Can biofuels finally take center stage?

Today, ethanol and biodiesel are predominantly produced from corn kernels, sugarcane or soybean oil. But researchers and investors are increasingly upbeat about another biofuel feedstock, lignocellulose--the most abundant biological material on earth.     

Microalgae and biofuels: a promising partnership?

Microalgae have much higher lipid yields than those of agricultural oleaginosous crops, and they do not compromise arable land. Despite this, current microalga-based processes suffer from several constraints pertaining to the biocatalyst and the bioreactor, which hamper technologically and economically feasible scale-up. Here, we briefly review recent active research and development efforts worldwide, and discuss the most relevant shortcomings of microalgal biofuels. This review goes one step further relative to related studies, because it tackles otherwise scarcely mentioned issues - for example, heterotrophic versus autotrophic metabolism, alkane versus glyceride synthesis, conduction versus bubbling of CO(2), and excretion versus accumulation of lipids. Besides promising solutions that have been hypothesized and arise from multidisciplinary approaches, we also consider less conventional ones. Microalgae and biofuels hold indeed a promising partnership, but a fully competitive technology is not expected to be available before the end of this decade, because the need for one order of magnitude increase in productivity requires development of novel apparatuses and transformed cells.     

Steps towards ‘drop-in’ biofuels: focusing on metabolic pathways

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Biofuels are dead: long live biofuels(?) – Part one

Beleaguered by criticisms, and abused by politicians for ecological target-setting, biofuels are in their darkest hour. But their bringing to trial should remind us - yet again - of something else: the highly questionable sustainability of most of modern agriculture. Is this the end of biofuels? Probably not, but it is certainly the end of a cheap solution to the problem of sustainable portable fuels. Part one of this two-part article focuses on the political and agricultural dimensions of the topic.     

Biofuels are dead: long live biofuels(?) – part two

Whilst obsessing over the policy catastrophe surrounding biofuels, we could easily lose sight of the prospects for science and technology to increase the sustainability of biofuel production by orders of magnitude. Part two of this feature examines the research and development of more sustainable biofuels.     

The time aspect of bioenergy – climate impacts of solid biofuels due to carbon dynamics

The climate impacts from bioenergy involve an important time aspect. Using forest residues for energy may result in high initial emissions, but net emissions are reduced over time since, if the residues were left on the ground, they would decompose and release CO₂ to the atmosphere. This article investigates the climate impacts from bioenergy with special focus on the time aspects. More specifically, we analyze the climate impacts of forest residues and stumps where combustion related emissions are compensated by avoided emissions from leaving them on the ground to decompose. These biofuels are compared with fossil gas and coal. Net emissions are defined as emissions from utilizing the fuel minus emissions from a reference case of no utilization. Climate impacts are estimated using the measures radiative forcing and global average surface temperature. We find that the climate impacts from using forest residues and stumps depend on the decomposition rates and the time perspective over which the analysis is done. Over a 100 year perspective, branches and tops have lower climate impacts than stumps which in turn have lower impacts than fossil gas and coal. Over a 20 year time perspective, branches and tops have lower climate impacts than all other fuels but the relative difference is smaller. However, stumps have slightly higher climate impacts over 20 years than fossil gas but lower impacts than coal. Regarding metrics for climate impacts, over shorter time scales, approximately 30 years or less, radiative forcing overestimates the climate impacts compared with impacts expressed by global surface temperature change, which is due to the inertia of the climate system. We also find that establishing willow on earlier crop land may reduce atmospheric CO₂, provided new land is available. However, these results are inconclusive since we haven't considered the effects of producing the agricultural crops elsewhere.     

Large-scale production of diesel-like biofuels – process design as an inherent part of microorganism development

Industrial biotechnology is playing an important role in the transition to a bio-based economy. Currently, however, industrial implementation is still modest, despite the advances made in microorganism development. Given that the fuels and commodity chemicals sectors are characterized by tight economic margins, we propose to address overall process design and efficiency at the start of bioprocess development. While current microorganism development is targeted at product formation and product yield, addressing process design at the start of bioprocess development means that microorganism selection can also be extended to other critical targets for process technology and process scale implementation, such as enhancing cell separation or increasing cell robustness at operating conditions that favor the overall process. In this paper we follow this approach for the microbial production of diesel-like biofuels. We review current microbial routes with both oleaginous and engineered microorganisms. For the routes leading to extracellular production, we identify the process conditions for large scale operation. The process conditions identified are finally translated to microorganism development targets. We show that microorganism development should be directed at anaerobic production, increasing robustness at extreme process conditions and tailoring cell surface properties. All the same time, novel process configurations integrating fermentation and product recovery, cell reuse and low-cost technologies for product separation are mandatory. This review provides a state-of-the-art summary of the latest challenges in large-scale production of diesel-like biofuels.     

Where does heteroclisis come from? Evidence from Romanian dialects

This study examines some cases of heteroclisis in the history of Romanian dialects, and concludes that the data call for a reconsideration of Stump’s distinction (Language 82:279–322, 2006) between ‘cloven’ heteroclisis, where the intraparadigmatic ‘split’ is aligned with some morphosyntactic feature distinction, and ‘fractured’ heteroclisis, where this is not the case and the pattern of heteroclisis is purely morphological. Stump’s account creates the impression that the ‘cloven’ variety is universally predominant, and that the ‘fractured’ variety tends to follow very closely the available ‘cloven’ patterns of the language. I shall suggest, instead, that the ‘fractured-only’ situation may in fact underlie heteroclisis cross-linguistically, the phenomenon being in general sensitive not directly to morphosyntactic content, but rather to characteristic, and often purely ‘morphomic’, patterns of stem-allomorphy. Research for this paper was undertaken as part of the Arts and Humantities Research Council-funded project Autonomous Morphology in Diachrony: comparative evidence from the Romance Languages, currently being conducted at Oxford University.     

Message from the Editor-in-Chief

The current issue of Acta Biochimica et Biophysica Sinica (ABBS) has turned a new page of this journal since its publication forty five years ago. It is perhaps an appropriate time to share with our readers about the evolution of this journal, the changes that have taken place, and the future that we are looking forward to. ABBS was first established in 1958 with Professor Ying-Lai WANG as the founding Editor-in-Chief and has been ever since an     

What Do We Learn from Spheroid Culture Systems? Insights from Tumorspheres Derived from Primary Colon Cancer Tissue

Due to their self-renewal and tumorigenic properties, tumor-initiating cells (TICs) have been hypothesized to be important targets for colorectal cancer (CRC). However the study of TICs is hampered by the fact that the identification and culturing of TICs is still a subject of extensive debate. Floating three-dimensional spheroid cultures (SC) that grow in serum-free medium supplemented with growth factors are supposed to be enriched in TICs. We generated SC from fresh clinical tumor specimens and compared them to SC isolated from CRC cell-lines as well as to adherent differentiated counterparts. Patient-derived SC display self-renewal capacity and can induce serial transplantable tumors in immuno-deficient mice, which phenotypically resemble the tumor of origin. In addition, the original tumor tissue and established SC retain several similar CRC-relevant mutations. Primary SC express key stemness proteins such as SOX2, OCT4, NANOG and LGR5 and importantly show increased chemoresistance ability compared to their adherent differentiated counterparts and to cell line-derived SC. Strikingly, cells derived from spheroid or adherent differentiating culture conditions displayed similar self-renewal capacity and equally formed tumors in immune-deficient mice, suggesting that self-renewal and tumor-initiation capacity of TICs is not restricted to phenotypically immature spheroid cells, which we describe to be highly plastic and able to reacquire stem-cell traits even after long differentiation processes. Finally, we identified two genes among a sphere gene expression signature that predict disease relapse in CRC patients. Here we propose that SC derived from fresh patient tumor tissue present interesting phenotypic features that may have clinical relevance for chemoresistance and disease relapse and therefore represent a valuable tool to test for new CRC-therapies that overcome drug resistance.     

Production of steviol from steviol glucosides using β-glycosidase from Sulfolobus solfataricus

Steviol is a diterpene isolated from the plant Stevia rebaudiana that has a potential role as an antihyperglycemic agent by stimulating insulin secretion from pancreatic beta cells and also has significant potential to diminish the renal clearance of anionic drugs and their metabolites. In this study, the lacS gene, which encodes a thermostable β-glycosidase (SSbgly) enzyme from the extremely thermoacidophillic archaeon Sulfolobus solfataricus, was cloned and expressed in E. coli Rossetta BL21(DE3)pLyS using lactose as an inducer. Through fermentation, SSbgly was expressed as a 61 kDa protein with activity of 24.3 U/mg and the OD₆₀₀ of 23 was reached after 18 h induction with 10 mM lactose. Purified protein was obtained by Ni-Sepharose chromatography with a yield of 92.3%. SSbgly hydrolyzed steviol glycosides to produce steviol with a yield of 99.2%. The optimum conditions for steviol production were 50 U/ml SSbgly and 90 mg/ml Ste at 75 °C as determined by the response surface method.     

Skill Memory Escaping from Distraction by Sleep��Evidence from Dual-Task Performance

Background

Sleep facilitates off-line consolidation of memories, as shown for learning of motor skills in the absence of concomitant distractors. We often perform complex tasks focusing our attention mostly on one single part of them. However, we are equally able to skillfully perform other concurrent tasks. One may even improve performance on disregarded parts of complex tasks, which were learned implicitly. In the present study we investigated the role of sleep in the off-line consolidation of procedural skills when attention is diverted from the procedural task because of interference from a concurrent task.

Methodology/Principal Findings

We used a dual-task paradigm containing (i) procedural serial reaction time task (SRTT), which was labeled as subordinate and unimportant and (ii) declarative word-pair association task (WPAT), performed concomitantly. The WPAT served as a masked distractor to SRTT and was strongly reinforced by the instructions. One experimental and three control groups were tested. The experimental group was re-tested after two nights of sleep (sleep group, SG). The first control group had sleep deprivation on the first post-learning night (nighttime-awake group, NA), the second control group was tested in the morning and then re-tested after 12-hours (daytime-awake group, DA); the third one had the same assignments as DA but with a subsequent, instead of a concomitant, WPAT (daytime-awake-subsequent-WPAT group, DAs). We found SRTT performance gains in SG but not in NA and DA groups. Furthermore, SG reached similar learning gains in SRTT as the DAs group, which gained in SRTT performance because of post-training interference from the declarative task.

Conclusions/Significance

The results demonstrate that sleep allows off-line consolidation, which is resistant to deteriorating effects of a reinforced distractor on the implicit procedural learning and allowing for gains which are consistent with those produced when inhibited declarative memories of SRTT do not compete with procedural ones.     

Psychrophilic α-amylase from Aeromonas veronii NS07 isolated from farm soils

Among 120 isolates examined in this study, three isolates were selected for amylase production on starch agar plates following incubation at 10 °C. Identification by 16SrRNA on selected bacterium disclosed the highest similarity for protean regions of this gene as Aeromonas veronii NS07. A 63 kDa psychrophilic amylase enzyme from NS07 strain was purified by two-steps chromatography. The enzyme had the highest specific activity at pH 4 and was active at the range of temperatures from 0 to 50 °C, although the optimum temperature for enzyme activity was found at 10 °C. Analysis of the N-terminal amino acid sequencing disclosed 20 amino acids from purified amylase which had no similarity with other known α-amylases, indicating that the presented enzyme was novel. Amylase activity was enhanced in relation to optimum activity with the presence of sodium sulphate (161%), MnCl₂ (298%), CaCl₂ (175%), FeCl₂ (182%), MgCl₂ (237%), ZnCl₂ (169%), NiCl₂ (139%), NaCl (158%), each at 5 mM, while EDTA, phenylmethane sulphonylfluoride (PMSF) (3 mM), urea (8 M) and SDS (1%) inhibited the enzyme up to 5%, 2%, 80% and 18%, respectively. NS07 strain seems to be suitable as biocatalyst for practical use in liquefaction of starch at low temperatures, detergent and textile industries.     

Synthesis of cello-oligosaccharides from cellobiose with β-glucosidase II from Aspergillus niger

An extracellular -glucosidase II of Aspergillus niger catalysed the synthesis of cello-oligosaccharides from cellobiose (15%, w/v). The enzyme was stable at and below 4°C for at least 230 days and also stable at 30°C with the presence of 2.0% (w/v) cellobiose. The maximum yield of cello-oligosaccharides was about 30% (mol/mol), based on cellobiose (130 mg/mL) consumed. © Rapid Science Ltd. 1998     

Can phenotypic rescue from harvest refuges buffer wild sheep from selective hunting?

Human harvests can unwittingly drive evolution on morphology and life history, and these selective effects may be detrimental to the management of natural resources. Although theory suggests that harvest refuges, as sources of unselected animals, could buffer the effects of human exploitation on wild populations, few studies have assessed their efficiency. We analyzed records from >7000 trophy bighorn rams (Ovis canadensis) harvested in Alberta, Canada, between 1974 and 2011 to investigate if the movement of rams from refuges toward harvested areas reduced the effects of selective harvesting on horn size through phenotypic rescue. Rams taken near refuges had horns on average about 3% longer than rams shot far from refuges and were slightly older, suggesting migration from refuges into hunted areas. Rams from areas adjacent to and far from harvest refuges, however, showed similar declines in horn length and increases in age at harvest over time, indicating a decreasing rate of horn growth. Our study suggests that the influx of rams from refuges is not sufficient to mitigate the selective effects of sheep trophy harvest. Instead, we suggest that selective hunting of highly mobile animals may affect the genetic structure of populations that spend part of the year inside protected areas.     

Glycopeptides from human κ-chains

Glycopeptides have been isolated from tryptic digests of kappa-type light chains separated from human myeloma proteins obtained from the serum of two patients, Car and Rai. The glycopeptides are derived from the variable region of the chain in both cases, but from different sections. On the basis of homology it is deduced that glycopeptide from Car, kappaI type, is derived from position 25-31 whereas that from Rai, kappaII type, is from position 62-77, their sequences being respectively Ala-Ser-Gln-Asn-Ile-Ser and Phe-Ser-Gly-Ser-Gly-Ser-Gly(Thr,Asp)Phe-Thr-Leu-Asx-Ile-Ser-Arg. The significance of the results is discussed in connexion with the nature of the attachment site of carbohydrate to protein.