The antenna cleaner gland in Messor rufitarsis (hymenoptera, formicidae)

TEM and SEM analysis of the tibio-tarsal antennal cleaner in Messor rufitarsis reveals a pore region on the surface of the basitarsus. These pores are originating from a cluster of highly prismatic epidermal cells that fill the anterior hemolymph space of the leg almost completely. Within the cytoplasma of the cells, basal labyrinth, nucleus/rough endoplasmic reticulum, 'secondary lysosomes', a lot of smooth endoplasmic reticulum and distal microvilli regions can be distinguished indicating that the cells are 'class I' gland cells. Their secretion appears to be transported to the antennal cleaner apparatus via a subcuticular space and pores. It is suggested that the secretion might be used for cleaning of the antenna and/or chemical communication. SEM examination of six additional species indicates that an antennal cleaner gland might be present throughout the ants.     

Sperm viability is influenced in vitro by the bovine seminal protein aSFP: effects on motility, mitochondrial activity and lipid peroxidation

The 13 kDa acidic seminal fluid protein (aSFP) is a major component of bovine semen exerting growth factor-like activity. The influence of the pure protein on sperm viability was observed by evaluating sperm motility using computer-assisted semen analysis. Furthermore, mitochondrial dehydrogenase activity as a parameter of sperm metabolism and the integrity of sperm membranes using a metal catalyzed lipid peroxidation assay were measured. Over a wide physiological range (0.003 to 4 g/l) aSFP did not influence motility and average-path velocity of sperm, but at the highest concentration (6 g/l) a significant reduction in motility could be observed. Mitochondrial activity was significantly stimulated at medium concentrations (0.125 to 2 g/l), whereas a 40% suppression was observed at maximum levels (4 g/l). A dose-dependent inhibition of lipid peroxidation could be demonstrated for medium and high concentrations of aSFP (0.125 to 4 g/l). Compared with other reducing agents, aSFP showed the highest potency in preventing oxidative stress. Such effects might be explained by the remarkable redox behavior of the protein. We suggest that in the bull aSFP may play a role in the regulation of sperm metabolism and the protection of sperm membranes from oxidative damage.     

Galanthamine production in “shoot-clump” cultures of Narcissus confusus in liquid-shake medium

Galanthamine (GAL) is increasingly used in the treatment of Alzheimer's disease. We have attempted to develop a method of producing this alkaloid using in vitro cultures of Narcissus confusus plants. The “shoot-clump” culture in liquid medium was shown to be an appropriate method for the micropropagation of this bulbous plant. The complete process included three steps:

1. culture of “twin-scales” starting from the bulbs;
2. culture of the newly formed shoots in a medium for bud proliferation (Murashige Skoog+1 mg l^-1 of 2,4-dichlorophenoxyacetic acid+5 mg l^-1 of benzyladenine), and
3. culture of “shoot-clumps” in a liquid-shake medium. Here we describe the effect of the addition of trans-cinnamic acid, a precursor in the biosynthesis of the Amaryllidaceae alkaloids, on the production of galanthamine and related alkaloids, and also on the growth of the “shoot-clump” culture. The production of galanthamine was found to be inhibited by the addition of the precursor, which promoted the production of the other alkaloid in the same biosynthetic pathway, N-formyl-norgalanthamine. The total production of galanthamine in the control cultures in day-long photoperiod was 2.50 mg per culture, of which 1.97 mg per culture were released into the medium.

     

Rhythmic melatonin secretion in different teleost species: an in vitro study

The rhythmic production of melatonin is governed by intrapineal oscillators in all fish species so far investigated except the rainbow trout. To determine whether the latter represents an exception among fish, we measured in vitro melatonin secretion in pineal organs of nine wild freshwater and six marine teleost species cultured at constant temperature and under different photic conditions. The results demonstrate that pineal organs of all species maintain a rhythmic secretion of melatonin under light:dark cycles and complete darkness, and strongly suggest that most fish possess endogenous intrapineal oscillators driving the rhythm of melatonin production, with the exception of the rainbow trout.Abbreviations LD light:dark - DD dark:dark - NAT N-acetyltransferase - RIA radioimmunoassay     

Energy metabolism and ATP free-energy change of the intertidal wormSipunculus nudus below a critical temperature

The intertidal wormSipunculus nudus was exposed to various temperatures for an analysis of the integrated changes in energy and acid-base status. Animals were incubated in sea water or maintained for up to 8 days at 4 and 0°C while dwelling in the sediment. Cannulation of the animals prior to experimentation allowed the analysis of blood gas parameters ( , and pH). fell to 0 torr within 8 days at 0°C. A simultaneous reduction of ventilatory activity was derived from measurements of the pattern of coelomic fluid pressure changes associated with ventilatory movements. The increase in and an onset of anaerobic metabolism, indicated by the accumulation of end products like acetate and propionate both in the coelomic fluid and the body wall musculature, led to the development of a progressive acidosis and a deviation from the alphastat regulation of intracellular pH seen in unburied animals. The drop in intracellular pH together with the depletion of the adenylates and the phosphagen, phospho-l-arginine, reflect a significant decrease in the Gibb's free-energy change of ATP hydrolysis. These changes are interpreted to indicate lethal cold injuries, because recovery was not possible when the animals were returned to 12°C after more than 2 days of exposure to 0°C. A low critical temperature indicating the onset of cold-induced anaerobiosis is concluded to exist below 4°C owing to the insufficient response of the ventilatory system to the developing hypoxia.     

Initial increase and subsequent loss of vasoactive intestinal polypeptide immunoreactivity in acetylcholinesterase-positive neurons of mouse islets transplanted to the kidney

Collagenase-isolated pancreatic islets from C57BL/6J mice were cultured overnight and transplanted under the kidney capsule of non-diabetic syngeneic hosts. Cryostat sections of grafts and fresh islets were stained for acetylcholinesterase (AChE) and vasoactive intestinal polypeptide-like immunoreactivity (VIP-LI). Immediately after isolation, as well as 2-5 days after transplantation, VIP-LI- and AChE-positive nerve cell bodies were clearly seen in the periphery of the islets. Grafts 3-5 days old exhibited a transient and marked increase in VIP-LI nerve cell bodies and fibers. Seven days after transplantation VIP-LI nerve structures began to decrease in number and after 26-52 weeks they were no longer detectable. In contrast, AChE-positive nerve cell bodies and fibers, which showed a relatively constant pattern of distribution, were observed throughout the entire observation period. Restaining experiments demonstrated the coexistence of VIP-LI and AChE activity in the neurons. It is concluded that the grafts were extensively equipped with an intrinsic VIP-ergic and AChE-positive innervation. The initial, transient enhancement of VIP-LI expression probably reflects an adaptation of the neuro-insular complex to the preganglionic denervation, or to the ectopic environment, or both.     

Candida biotypes in patients with oral leukoplakia and lichen planus

Prevalence of yeasts in 35 leukoplakia and 34 oral lichen planus patients was compared with that observed in persons without oral diseases. Serotype and morphotype were determined on Candida albicans isolates. Yeasts were isolated from the oral cavity specimens of 43.7% of the patients. C. albicans (serotype A) was the predominant species (76% in leukoplakia, 88.2% in lichen planus and 60.8% in healthy persons). Sixteen morphotypes were encountered on malt extract agar, being 732, 733, 734, 753 and 754 the most frequently found. Morphotypes SP1N and SP1Y were the most common on Sabouraud-trypheniltetrazolium agar (68.4% of the isolates from leukoplakia and 73.3% from lichen planus, but only 46.6% of the isolates from healthy oral mucosa showed SP1N morphotype). Presence of oral lesions was associated with a marked reduction in the yeast species and C. albicans biotypes, suggesting that C. albicans and particularly some of its biotypes, show a high potential of adaptation to the changes associated with the development of oral leukoplakia and lichen planus.     

Candida albicans stress mannoproteins expression in superficial and systemic candidiasis

The presence of heat shock mannoproteins (HSMPs) reactive with sIgA was demonstrated in several C. albicans strains. The subculture of the C. albicans isolated from mucosal surfaces on Sabouraud's dextrose agar at 25 °C switched off the HSMP expression. A re-expression of the HSMPs was obtained in the same medium by shifting the temperature of incubation to 37 °C. However, expression of HSMPs in two strains isolated from deep infections was maintained during several subcultures on Sabouraud's dextrose agar at 25 °C. A glycoprotein of 200 kDa seemed to be the main HSMP reacting with vaginal sIgA. The data presented in this study suggest that factors other than temperature can influence the expression of C. albicans HSMPs and therefore these antigens should be referred as stress mannoproteins.Abbreviations HSMPs heat shock mannoproteins - MAb monoclonal antibody - sIgA secretory IgA     

Electrooptical analysis of alpha-chymotrypsin at physiological salt concentration

The electric dichroism of alpha-chymotrypsin has been measured in a buffer containing 0.1 M Na(+), 10 mM Mg(2+) and 25 mM Tris-cacodylate pH 7.2. The reduced dichroism as a function of the electric field strength can be represented by the orientation function for permanent dipoles and is not consistent with the orientation function for induced dipoles. After correction for the internal directing field, the dipole moment is 1.1 x 10(-27) Cm (+/- 10%), corresponding to 340 D, at 20 degrees C. The assignment of the permanent dipole moment is confirmed by the shape of the dichroism rise curves, which require two exponentials with amplitudes of opposite sign for fitting. The dichroism decay time constants measured in the range of temperatures between 2 and 30 degrees C indicate a temperature induced change of the structure, which is equivalent to an increase of the hydrodynamic radius from r = 26.6 A at 2 degrees C to 28.5 A at 30 degrees C. Our results demonstrate that electrooptical investigations of proteins with a high time resolution can be extended to physiological salt concentrations without serious problems by use of appropriate instruments.