Free amino acids are important for the retention of protein and non-protein meals by the midgut of Aedes aegypti females

There is a relationship between the normal progress of digestion and the retention or elimination of the proteins ingested with the meal by Aedes aegyti females. The addition of soybean trypsin inhibitor (STI) to a protein meal prevented digestion and resulted in a rapid elimination of the undigested proteins. The addition of a mix of free amino acids to a protein meal together with STI resulted in a significant increase in the retention of the undigested proteins during the first 10-15 hrs after feeding. The effect of the free amino acids on the retention of the proteins was concentration-dependent between 250 microg/ml and 5 mg/ml. Free amino acids were also important for the retention of non-protein meals. When females were fed a meal containing FITC-dextran (20 kD), most of this compound was eliminated into the feces by 10 hrs; the addition of free amino acid resulted in a significant increase in the retention of the FITC-dextran by the midgut during the first 15 hrs after feeding. The presence of free amino acids in the midgut lumen seems to be an important signal used by the mosquito to regulate the retention of the meal.     

An inexpensive medium for production of arachidonic acid by <Emphasis Type="Italic">Mortierella alpina</Emphasis>

The production of arachidonic acid was studied in the fungus Mortierella alpina using an inexpensive medium. Glucose derived from maize starch hydrolysate was the sole carbon source and defatted soybean meal and sodium nitrate were the nitrogen sources. Optimal arachidonic acid yield (1.47 g l^-1) was observed at a glucose concentration of 100 g l^-1. Various treatments of defatted soybean meal to extract soluble nitrogen nutrients were evaluated. Alkali extract was the most effective for arachidonic acid production. A mixture of soybean alkali-extract protein and sodium nitrate was an excellent nitrogen source for fungal growth, lipid accumulation, and arachidonic acid production. A maximum yield of 1.87 g arachidonic acid l^-1 was obtained with a soybean protein concentration of 4.6 g l^-1 and a sodium nitrate concentration of 2.3 g l^-1. Electronic Publication     

两株真菌降解菜籽饼中植酸的研究

利用选择性培养基从土壤中分离到两株能降解植酸的丝状真菌。这些菌株能利用肌醇作为唯一的碳源和能源而生长。在液态发酵中植酸的降解率分别为74．4％和95．0％;在固态发酵中植酸的降解率为40％左右。某些金属离子对菌株的降解率的提高具有一定的促进作用。对温度、pH和水分等影响因子也进行了初步的探讨。经初步鉴定,这两株菌株中有一株为拟青霉（Paecilomycessp）,另一株为青霉（Penicilliumsp．）,它们均不产黄曲霉素素。     

LIPOPHILIC PIGMENTS FROM CYANOBACTERIAL (BLUE-GREEN ALGAL) AND DIATOM MATS IN HAMELIN POOL,SHARK BAY,WESTERN AUSTRALIA1

Lipophilic pigments were examined in microbial mat communities dominated by cyanobacteria in the intertidal zone and by diatoms in the subtidal and sublittoral zones of Hamelin Pool, Shark Bay, Western Australia. These microbial mats have evolutionary significance because of their similarity to lithified stromatolites from the Proterozoic and Early Paleozoic eras. Fucoxanthin, diatoxanthin, diadinoxanthin, β-carotene, and chlorophylls a and c characterized the diatom mats, whereas cyanobacterial mats contained myxoxanthophyll zeaxanthin, echinenone, β-carotene, chlorophyll a and, in some cases, sheath pigment. The presence of bacteriochlorophyll a with in the mats suggest a close association of photosynthetic bacteria with diatoms and cyanobacteria. The high carotenoids: chlorophyll a ratios (0.84–2.44 wt/wt) in the diatom mats suggest that carotenoids served a photoprotective function in this high light environment. By contrast, cyanobacterial sheath pigment may have largely supplanted the photoprotective role of carotenoids in the intertidal mats.     

Activity of oxyntomodulin on gastric acid secretion induced by histamine or a meal in the rat

Conscious rats with chronic gastric fistula were trained for drinking a 14-ml milk meal. The activity of an intestinal hormone, oxyntomodulin (OXM), was studied in this model and compared to that observed when histamine was the stimulus. Under histamine (0.25 mg·kg⁻¹·h⁻¹) stimulation, OXM at doses (60–120 pmol·kg⁻¹·h⁻¹) that induced physiological circulating levels inhibited gastric acid secretion up to 50%. Under meal stimulation, OXM reduced up to 29% acid secretion at doses (1–1.5 nmol·kg⁻¹·h⁻¹) inducing supraphysiological levels. We conclude that at physiological concentrations OXM cannot counteract the complex processes triggered by a meal. OXM would be a component of enterogastrone, a combination of several intestinal hormones acting in synergy. The OXM action is related to pathways recognizing the C-terminal 19–37 moiety of the molecule.     

Ultrastructure of cuticle deposited inPlodia interpunctella wing discs after variousβ-ecdysone treatments in vitro

Summary Wing discs of the Indian meal moth may be cultured for extended periods in vitro. The discs produced a tanned cuticle after continuous incubation with -ecdysone in medium conditioned with fat body or after a 24-h pulse incubation with -ecdysone in plain medium. We investigated the ultrastructure of the cuticle deposited by such discs. We found that the treatment that produced the most complete cuticle in vitro was the 24-h pulse of hormone. We observed that cuticle formation in vitro was not all-or-none. Depending on culture conditions, discs produced cuticulin only, complete epicuticle, epicuticle plus diffuse endocuticle, epicuticle plus lamellate endocuticle, or even multiple layers of cuticle. The ultrastructural evidence suggests that continuous incubation with -ecdysone in plain medium does not always inhibit cuticle formationper se, but does prevent tanning of the partially formed cuticle.     

Effects of high dietary levels of soybean meal and its constituents (potassium,oligosaccharides) on foot pad dermatitis in growing turkeys housed on dry and wet litter

Soybean meal (SBM) is the main protein source in diets for turkeys. High dietary levels of SBM are thought to increase the incidence of foot pad dermatitis (FPD). Therefore, this study was conducted to test potential effects of high SBM and to elucidate which constituents in SBM might be associated with the development of FPD. Two week-old female turkeys were allotted to four groups of 29 birds each, and housed on dry wood shavings in floor pens over a period of three weeks. Four different diets were fed: control, high SBM, high potassium (K) or high oligosaccharide (OL) diet. Additionally, for only 8 h/d half of the animals in each group were exposed to wet litter (27% DM) in adjacent separate boxes. The foot pads of all birds were assessed on days 0, 7, 14 and 21 for external lesions. For the histopathology of the foot pads, on day 0 three birds from each group, and on days 7 and 14 six birds per feeding group were selected. The remaining birds in each group were sacrificed on day 21 and their pads were evaluated histologically. High dietary levels of SBM, potassium or oligosaccharides did not influence the severity of FPD on dry litter, but slightly increased the severity on wet litter. However, there were no histopathological differences in FPD severity between these dietary treatments within each litter form compared to the control. Nevertheless, the FPD severity was in general higher on wet litter. Thus, litter moisture appears to be one of the most important factors involved in FPD in turkeys. In addition, all nutritional factors which increase water intake and excreta or litter moisture may contribute to an increased development and severity of FPD in turkeys.     

Blood intake by Aedes aegypti not regulated by insemination

A chemical method of determining the amount of blood ingested by mosquitoes was used to test the claim of Adlakha and Pillai (1976) that insemination is involved in the regulation of blood meal size. Inseminated and uninseminated Aedes aegypti do not differ in the amount of blood ingested. The data show that if excretion before, during, and after feeding, is not accounted for, unacceptable errors are introduced in blood meal size determinations.