Genetic Screens Identify Host Factors for SARS-CoV-2 and Common Cold Coronaviruses

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A case of Klinefelter's syndrome associated with hypothalamic-pituitary dysfunction caused by an intracranial germ cell tumor

A 17 year-old boy was admitted to the hospital because of thirst, polyuria (5-61/day), delayed sexual development and muscle weakness. He appeared obese, had an eunuchoidal body habitus and was excessively tall. Chromosomal analysis revealed a 47XXY karyotype. Serum cortisol was 1.3 microgram/dl, LH, 10.4 mIU/ml, FSH, 2.0 mIU/ml, and testosterone, 10 ng/dl. Endocrinological dynamic tests indicated diabetes insipidus and hypopituitarism of a hypothalamic type. Brain CT disclosed the existence of a tumor shadow around the calcified pineal body, extending towards the suprasellar region. Replacement therapy with glucocorticoid and DDAVP was started. The patient complained of a headache and plasma AFP and hCG concentrations were 868 ng/ml and 68.6 IU/ml respectively. A hCG- and AFP- producing germ cell tumor was suspected and radiation therapy with 60Co was performed. Plasma AFP and hCG were decreased with significant clinical improvement. Soon after irradiation, he started to complain of a headache and had elevated AFP and hCG levels. Right hemiparesis and unconsciousness suddenly appeared and he died of left thalamic bleeding. This is the first case of Klinefelter's syndrome associated with intracranial germ cell tumor. Plasma testosterone levels fluctuated in parallel with the change in plasma hCG levels. This shows that the Leydig cells in this patient could respond to some extent to tumor-producing hCG.     

Stability of cytochromes c′ from psychrophilic and piezophilic Shewanella species: implications for complex multiple adaptation to low temperature and high hydrostatic pressure

Extremophiles - The stability of dimeric cytochrome c′ from a thermophile, as compared with that of a homologous mesophilic counterpart, is attributed to strengthened interactions around the...     

Impact of PbI2 Passivation and Grain Size Engineering in CH3NH3PbI3 Solar Absorbers as Revealed by Carrier‐Resolved Photo‐Hall Technique

With power conversion efficiencies now exceeding 25%, hybrid perovskite solar cells require deeper understanding of defects and processing to further approach the Shockley‐Queisser limit. One approach for processing enhancement and defect reduction involves additive engineering—, e.g., addition of MASCN (MA = methylammonium) and excess PbI₂ have been shown to modify film grain structure and improve performance. However, the underlying impact of these additives on transport and recombination properties remains to be fully elucidated. In this study, a newly developed carrier‐resolved photo‐Hall (CRPH) characterization technique is used that gives access to both majority and minority carrier properties within the same sample and over a wide range of illumination conditions. CRPH measurements on n‐type MAPbI₃ films reveal an order of magnitude increase in carrier recombination lifetime and electron density for 5% excess PbI₂ added to the precursor solution, with little change noted in electron and hole mobility values. Grain size variation (120–2100 nm) and MASCN addition induce no significant change in carrier‐related parameters considered, highlighting the benign nature of the grain boundaries and that excess PbI₂ must predominantly passivate bulk defects rather than defects situated at grain boundaries. This study offers a unique picture of additive impact on MAPbI₃ optoelectronic properties as elucidated by the new CRPH approach.     

Context-Dependent Role of Mitochondrial Fusion-Fission in Clonal Expansion of mtDNA Mutations

The accumulation of mutant mitochondrial DNA (mtDNA) molecules in aged cells has been associated with mitochondrial dysfunction, age-related diseases and the ageing process itself. This accumulation has been shown to often occur clonally, where mutant mtDNA grow in number and overpopulate the wild-type mtDNA. However, the cell possesses quality control (QC) mechanisms that maintain mitochondrial function, in which dysfunctional mitochondria are isolated and removed by selective fusion and mitochondrial autophagy (mitophagy), respectively. The aim of this study is to elucidate the circumstances related to mitochondrial QC that allow the expansion of mutant mtDNA molecules. For the purpose of the study, we have developed a mathematical model of mitochondrial QC process by extending our previous validated model of mitochondrial turnover and fusion-fission. A global sensitivity analysis of the model suggested that the selectivity of mitophagy and fusion is the most critical QC parameter for clearing de novo mutant mtDNA molecules. We further simulated several scenarios involving perturbations of key QC parameters to gain a better understanding of their dynamic and synergistic interactions. Our model simulations showed that a higher frequency of mitochondrial fusion-fission can provide a faster clearance of mutant mtDNA, but only when mutant–rich mitochondria that are transiently created are efficiently prevented from re-fusing with other mitochondria and selectively removed. Otherwise, faster fusion-fission quickens the accumulation of mutant mtDNA. Finally, we used the insights gained from model simulations and analysis to propose a possible circumstance involving deterioration of mitochondrial QC that permits mutant mtDNA to expand with age.     

Japanese Lifestyle during Childhood Prevents the Future Development of Obesity among Japanese-Americans

Objective

To evaluate whether a Japanese lifestyle during childhood could protect against the future development of obesity-associated metabolic diseases by comparing native Japanese with Japanese-Americans in whom genetic factors are the same.

Methods

Study subjects were 516 native Japanese and 781 Japanese-Americans who underwent medical examinations between 2007 and 2010. Japanese-Americans were divided into 444 first-generation immigrants (JA-1), who were born in Japan, and 337 second- or later-generation descendants (JA-2), who were born in the United States. The JA-2 group was then divided into the kibei subgroup (N = 79), who had moved to Japan before the age of 18 years and later returned to the United States, and the non-kibei subgroup (N = 258), who had never lived in Japan.

Results

The JA-2 group had the highest percentages of obesity, metabolic syndrome, and type 2 diabetes compared with native Japanese and JA-1. Furthermore, among JA-2, the prevalence of obesity and metabolic syndrome in the kibei subgroup was significantly lower than that in the non-kibei subgroup. The prevalence of diabetes in the kibei subgroup also tended to be lower than in the non-kibei subgroup.

Conclusions

The prevalence of obesity and metabolic diseases differed with residence in Japan during childhood among Japanese-Americans. These findings indicate the possibility that Japanese lifestyle during childhood could reduce the future risks for obesity-associated metabolic diseases.     

Ants on plants: a meta-analysis of the role of ants as plant biotic defenses

We reviewed the evidence on the role of ants as plant biotic defenses, by conducting meta-analyses for the effects of experimental removal of ants on plant herbivory and fitness with data pooled from 81 studies. Effects reviewed were plant herbivory, herbivore abundance, hemipteran abundance, predator abundance, plant biomass and reproduction in studies where ants were experimentally removed (n = 273 independent comparisons). Ant removal exhibited strong effects on herbivory rates, as plants without ants suffered almost twice as much damage and exhibited 50% more herbivores than plants with ants. Ants also influenced several parameters of plant fitness, as plants without ants suffered a reduction in biomass (−23.7%), leaf production (−51.8%), and reproduction (−24.3%). Effects were much stronger in tropical regions compared to temperate ones. Tropical plants suffered almost threefold higher herbivore damage than plants from temperate regions and exhibited three times more herbivores. Ant removal in tropical plants resulted in a decrease in plant fitness of about 59%, whereas in temperate plants this reduction was not statistically significant. Ant removal effects were also more important in obligate ant–plants (=myrmecophytes) compared to plants exhibiting facultative relationships with hemiptera or those plants with extrafloral nectaries and food bodies. When only tropical plants were considered and the strength of the association between ants and plants taken into account, plants with obligate association with ants exhibited almost four times higher herbivory compared to plants with facultative associations with ants, but similar reductions in plant reproduction. The removal of a single ant species increased plant herbivory by almost three times compared to the removal of several ant species. Altogether, these results suggest that ants do act as plant biotic defenses, but the effects of their presence are more pronounced in tropical systems, especially in myrmecophytic plants. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. N. P. de U. Barbosa, L. Diniz, Y. Oki and F. Pezzini contributed equally to this work and are listed in alphabetical order.