A comparative study of feeding methods: Effect on the growth,behaviour and biochemical performance of juvenile Beluga sturgeon (Huso huso Linnaeus, 1758)

This study compared the influence of feeding methods on growth parameters of young‐of‐year Beluga sturgeon Huso huso in a 6‐week trial. Fish with an average weight 150.3 ± 0.8 g (±SE) were stocked into nine circular concrete tanks (30 fish per tank) in an open circular system with water temperature of 18.9°C. All fish were fed by three different feeding methods: (a) hand‐fed (HF), (b) continuously available (automated feeder; AF), (c) half of daily feed provided by hand, and another half by automated feeder (combined feeding). For the hand‐feeding method, fish were fed at 09:00, 14:00, 19:00, and 24:00. The entire automatic feeding groups were fed with the same amount of feed. The mean final body weight was the highest in fish fed by AF compared to fish fed by HF. Body weight increase, condition factor, specific growth rate, and feed conversion ratio did not differ among the feeding groups. Fish fed by AF revealed higher swimming activity than the HF group. No significant changes were found in hematocrit, glucose and total protein concentrations among treatments. The results showed less dependence of growth and physiology of Beluga sturgeon on feeding method, but automated‐feeding was shown to be suitable for sturgeon rearing because of further low labour costs in rearing systems.     

Electron transfer in ferredoxin: are tunneling pathways evolutionarily conserved?

A theoretical study of electron transfer (ET) pathways in a recently crystallized Clostridium acidurici ferredoxin is reported. The electronic structure of the protein complex is treated at the semiempirical extended Hückel level, and the tunneling pathways are calculated with the rigorous quantum mechanical method of tunneling currents. The model predicts two pathways between the two [4Fe-4S] cubanes: a strong one running directly from Cys(14) to Cys(43) and a weaker one from Cys(14) via Ile(23) to Cys(18), whereas other amino acids do not play a significant role in the electron tunneling. The cysteine ligands conduct almost all of the current when Ile(23) is mutated to valine in silico, so that there is no appreciable change in the ET rate. The calculated value of the transfer matrix element is consistent with the experimentally determined rate of transfer. Results of the sequence analysis performed on this ferredoxin reveal that Ile(23) is a highly variable amino acid compared with the cubane-ligating cysteine amino acids, even though Ile(23) lies directly between the donor and acceptor complexes. We further argue that the homologous proteins with a [3Fe-4S] cofactor, which does not have one of the four cysteine ligands, use the same tunneling pathways as those in this ferredoxin, on the basis of the high homology as well as the absolute conservation of Cys(14) and Cys(43) which serve as the main tunneling conduit. Our results explain why mutation of amino acids around and between the donor and acceptor cubane clusters, including that of Ile(23), does not appreciably affect the rate of transfer and add support to the proposal that there exist evolutionarily conserved electron tunneling pathways in biological ET reactions.     

Land barriers and open oceans: effects on gene diversity and population structure in Avicennia germinans L. (Avicenniaceae)

Avicennia germinans L. is a widespread mangrove species occupying the west coast of Africa and the Atlantic and Pacific coasts of the Americas from the Bahamas to Brazil and Baja California to Peru. An amplified fragment length polymorphism (AFLP) molecular analysis was carried out to assess genetic architecture within this species and to evaluate the effects of the Atlantic Ocean and the Central American Isthmus (CAI) on population and regional genetic diversity and differentiation. In total, 349 polymorphic AFLP fragments were identified among 144 individuals from 14 populations from the east Atlantic, west Atlantic and east Pacific. Levels of genetic diversity varied considerably among populations, but were generally higher in populations from the east Atlantic. Regional differentiation between the Pacific coast and Atlantic populations was greater than between east and west Atlantic populations, suggesting that the CAI has had an important influence on population genetic structure in this species. The lower level of divergence of east Atlantic from west Atlantic populations suggests some dispersal across the Atlantic Ocean, although migration rates are probably low; Nm from GST equal to 0.41 and accumulation of private and rare alleles in the east Atlantic. Population differentiation did not appear to follow an isolation by distance model and has probably resulted from complex patterns of population bottlenecks, and founder events due to landscape changes during the Pleistocene, particularly in the west Atlantic. The molecular data provide no support for the treatment of east Atlantic populations as a separate species A. africana.     

Linum persicum: Lignans and placement in Linaceae†

Aryltetralin lignans (podophyllotoxin type) are the main lignan constituents of species belonging to Linum section Syllinum (Linaceae). Linum persicum, a perennial plant native to Iran closely related to L. album, has not yet been studied. To evaluate the lignan profile, fresh plants of L. persicumwere collected and divided into different parts and analyzed by HPLC. The main aryltetralin lignans found inL. persicumplant parts, callus and cell cultures were podophyllotoxin (PTOX), 6-methoxypodophyllotoxin (MPTOX) and - and -peltatin. Furthermore, the systematic relationship between L. persicum and other Linum species are discussed in the light of morphological and phytochemical aspects. Abbreviations: MPTOX – 6-methoxypodophyllotoxin; PTOX – podophyllotoxin; DOP – deoxypodophyllotoxin.     

Essential oil of one of the Iranian skullcaps

The hydro-distilled essential oil from dried aerial parts of one of widespread Iranian skullcaps, Scutellaria pinnatifida A. Hamilt. sap. alpina (Bornm.) Rech. grown in Khorassan province was analyzed by GC and GC/MS. Thirty components were characterized ing 93.8% of the total components detected. The major components of the oil were germacrene-D (39.7%) and beta-caryophyllene (15.0%).     

In Silico Analysis of Acinetobacter baumannii Phospholipase D as a Subunit Vaccine Candidate

The rate of human health care-associated infections caused by Acinetobacter baumannii has increased significantly in recent years for its remarkable resistance to desiccation and most antibiotics. Phospholipases, capable of destroying a phospholipid substrate, are heterologous group of enzymes which are believed to be the bacterial virulence determinants. There is a need for in silico studies to identify potential vaccine candidates. A. baumannii phospholipase D (PLD) role has been proved in increasing organism’s resistance to human serum, destruction of host epithelial cell and pathogenesis in murine model. In this in silico study high potentials of A. baumannii PLD in elicitation of humoral and cellular immunities were elucidated. Thermal stability, long half-life, non-similarity to human and gut flora proteome and non-allergenicity were in a list of A. baumannii PLD positive properties. Potential epitopic sequences were also identified that could be used as peptide vaccines against A. baumannii and various other human bacterial pathogens.     

The COP9 signalosome is vital for timely repair of DNA double-strand breaks

The DNA damage response is vigorously activated by DNA double-strand breaks (DSBs). The chief mobilizer of the DSB response is the ATM protein kinase. We discovered that the COP9 signalosome (CSN) is a crucial player in the DSB response and an ATM target. CSN is a protein complex that regulates the activity of cullin ring ubiquitin ligase (CRL) complexes by removing the ubiquitin-like protein, NEDD8, from their cullin scaffold. We find that the CSN is physically recruited to DSB sites in a neddylation-dependent manner, and is required for timely repair of DSBs, affecting the balance between the two major DSB repair pathways—nonhomologous end-joining and homologous recombination repair (HRR). The CSN is essential for the processivity of deep end-resection—the initial step in HRR. Cullin 4a (CUL4A) is recruited to DSB sites in a CSN- and neddylation-dependent manner, suggesting that CSN partners with CRL4 in this pathway. Furthermore, we found that ATM-mediated phosphorylation of CSN subunit 3 on S410 is critical for proper DSB repair, and that loss of this phosphorylation site alone is sufficient to cause a DDR deficiency phenotype in the mouse. This novel branch of the DSB response thus significantly affects genome stability.