Advective hydrogel membrane chromatography for monoclonal antibody purification in bioprocessing

Protein A chromatography is widely employed for the capture and purification of monoclonal antibodies (mAbs). Because of the high cost of protein A resins, there is a significant economic driving force to seek new downstream processing strategies. Membrane chromatography has emerged as a promising alternative to conventional resin based column chromatography. However, to date, the application has been limited to mostly ion exchange flow through (FT) mode. Recently, significant advances in Natrix hydrogel membrane has resulted in increased dynamic binding capacities for proteins, which makes membrane chromatography much more attractive for bind/elute operations. The dominantly advective mass transport property of the hydrogel membrane has also enabled Natrix membrane to be run at faster volumetric flow rates with high dynamic binding capacities. In this work, the potential of using Natrix weak cation exchange membrane as a mAb capture step is assessed. A series of cycle studies was also performed in the pilot scale device (> 30 cycles) with good reproducibility in terms of yield and product purities, suggesting potential for improved manufacturing flexibility and productivity. In addition, anion exchange (AEX) hydrogel membranes were also evaluated with multiple mAb programs in FT mode. Significantly higher binding capacity for impurities (support mAb loads up to 10Kg/L) and 40X faster processing speed were observed compared with traditional AEX column chromatography. A proposed protein A free mAb purification process platform could meet the demand of a downstream purification process with high purity, yield, and throughput. © 2015 American Institute of Chemical Engineers Biotechnol. Prog., 31:974–982, 2015     

The effects of feeding by the rice water weevil, Lissorhoptrus oryzophilus Kuschel, on the growth and yield components of rice, Oryza sativa

Abstract 1 The effects of feeding by larvae of the rice water weevil, Lissorhoptrus oryzophilus Kuschel, on the growth and yield components of rice, Oryza sativa, were evaluated using four varieties of rice, ‘Cocodrie’, ‘Cypress’, ‘Bengal’ and ‘XP1003’, over 2 years. 2 Both adults and larvae of L. oryzophilus feed on rice plants, but it is feeding by the larval stage that causes economic losses. Feeding by L. oryzophilus larvae resulted in extensive damage to root systems. Pruning of root systems resulted in a decrease in tiller number and shoot biomass of rice plants in the vegetative stage of growth. 3 Yield losses were due to a combination of decreases in panicle densities, numbers of grains per panicle, and grain weights. Decreases in panicle densities were a direct result of the reductions in tiller numbers. Reductions in numbers of grains per panicle and grain weights probably resulted from decreases in shoot biomass. 4 Injury by rice water weevil larvae is chronic. The tillering stage of rice suffered the majority of weevil damage, but the growth effects were not manifested until later.     

Plant-mediated interactions between the rice water weevil and fall armyworm in rice

Greenhouse studies were conducted to investigate plant-mediated interactions between an above-ground and a below-ground herbivore when sharing a common host plant, rice (Oryza sativa L). Two common pests of rice were used: the rice water weevil (RWW), Lissorhoptrus oryzophilus Kuschel, as the root herbivore, and the fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith) as the foliage-feeding herbivore. Rice water weevil larval performance was assessed by measuring larval density and average weight in response to different levels of defoliation by FAW larvae. The reciprocal experiment was done to evaluate FAW performance (growth rate) in response to RWW feeding. Severe defoliation by FAW decreased RWW densities by 32% and reduced larval weights by 48% compared to larvae on roots of non-defoliated plants. Effects in the converse experiments were not as strong. FAW growth rates were reduced 9–37% when feeding on rice leaves from plants damaged by RWW compared to larvae feed leaves from the no damage treatment. These reciprocal negative effects show that RWW and FAW are potential competitors when sharing a rice plant. Because RWW and FAW did not interact directly, competition was plant-mediated.     

Variation in the ribosomal internal transcribed spacers and 5.8S rDNA among five species of Acropora (Cnidaria; Scleractinia): patterns of variation consistent with reticulate evolution

The ITS sequences of Acropora spp. are the shortest so far identified in any metazoan and are among the shortest seen in eukaryotes; ITS1 was 70-80 bases, and ITS2 was 100-112 bases. The ITS sequences were also highly variable, but base composition and secondary structure prediction indicate that divergent sequence variants are unlikely to be pseudogenes. The pattern of variation was unusual in several other respects: (1) two distinct ITS2 types were detected in both A. hyacinthus and A. cytherea, species known to hybridize in vitro with high success rates, and a putative intermediate ITS2 form was also detected in A. cytherea; (2) A. valida was found to contain highly (29%) diverged ITS1 variants; and (3) A. longicyathus contained two distinct 5.8S rDNA types. These data are consistent with a reticulate evolutionary history for the genus Acropora.      

The Genetic Structure of Marijuana and Hemp

Despite its cultivation as a source of food, fibre and medicine, and its global status as the most used illicit drug, the genus Cannabis has an inconclusive taxonomic organization and evolutionary history. Drug types of Cannabis (marijuana), which contain high amounts of the psychoactive cannabinoid Δ ⁹-tetrahydrocannabinol (THC), are used for medical purposes and as a recreational drug. Hemp types are grown for the production of seed and fibre, and contain low amounts of THC. Two species or gene pools (C. sativa and C. indica) are widely used in describing the pedigree or appearance of cultivated Cannabis plants. Using 14,031 single-nucleotide polymorphisms (SNPs) genotyped in 81 marijuana and 43 hemp samples, we show that marijuana and hemp are significantly differentiated at a genome-wide level, demonstrating that the distinction between these populations is not limited to genes underlying THC production. We find a moderate correlation between the genetic structure of marijuana strains and their reported C. sativa and C. indica ancestry and show that marijuana strain names often do not reflect a meaningful genetic identity. We also provide evidence that hemp is genetically more similar to C. indica type marijuana than to C. sativa strains.     

Comparative tests of ectoparasite species richness in seabirds

Background  

The diversity of parasites attacking a host varies substantially among different host species. Understanding the factors that explain these patterns of parasite diversity is critical to identifying the ecological principles underlying biodiversity. Seabirds (Charadriiformes, Pelecaniformes and Procellariiformes) and their ectoparasitic lice (Insecta: Phthiraptera) are ideal model groups in which to study correlates of parasite species richness. We evaluated the relative importance of morphological (body size, body weight, wingspan, bill length), life-history (longevity, clutch size), ecological (population size, geographical range) and behavioural (diving versus non-diving) variables as predictors of louse diversity on 413 seabird hosts species. Diversity was measured at the level of louse suborder, genus, and species, and uneven sampling of hosts was controlled for using literature citations as a proxy for sampling effort.     

Tatlockia micdadei (Pittsburgh pneumonia agent) growth kinetics may explain its infrequent isolation from water and the low prevalence of Pittsburgh pneumonia.

Sediment and indigenous microflora taken from water distribution systems has been shown to promote the survival of Legionella pneumophila. The effect of sediment and indigenous microflora on Tatlockia micdadei (Pittsburgh pneumonia agent, PPA) was evaluated by growth curve experiments. Symbiosis between PPA and environmental bacteria was demonstrated by satellitism experiments. Unlike L. pneumophila, the concentration of PPA remained stationary in test tube suspensions containing both microflora and sediment. The difference in the ecology between the two organisms may explain the infrequent environmental recovery of PPA and, ultimately, the epidemiologic differences between Legionnaires disease and Pittsburgh pneumonia.     

Chromosomal gene transfer during conjugation by Staphylococcus aureus is mediated by transposon-facilitated mobilization.

A chromosomal copy of the transposon Tn551 and a copy coresident on a gentamicin-resistant conjugative plasmid of Staphylococcus aureus resulted in the mobilization of chromosomal genes during filter mating. Gene mobilization was recA dependent and was not restricted to any specific region of the chromosome. Both essential and nonessential genes were transferred.