Effect of toxic and non-toxic sugars on motility of honey bee (Apis mellifera L.) spermatozoa

Zusammenfassung Die Motilität der Spermien bei der HonigbieneApis mellifera L. wird in vitro furch die Monosaccharide Glukose, Fruktose und Galaktose, die Dissacharide Maltose, Melibiose und Trehalose, sowie das Trisaccharid Melezitose ausgelöst. Mamose Rhamnose und Raffinose hingegen sind unwirksam. Von den wirksamen Zuckern sind Galaktose und Melibiose für Bienen giftig.     

Changes in the concentration of vasoactive intestinal peptide in intestinal lymph in response to vagal stimulation in the calf

Summary Stimulation of both vagi caused a significant rise in arterial plasma vasoactive intestinal peptide (VIP) concentration in 3–5-week-old calves with cut splanchnic nerves. This was associated with a pronounced rise in the VIP concentration of intestinal lymph showing that vagal stimulation causes release of VIP from splanchnic viscera.Acknowledgment. This work has been supported by grants from the Agricultural Research Council and the Medical Research Council and we are indebted to Dr D.M. Burley (CIBA) for his continued support.     

Good, bad or offal? The evaluation of raw pancreas therapy and the rhetoric of control in the therapeutic trial, 1925

In 1925 a debate erupted in the correspondence columns of the British Medical Journal concerning the effectiveness of eating raw pancreas as a treatment for diabetes. Enthusiasts were predominantly general practitioners (GPs), who claimed success for the therapy on the basis of their clinical impressions. Their detractors were laboratory-oriented 'biochemist-physicians,' who considered that their own experiments demonstrated that raw pancreas therapy was ineffective. The biochemist-physicians consistently dismissed the GPs' observations as inadequately 'controlled'. They did not define the meaning of 'control' in this context, although it clearly did not have the term's present-day meaning of a trial employing an untreated comparison group of patients. Rather, the physician-biochemists' 'properly controlled' experiments involved careful regulation of their patients' diet and other environmental factors, and evaluation of the therapy's success through biochemical, rather than just clinical, criteria. However, my analysis suggests that these factors alone are inadequate to account for the biochemist-physicians' dismissal of the GPs' work as 'uncontrolled'. I suggest that the biochemist-physicians were deliberately exploiting the powerful rhetorical connotations of the term 'control'. Ultimately, they implied that only a trial which they themselves had conducted could be deemed 'adequately controlled'.     

Escherichia coli K-12 undergoes adaptive evolution to achieve in silico predicted optimal growth

Annotated genome sequences can be used to reconstruct whole-cell metabolic networks. These metabolic networks can be modelled and analysed (computed) to study complex biological functions. In particular, constraints-based in silico models have been used to calculate optimal growth rates on common carbon substrates, and the results were found to be consistent with experimental data under many but not all conditions. Optimal biological functions are acquired through an evolutionary process. Thus, incorrect predictions of in silico models based on optimal performance criteria may be due to incomplete adaptive evolution under the conditions examined. Escherichia coli K-12 MG1655 grows sub-optimally on glycerol as the sole carbon source. Here we show that when placed under growth selection pressure, the growth rate of E. coli on glycerol reproducibly evolved over 40 days, or about 700 generations, from a sub-optimal value to the optimal growth rate predicted from a whole-cell in silico model. These results open the possibility of using adaptive evolution of entire metabolic networks to realize metabolic states that have been determined a priori based on in silico analysis.     

Evidence of recent volcanic activity on the ultraslow-spreading Gakkel ridge

Seafloor spreading is accommodated by volcanic and tectonic processes along the global mid-ocean ridge system. As spreading rate decreases the influence of volcanism also decreases, and it is unknown whether significant volcanism occurs at all at ultraslow spreading rates (<1.5 cm yr(-1)). Here we present three-dimensional sonar maps of the Gakkel ridge, Earth's slowest-spreading mid-ocean ridge, located in the Arctic basin under the Arctic Ocean ice canopy. We acquired this data using hull-mounted sonars attached to a nuclear-powered submarine, the USS Hawkbill. Sidescan data for the ultraslow-spreading (approximately 1.0 cm yr(-1)) eastern Gakkel ridge depict two young volcanoes covering approximately 720 km2 of an otherwise heavily sedimented axial valley. The western volcano coincides with the average location of epicentres for more than 250 teleseismic events detected in 1999, suggesting that an axial eruption was imaged shortly after its occurrence. These findings demonstrate that eruptions along the ultraslow-spreading Gakkel ridge are focused at discrete locations and appear to be more voluminous and occur more frequently than was previously thought.     

Muscarinic involvement in vascular and adrenal medullary responses to splanchnic nerve stimulation in conscious calves

Stimulation of the peripheral end of the right splanchnic nerve (4 Hz for 10 min) in the presence of hexamethonium caused a small but significant rise in mean aortic blood pressure which was subsequently abolished by atropine. There were also small but significant increases in the outputs of catecholamines, [Met⁵]-enkephalins and corticotrophin releasing factor (CRF) from the right adrenal gland. The catecholamine response was roughly halved after atropine while the outputs of enkephalins and CRF were unaffected. It is concluded that splanchnic sympathetic postganglionic neurones supplying the vasculature are completely blocked by cholinergic blockade whereas adrenal medullary responses persist in an attenuated form.     

Prevention of insulin-dependent diabetes mellitus in non-obese diabetic mice by transgenes encoding modified I-A beta-chain or normal I-E alpha-chain

Insulin-dependent diabetes mellitus (IDDM) is a disease with an autoimmune aetiology. The inbred non-obese diabetic (NOD) mouse strain provides a good animal model of the human disease and genetic analysis suggests that, as in man, at least one of the several genes controlling the development of IDDM is linked to the major histocompatibility complex. The NOD mouse does not express I-E owing to a deletion in the promoter region of the I-E alpha-chain gene, and the sequence of NOD I-A beta-chain in the first external domain is unique with His 56 and Ser 57 replacing Pro and Asp, respectively, at these positions. There has been considerable interest in the role amino acid 57 might have in conferring susceptibility to autoimmune diseases, including IDDM. The presence of a charged residue (such as Asp) at this position might affect the conformation of the peptide binding groove. But it could be assumed that Pro 56 gives rise to a different conformation of I-A beta-chain than does His 56. We therefore constructed transgenic NOD mice in which the transgene encoded a modified A beta nod with Pro 56, and studied its effect on the development of IDDM in this mouse strain. Previous studies have suggested that NOD mice expressing I-E as a result of the introduction of an I-E alpha-chain (E alpha) transgene are protected from the development of insulitis and hence IDDM. To explore further the protective effect of this molecule we constructed a second class of transgenic NOD mouse carrying an E alpha d transgene. Both transgenes protected the mice from IDDM, but this was not associated with a complete deletion of any T cells expressing commonly used T-cell receptor V beta genes.