In vitro effect of pulsed 900 MHz GSM radiation on mitochondrial membrane potential and motility of human spermatozoa

Ejaculated, density purified, human spermatozoa were exposed to pulsed 900 MHz GSM mobile phone radiation at two specific absorption rate levels (SAR 2.0 and 5.7 W/kg) and compared with controls over time. Change in sperm mitochondrial membrane potential was analysed using flow cytometry. Sperm motility was determined by computer assisted sperm analysis (CASA). There was no effect of pulsed 900 MHz GSM radiation on mitochondrial membrane potential. This was also the case for all kinematic parameters assessed at a SAR of 2.0 W/kg. However, over time, the two kinematic parameters straight line velocity (VSL) and beat-cross frequency (BCF) were significantly impaired (P < 0.05) after the exposure at SAR 5.7 W/kg and no exposure by time interaction was present. This result should not be ascribed to thermal effects, due to the cooling methods employed in the RF chamber and temperature control within the incubator.     

Collapse of a new living species of giant clam in the Red Sea

Giant clams are among the most spectacular but also the most endangered marine invertebrates. Their large size and easy accessibility has caused overfishing and collapse of the natural stocks in many places and local extinction in some of the species [1, 2]. The diversity of giant clams is extremely low because of reliction in this Tethyan group [3, 4]. The latest additions of living species date back almost two decades [5-7], fixing the number of extant Tridacna at seven species [3]. Here, we report the discovery of a new species of giant clam: Tridacna costata sp. nov. features characteristic shells with pronounced vertical folds, is genetically distinct, and shows an earlier and abbreviated reproduction than its Red Sea congeners. This species represents less than 1% of the present stocks but up to >80% of the fossil shells. The decline in proportion and shell size (20x) indicates overharvesting [8] dating back to the early human occupation of the Red Sea >125,000 years ago [9]. This earliest depletion reported so far of a shallow-water megafaunal invertebrate has important ramifications for human dispersal out of Africa [10]. Its oversight in one of the best-investigated reef provinces [11-13] illustrates the dearth of knowledge on marine biodiversity.     

Primary lung tumour visualised by transthoracic echocardiography

Background

Stroke is the third most common cause of death in the UK and the largest single cause of severe disability. Each year more than 110,000 people in England suffer from a stroke which costs the National Health Service (NHS) over GBP2.8 billion. Thus, it is imperative that patients at risk be screened for underlying carotid artery atherosclerosis.

Aim

To assess the role of carotid ultrasound in different carotid screening programmes.

Methods

A literature overview was carried out by using PubMed search engine, to identify different carotid screening programmes that had used ultrasound scan as a screening tool.

Results

It appears that the carotid ultrasound is an effective method for screening carotid artery disease in community as it effectively predicts the presence of stenosis with high accuracy. There is a need for primary care to recommend high risk patients for regular screening, to reduce stroke and transient ischemic attack (TIA) related morbidity and mortality.

Conclusion

Screening programmes using carotid ultrasonography contribute to public health awareness and promotion which in long term could potentially benefit in disease prevention and essentially promote better standards of healthcare.     

The integrative element pSAM2 from Streptomyces: kinetics and mode of conjugal transfer

pSAM2 is an 11 kb integrative element from Streptomyces ambofaciens that is capable of conjugal transfer. A system based on differential DNA modification by SalI methyltransferase was used to localize pSAM2 in the donor or recipient strain, and thus to determine the various steps associated with transfer. Initiation (i.e. excision and replication of pSAM2 in the donor) occurs a few hours after mating with a recipient strain. pSAM2 replicates in the recipient strain, spreads within the mycelium and then integrates into the chromosome. Transfer generally involves single-stranded DNA. In Streptomyces, only a few genes, such as traSA for pSAM2, are required for conjugal transfer. Using the differential sensitivity to the SalI restriction-modification system of transfers involving single- and double-stranded DNA, we found that pSAM2 was probably transferred to the recipient as double-stranded DNA. This provides the first experimental evidence for the transfer of double-stranded DNA during bacterial conjugation. Thus, TraSA, involved in pSAM2 transfer, and SpoIIIE, which is involved in chromosome partitioning in Bacillus subtilis, display similarities in both sequence and function: both seem to transport double-stranded DNA actively, either from donor to recipient or from mother cell to prespore.     

Effect of essential amino acids on the phosphorylation of a 40S ribosomal protein and protein synthesis in Acanthamoeba castellanii

Reversible and multiple phosphorylation of a 40S ribosomal protein is observed in a variety of eukaryotic cells. In the primitive eukaryote Acanthamoeba, one or three phosphorylated S3 derivatives are observed during growth phase in nondefined nutrient medium (ND cells) or in chemically defined nutrient medium (D cells), respectively. In both cases, stationary phase cells exhibit nonphosphorylated S3; however, transfer of these cells into the respective fresh nutrient media results in a transient accumulation of four phosphorylated S3 derivatives. Transfer of D cells into nutrient medium, deficient in all or any single essential amino acids, leads to reversible inhibition of S3 phosphorylation and growth arrest. The low level of phosphorylated S3 is not simply the consequence of growth arrest, since in cells where growth is arrested differently, the level of phosphorylated S3 can be high. In response to amino acid deficiency, a number of other changes can be observed. These include a 2-3-fold decrease of total protein synthesis, 13 changes in the cellular protein pattern, and specific alterations in the ribosome absorbance profiles and in the distribution of poly-A+ RNA within subribosomal and ribosomal fractions. While the rate of total protein synthesis seems to be associated with the level of phosphorylated S3, the level of the synthesis of at least 10 of the particular proteins can be dissociated from the level of S3 phosphorylation.     

Transformation efficiencies and progeny analysis after varying different parameters of direct gene transfer of Nicotiana tabacum protoplasts

Nicotiana tabacum protoplasts were transformed by polyethylene glycol (PEG)-mediated uptake and electroporation, with circular and linear DNA, and with or without X-ray irradiation. We investigated the influence on the transient expression by these parameters as well as on the frequencies for stable transformation. Plants were regenerated and selfed, and the progenies of the transformed plants were analysed and used to compare the pattern of gene integration by these different variations in transformation methods. The results from the transient expression as judged by glucuronidase (GUS) activity, showed electroporation to give higher and more reproducible results than PEG-mediated uptake. Using linear instead of circular DNA increased the rate of stable transformation about 3 times. Including a mild X-ray treatment gave an increase in the same range. When the inheritance of the transferred trait was investigated, it was found that protoplasts transformed with linear DNA resulted in the highest number of plants with single-copy insertions. Protoplasts transformed with circular DNA showed the highest incidence of losing the trait, while plants in which the transformation included an X-ray treatment, had the highest frequency of multicopy insertion events.     

Risk taking in relation to reproductive investments and future reproductive opportunities: field experiments on nest-guarding common gobies, Pomatoschistus microps

The common goby, Pomatoschistus microps, has parental care,with males building nests and guarding the fertilized eggs untilhatching. We carried out field experiments to estimate the responseof males to predation risk in relation to developmental stageof their brood and time of the season. Artificial nest substrateswere placed in a shallow bay with soft substrate. After thenest had been built and eggs laid in it, a glass jar containinga potential predator (an eelpout, Zoarces viviparus) was placed15 cm from the goby's nest. We subsequently chased the malegoby away from the nest and measured his flight distance andtime until return. This was repeated once a day in May, June,and August. Time away from the nest decreased in the courseof one brood cycle, with a steeper slope in May compared tothe other months, as a result of longer times away from thenest in the beginning of the experiment. Flight distance decreasedslightly over one brood cycle and was longer in June than inMay and August. In another experiment, a male P. microps waspresented to the nest-guarding male, simulating a potentialcompetitor for the nest. Again, we found a decrease in returntime with advancement of the brood cycle, but the fish returnedfaster than when facing a predator, especially in the beginningof the brood cycle. No effect of habituation to the treatmentwas found, but there seemed to be a slight influence of developmentstage of the eggs. Thus, risk taking by nest-guarding male P.microps appears to be influenced by time already spent guardingone particular brood and the prospect for future reproductiveopportunities. [Behav Ecol 1991 ;2:351–359]     

Structural studies around cysteine and cystine residues in the “blue” oxidase fungal laccase B. Similarity in amino acid sequence with ceruloplasmin

Fungal laccase B from Polyporus versicolor is a “blue” oxidase containing four copper ions. It consists of a single polypeptide chain of about 545 amino acid residues. The enzyme has been hydrolyzed with pepsin, pronase and thermolysin, and peptides containing the single sulfhydryl group and one of the disulfide bridges have been isolated and characterized. The results show that there is some similarity in amino acid sequence on both sides of the disulfide bridge indicating an internal homology in the laccase molecule. The structure around the single cysteine residue (Leu-His-Cys-His-Ile-Asx-Phe) differs considerably from the cysteine region in low-molecular-weight “blue” proteins like plastocyanin and azurin which contain a single copper ion. However, it shows a pronounced similarity with the sequence around a cysteine residue in human ceruloplasmin suggesting that this structure has an important role in the multi-copper oxidases that is absent or different in the small “blue” proteins. We propose that this role is to constitute a bridge between different copper ions in the molecule and mediate the specific interaction between those which is a crucial feature in the catalytic action of the multi-copper oxidases.