Synthesis and biological activity of aminoguanidine and diaminoguanidine analogues of the antidiabetic/antiobesity agent 3-guanidinopropionic acid

3-Guanidinopropionic acid (1) has been demonstrated both to improve insulin sensitivity and to promote weight loss selectively from adipose tissue in animal models of non-insulin-dependent diabetes mellitus (NIDDM). However, 1 has also been shown to be a substrate for both the creatine transporter and creatine kinase, leading to marked accumulation in muscle tissue as the corresponding N-phosphate. The corresponding aminoguanidine analogue 2 was recently discovered to retain the antidiabetic activity of 1 while being markedly less susceptible to creatine-like metabolism, suggesting that it should have less potential to accumulate in muscle. Further structural modification of 2 was undertaken to investigate whether the antidiabetic potency could be augmented while maintaining resistance to creatine-like metabolism. Modifications such as alpha-alkylation, homologation, and bioisosteric replacement of the aminoguanidine all were detrimental to antidiabetic activity. However, the simple regioisomeric aminoguanidinoacetic acid 9 and diaminoguanidinoacetic acid analogue 7 were found to be equipotent to 2, leading eventually to the discovery of the significantly more potent diaminoguanidinoacetic acid regioisomers 52 and 53. Further attempts to modify the more active template represented by 52 led only to reductions in antidiabetic activity. Each of the new active analogues displayed the same resistance to creatine-like metabolism as 2. Further testing of 7, 9, and 53 in obese diabetic ob/ob mice confirmed that weight loss is induced selectively from adipose tissue, similar to the lead 1. Administration of 53 to insulin-resistant rhesus monkeys led to reductions in both fasting and post-prandial plasma glucose levels with concomitant reductions in plasma insulin levels, suggesting that the compound improved the action of endogenous insulin. Compounds 7 and 53 were selected for further preclinical development.

Synthesis and biological activity of analogues of the antidiabetic/antiobesity agent 3-guanidinopropionic acid: discovery of a novel aminoguanidinoacetic acid antidiabetic agent

3-Guanidinopropionic acid (1, PNU-10483) has been demonstrated to both improve insulin sensitivity and to promote weight loss selectively from adipose tissue in animal models of non-insulin-dependent diabetes mellitus (NIDDM). However, 1 has also been shown to be a substrate for both the creatine transporter and creatine kinase, leading to marked accumulation in muscle tissue as the corresponding N-phosphate 4. In an effort to identify novel entities that maintain antidiabetic potency without susceptibility to creatine-like metabolism, an analogue program was undertaken to explore the effects of various structural modifications, including homologation, simple substitution, single atom mutations, and bioisosteric replacements for the guanidine and carboxylic acid. Overall, the scope of activity encompassed by the set of new analogues proved to be exceedingly narrow. Notable exceptions demonstrating equivalent or improved antidiabetic activity included the alpha-amino derivative 29, aminopyridine 47, isothiourea 67, and aminoguanidine 69. On the basis of its superior therapeutic ratio, aminoguanidine 69 was selected for preclinical development and became the foundation for a second phase of analogue work. Furthermore, in vitro studies demonstrated that 69 is markedly less susceptible to phosphorylation by creatine kinase than the lead 1, suggesting that it should have less potential for accumulation in muscle tissue than 1.

Identification and characterization of a novel transcript of the murine growth hormone receptor gene exhibiting development- and tissue-specific expression

The growth hormone (GH) receptor gene is characterized by heterogeneity in the 5'-untranslated region (UTR). The technique of 5'-rapid amplification of cDNA ends (RACE) was employed to identify potentially novel 5'-UTRs for the GH receptor gene. One of the RACE clones displayed sequence homology to the human V5-UTR; hence this transcript was designated as L5. Sequence analysis of genomic DNA established that L5 was immediately upstream of exon 2. Northern blot analysis indicated that two bands of sizes congruent with4.8 kb, corresponding to GH receptor mRNA, and congruent with1.5 kb corresponding to GH binding protein mRNA, were detectable in liver, skeletal muscle, kidney and heart but not in brain, spleen, lung or testis. Fluorescent 5'-nuclease real-time RT-PCR based analysis indicated that in the placenta and fetal liver, the L5 transcript represented 10-15% of the GH receptor transcripts. In the adult liver, heart and kidney, the L5 transcript is less abundant accounting for 1-5% of the total GH receptor transcripts. Primer extension and ribonuclease protection assays were performed to identify the major transcription start site at 778 bp from the ATG codon. Transient transfection experiments revealed that the 5'-flanking sequence had promoter activity in rat placental trophoblast (HRP.1), Chinese hamster ovary (CHO) and mouse liver (BNL CL.2) cells. Analysis of expression of the L5 transcript in the non-obese diabetic (NOD) mouse, a model of spontaneous autoimmune diabetes, indicated that the expression of the L5 transcript was decreased in liver and kidney by 80-90 and 40-50%, respectively, but expression remained unchanged in the heart.

Intrathoracic migration of Steinmann pins

The migration of surgical wires and pins placed for repair of orthopedic injury is well recognized. Such migration usually follows a retrograde path and the wires protrude near their entry point into the native bone. Occasionally, the migration occurs in an antegrade manner and produces injury. We describe a case where three Steinmann pins placed for fixation of a humeral neck fracture migrated, one slipping backwards towards the humeral entry point and two pins migrating into the thorax.

Purification, characterization, and primary structure of a chitinase from Pseudomonas sp. YHS-A2

A chitinase gene (chiA) from Pseudomonas sp. YHS-A2 was cloned into Escherichia coli using pUC19. The nucleotide sequence determination revealed a single open reading frame of chiA comprised of 1902 nucleotide base pairs and 633 deduced amino acids with a molecular weight of 67,452 Da. Amino acid sequence alignment showed that ChiA contains two putative chitin-binding domains and a single catalytic domain. Two proline-threonine repeat regions, which are linkers between catalytic and substrate-binding domains in some cellulases and xylanases, were also found. From E. coli, ChiA was purified 12.8-fold relative to the periplasmic fraction. The Michaelis constant and maximum initial velocity for p-nitrophenyl-N,N'-diacetylchitobiose were 1.06 mM and 44.4 micromol/h per mg protein, respectively. The purified ChiA binds not only to colloidal chitin but also to other substrates (avicel, chitosan, and xylan), but the binding affinity of avicel, chitosan, and xylan is around 10 times lower than that of colloidal chitin. The reaction of ChiA with colloidal chitin and chitooligosaccharides (trimer-hexamer) produced an end product of N,N'-diacetylchitobiose, indicating that ChiA is a chitobiosidase.

Ethnic and geographic variations in the prevalence of hepatitis A, B and C among aboriginal villages in Hualien, Taiwan

BACKGROUND

Taiwan is endemic for viral hepatitis infections. A field survey was performed in the isolated aborigines in Hualien, eastern Taiwan, to investigate the geographic and ethnic variations in hepatitis epidemiology.

MATERIALS AND METHODS

From 1996 to 1998, blood was drawn from 1,748 subjects from two southern Ami and two northern Atayal villages for serum markers of hepatitis A, B and C.

RESULTS

Hepatitis A infection approached 100% in all groups. Hepatitis B infection and carrier rates were higher in the Atayal than in the Ami (92.3% vs. 49.1% and 20.8% vs. 5.3%; p<0.01). Hepatitis C infection rates were higher in three villages (27.5%, 20.1% and 25.4% vs. 3.6%; p<0.01). Hepatitis C infection increased with age (p<0.01) while hepatitis B infection did not.

CONCLUSION

Hepatitis A infected most aborigines before the age of 15 years. Hepatitis B seldom infected people after the age of 15 years, while hepatitis C continued to infect people who were older. Geographic factors are important for hepatitis C infection, whereas for hepatitis B infection, in addition ethnicity is also important.

T-DNA insertional mutagenesis for functional genomics in rice

We have produced 22 090 primary transgenic rice plants that carry a T-DNA insertion, which has resulted in 18 358 fertile lines. Genomic DNA gel-blot and PCR analyses have shown that approximately 65% of the population contains more than one copy of the inserted T-DNA. Hygromycin resistance tests revealed that transgenic plants contain an average of 1.4 loci of T-DNA inserts. Therefore, it can be estimated that approximately 25 700 taggings have been generated. The binary vector used in the insertion contained the promoterless beta-glucuronidase (GUS) reporter gene with an intron and multiple splicing donors and acceptors immediately next to the right border. Therefore, this gene trap vector is able to detect a gene fusion between GUS and an endogenous gene, which is tagged by T-DNA. Histochemical GUS assays were carried out in the leaves and roots from 5353 lines, mature flowers from 7026 lines, and developing seeds from 1948 lines. The data revealed that 1.6-2.1% of tested organs were GUS-positive in the tested organs, and that their GUS expression patterns were organ- or tissue-specific or ubiquitous in all parts of the plant. The large population of T-DNA-tagged lines will be useful for identifying insertional mutants in various genes and for discovering new genes in rice.

The first organo-templated cobalt phosphate with a zeolite topology

An organic molecule containing cobalt phosphate (denoted CoPO-GIS) which is isostructural with the zeolite gismondine has been synthesized under solvothermal conditions by using [Co(en)3]Cl3 and phosphoric acid as the reactants and ethylene glycol as the solvent. CoPO-GIS ((H3NCH2CH2NH3)0.5.CoPO4) crystallizes in the monoclinic space group C2/c with a = 14.744(3) A, b = 8.850(3) A, c = 10.062(3) A, beta = 131.609(19) degrees, and Z = 8. The structure consists of a 3-D network of strictly alternating CoO4 and PO4 tetrahedra interconnected by oxygen bridges, and the charge-balancing diprotonated ethylenediamine cations are highly ordered in the cages of the CoPO4 framework. CoPO-GIS is the only amine-containing cobalt phosphate with a known zeolite topology.

[Analysis of wavelet scalogram of blood flow ultrasonic Doppler signal]

OBJECTIVE

To study the power spectrum density of blood flow ultrasonic Doppler signal using wavelet analysis.

METHOD

Doppler signal of blood flow in human common carotid artery was studied with wavelet scalogram analysis, an affine smoothing Wigner-Ville transform with a constant "Q" character.

RESULT

Wavelet scalogram of blood flow ultrasonic signal had a higher distinguishability than STFT spectrogram in the low frequency portion, but had poorer decussation terms than spectrogram.

CONCLUSION

It is practicable to estimate the spectrum of Doppler signals of blood flow by the wavelet analysis method. And this can be used in low speed blood flow for higher resolution of spectrum in the low frequency portion.

[Multiprocessor study and design for digital color ultrasonic medical imaging system]

In this paper, the design of a multi-processor for digital color ultrasonic medical imaging system is discussed. It is a shared memory multiprocessor of MIMD architecture. The whole system is devided into several parts according to the complexity of the signal-processing, and each part is allocated a certain duties. Besides, the solving method of multiprocessor's bus conflicting is discussed and an architecture block diagram is given in the paper.

Purification of membrane-bound lactoferrin from the human milk fat globule membrane

Although lactoferrin is known as a basic soluble glycoprotein, the presence of the membrane-bound form of this protein has also been demonstrated in human milk. Membrane-bound lactoferrin was extracted from the human milk fat globule membrane with a detergent mixture of 1% Tween-20, 0.5% C12E8, and 0.5 M KCl in 20 mM Tris-HCl (pH 7.4). Lactoferrin in the detergent-soluble fraction was purified by affinity chromatography with Concanavalin A and by hydrophobic chromatography with phenyl-Superose. The purified protein gave a single band of 80 kDa by SDS-PAGE. Its N-terminal amino acid sequence was consistent with that of human lactoferrin.

Role of the Sp family of transcription factors in the ontogeny of growth hormone receptor gene expression

The growth hormone (GH) receptor is essential for the actions of growth hormone on postnatal growth and metabolism. GH receptor transcripts are characterized by the presence of disparate 5'-untranslated exons. Factors regulating the expression of the GC rich L2 transcript of the murine GH receptor gene have hitherto remained unidentified. To characterize the mechanisms regulating expression of the L2 transcript, primer extension and ribonuclease protection assays were used to identify transcription start sites in RNA from liver of adult mice. Transient transfection experiments revealed that 2.0 kilobase pairs of the L2 5'-flanking sequence exhibited promoter activity in BNL CL.2 (mouse liver) cells, CV-1 (monkey kidney) cells, and HRP.1 trophoblasts. Deletional analysis localized a major regulatory region to within 75 base pairs of the 5' transcription start site. Sequence analysis revealed that the region contained consensus binding sites for the Sp family of transcription factors. Standard gel shift and supershift analysis using liver nuclear extracts established that Sp1 and Sp3 bound this regulatory element. Transfection of wild type but not mutant decoy oligonucleotides into BNL CL.2 cells decreased the activity of the L2 promoter. Overexpression of Sp1 and Sp3 protein in Drosophila Schneider cells established that Sp3 is more potent than Sp1 in transactivating the L2 promoter. Co-transfection experiments further established that Sp1 antagonizes the activity of Sp3 to transactivate the L2 promoter. Western blot analysis of liver nuclear extracts revealed that the levels of Sp3 increase significantly after birth, suggesting a role for the Sp family of transcription factors in controlling the fetal to postnatal increase in GH receptor gene expression.

The Aspergillus nidulans sfaD gene encodes a G protein beta subunit that is required for normal growth and repression of sporulation

flbA encodes an Aspergillus nidulans RGS (regulator of G protein signaling) domain protein that antagonizes FadA (G(i)alpha-subunit of heterotrimeric G protein)-mediated growth signaling to allow asexual development. We previously defined and characterized five suppressors of flbA (sfa) loss-of-function mutations and showed that one suppressor (sfaB) resulted from a novel dominant-negative allele of fadA. In this report we show that a second suppressor gene (sfaD) is predicted to encode the beta subunit of a heterotrimeric G protein. Deletion of sfaD suppressed all defects resulting from complete loss-of-flbA function mutations, caused a hyperactive sporulation phenotype and severely reduced vegetative growth. However, the sfaD deletion could not suppress the growth activation caused by dominant-activating fadA alleles, indicating that constitutively active FadA can cause proliferative growth in the absence of Gbetagamma signaling. We propose that SfaD and FadA are both positive growth regulators with partially overlapping functions and that FlbA has an important role in controlling the activities of both proteins. Inactivation of signaling events stimulated by both components of the heterotrimeric G protein is essential for both sexual and asexual sporulation.

Prevalence of TT virus DNA in eastern Taiwan aborigines

We studied the prevalence of TT virus (TTV) DNA in the general population of the eastern Taiwan aborigine villages, about 11% (34 of 317). There is no association between the presence of HBsAg and TTV DNA or between the presence of HCV RNA and TTV DNA. Therefore, the infection of HBV or HCV and the presence of TTV DNA appear to be independent from each other. The association between the presence of TTV DNA and the elevated alanine aminotransferase (and/or aspartate aminotransferase) activity was also investigated. The presence of TTV DNA was not found to be correlated with abnormal liver function (P = 0.574) when age, gender, and the presence of HBsAg, HCV RNA, and HGV RNA were all considered in the assay. The sequence homology of TTV DNA fragments between different isolates from Taiwan and N22 (the clone obtained from the original prototype strain) from Japan ranged from 84 to 97%. The recombinant protein encoded by the TTV DNA fragment corresponding to the open reading frame of N22 was expressed in E. coli successfully. However, no serum response against the recombinant protein was detected.

Purification and properties of bacteriolytic enzymes from Bacillus licheniformis YS-1005 against Streptococcus mutans

To find a novel lytic enzyme against cariogenic Streptococci, strains showing strong lytic activity have been screened from soil using Streptococcus mutans. A strain identified as Bacillus licheniformis secreted two kinds of lytic enzymes, which were purified by methanol precipitation, CM-cellulose chromatography, gel filtration, and hydroxyapatite chromatography. The molecular weights of these two enzymes, L27 and L45, were 27,000 and 45,000, respectively. Optimum pH and temperature of both enzymes for lytic activity were pH 8 and 37 degrees C. L27 and L45 digest the peptide linkage between L-Ala and D-Glu in peptidoglycan of Streptococcus mutans. The lytic activity was highly specific for Streptococcus mutans, suggesting their potential use as a dental care product.

Extragenic suppressors of loss-of-function mutations in the aspergillus FlbA regulator of G-protein signaling domain protein

We showed previously that two genes, fl bA and fadA, have a major role in determining the balance between growth, sporulation, and mycotoxin (sterigmatocystin; ST) production by the filamentous fungus Aspergillus nidulans. fadA encodes the alpha subunit for a heterotrimeric G-protein, and continuous activation of FadA blocks sporulation and ST production while stimulating growth. fl bA encodes an A. nidulans regulator of G-protein signaling (RGS) domain protein that antagonizes FadA-mediated signaling to allow development. To better understand FlbA function and other aspects of FadA-mediated growth control, we have isolated and characterized mutations in four previously undefined genes designated as sfaA, sfaC, sfaD, and sfaE (suppressors of flbA), and a new allele of fadA (fadAR205H), all of which suppress a fl bA loss-of-function mutation ( fl bA98). These suppressors overcome fl bA losses of function in both sporulation and ST biosynthesis. fadAR205H, sfaC67, sfaD82, and sfaE83 mutations are dominant to wild type whereas sfaA1 is semidominant. sfaA1 also differs from other suppressor mutations in that it cannot suppress a fl bA deletion mutation (and is therefore allele specific) whereas all the dominant suppressors can bypass complete loss of fl bA. Only sfaE83 suppressed dominant activating mutations in fadA, indicating that sfaE may have a unique role in fadA- fl bA interactions. Finally, none of these suppressor mutations bypassed fl uG loss-of-function mutations in development-specific activation.

Induction of quinone reductase by a methanol extract of Scutellaria baicalensis and its flavonoids in murine Hepa 1c1c7 cells

The effect of extracts of scutellariae radix (Scutellaria baicalensis Georgi) and its flavonoids, baicalin, baicalein and wogonin, on induction of quinone reductase (QR) in the Hepa 1c1c7 murine hepatoma cell line was examined. A significant and dose-dependent induction of QR activity was observed in the methanol extract of scutellariae radix and baicalin. HPCL analysis showed that baicalin was contained as a main component in the methanol extract of scutellariae radix, indicating that baicalin may be the major active principle of QR induction mediated by scutellariae radix extract. To elucidate the mechanism of baicalin-mediated induction of QR enzyme activity, the effect on QR mRNA levels in Hepa 1c1c7 cell cultures was investigated. Using reverse transcriptase-polymerase chain reaction techniques, time- and dose-dependent induction of QR mRNA levels by baicalin were demonstrated in Hepa 1c1c7 cells. On the basis of these results, the scutellariae radix extract or baicalin can be regarded as a readily available, promising, novel cancer chemopreventive agent.

Coordinate control of secondary metabolite production and asexual sporulation in Aspergillus nidulans

Microbial secondary metabolite production is frequently associated with developmental processes such as sporulation, but there are few cases where this correlation is understood. Recent work with the filamentous fungus Aspergillus nidulans has provided new insights into the mechanisms coordinating production of the toxic secondary metabolite sterigmatocystin with asexual sporulation. These processes have been shown to be linked through a common need to inactivate a heterotrimeric G protein dependent signaling pathway that, when active, serves to stimulate growth while blocking both sporulation and sterigmatocystin biosynthesis.

Topographic localization of neuropeptide Y mRNA in the monkey brainstem

Neuropeptide Y (NPY) modulates cardiovascular, feeding and reproductive functions. Peripheral neurohumoral inputs from these systems are integrated and transformed into efferent signals in the brainstem. Detailed mapping of NPY-expressing cells in the brainstem has not been established in primates. In this report we utilized the in situ hybridization (ISH) method to identify brainstem areas that contain NPY mRNA in four ovariectomized rhesus macaques treated with estradiol-17beta. A 35S-labeled human NPY cRNA probe was used for ISH in paraformaldehyde-fixed brainstem blocks that were sectioned at 20 microm thickness. In the upper cervical spinal cord, NPY mRNA signals were confined to the substantia gelatinosa along the spinal tract of the trigeminal nerve. In the medulla, NPY images were found in the nucleus of solitary tract, dorsal motor nucleus of vagus nerve, nucleus of the spinal tract of trigeminal nerve, lateral reticular nucleus and the reticular formation. In the pons, NPY mRNA was confined to cells in the locus coeruleus and the nucleus of raphe. NPY signals were observed in the ventral portion of the periaqueductal grey, the dorsal nucleus of raphe and the reticular formation of mesencephalon in the midbrain. Whereas the brainstem distribution of NPY-containing cells in the rhesus macaque overlap those regions that are rich in catecholamines, NPY perikarya were also present in 'noncatecholaminergic' areas. For example, the reticular formation of both the medulla and mesencephalon abundantly expressed NPY mRNA. The functional significance of, and the effects of estrogen on, these patterns in NPY expression is unknown.

Transcription factor MSY-1 regulates expression of the murine growth hormone receptor gene

Previous studies identified and partially characterized a 42-base pair regulatory element in the 5'-flanking region of the L1 transcript of the murine growth hormone (GH) receptor gene that interacted with both double- and single-stranded DNA-binding proteins. We present evidence that the double-stranded DNA-binding protein is NF-Y, a CCAAT box-binding protein. Experiments with a dominant negative form of NF-Y indicate that NF-Y does not play a direct role in regulating the activity of the FP42 element. A cDNA clone that specifically interacts with the upper (coding) strand of the regulatory element was isolated by screening a cDNA expression library using the Southwestern technique. DNA sequencing, electrophoretic mobility shift assay, Southwestern blot analysis, and supershift EMSA confirm the identity of the single-stranded binding protein to be MSY-1, a DNA-binding protein that is evolutionary conserved from prokaryotes to eukaryotes. Mapping of single-stranded DNA configurations reveals that MSY-1 can facilitate the formation of single-stranded DNA regions in the GH receptor 5'-flanking region. Transient transfection experiments support the role of MSY-1 as a repressor of GH receptor gene activation. Southwestern blot analysis indicates that the levels of nuclear MSY-1 are decreased in the livers of pregnant mice, suggesting a role for MSY-1 in the increased expression of the GH receptor during pregnancy.

Cloning of the thermostable phytase gene (phy) from Bacillus sp. DS11 and its overexpression in Escherichia coli

Phytase hydrolyzes phytate to release inorganic phosphate, which would decrease the addition of phosphorus to feedstuffs for monogastric animals and thus reduce environmental pollution. The gene encoding phytase from Bacillus sp. DS11 was cloned in Escherichia coli and its sequence determined. A 560-bp DNA fragment was used as a probe to screen the genomic library. It was obtained through PCR of Bacillus sp. DS11 chromosomal DNA and two oligonucleotide primers based on N-terminal amino acid sequences of the purified protein and the cyanogen bromide-cleaved 21-kDa fragment. The phy cloned was encoded by a 2.2-kb fragment. This gene comprises 1152 nucleotides and encodes a polypeptide of 383 amino acids with a deduced molecular mass of 41,808 Da. Phytase was produced to 20% content of total soluble proteins in E. coli BL21 (DE3) using the pET22b(+) vector with the inducible T7 promoter. This is the first nucleic sequence report on phytase from a bacterial strain.

Isolation and sequence analysis of metalloprotease gene from Vibrio mimicus

The vmc gene encoding a metalloprotease of Vibrio mimicus (ATCC 33653) was cloned in Escherichia coli and sequenced. The vmc gene contained 1884 nt sequence which codes a polypeptide of 628 amino acids with a predicted molecular mass of 71,275 Da. The deduced amino acid sequence had the similarity of 68.5% with V. parahaemolyticus metalloprotease. The consensus sequence of a zinc binding motif (HEXXH) was identified to be HEYTH. The zymography analysis showed a gelatinolytic protein band around molecular mass of 61 kDa, and this result suggested that the cloned metalloprotease may undergo processing during secretion.

Asexual sporulation in Aspergillus nidulans

The formation of mitotically derived spores, called conidia, is a common reproductive mode in filamentous fungi, particularly among the large fungal class Ascomycetes. Asexual sporulation strategies are nearly as varied as fungal species; however, the formation of conidiophores, specialized multicellular reproductive structures, by the filamentous fungus Aspergillus nidulans has emerged as the leading model for understanding the mechanisms that control fungal sporulation. Initiation of A. nidulans conidiophore formation can occur either as a programmed event in the life cycle in response to intrinsic signals or to environmental stresses such as nutrient deprivation. In either case, a development-specific set of transcription factors is activated and these control the expression of each other as well as genes required for conidiophore morphogenesis. Recent progress has identified many of the earliest-acting genes needed for initiating conidiophore development and shown that there are at least two antagonistic signaling pathways that control this process. One pathway is modulated by a heterotrimeric G protein that when activated stimulates growth and represses both asexual and sexual sporulation as well as production of the toxic secondary metabolite, sterigmatocystin. The second pathway apparently requires an extracellular signal to induce sporulation-specific events and to direct the inactivation of the first pathway, removing developmental repression. A working model is presented in which the regulatory interactions between these two pathways during the fungal life cycle determine whether cells grow or develop.

Topographic comparison of the expression of norepinephrine transporter, tyrosine hydroxylase and neuropeptide Y mRNA in association with dopamine beta-hydroxylase neurons in the rabbit brainstem

In mammalian species, ovulation occurs following a massive release of hypothalamic gonadotropin-releasing hormone (GnRH). Several chemicals, including norepinephrine (NE) and neuropeptide Y (NPY), are responsible for the initiation and/or magnitude and duration of this pre-ovulatory GnRH surge. In the central nervous system, NE neural cell bodies are located in the brainstem; some are co-localized with NPY neurons and/or co-express the NE transporter (NET) gene which dictates NET protein production. The activity of NET at NE terminals is critical for synaptic NE function. In the rabbit, coitus induces a hypothalamic NE release which precedes the GnRH surge. We hypothesize that the coital stimulus is transmitted to the brainstem and transformed and integrated into GnRH-stimulating signals via NE, NET and/or NPY. However, very little is known about the distribution of cells expressing NET, NPY and tyrosine hydroxylase (TH, the rate-limiting enzyme of NE synthesis) in this species. Therefore, we utilized the sensitive in situ hybridization technique to identify the presence of these messages in conjunction with the location of NE cells, the latter being marked by dopamine beta-hydroxylase (DBH), the specific enzyme for NE synthesis. Three non-mated New Zealand White does were perfused with 4% paraformaldehyde and their brainstems were sectioned at 20-micron thick between 2 mm caudal to the obex and the rostral pons. Serial sections were immunohistochemically stained for DBH and hybridized with rabbit-specific TH and NET cRNAs and a human NPY probe. The data suggest that several DBH-positive areas in the medulla expressed one or more messages, i.e. the lateral tegmentum (A1) and the nucleus of the solitary tract (A2) expressed all three mRNAs, the area postrema (AP) contained NET and TH mRNAs but not NPY cells. In the pons, the locus coeruleus (LC), subnucleus of coeruleus (LCs) and lateral tegmental nuclei (A5) expressed NET and TH mRNAs but contained little or no NPY message. The distribution patterns of TH and NET appeared to be similar in the LC, LCs, A2 and AP.

Dominant mutations affecting both sporulation and sterigmatocystin biosynthesis in Aspergillus nidulans

The initiation of conidiophore development in the filamentous fungus Aspergillus nidulans is a complex process requiring the activities of several genes including fluG, flbA, flbB, flbC, flbD, and flbE. Recessive mutations in any one of these genes result in greatly reduced expression of the brlA developmental regulatory gene and a colony morphology described as fluffy. These fluffy mutants have somewhat diverse phenotypes but generally grow as undifferentiated masses of vegetative hyphae to form large cotton-like colonies. In this paper we describe a genetic screen to identify dominant mutations resulting in similar fluffy colony morphologies. We have identified 36 dominant fluffy mutant strains and shown that 29 of these mutants have greatly reduced brlA expression as compared to wild-type. In addition, we have found that 19 of these mutants are not only developmentally altered but also fail to produce the toxic, carcinogenic, secondary metabolite sterigmatocystin. At least three of the mutants isolated result from dominant activating mutations in fadA which encodes the G alpha subunit of a heterotrimeric G-protein. Another of the mutants results from a dominant interfering mutation in brlA. We discuss the approaches taken to characterize these potentially important regulators of growth, development and secondary metabolism.