Courting Failure in a Pencilfish,Nannostomus b. beckfordi

We analysed a sample of 4341 activity bouts from 12 male Nannostomus b. beckfordi interacting with ♀♀. Only 22 % of the gamopractic bouts ended in spawning. In 50 % of the bouts the pair separated without spawning or interference, partly as a result of male aggression. Interference frcm conspecifics was also a major cause of failure, terminating 28 % of the gamopractic bouts. Successful courtship bouts contain more gamopractic behaviour than do abortive bouts, even in the first 6 s, and also show greater stereotypy.     

Nutritional studies of histoplasma capsulatum

Summary A chemically defined medium, composed of inorganic salts, glucose, asparagine, cystine, and a vitamin supplement, has been devised for growth of the yeast phase ofHistoplasma capsulatum. Growth in this medium was abundant and compared favorably with that in media containing complex natural material. Conversion of each of the 20 strains examined was accomplished by one or more passages on agar slants of the medium and incubation of the cultures at 37° C. Yeast phase cultures on this medium have been stored for 6 months or more at approximately 4° C without conversion or loss of viability. Of the 20 strains examined for vitamin requirements of the yeast phase, all were partially deficient for thiamine; nine for inositol; five, either partially or completely deficient for niacin; and one, completely deficient for biotin.No specific amino acid was required for growth of the yeast phase, but an organic source of sulfur and one of nitrogen were essential. Cystine and cysteine were equally effective for growth of the yeast phase when supplied on an equivalent sulfur basis and very little difference in growth occurred in media which contained equal amounts of nitrogen in any one of the following compounds: asparagine, glutamic acid, aspartic acid, and proline,Of the 20 strains, all but one, which requires biotin, were capable of continued growth in the mycelial phase when subcultured on an agar medium containing only inorganic salts and dextrose, but growth was improved significantly by asparagine or casein hydrolysate.This investigation was supported in part by a PHS research grant (AI-03524) from the National Institute of Allergy and Infectious Diseases, Public Health Service.     

Characteristics of hollows and hollow‐bearing trees in semi‐arid river red gum woodland and potential limitations for hollow‐dependent wildlife

Up to 37 species of the birds and microbats inhabiting inland Australia are dependent on tree cavities for breeding or roosting. The river red gum (Eucalyptus camaldulensis), a well‐known hollow‐bearing tree species, occurs in linear semi‐arid woodland along thousands of kilometres of ephemeral river channels and is the only tree species that provides widespread, aggregated hollow resources across a landscape otherwise dominated by shrublands. Here we assess the type and quantity of hollows available along ephemeral rivers of the MacDonnell Ranges bioregion in central Australia and determine which characteristics of river red gums best predict the abundance and characteristics of different tree hollows, as first steps towards assessing the current availability of hollows in the region. Approximately a third of all river red gums sampled were hollow‐bearing, but individual trees with abundant hollows were rare. Further, 36% of hollows had an entrance ≤ 5 cm, and 37% had entrances which were 6–10 cm in diameter, whereas only 13% of hollows had an entrance diameter > 20 cm suitable for larger hollow‐using species. Large and high hollows only occurred on trees that did not display post‐disturbance resprouting. Trees with multiple and diverse hollows were rare and tended to be in advanced stages of senescence and had larger stems (82.3 ± 3.33 cm) and were taller (14.4 ± 0.53 m) compared to non‐hollow‐bearing trees (23.44 ± 1.68 cm, 8.0 ± 0.34 m). Further research is required to establish whether the current abundance of hollows and diversity of hollow types are limiting to cavity‐dependent wildlife, and to identify any threats to availability of hollows.     

The Vascular Effects of Sodium Tanshinone IIA Sulphonate in Rodent and Human Pregnancy

Danshen, in particular its derivative tanshinone IIA (TS), is a promising compound in the treatment of cardiovascular diseases and has been used for many years in traditional Chinese medicine. Although many actions of TS have been researched, its vasodilator effects in pregnancy remain unknown. There have been a few studies that have shown the ability of TS to reduce blood pressure in women with hypertensive pregnancies; however, there are no studies which have examined the vascular effects of TS in the pregnant state in either normal or complicated pregnancies. Our aim was to determine the vasoactive role of TS in multiple arteries during pregnancy including: rat resistance (mesenteric and uterine) and conduit (carotid) arteries. Further, we aimed to assess the ability of TS to improve uterine blood flow in a rodent model of intrauterine growth restriction. Wire myography was used to assess vascular responses to the water-soluble derivative, sodium tanshinone IIA sulphonate (STS) or to the endothelium-dependent vasodilator, methylcholine. At mid-pregnancy, STS caused direct vasodilation of rat resistance (pEC₅₀ mesenteric: 4.47±0.05 and uterine: 3.65±0.10) but not conduit (carotid) arteries. In late pregnancy, human myometrial arteries responded with a similar sensitivity to STS (pEC₅₀ myometrial: 3.26±0.13). STS treatment for the last third of pregnancy in eNOS^-/- mice increased uterine artery responses to methylcholine (E_max eNOS^-/-: 55.2±9.2% vs. eNOS^-/- treated: 75.7±8.9%, p<0.0001). The promising vascular effects, however, did not lead to improved uterine or umbilical blood flow in vivo, nor to improved fetal biometrics; body weight and crown-rump length. Further, STS treatment increased the uterine artery resistance index and decreased offspring body weight in control mice. Further research would be required to determine the safety and efficacy of use of STS in pregnancy.     

Effect of Linker Length on Avidin Binding to Biotinylated Gramicidin A

Biotinylated gramicidins are an important component of the AMBRI^® “ion channel switch™” biosensor. These gramicidin A (gA) analogues have a biotin attached to the C-terminus of gA via a number of aminocaproyl linker groups (X). The structure of gA5XB has been determined in deuterated sodium dodecyl sulfate micelles and is similar to native gA and other modified gA analogues. The biotin and aminocaproyl groups were mobile and located in the aqueous phase and when avidin was added, NMR and MS studies showed that gA5XB bound more effectively to avidin than gA2XB. The length and flexibility of the linker appears to be important for biotin–avidin binding and, in the AMBRI^® biosensor, gA5XB is a more effective gated ion channel than gA2XB. The conformation and dynamics of the aminocaproyl linker groups were investigated using ²H solid-state NMR. Deuterated aminocaproyl linkers were coupled to gA and incorporated into oriented bilayers in order to analyse the order and dynamics of the aminocaproyl linker. The small ²H splittings and the T ₁ relaxation times indicated that the aminocaproyl linker is undergoing fast rotation in phospholipid bilayers. Native d ₄ -gA as well as d ₄ -gA2XB, where the ethanolamine has been deuterated, were also incorporated into oriented bilayers. Solid-state ²H NMR data showed that the addition of the linker group restricted the mobility of the ethanolamine. However, these modifications to the C-terminus of gA did not interfere with ion channel function and clarify how the biotinylated gA analogues perform in the lipid bilayer as part of the AMBRI^® biosensor.Australian Peptide Conference Issue.