Invasion status of Florida bass Micropterus floridanus (Lesueur, 1822) in South Africa

Largemouth bass Micropterus salmoides are a popular North American angling species that was introduced into South Africa in 1928. To enhance the largemouth bass fisheries, Florida bass Micropterus floridanus were introduced into KwaZulu Natal, South Africa, in 1980. Knowledge on the status of M. floridanus in South Africa is required, because it lives longer and reaches larger sizes than M. salmoides, which may result in heightened impacts on native biota. Because M. floridanus are morphologically similar, but genetically distinct from M. salmoides, the distribution of this species was assessed by genetically screening 185 Micropterus sp. individuals sampled from 20 localities across South Africa using the mitochondrial ND2 gene. Individuals with mitochondrial DNA matching M. salmoides were recovered from 16 localities, whereas M. floridanus mitochondrial DNA was recovered from 13 localities. At nine localities (45%), the mitochondrial DNA of both species was detected. These results demonstrate M. floridanus dispersal to multiple sites across South Africa.     

Suitability of stratagene reference RNA for analysis of lymphoid tissues

We evaluated a lymphoid RNA standard prepared in our laboratory for spotted microarrays against the Universal Human Reference standard from Stratagene. Our goal was to determine if the Stratagene standard, which contains only two lymphoid cell lines out of a pool of 10 human cancer cell lines, had acceptable gene coverage to serve as a comprehensive standard for gene expression profiling of lymphoid tissues. Our lymphoid standard was prepared from thymus, spleen, tonsil, and cell lines representing immature B cells, plasma cells, and natural killer (NK) cells, thus covering the entire spectrum of lymphoid cells and most stromal elements present in specialized lymphoid tissues. The two standards were co-hybridized on oligonucleotide microarrays containing 17,260 genes, and both had fluorescence intensities above background for approximately 85% of the genes. Despite the limited representation of lymphoid cells in the Stratagene standard, only 4.2% genes exhibited expression differences greater than 2-fold including only 0.35% with differences greater than 4-fold. Although the lymphoid standard reflected a more comprehensive representation of immune system-associated genes, the Stratagene standard has the advantage of being commercially available, enabling easier comparison across laboratories and allowing comparative studies across a long period of time.     

Termites Improve the Horizontal Movement of Carbonized Particles: A Step towards Sustainable Utilization of Biochar

Soil amendments containing carbonized materials increase the soil carbon reservoir, influence plant productivity, and, ultimately, help to clean the environment. There is data on the effect of such additions on soil physicochemical properties or plant growth, but few studies have focused on how these carbonized materials are distributed by termite species in the soil ecosystem. It is the first comprehensive study of the transportation of biochar (BC) by termite species under tropical environmental conditions in Pakistan. The present study was carried out to test the hypothesis that if termite species I) were involved in the distribution of biochar particles II) if yes, then how far these particles were transported during the study period (10 days) and III) check their preference between the enriched BC (EBC) and non-enriched BC. BC was enriched with the cattle slurry after its pyrolysis in the study. The results showed that EBC particles were significantly more widely distributed than non-enriched BC particles, but both types of BC were transported more than 4 cm (ring 4) within 10 days (at the end of the experiment). The current study also revealed that EBC was easily attached to the setae, cuticle, and legs of termites, implying that it could potentially be transported over a greater distance. Furthermore, transportation of EBC over larger distances indicated a potential preference of termite species between the EBC and BC particles. During the study, however, the preference among the termite species was also observed. Under the prevailing study conditions, the Coptotermes heimi and Heteroterme indicola species transported the EBC further than Microtermes obesi and Odontotermes obesus. These findings revealed that transportation preferences were observed among the four termite species. In conclusion, the current study found that termites were involved in the distribution of BC particles, with a preference for EBC and that these have the potential to transport BC particles more than 4 cm within 10 days. Furthermore, two species Coptotermes heimi and Heteroterme indicola may be more suitable candidates for EBC transpiration in Pakistani soils. It was necessary to conduct additional research into the effect of temperature on the transportation process.     

Brain slice stimulation using a microfluidic network and standard perfusion chamber

We have demonstrated the fabrication of a two-level microfluidic device that can be easily integrated with existing electrophysiology setups. The two-level microfluidic device is fabricated using a two-step standard negative resist lithography process. The first level contains microchannels with inlet and outlet ports at each end. The second level contains microscale circular holes located midway of the channel length and centered along with channel width. Passive pumping method is used to pump fluids from the inlet port to the outlet port. The microfluidic device is integrated with off-the-shelf perfusion chambers and allows seamless integration with the electrophysiology setup. The fluids introduced at the inlet ports flow through the microchannels towards the outlet ports and also escape through the circular openings located on top of the microchannels into the bath of the perfusion. Thus the bottom surface of the brain slice placed in the perfusion chamber bath and above the microfluidic device can be exposed with different neurotransmitters. The microscale thickness of the microfluidic device and the transparent nature of the materials [glass coverslip and PDMS (polydimethylsiloxane)] used to make the microfluidic device allow microscopy of the brain slice. The microfluidic device allows modulation (both spatial and temporal) of the chemical stimuli introduced to the brain slice microenvironments.     

Possible role of eclosion rhythm in mediating the effects of light-dark environments on pre-adult development in <Emphasis Type="Italic">Drosophila melanogaster</Emphasis>

Background  

In insects, circadian clocks have been implicated in affecting life history traits such as pre-adult development time and adult lifespan. Studies on the period (per) mutants of Drosophila melanogaster, and laboratory-selected lines of Bactrocera cucurbitae suggested a close link between circadian clocks and development time. There is a possibility of clock genes having pleiotropic effects on clock period and pre-adult development time. In order to avoid such pleiotropic effects we have used wild type flies of same genotype under environments of different periodicities, which phenotypically either speeded up or slowed down the eclosion clock of D. melanogaster.     

A Novel Multifunctional Crosslinking PVA/CMCS Hydrogel Containing Cyclic Peptide Actinomycin X2 and PA@Fe with Excellent Antibacterial and Commendable Mechanical Properties

Bacterial infected environments and resulting bacterial infections have been threatening the human health globally. Due to increased bacterial resistance caused by improper and excessive use of antibiotics, antibacterial biomaterials are being developed as alternatives to antibiotics in some cases. Herein, an advanced multifunctional hydrogel with excellent antibacterial properties, enhanced mechanical properties, biocompatibility and self-healing performance, was designed through freezing-thawing method. This hydrogel network is composed of polyvinyl alcohol (PVA), carboxymethyl chitosan (CMCS), protocatechualdehyde (PA), ferric iron (Fe) and an antimicrobial cyclic peptide actinomycin X2 (Ac.X2). The double dynamic bonds among protocatechualdehyde (PA), ferric iron (Fe) and carboxymethyl chitosan containing coordinate bond (catechol-Fe) as well as dynamic Schiff base bonds and hydrogen bonds endowed the hydrogel with enhanced mechanical properties. Successful formation of hydrogel was confirmed through ATR-IR and XRD, and structural evaluation through SEM analysis, whereas mechanical properties were tested with electromechanical universal testing machine. The resulting PVA/CMCS/Ac.X2/PA@Fe (PCXPA) hydrogel has favorable biocompatibility and excellent broad-spectrum antimicrobial activity against both S. aureus (95.3 %) and E. coli (90.2 %) compared with free-soluble Ac.X2, which exhibited subpar performance against E. coli reported in our previous studies. This work provides a new insight on preparing multifunctional hydrogels containing antimicrobial peptides as antibacterial material.     

Synthesis and DNA‐binding study of imidazole linked thiazolidinone derivatives

A novel series of imidazole‐linked thiazolidinone hybrid molecules were designed and synthesized through a feasible synthetic protocol. The molecules were characterized with Fourier transform infrared (FT‐IR), ¹H nuclear magnetic resonance (NMR), ¹³C NMR and high‐resolution mass spectrometry (HRMS) techniques. In vitro susceptibility tests against Gram‐positive (S. aureus and B. subtilis ) and Gram‐negative bacteria (E. coli and P. aeruginosa ) gave highly promising results. The most active molecule (3e) gave a minimal inhibitory concentration (MIC) value of 3.125 μg/mL which is on par with the reference drug streptomycin. Structure–activity relationships revealed activity enhancement by nitro and chloro groups when they occupied meta position of the arylidene ring in 2‐((3‐(imidazol‐1‐yl)propyl)amino)‐5‐benzylidenethiazolidin‐4‐ones. DNA‐binding study of the most potent molecule 3e with salmon milt DNA (sm‐DNA) under simulated physiological pH was probed with UV–visible absorption, fluorescence quenching, gel electrophoresis and molecular docking techniques. These studies established that compound 3e has a strong affinity towards DNA and binds at DNA minor groove with a binding constant (K_b) 0.18 × 10² L mol^?1. Molecular docking simulations predicted strong affinity of 3e towards DNA with a binding affinity (ΔG) ‐8.5 kcal/mol. Van der Waals forces, hydrogen bonding and hydrophobic interactions were predicted as the main forces of interaction. The molecule 3e exhibited specific affinity towards adenine–thiamine base pairs. Copyright © 2016 John Wiley & Sons, Ltd.     

Structures of synthetic nanobody–SARS-CoV-2 receptor-binding domain complexes reveal distinct sites of interaction

Combating the worldwide spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the emergence of new variants demands understanding of the structural basis of the interaction of antibodies with the SARS-CoV-2 receptor-binding domain (RBD). Here, we report five X-ray crystal structures of sybodies (synthetic nanobodies) including those of binary and ternary complexes of Sb16–RBD, Sb45–RBD, Sb14–RBD–Sb68, and Sb45–RBD–Sb68, as well as unliganded Sb16. These structures reveal that Sb14, Sb16, and Sb45 bind the RBD at the angiotensin-converting enzyme 2 interface and that the Sb16 interaction is accompanied by a large conformational adjustment of complementarity-determining region 2. In contrast, Sb68 interacts at the periphery of the SARS-CoV-2 RBD–angiotensin-converting enzyme 2 interface. We also determined cryo-EM structures of Sb45 bound to the SARS-CoV-2 spike protein. Superposition of the X-ray structures of sybodies onto the trimeric spike protein cryo-EM map indicates that some sybodies may bind in both “up” and “down” configurations, but others may not. Differences in sybody recognition of several recently identified RBD variants are explained by these structures.     

Prevalence of Neospora caninum antibodies in sheep and goats in Pakistan

The purpose of the present study was to obtain seroepidemiological information on the Neospora caninum infection status of sheep and goats in different areas of Punjab Province and Azad Kashmir (Pakistan). A cross-sectional study, with the use of a competitive ELISA, showed an overall 27.7% (35 of 128) (95% confidence interval [CI] ± 7.7%) and 8.6% (13 of 142) (95% CI ± 4.6%) seroprevalence of N. caninum antibodies in sheep and goats, respectively. The difference in seroprevalence between sheep and goat populations was statistically significant (P < 0.05). The highest prevalence (37.4% ± 13.2%) was recorded in the tailless breed of sheep.