Formation of crystalloid inclusions in the small intestine of neonatal pigs: an immunocytochemical study using colloidal gold

Summary Enterocytes of the small intestine in 1-day-old suckling piglets contain numerous vesicles in the apical cytoplasm and a large granule located beneath the nucleus. Within the next 3 days, these granules transform into electron-dense crystalloid inclusions. These membrane-bound inclusions are up to 10 m in length and 1–2 m in diameter, and they are composed of electron-dense lamellae 3.9 nm apart. Postembedding immunocytochemistry, using rabbit anti-porcine IgG and goat anti-rabbit IgG conjugated to 10 nm colloidal gold, revealed that both the granules and the crystalloid inclusions contained a high concentration of maternal IgG. Although the IgG content of the crystalloid inclusions was detected on epoxy-embedded sections, the use of LR White resin resulted in a much higher density of labelling. Quantification of the labelling density showed that the concentration of IgG in the crystalloid inclusions was approximately ten times higher than that in the lumenal colostrum and approximately three times higher than that in the granules. These observations showed that there are at least three compartments involved in the accretion of IgG in the small intestine of neonatal piglets: smaller apical endocytotic vesicles, large subnuclear granules and crystalloid inclusions. The role of these compartments in maternal immunoglobulin absorption and in the acquisition of passive immunity has yet to be explored.     

Influence of guanine nucleotides on complex formation between Ras and CDC25 proteins.

The Saccharomyces cerevisiae CDC25 gene and closely homologous genes in other eukaryotes encode guanine nucleotide exchange factors for Ras proteins. We have determined the minimal region of the budding yeast CDC25 gene capable of activity in vivo. The region required for full biological activity is approximately 450 residues and contains two segments homologous to other proteins: one found in both Ras-specific exchange factors and the more distant Bud5 and Lte1 proteins, and a smaller segment of 48 amino acids found only in the Ras-specific exchange factors. When expressed in Escherichia coli as a fusion protein, this region of CDC25 was found to be a potent catalyst of GDP-GTP exchange on yeast Ras2 as well as human p21H-ras but inactive in promoting exchange on the Ras-related proteins Ypt1 and Rsr1. The CDC25 fusion protein catalyzed replacement of GDP-bound to Ras2 with GTP (activation) more efficiently than that of the reverse reaction of replacement of GTP for GDP (deactivation), consistent with prior genetic analysis of CDC25 which indicated a positive role in the activation of Ras. To more directly study the physical interaction of CDC25 and Ras proteins, we developed a protein-protein binding assay. We determined that CDC25 binds tightly to Ras2 protein only in the absence of guanine nucleotides. This higher affinity of CDC25 for the nucleotide-free form than for either the GDP- or GTP-bound form suggests that CDC25 catalyzes exchange of guanine nucleotides bound to Ras proteins by stabilization of the transitory nucleotide-free state.     

采用康宁克通—A治疗鼻息肉的临床疗效观察

鼻息肉与变态反应之间有密切联系。本文拟报道康克通—A用于鼻息肉摘除术前、后以延迟与防止息肉复发的临疗效观察。     

Rapid and reliable high-performance liquid chromatographic method for analysing human plasma serotonin, 5-hydroxyindoleacetic acid, homovanillic acid and 3,4-dihydroxyphenylacetic acid

The simultaneous measurement of homovanillic acid, 3,4-dihydroxyphenylacetic acid, serotonin and 5-hydroxyindoleacetic acid in human plasma by an ultrafiltration and microbore high-performance liquid chromatography—electrochemical detection technique is established. Conventional preparation of blood is very tedious and time-consuming, but isocratic separation of the analytes in plasma ultrafiltrates using a microbore column could be achieved within 10 min. Hence, theoretically, over 140 analyses can be performed in a working day. The detection limit (signal-to-noise ratio = 3) of this method is about 0.1–0.5 pg per injection for all analytes. The required volume of plasma samples can be less than 100 μl. Hence, blood loss is minimal, especially in repeated blood sampling. This rapid, simple and sensitive method can, therefore, be used as a routine clinical tool in the simultaneous measurement of plasma homovanillic acid, 3,4-dihydroxyphenylacetic acid, serotonin and 5-hydroxyindoleacetic acid.     

Selenium in combination with a tomato lipid extract as a therapy for benign prostatic hyperplasia and its alterations in rats with induced BPH

Benign prostatic hyperplasia (BPH) is the most common adenoma in old men. Tomatoes are a rich source of bioactive compounds that, as well as selenium (Se), possess antioxidant and antiproliferative activity. The aim was to evaluate the therapeutic effect of Se in combination with a tomato extract in aged rats with BPH. Aged male Wistar rats were divided in the following groups (n = 10 rats/group): Control (C), BPH, BPH + Finasteride (BPH + F), BPH + Tomato Lipidic Extract (BPH + E), BPH + Selenium (BPH + S) and BPH plus E plus S (BPH + E + S). After 4 weeks of treatment, prostate weight, diuresis, antioxidants enzymes, prooxidants and inflammatory markers, growth factors and androgens were determined. BPH + E + S reduced prostate weight by 59.29% and inhibited growth by 99.35% compared to BPH + F which only decreased weight and inhibited growth by 15.31% and 57.54%, respectively. Prooxidant markers were higher with BPH + F (49.4% higher vs. BPH), but BPH + E + S decreased these markers (94.27% vs. BPH) and increased antioxidant activity. Finally, diuresis was higher with the BPH + E + S combination and markers of inflammation and growth factors were significantly lower with respect to BPH + F. Our findings provide a beneficial and protective therapeutic option of E + S directed against androgens, oxidative stress and inflammation that regulates cell proliferation in the prostate gland.     

Engineered nickel bioaccumulation in Escherichia coli by NikABCDE transporter and metallothionein overexpression

Mine wastewater often contains dissolved metals at concentrations too low to be economically extracted by existing technologies, yet too high for environmental discharge. The most common treatment is chemical precipitation of the dissolved metals using limestone and subsequent disposal of the sludge in tailing impoundments. While it is a cost-effective solution to meet regulatory standards, it represents a lost opportunity. In this study, we engineered Escherichia coli to overexpress its native NikABCDE transporter and a heterologous metallothionein to capture nickel at concentrations in local effluent streams. We found the engineered strain had a 7-fold improvement in the bioaccumulation performance for nickel compared to controls, but also observed a drastic decrease in cell viability due to metabolic burden or inducer (IPTG) toxicity. Growth kinetic analysis revealed the IPTG concentrations used based on past studies lead to growth inhibition, thus delineating future avenues for optimization of the engineered strain and its growth conditions to perform in more complex environments.     

The importance of ecological research for ecosystem management: The case of browsing by swamp wallabies (Wallabia bicolor) in commercially harvested native forests

Summary Ecosystem management often proceeds within the context of sub‐optimal relationships between ecologists and ecosystem managers, and management outcomes could be improved with greater collaboration between members of these disciplines. This paper identifies an ecosystem management problem resulting from the interaction between timber harvesting and browsing wallabies, and this case study is used to exemplify how ecological data and expertise can contribute to the process of ecosystem management. It is argued that appropriate use of existing ecological data, establishment of strategic new research and the implementation of management actions as experimental hypothesis tests can facilitate achievement of management objectives, but greater collaboration between ecologists and managers is required before this can occur. Reasons for sub‐optimal relationships are outlined, and the potential for structural change within large State‐run ecosystem management agencies to improve interactions between managers and ecologists is discussed.     

Experimental dissociation of the effects of diet, age and breeding experience on primary reproductive effort in zebra finches Taeniopygia guttata

Reproductive performance varies with age in a wide range of organisms, and increasingly such patterns are interpreted in terms of state-dependent models. We sought to characterise 'state' with regards to age-related variation in clutch size, egg mass and timing of breeding in captive zebra finches Taeniopygia guttata , focusing on the roles of diet quality, age and breeding experience. Females on a high-quality diet laid larger clutches of larger eggs than did females on a low-quality diet. The effect of age on reproductive performance was examined by comparing females breeding (i.e. paired) for the first time at either 3- and/or 6-months of age. Clutch size increased with age but on the low-quality diet only, not on the high-quality diet. Furthermore, clutch size decreased between 3- and 6-months of age in birds bred first on the high-quality diet and then on the low-quality diet. Age did not affect egg mass but older birds had shorter laying intervals. Reproductive performance did not differ between females breeding at 6-months of age for the first or second time: the effects of age were not due to 'training' effects or experience specific to breeding (e.g. undergoing the physiological process of egg formation). In conclusion, nutritional condition (diet) emerged as a central component of state that could strongly influence, and even reverse, any age-dependent increase in primary reproductive performance.     

Production enhancement of Pseudomonas amyloderamosa isoamylase

Isoamylase production in batchwise and fed-batch cultures of Pseudomonas amyloderomosa (strain WU7211-2) was investigated. By feeding maltose in a mode motivated by its structure gene (iam), the final isoamylase activity of 5100 U/ml was achieved, as compared to 4100 U/ml in batch cultivation and 3800 U/ml in shaken flasks. The enhancement may be due to the fact that the production of isoamylase can be induced effectively by the maltose only if the glucose concentration is maintained below the inhibitory level. Also, cultivations based on 500-ml shaken flasks, performed with different amount of proteimax HE90, showed that higher amounts of proteimax HE90 resulted in an increased value of pH that had an adverse effect on isoamylase yield.The authors wish to thank the Food Industry Research and Development Institute (FIRDI), Taiwan, R.O.C for the financial support (Cooperative Agreement 94M904-2B). Appreciation is also extended to Drs. C.C. Liao, W.S. Chu and L.L. Lin of FIRDI for their valuable discussions.