified: 2022-08-26 description: In 2009, the historical mount of the holotype of Nothosaurus mirabilis from the Upper Muschelkalk of Oschenberg (Laineck Mountain Range, near Bayreuth, southern Germany) was disassembled and the original postcranial skeleton was reworked and remounted in find position. Its morphology is described and figured for the first time in detail. Further on, a thorough overview of the sedimentary environment and the historical activities around the Upper Muschelkalk quarries in the vicinity of Bayreuth is given. The holotype of N. mirabilis is one out of only two fairly complete nothosaur skeletons known from the Bayreuth Upper Muschelkalk and greatly emends our knowledge of the morphology of the species and the genus. It will further allow an assignment of isolated elements to this taxon. The specimen consists of an articulated and complete neck and anterior trunk vertebral column as well as several articulated parts of the anterior tail region. The sacral region is partially preserved but disarticulated. Besides vertebrae, ribs and gastral fragments, both humeri, the right femur, few zeugopodial and autopodial elements, and the right pelvic girdle are preserved. The very high neural spines of the holotype are stabilized by a supersized zygosphene-zygantrum articulation reaching far dorsally. Together with the large intercentral spaces this character suggests lateral undulation of the trunk region during fast swimming whereas propelling with the broad and wing-shaped humerus and the flat ulna was used during slower swimming. The total body length for this not fully grown individual is reconstructed as between 290 to 320 cm. Preservation, degree of completeness, and articulation of the individual is unique. The skull and shoulder girdle are both lost, whereas articulated strings of the vertebral column have turned and appendicular bones have shifted posteriorly or anteriorly, respectively, indicating water movements and possibly also scavenging. creator: Nicole Klein creator: Stefan Eggmaier creator: Hans Hagdorn uri: https://doi.org/10.7717/peerj.13818 license: https://creativecommons.org/licenses/by/4.0/ rights: © 2022 Klein et al. title: A new species of lotic breeding salamander (Amphibia, Caudata, Hynobiidae) from Shikoku, Japan link: https://peerj.com/articles/13891 last-modified: 2022-08-26 description: BackgroundHynobius hirosei is a lotic-breeding salamander endemic to Shikoku Island in western Japan. Significant allozymic and morphological differences have been found among the populations of this species; however, the degree and pattern of intraspecific variation have not been surveyed using a sufficient number of samples.MethodsFor the taxonomic revision of H. hirosei, we conducted genetic and morphological surveys using samples collected throughout the distribution. Phylogenetic analysis using the cytochrome b region of mitochondrial DNA and population structure analysis using single nucleotide polymorphisms were conducted to evaluate the population structure within the species and the degree of genetic differentiation. Subsequently, a morphological survey based on multivariate and univariate analyses was performed to assess the morphological variation.ResultsGenetic analyses revealed three genetic groups (Tsurugi, Central, and Nanyo) within H. hirosei, with the Nanyo group distributed allopatrically from the others, and the Tsurugi and Central groups distributed parapatrically with the formation of a hybrid zone between them. The Nanyo group was morphologically distinguishable from the remaining samples, including the topotype of H. hirosei, based on a smaller body size and several ratio values of characters to snout-vent length, longer axilla-groin distance, shorter tail length, shorter internarial distance, longer upper eyelid length, and larger medial tail width. These results support the notion that the Nanyo group is an undescribed species. However, the remaining genetically differentiated groups could not be divided in the present study. Herein, we described the Nanyo group as a new species. creator: Sally Kanamori creator: Kanto Nishikawa creator: Masafumi Matsui creator: Shingo Tanabe uri: https://doi.org/10.7717/peerj.13891 license: https://creativecommons.org/licenses/by/4.0/ rights: © 2022 Kanamori et al.