The role of mitochondrial energetics in the origin and diversification of eukaryotes

The origin of eukaryotic cell size and complexity is thought by some to have required an energy excess provided by mitochondria, whereas others claim that mitochondria provide no energetic boost to eukaryotes. Recent observations show that energy demand scales continuously and linearly with cell volume across both prokaryotes and eukaryotes, and thus suggest that eukaryotes do not have an increased energetic capacity over prokaryotes. However, amounts of respiratory membranes and ATP synthases scale super-linearly with cell surface area. Furthermore, the energetic consequences of the contrasting genomic designs between prokaryotes and eukaryotes have yet to be precisely quantified. Here, we investigated (1) potential factors that affect the cell volumes at which prokaryotes become surface area-constrained, and (2) the amount of energy that is divested to increasing amounts of DNA due to the contrasting genomic designs of prokaryotes and eukaryotes. Our analyses suggest that prokaryotes are not necessarily constrained by their cell surfaces at cell volumes of 100-103 µm3, and that the genomic design of eukaryotes is only slightly advantageous at genomes sizes of 106-107 bp. This suggests that eukaryotes may have first evolved without the need for mitochondria as these ranges hypothetically encompass the Last Eukaryote Common Ancestor and its proto-eukaryotic ancestors. However, our analyses also show that increasingly larger and fast-dividing prokaryotes would have a shortage of surface area devoted to respiration and would disproportionally divest more energy to DNA synthesis at larger genome sizes. We thus argue that, even though mitochondria may not have been required by the first eukaryotes, the successful diversification of eukaryotes into larger and more active cells was ultimately contingent upon the origin of mitochondria.

You aren't what you eat, you become what you eat

Obesity (and the consequent obesity epidemic) is a complex, adaptive process, taking place over a time span of many years. Energy intake is recognized as a potentially important driver of obesity, especially in the context of an identifiable energy imbalance which, it is surmised, must lead to weight gain. Similarly, energy expenditure must play an important role. However, both show an enormous degree of individual variation. Therefore, measuring them is an exceedingly difficult task, especially in the context of large populations and long time periods. It has been argued that population-level observed weight gain can be traced back to very small daily energy imbalances while, at the same time, positing that a much larger maintenance energy gap is responsible for maintaining the energy requirements of the increased weight population. In this paper we examine the relation between BMI and energy intake as functions of age. The convexity of the BMI curves as a function of age and gender demonstrate the enhanced obesity risk apparent in young adults and women, and imply that no settling points exist at the population level. Consistent with other studies, overall weight increases are consistent with a very small daily energy imbalance, about 7 cal. Consumption as a function of age shows a small, steady, linear decrease of about 8 cal per year, and can be associated with a maximal energy excess/deficit of about 250cal for the youngest and oldest age groups. By examining weight differences between age groups as a function of age, we argue that this excess/deficit is an important motor for the observed weight differences, and argue that the apparent energy imbalance of 250 cal, due to excess consumption, leads to an effective imbalance of only 7 cal due to the existence of various physiological and behavioral mechanisms that enhance weight homeostasis and effectively reduce the energy excess from 250 cal to 7 cal. We discuss several possibilities for such mechanisms.

Overview of Nutritional Status of Pregnant Women with Preeclampsia: Case Study in Aru Islands Regency, Dobo City, Southeast Maluku

Background: Preeclampsia is a syndrome in terms of hypertension after 20-week pregnancy referring to a pregnant woman that previously had normal blood pressure, followed by having hypertension, proteinuria, edema and generally occurs in the third trimester of pregnancy. Preeclampsia is one of five main causes of maternal mortality up to 12% in the world as well. Objective: This study was conducted to describe nutritional status of pregnant women with preeclampsia in Aru Islands Regency, Dobo City, Southeast Maluku. Methodology: This study used mix methods, namely, quantitative and qualitative research with Case Study design. Qualitative research was to determine nutritional status of pregnant women with preeclampsia and quantitative research was to record nutrition intake of pregnant women and measure nutritional status of pregnant women with preeclampsia. Results & Discussion: Characteristics of participants with preeclampsia were more than 27 years old, worked as housewife that could be one of stress triggers and had some risk to increase preeclampsia cases because of stress that caused blood pressure increase. Preeclampsia was detected in pregnancy term of participants about 20-30 weeks according to Maternal and Child Health data. Preeclampsia risk was doubly by every increase in body weight (5-7 kg). Participants had body weight increase ranging from 8-25 kg which caused preeclampsia risk increase. Parameters of recommended dietary allowances of pregnant women including energy excess, protein deficit, fat excess, calcium and zinc deficiency were secondary factor of preeclampsia risk increase in Aru Islands Regency, Dobo City, Southeast Maluku.

Sensitivity of a Liquid Xenon Detector to Neutrino–Nucleus Coherent Scattering and Neutrino Magnetic Moment from Reactor Neutrinos

Liquid xenon is one of the leading targets to search for dark matter via its elastic scattering on nuclei or electrons. Due to their low-threshold and low-background capabilities, liquid xenon detectors can also detect coherent elastic neutrino–nucleus scattering (CEνNS) or neutrino–electron scattering. In this paper, we investigate the feasibility of a compact and movable liquid xenon detector with an active target mass of O(10∼100) kg and single-electron sensitivity to detect CEνNS from anti-neutrinos from a nuclear reactor. Assuming a single- and few-electron background rate at the level achieved by the XENON10/100 experiments, we expect a 5-σ detection of CEνNS with less than 400 kg-days of exposure. We further investigate the sensitivity of such a detector to neutrino magnetic moment with neutrino electron scattering. If an electronic recoil background rate of 0.01∼0.1 events/keV/kg/day above 1 keV can be achieved with adequate shielding, a liquid xenon detector can reach a neutrino magnetic moment sensitivity of 10−11μB, which would improve upon the current most-constraining laboratory limits from the GEMMA and Borexino experiments. Additionally, such a detector would be able to probe the region compatible with a magnetic moment interpretation of the low-energy excess electronic recoil events recently reported by XENON1T.

Erratum to: A new analysis of the MiniBooNE low-energy excess

After publication we discovered that some entries in table 2 and the corresponding contours in figures 3 and 4 have been misprinted. We provide here the correct version of table 2 and figures 3 and 4. The discussion and conclusions in the text of the paper remain unchanged.