The Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) virus is continuously evolving, and this poses a major threat to antibody therapies and currently authorized Coronavirus Disease 2019 ...(COVID-19) vaccines. It is therefore of utmost importance to investigate and predict the putative mutations on the spike protein that confer immune evasion. Antibodies are key components of the human immune system's response to SARS-CoV-2, and the spike protein is a prime target of neutralizing antibodies (nAbs) as it plays critical roles in host cell recognition, fusion, and virus entry. The potency of therapeutic antibodies and vaccines partly depends on how readily the virus can escape neutralization. Recent structural and functional studies have mapped the epitope landscape of nAbs on the spike protein, which illustrates the footprints of several nAbs and the site of escape mutations. In this review, we discuss (1) the emerging SARS-CoV-2 variants; (2) the structural basis for antibody-mediated neutralization of SARS-CoV-2 and nAb classification; and (3) identification of the RBD escape mutations for several antibodies that resist antibody binding and neutralization. These escape maps are a valuable tool to predict SARS-CoV-2 fitness, and in conjunction with the structures of the spike-nAb complex, they can be utilized to facilitate the rational design of escape-resistant antibody therapeutics and vaccines.
Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) is a newly emerging, highly transmissible, and pathogenic coronavirus in humans that has caused global public health emergencies and ...economic crises. To date, millions of infections and thousands of deaths have been reported worldwide, and the numbers continue to rise. Currently, there is no specific drug or vaccine against this deadly virus; therefore, there is a pressing need to understand the mechanism(s) through which this virus enters the host cell. Viral entry into the host cell is a multistep process in which SARS-CoV-2 utilizes the receptor-binding domain (RBD) of the spike (S) glycoprotein to recognize angiotensin-converting enzyme 2 (ACE2) receptors on the human cells; this initiates host-cell entry by promoting viral-host cell membrane fusion through large-scale conformational changes in the S protein. Receptor recognition and fusion are critical and essential steps of viral infections and are key determinants of the viral host range and cross-species transmission. In this review, we summarize the current knowledge on the origin and evolution of SARS-CoV-2 and the roles of key viral factors. We discuss the structure of RNA-dependent RNA polymerase (RdRp) of SARS-CoV-2 and its significance in drug discovery and explain the receptor recognition mechanisms of coronaviruses. Further, we provide a comparative analysis of the SARS-CoV and SARS-CoV-2 S proteins and their receptor-binding specificity and discuss the differences in their antigenicity based on biophysical and structural characteristics.
In this paper, the decadal datasets available from the space-borne lidar, Cloud Aerosol Lidar with Orthogonal Polarization (CALIOP) onboard Cloud-Aerosol Lidar and Infrared Pathfinder Satellite ...Observations (CALIPSO) are analyzed in order to understand the spatial and vertical distributions of aerosols at a global scale. Decadal (September 2006–August 2016) Level 3 night time Standard All-sky data products, created using quality controlled Level 2 datasets are utilized in the study. Columnar aerosol properties are discussed in conjugation with vertical properties of the three major aerosol types i.e. dust, polluted dust and smoke. It is found that the global mean aerosol optical depth (AOD) amounts to 0.10, with AOD values of 0.13 and 0.09 for land and ocean respectively, during the last decade. Mean aerosol extinction coefficients are also reported for four altitude bins i.e. 0–1 km, 1–2 km, 2–3 km and 3–4 km above mean sea level (a.m.s.l.). It is observed that dust and smoke particles have stronger vertical transport compared to polluted dust particles, which are generally found to be confined within the lower altitudes. In order to observe the changes in aerosol loading over different parts of the globe, de-seasonalized trends of AOD and vertical extinction coefficients are computed using linear regression technique. Globally, the total columnar particle load shows a significant negative trend during the last decade. In particular, trends of total particle loading (AOD and extinction) are decreasing over North America, South America, East China and Australia. However, the smoke emissions (columnar and vertically distributed) have increased over India, Russia, North America, Australia and Central Africa. This is of concern in the context of rising temperatures accompanied with increasing wildfires throughout the globe. Additionally, enhanced levels of polluted dust over the developing regions of Africa and Asia are also revealed.
•Decadal trends of dust, polluted dust and smoke are reported.•Globally, smoke emissions have increased.•Dust levels have increased over North America during the last decade.•Decreasing polluted dust over America, Europe and East China
The farmers are approaching river/reservoir beds to produce crops and vegetables during the lean periods, especially post-monsoon, winter, and summer, for their livelihood in changing climatic ...scenarios. Comparing C fractions, C stocks, and microbial indices between the terrestrial (conventional agricultural land: CAL) and riparian zones (reservoir riparian zones: RSRZ and river riparian zones: RRZ) reveals that cultivating riparian zones is environmentally stressful and climatically vulnerable to livelihood practices. The moist riverbed conditions for cultivation result in the accumulation of residual biomass and the burial of soil organic matter. The C fractions showed decreasing trends as CAL > RSRZ > RRZ. The mean TOC stock was found high in the CAL soils (45.04 Mg C ha−1) than in the RRZ (40.65 Mg C ha−1) and RSRZ soils (38.01 Mg C ha−1). The labile C fraction (KMnO4-C) varied from 2.34 to 3.29 % of TOC, and the RSRZ and RRZ soils showed 14.50 % and 40.32 % less KMnO4-C than the CAL soils. The relationship between KMnO4-C and mineralizable C (Cmin) showed high potential for organic carbon stabilization in riparian soils. The microbial biomass carbon (MBC) and basal soil respiration (BSR) values were nearly half of the CAL in the RRZ soils indicating limited carbon substrate availability to the microbial decomposition. Low mineralization quotient (qM) and high metabolic quotient (qCO2) indicated stressful microbial utilization of labile TOC in the RRZ soils. The high carbon management index (CMI) showed the potential to store and sequester TOC in riparian soils. The artificial neural networks (ANN) were used to examine the impact of soil properties on the prediction efficiency of TOC stocks in the three farming zones.
•Carbon fractions in riparian soils were less than in conventional agriculture soils.•Low qM and high qCO2 in riparian soils showed less degree of C mineralization.•The holocoenotic labile C fractions were KMnO4-C and Cmin.•NLC showed high C stock prediction irrespective of agricultural zones.
The threat of heavy metal pollution to environmental health is getting worldwide attention due to their persistence and non-biodegradable nature. Ineffectiveness of various physicochemical methods ...due to economical and technical constraints resulted in the search for a cost-effective and eco-friendly biological technique for heavy metal removal from the environment. The two effective biotic methods used are biosorption and bioaccumulation. A comparison between these two processes demonstrated that biosorption is a better heavy metal removal process than bioaccumulation. This is due to the intoxication of heavy metal by inhibiting their entry into the microbial cell. Genes and enzymes related to bioremoval process are also discussed. On comparing the removal rate, bacteria are surpassed by algae and fungi. The aim of this review is to understand the biotic processes and to compare their metal removal efficiency.
The study elucidate upon the evaluation of satellite retrievals with ground based aerosol optical depth (AOD) measurements, their utilization in LiDAR ratio (LR) estimation, boundary layer (BL) ...height determination and the case studies on aerosol transport over Himalayan region. The AOD retrievals from the latest level-2 data collections (C5.1 and C6.0) of MODerate resolution Imaging Spectroradiometer (MODIS) onboard Aqua and Terra satellites and Cloud-Aerosol LiDAR and Infrared Pathfinder Satellite Observations (CALIPSO) versions (4.10 and 3) are subjected for quantitative analysis to assess the level of agreement with the quality assured level-2 ground based AErosol RObotic NETwork (AERONET) measurements over Manora peak (29.36° N, 79.46°E), a high altitude site in the Himalayas. Analysis revealed that the AOD from the latest MODIS Terra C6.0 deep blue (DB) 30km×30km and CALIPSO ver. 4.10 (overpass within ~100km distance) are in a very good agreement (R≥0.9) with that from coincident AERONET measurements averaged over the span of ±30min. About 77% of the AOD retrieved using MODIS and ~87% from CALIPSO were found to be within the expected error (EE) limits. The AOD comparison between MODIS Terra C6.0DB and CALIPSO ver. 4.10, suggested their synergic use for aerosol characterization over Himalayas. In comparison to the ver. 3, CALIPSO ver. 4.10 is found to have undergone substantial changes, and their long term inter-comparison in the grid 28.86°-29.86° N and 78.96°–79.96° E revealed that their vertical feature and aerosol sub-types are in agreement of ~94.6% and ~68.6%, respectively. Utilizing the AOD retrievals from AERONET and MODIS collections, the iteratively computed LR for three LiDAR systems was found to be lower (<16) during winter and higher (>43) during summer. Study on the BL height estimations suggested that the wavelet covariance transform (WCT) method for CALIPSO could be the best choice as compared to the threshold method, and complements well with the specific humidity gradient method used with the radiosonde observation. Case studies on the continental transport of smoke plumes emanating from crop-residue burning in post-monsoon, and long range transport of aerosols and dust over the region in summer are also discussed using the collocated measurements from ground-based AERONET and LiDAR, in conjunction with MODIS, CALIPSO, reanalysis data and trajectory modeling.
•Evaluation of the most recent versions of satellite products.•Excellent performance of MODIS Terra C6.0DB and CALIPSO ver. 4.10.•Diverse utilization of satellite aerosol retrievals over complex terrain.•LiDAR Ratio computation and Boundary layer height estimation.•Himalayan region receives dust and continental pollutants from distant regions.
Biocatalytic potential of microorganisms have been employed for centuries to produce bread, wine, vinegar and other common products without understanding the biochemical basis of their ingredients. ...Microbial enzymes have gained interest for their widespread uses in industries and medicine owing to their stability, catalytic activity, and ease of production and optimization than plant and animal enzymes. The use of enzymes in various industries (e.g., food, agriculture, chemicals, and pharmaceuticals) is increasing rapidly due to reduced processing time, low energy input, cost effectiveness, nontoxic and eco-friendly characteristics. Microbial enzymes are capable of degrading toxic chemical compounds of industrial and domestic wastes (phenolic compounds, nitriles, amines etc.) either via degradation or conversion. Here in this review, we highlight and discuss current technical and scientific involvement of microorganisms in enzyme production and their present status in worldwide enzyme market.
Graphical abstract
The nature and sources of ionic species were studied in the monsoon rainwater collected from two monuments of the sixteenth–seventeenth century CE in the Yamuna River basin from 2016 to 2018. The ...results showed the acidic pH of the rainwater with high dissolved SO
4
−2
and NO
3
−
, and soil-derived components (Ca
+2
, Mg
+2
, and K
+
). The anionic (SO
4
−2
, NO
3
−
, Cl
−
, F
−
, and HCO
3
−
) and cationic (Ca
+2
, Mg
+2
, K
+
, NH
4
+
, and Na
+
) concentrations showed regional differences in yearly contribution mainly from the fossil fuel combustion, soil dust, and farm residue burning. The rainwater analysis showed low dissolved ions at SCTK (Sheikh Chilli’s Tomb, Kurukshetra) compared to KBMP (Kabuli Bagh Mosque, Panipat). The mean concentration of SO
4
−2
was 1.5 times higher than the NO
3
−
apportioning the sulfate as a dominant acidifying constituent in rainwater. Pearson’s correlation and principal component analysis (PCA) showed terrestrial and marine origins of dissolved ions in the rainwater. The Na-normalized molar ratios and the analysis of sea salt and non-sea salt fractions indicate the dominance of non-marine contributions in the precipitation. Based on neutralization factors, cations showed neutralization of rainwater acidity as follows: NF
Ca
+2
> NF
Mg
+2
> NF
NH4
+
> NF
K
+
. The potential index showed the dominance of the neutralization potential (NP) on acidic potential (AP) at both locations.
Aerosol distribution at global and regional scales is one of the crucial parameters for climate change assessment. The study presents global spatio-temporal variations in aerosol optical depth (AOD) ...retrieved by Moderate Resolution Imaging Spectroradiometer (MODIS) and Multiangle Imaging Spectroradiometer (MISR) sensors at spatial resolutions of 1°×1° and 0.5°×0.5° respectively. Spatial correlations between MODIS and MISR AOD are reported on annual scale. The entire globe is divided into six sub-regions, i.e., North-West, North, North-East, South-West, South and South-East. The annual and seasonal mean AOD variations are obtained by analyzing Level 3 monthly datasets for the period 2001–2014. Relative changes (%) in AOD between the first and last seven years (i.e. 2001–2007 and 2008–2014 respectively) are discussed at annual and seasonal levels. AOD trends are calculated using the weighted least squares regression approach and weights are assigned to the AOD values corresponding to the expected errors. Statistically significant trends are reported at 95% confidence level. The results inferred from both the sensors are found to be in quite acceptable agreement. Increasing trends are found in the economically growing parts of Asian landmass and the surrounding oceanic regions, especially Arabian Sea and Bay of Bengal. On the other hand, decreasing trends are observed over parts of Europe, South America and North America. The study also focuses on examining the AOD trends over the ten most populous nations of the world. In terms of aerosol loadings, Bangladesh, Pakistan and Nigeria turned out to be the most polluted amongst the most populous countries. Significantly increasing trends in AOD are reported over the Indian subcontinent.
•Spatio-temporal variation of AOD, changes and trends are reported.•Decreasing trends of AOD are for North America, South America and Europe.•Increasing AOD trends are for Arabian Peninsula and surrounding landmass.•Bangladesh, Pakistan, Nigeria and India are amongst heavily polluted countries.
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