Anisotropy and lifetime decay of green fluorescent protein in glycerol

Fluorescence is a phenomena that can be observed on the surface of tonic water in sunlight, perceiving the emission of blue light from a substance called quinine. In 1845 Sir John F. W. Herschel [1] discovered the previous phenomena. Nowadays, fluorescence embodies a useful research tool in various scientific fields such as biology, not only acting as a stain for diverse applications such as tracing cell organelles but also giving presumably important information about its environment such as the viscosity of the medium. This work is focused on the green fluorescent protein (GFP) with the objective to measure its emission spectra, its lifetime and anisotropy decay. According to the executed experiment, the result for the emission peak is, located in the green wavelength range at λem = 510 nm. The lifetime decay also shows the expected behavior, involving the effects that occur during the excitation period. For the anisotropy decay measurements, the objective is to compare the measuring results with different models for the three dimensional shape of the GFP. Knowing a term called rotational correlation time θ from the experiment, the volume V of the protein can be determined. If the volume is defined and θ is measured, the viscosity of the medium that surrounds the GFP can be found. This part of the research was complicated as not all of the obtained data followed the expectations, hence, both models and ideas how to improve the procedure will be discussed theoretically in more detail

Unveiling the chemical fingerprint of phosphorus-rich stars I. In the infrared region of APOGEE-2

The origin of phosphorus, one of the essential elements for life on Earth, is currently unknown. Prevalent models of Galactic chemical evolution (GCE) underestimate the amount of P compared to observations. The recently discovered P-rich ([P/Fe] > 1 dex) and metal-poor giants further challenge current theories on stellar nucleosynthesis. Since the observed stars are low-mass giants, our primary goal is to find clues on their progenitor. By increasing the number of known P-rich stars, we aim to narrow down a reliable chemical abundance pattern and to place robust constraints on the responsible nucleosynthetic mechanism. In the long term, identifying the progenitor of the P-rich stars may contribute to the search for the source of P in our Galaxy. We performed a detailed chemical abundance analysis based on the H-band spectra from APOGEE-2 (DR17). Employing the BACCHUS code, we measured the abundances of 13 elements in the sample, which is mainly composed of a recent collection of Si-enhanced giants. We also analyzed the orbital motions and compared the abundance results to possible nucleosynthetic formation scenarios, and also to detailed GCE models. We enlarged the sample of confirmed P-rich stars from 16 to 78 giants, which represents the largest sample of P-rich stars to date. Significant enhancements in O, Al, Si and Ce, as well as systematic correlations among the elements, unveil the chemical fingerprint of the P-rich stars. The high Mg and C+N found in some of the P-rich stars with respect to P-normal stars is not confirmed over the full sample. Strikingly, the strong over-abundance in the $\alpha$-element Si is accompanied by normal Ca and S abundances. Our analysis of the orbital motion showed that the P-rich stars do not belong to a specific sub-population. In addition, we confirm that the majority of the sample stars are not part of binary systems.Comment: 29 pages, 18 figures, 8 tables, accepted for publication in Astronomy & Astrophysic

Improved upper limb function in non-ambulant children with SMA type 2 and 3 during nusinersen treatment: a prospective 3-years SMArtCARE registry study

Background The development and approval of disease modifying treatments have dramatically changed disease progression in patients with spinal muscular atrophy (SMA). Nusinersen was approved in Europe in 2017 for the treatment of SMA patients irrespective of age and disease severity. Most data on therapeutic efficacy are available for the infantile-onset SMA. For patients with SMA type 2 and type 3, there is still a lack of sufficient evidence and long-term experience for nusinersen treatment. Here, we report data from the SMArtCARE registry of non-ambulant children with SMA type 2 and typen 3 under nusinersen treatment with a follow-up period of up to 38 months. Methods SMArtCARE is a disease-specific registry with data on patients with SMA irrespective of age, treatment regime or disease severity. Data are collected during routine patient visits as real-world outcome data. This analysis included all non-ambulant patients with SMA type 2 or 3 below 18 years of age before initiation of treatment. Primary outcomes were changes in motor function evaluated with the Hammersmith Functional Motor Scale Expanded (HFMSE) and the Revised Upper Limb Module (RULM). Results Data from 256 non-ambulant, pediatric patients with SMA were included in the data analysis. Improvements in motor function were more prominent in upper limb: 32.4% of patients experienced clinically meaningful improvements in RULM and 24.6% in HFMSE. 8.6% of patients gained a new motor milestone, whereas no motor milestones were lost. Only 4.3% of patients showed a clinically meaningful worsening in HFMSE and 1.2% in RULM score. Conclusion Our results demonstrate clinically meaningful improvements or stabilization of disease progression in non-ambulant, pediatric patients with SMA under nusinersen treatment. Changes were most evident in upper limb function and were observed continuously over the follow-up period. Our data confirm clinical trial data, while providing longer follow-up, an increased number of treated patients, and a wider range of age and disease severity

Root effect hemoglobin may have evolved to enhance general tissue oxygen delivery

The Root effect is a pH-dependent reduction in hemoglobin-O2 carrying capacity. Specific to ray-finned fishes, the Root effect has been ascribed specialized roles in retinal oxygenation and swimbladder inflation. We report that when rainbow trout are exposed to elevated water carbon dioxide (CO2), red muscle partial pressure of oxygen (PO2) increases by 65%—evidence that Root hemoglobins enhance general tissue O2 delivery during acidotic stress. Inhibiting carbonic anhydrase (CA) in the plasma abolished this effect. We argue that CA activity in muscle capillaries short-circuits red blood cell (RBC) pH regulation. This acidifies RBCs, unloads O2 from hemoglobin, and elevates tissue PO2, which could double O2 delivery with no change in perfusion. This previously undescribed mechanism to enhance O2 delivery during stress may represent the incipient function of Root hemoglobins in fishes

Acid-base physiology and CO2 homeostasis: Regulation and compensation in response to elevated environmental CO2

Acid-base balance is one of the most tightly regulated physiological processes. Accumulation of metabolic CO2 produced at the tissues causes extra- or intracellular acidosis that can disrupt cellular processes. Consequently, fish have a well-developed system for CO2 transport and excretion; however, the system varies significantly among fish groups, which we review in this chapter. Elevated environmental CO2 that occurs naturally or due to anthropogenic factors (e.g., climate change and in aquaculture), in both freshwater and seawater, induces a rapid acid-base disturbance in fish. The resulting acidosis is compensated by a net elevation in plasma in exchange for [Cl−], primarily through processes at the gills, but also the kidney. The rate and completeness of acid-base compensation during CO2 exposure is affected by water ion composition, and at high CO2 levels, there appears to be an upper limit to the increase in plasma . Fish that naturally live in such high CO2 environments appear to have an exceptional capacity for intracellular pH regulation. While it has long been thought that fish would not be affected by climate change relevant CO2 levels, negative physiological effects are seen. The effect of fluctuating CO2 levels in both marine and freshwater environments may be especially problematic, and an area where more research is required