Ecotoxicological risk assessment due to the presence of bisphenol A and caffeine in surface waters in the Sinos River Basin - Rio Grande do Sul - Brazil / Risco ecotoxicológico devido à presença de bisfenol A e cafeína nas águas superficiais na Bacia do Rio Sinos - Rio Grande do Sul - Brasil

Abstract Bisphenol A (BPA) is an emerging contaminant, regularly detected in aquatic ecosystems, considered as an endocrine disrupting compound (EDC). Caffeine is another chemical related to human activity, often found in surface waters. The objective of this study was to evaluate the ecotoxicological risk due to BPA and caffeine in water samples from the Sinos River basin, Rio Grande do Sul, Brazil. Water samples were collected at three sites monthly from May 9 th, 2016 to April 11th, 2017 (n = 36). BPA concentrations in water samples collected were in the range of not detected to 517 ng L-1 and caffeine concentrations in the range of 41.7 to 28,439.6 ng L-1. The concentration of BPA in the analyzed samples had a moderate correlation with caffeine (rs = 0.402). High ecotoxicological risk for BPA was characterized in 77.77% of samples, with 11.11% presenting medium and 11.1% presenting low risk. For caffeine 13.9%, 50% and 36.11% of the samples presented high, medium and low risk, respectively. Caffeine concentrations in water can be used as predictors of BPA concentrations above 10 ng L-1, the lower concentration of ecotoxicological risk, with specificity of 66.7% and sensitivity of 70.4%. The assessment of aquatic risks has shown that both investigated compounds pose risks to organisms in the studied surface waters, mouth of the Pampa stream, mouth of the Luiz Rau stream and catchment point for public supply in Lomba Grande.

Resumo Bisfenol A (BPA) é um contaminante emergente regularmente detectado em ecossistemas aquáticos, é considerado um agente modificador endócrino (EDC). Além disso, outro produto químico relacionado com atividade humana, encontrado com frequência nas águas superficiais, é a cafeína. O objetivo deste estudo foi avaliar a ocorrência de risco ecotoxicológico devido a BPA e cafeína em amostras de água da Bacia Hidrográfica do Rio Sinos, Rio Grande do Sul, Brasil. Foram coletadas amostras de água em três locais mensalmente no período de 9 de maio de 2016 a 11 de abril de 2017 (n = 36). As concentrações de BPA em amostras de água coletadas estavam na faixa de não detectada a 517 ng L-1 e concentrações de cafeína na faixa de 41,7 a 28,439,6 ng L-1. A concentração de BPA nas amostras analisadas apresentou correlação moderada com a cafeína (rs = 0,402). Alto risco ecotoxicológico para BPA foi caracterizado em 77,77% das amostras, com 11,11% apresentando médio e 11,1% apresentando baixo risco. Para cafeína 13,9%, 50% e 36,11% das amostras apresentaram risco alto, médio e baixo, respectivamente. Concentrações de cafeína em água podem ser utilizadas como preditoras de concentrações de BPA acima de 10 ng L-1, menor concentração de risco ecotoxicológico, com especificidade de 66,7% e sensibilidade de 70,4%. A avaliação dos riscos aquáticos revelou que ambos os compostos investigados representam risco para os organismos nas águas superficiais estudadas, foz do arroio Pampa, foz do arroio Luiz Rau e ponto de captação para abastecimento público em Lomba Grande.

Iron diapirs entrain silicates to the core and initiate thermochemical plumes.

Segregation of the iron core from rocky silicates is a massive evolutionary event in planetary accretion, yet the process of metal segregation remains obscure, due to obstacles in simulating the extreme physical properties of liquid iron and silicates at finite length scales. We present new experimental results studying gravitational instability of an emulsified liquid gallium layer, initially at rest at the interface between two glucose solutions. Metal settling coats liquid metal drops with a film of low density material. The emulsified metal pond descends as a coherent Rayleigh-Taylor instability with a trailing fluid-filled conduit. Scaling to planetary interiors and high pressure mineral experiments indicates that molten silicates and volatiles are entrained toward the iron core and initiate buoyant thermochemical plumes that later oxidize and hydrate the upper mantle. Surface volcanism from thermochemical plumes releases oxygen and volatiles linking atmospheric growth to the Earth's mantle and core processes.

Ecotoxicological risk assessment due to the presence of bisphenol A and caffeine in surface waters in the Sinos River Basin - Rio Grande do Sul - Brazil

Abstract Bisphenol A (BPA) is an emerging contaminant, regularly detected in aquatic ecosystems, considered as an endocrine disrupting compound (EDC). Caffeine is another chemical related to human activity, often found in surface waters. The objective of this study was to evaluate the ecotoxicological risk due to BPA and caffeine in water samples from the Sinos River basin, Rio Grande do Sul, Brazil. Water samples were collected at three sites monthly from May 9 th, 2016 to April 11th, 2017 (n = 36). BPA concentrations in water samples collected were in the range of not detected to 517 ng L-1 and caffeine concentrations in the range of 41.7 to 28,439.6 ng L-1. The concentration of BPA in the analyzed samples had a moderate correlation with caffeine (rs = 0.402). High ecotoxicological risk for BPA was characterized in 77.77% of samples, with 11.11% presenting medium and 11.1% presenting low risk. For caffeine 13.9%, 50% and 36.11% of the samples presented high, medium and low risk, respectively. Caffeine concentrations in water can be used as predictors of BPA concentrations above 10 ng L-1, the lower concentration of ecotoxicological risk, with specificity of 66.7% and sensitivity of 70.4%. The assessment of aquatic risks has shown that both investigated compounds pose risks to organisms in the studied surface waters, mouth of the Pampa stream, mouth of the Luiz Rau stream and catchment point for public supply in Lomba Grande.

Resumo Bisfenol A (BPA) é um contaminante emergente regularmente detectado em ecossistemas aquáticos, é considerado um agente modificador endócrino (EDC). Além disso, outro produto químico relacionado com atividade humana, encontrado com frequência nas águas superficiais, é a cafeína. O objetivo deste estudo foi avaliar a ocorrência de risco ecotoxicológico devido a BPA e cafeína em amostras de água da Bacia Hidrográfica do Rio Sinos, Rio Grande do Sul, Brasil. Foram coletadas amostras de água em três locais mensalmente no período de 9 de maio de 2016 a 11 de abril de 2017 (n = 36). As concentrações de BPA em amostras de água coletadas estavam na faixa de não detectada a 517 ng L-1 e concentrações de cafeína na faixa de 41,7 a 28,439,6 ng L-1. A concentração de BPA nas amostras analisadas apresentou correlação moderada com a cafeína (rs = 0,402). Alto risco ecotoxicológico para BPA foi caracterizado em 77,77% das amostras, com 11,11% apresentando médio e 11,1% apresentando baixo risco. Para cafeína 13,9%, 50% e 36,11% das amostras apresentaram risco alto, médio e baixo, respectivamente. Concentrações de cafeína em água podem ser utilizadas como preditoras de concentrações de BPA acima de 10 ng L-1, menor concentração de risco ecotoxicológico, com especificidade de 66,7% e sensibilidade de 70,4%. A avaliação dos riscos aquáticos revelou que ambos os compostos investigados representam risco para os organismos nas águas superficiais estudadas, foz do arroio Pampa, foz do arroio Luiz Rau e ponto de captação para abastecimento público em Lomba Grande.

Montelukast reduces seizures in pentylenetetrazol-kindled mice.

Cysteinyl leukotrienes (CysLTs) have been implicated in seizures and kindling; however, the effect of CysLT receptor antagonists on seizure frequency in kindled animals and changes in CysLT receptor expression after pentylenetetrazol (PTZ)-induced kindling have not been investigated. In this study, we evaluated whether the CysLT1 inverse agonist montelukast, and a classical anticonvulsant, phenobarbital, were able to reduce seizures in PTZ-kindled mice and alter CysLT receptor expression. Montelukast (10 mg/kg, sc) and phenobarbital (20 mg/kg, sc) increased the latency to generalized seizures in kindled mice. Montelukast increased CysLT1 immunoreactivity only in non-kindled, PTZ-challenged mice. Interestingly, PTZ challenge decreased CysLT2 immunoreactivity only in kindled mice. CysLT1 antagonists appear to emerge as a promising adjunctive treatment for refractory seizures. Nevertheless, additional studies are necessary to evaluate the clinical implications of this research.

Montelukast reduces seizures in pentylenetetrazol-kindled mice

Cysteinyl leukotrienes (CysLTs) have been implicated in seizures and kindling; however, the effect of CysLT receptor antagonists on seizure frequency in kindled animals and changes in CysLT receptor expression after pentylenetetrazol (PTZ)-induced kindling have not been investigated. In this study, we evaluated whether the CysLT1 inverse agonist montelukast, and a classical anticonvulsant, phenobarbital, were able to reduce seizures in PTZ-kindled mice and alter CysLT receptor expression. Montelukast (10 mg/kg, sc) and phenobarbital (20 mg/kg, sc) increased the latency to generalized seizures in kindled mice. Montelukast increased CysLT1 immunoreactivity only in non-kindled, PTZ-challenged mice. Interestingly, PTZ challenge decreased CysLT2 immunoreactivity only in kindled mice. CysLT1 antagonists appear to emerge as a promising adjunctive treatment for refractory seizures. Nevertheless, additional studies are necessary to evaluate the clinical implications of this research.

Adenoviruses of canine and human origins in stool samples from free-living pampas foxes (Lycalopex gymnocercus) and crab-eating foxes (Cerdocyon thous) in São Francisco de Paula, Rio dos Sinos basin.

The spread of enteric viruses of domestic animals and human beings to wild species can be facilitated by the resistance of these viruses on the environment and their ability to be transmitted by water and contaminated food. The health status of the populations of pampas foxes Lycalopex gymnocercus) and crab-eating foxes (Cerdocyon thous) is largely unknown and the landscapes occupied by these animals in southern Brazil have been threatened by human occupation and expansion of agriculture. In this work, the search of genomes of human and canine adenoviruses in feces from these wild carnivores was used to track the dissemination of domestic animals and human pathogens to the free-living populations in a wildlife reserve located in southern Brazil. This was performed by virus-specific differential real-time polymerase chain reactions (qPCR) on stool specimens, avoiding capture and additional stress to the animals. Genus-specific conventional reverse-transcriptase PCR (RT-PCR) was complementarily performed aiming the detection of enteroviruses (EV) and rotaviruses (RV) on these same samples. HAdV genomes were found on 14 out of the 17 (82.35%) stool samples analysed, whereas CAV was found co-infecting 5 of these samples. RV genomes were detected on 7 of the 17 samples (41.18%) and all samples were negative for EV. The results point to the dispersion of HAdV and RV at a high rate to these species of South American wild carnivores, which can be an effect of growing anthropisation of the habitat of these animals.

Moving beyond classical markers of water quality: detection of enteric viruses and genotoxicity in water of the Sinos River.

It is well recognized that the classical biological and chemical markers of environmental pollution do not necessarily indicate the presence or absence of emerging threats to public health, such as waterborne viruses and genotoxicants. The purpose of this preliminary study was to evaluate the presence of material of enteroviruses (EV), rotavirus (RV) and adenovirus (AdV) and genotoxicity in water samples from points of routine monitoring of water quality in the main course of the Sinos River. The points are classified into different levels of pollution in accordance to the Brazilian federal regulations. Viral genomes from EV, AdV were detected in two of the 4 collection points regardless of the level of urbanisation of the surrounding areas. In contrast, genotoxicity was not observed in piava (Leporinus obtusidens) fingerlings cultivated on these same water samples. Results were compared with classical physical, chemical and microbiological parameters. There was no clear evidence of association between any of the classical markers and the presence of viral genomes in the water samples tested.

Human adenovirus (HAdV), human enterovirus (hEV), and genogroup A rotavirus (GARV) in tap water in southern Brazil.

The effects of viral gastroenteritis are more devastating in children than in any other age category. Thus, children exposed to the consumption of low quality water are at an increased risk of infection, especially in regions where sanitation is inadequate. The present study aimed to provide a survey of the occurrence of representative enteric viruses: human adenovirus (HAdV), human enteroviruses (hEV), and genogroup A rotavirus (GARV) in tap water samples collected in public schools located at six municipalities of Rio Grande do Sul, southern Brazil. Seventy-three schools were included in the study and tap water samples were analyzed by conventional PCR for the presence of HAdV, hEV, and GARV genomes. hEV showed the highest detection rate (27.4%), followed by HAdV (23.3%), and GARV (16.4%). New approaches to water monitoring should be considered to promote a better water quality and reduce the risk of waterborne diseases, especially considering drinking water to be served to vulnerable individuals.

First description of Adenovirus, Enterovirus, Rotavirus and Torque teno virus in water samples collected from the Arroio Dilúvio, Porto Alegre, Brazil.

Adenovirus (AdV), enterovirus (EV), genogroup A rotaviruses (GARV) and Torque teno virus (TTV) are non-enveloped viral agents excreted in feces and so may contaminate water bodies. In the present study, the molecular detection of these viruses was performed in samples of surface water collected from the Arroio Dilúvio, a waterstream that crosses the city of Porto Alegre, RS, Brazil, receiving great volumes of non-treated sewage from a large urban area. Sampling was performed during 2009, in three different occasions (January, April and September). The highest detection rate was observed for EV (64.28%), followed by TTV (28.57%) and AdV (21.43%). Rotaviruses were not detected. More than on kind of tested virus was detected in five (35. 71%) of 14 samples. January was the month with the highest viral detection rate, being all samples, collected in this month, positive for at least one group of tested virus. The correlation between the detection of these different viral agents and environmental factors is discussed. To the knowledge of the authors, this is the first description of viral genomes in water samples taken from the Arroio Dilúvio, Porto Alegre (Brazil).

Assessment of enteric viruses in a sewage treatment plant located in Porto Alegre, southern Brazil.

In order to verify the microbial quality of the influents and effluents of one STP from southern Brazil, an eight-month survey was conducted to examine the presence of total and fecal coliforms and of adenovirus (HAdV), enterovirus (EV), genogroup A rotaviruses (GARV) and Torque teno virus (TTV), in treated effluent samples from São João/Navegantes STP, Porto Alegre (Brazil). A total of 16 samples were collected, eight of influent (raw sewage, prior to treatment), and the other eight of the effluent (post-treatment sewage). Total and fecal coliform levels ranging from 3.6 × 10(4) to 4.4 × 10(7) MPN/100 mL and 2.9 × 10(3) to 1.7 × 10(7) MPN/100 mL, were detected in all samples. In raw sewage, HAdV (25%) and GARV (28.6%) viral genomes were detected. The analysis of effluent samples revealed the presence of HAdV (50%), EV (37.5%), and TTV (12.5%) genomic fragments. All samples, regardless of the month analysed, presented detection of a least one virus genus, except for in April. Higher virus detection rates were observed in treated sewage samples (62.5%), and in 80% of them (effluent positive samples) HAdV was detected. Results showed that improvements in sewage monitoring and treatment processes are necessary to reduce the viral and bacterial load on the environment in southern Brazil. To the knowledge of the authors, this is the first study showing the monitoring of viral genomes in influent and effluent samples from a STP located in Porto Alegre (Rio Grande do Sul, Brazil), southern Brazil.

Immunoadjuvant and anti-inflammatory plant saponins: characteristics and biotechnological approaches towards sustainable production.

Saponins can be classified as triterpenoid (C30) or steroidal (C27), based on their carbon nucleus (aglycone). Sugar residues are linked to the aglycone, conferring an amphiphilic nature on these molecules, which is relevant for their biological activities. Saponins include a large variety of molecules that find several applications in pharmacology. Saponins have been shown to display immunoadjuvant, anti-inflammatory, antiplatelet, hypocholesterolemic, antitumoral, anti-HIV, antibacterial, insecticide, fungicide and anti-leishmanial activities. Anti-inflammatory medicines are increasingly demanded to treat various forms of arthritis in aging and obese populations and to help reduce the doses and duration of conventional corticotherapy with less side effects and without immunosuppression. The vaccine market for both human and veterinary uses is close to US$ 15 billion, progressively inflated by the recurrent threat of global pandemics.This paper provides an overview of recent advances (main focus on the last five years) on plant saponins that show anti-inflammatory and/or immunoadjuvant activities: source plants, isolation procedures, mechanism of action and biotechnological approaches towards sustainable production of bioactive saponins. Special attention is given to ginseng and Quillaja saponins. Strategies based on plant cultivation, cell and tissue culture, elicitation, and metabolic engineering for improved production of saponins are described. Future directions for research in the field and strategies to overcome bottlenecks are also discussed.

Bleomycin lung toxicity: who are the patients with increased risk?

Bleomycin is an antibiotic drug with anticancer properties produced by Streptomyces verticillus [Cheson BD. Pharmacology of cancer chemotherapy: miscellaneous chemotherapeutic agents. In De Vita Jr. VT, Hellmann S, Rosenberg AS, editors. Cancer principles and practice of oncology. Lippincott Willians & Wilkins; 2001. p. 452-459]. It was isolated in 1966 by Umezawa et al. and its mechanism of action is breaking the DNA double helix by the production of free radicals, which is oxygen and iron dependent [Cheson BD. Pharmacology of cancer chemotherapy: miscellaneous chemotherapeutic agents. In De Vita Jr. VT, Hellmann S, Rosenberg AS, editors. Cancer principles and practice of oncology. Lippincott Willians & Wilkins; 2001. p. 452-459; Hay J, Shahzeidi S, Laurent G. Mechanisms of bleomycin-induced lung damage. Arch Toxicol 1991;65:81-94]. Bleomycin may be inactivated by bleomycin hidrolase presents in normal and tumoral cells [Cheson BD. Pharmacology of cancer chemotherapy: miscellaneous chemotherapeutic agents. In De Vita Jr. VT, Hellmann S, Rosenberg AS, editors. Cancer principles and practice of oncology. Lippincott Willians & Wilkins; 2001. p. 452-459; Hay J, Shahzeidi S, Laurent G. Mechanisms of bleomycin-induced lung damage. Arch Toxicol 1991;65:81-94; Jules-Elysee K, White DA. Bleomycin-induced pulmonary toxicity. Clinics Chest Med 1990;11:1-20]. The complex bleomycin-Fe has been the most studied because bleomycin joins the DNA and Fe at the same time, and release of free radicals happens in the presence of molecular oxygen [Hay J, Shahzeidi S, Laurent G. Mechanisms of bleomycin-induced lung damage. Arch Toxicol 1991;65:81-94]. Bleomycin has a renal metabolism with 50% of dose eliminated in 4h after its administration and 70% in the next 24h. Its half-life (T 1/2) is not altered, although the creatinine clearance drops to 25-35 ml/min [Cheson BD. Pharmacology of cancer chemotherapy: miscellaneous chemotherapeutic agents. In De Vita Jr. VT, Hellmann S, Rosenberg AS, editors. Cancer principles and practice of oncology. Lippincott Willians & Wilkins; 2001. p. 452-459; Hay J, Shahzeidi S, Laurent G. Mechanisms of bleomycin-induced lung damage. Arch Toxicol 1991;65:81-94]. This drug has been used as cytostatic treatment of many malignant tumors, such as germ cell tumors, lymphomas, head and neck, and Kaposi's sarcomas [Chen XL, Li WB, Zhou AM et al. Role of endogenous peroxynitrite in pulmonary injury and fibrosis induced by bleomycin A5 in rats. Acta Pharmacol Sin 2003;24:697-702]. Minor important adverse effects are myelossupression, nauseas, vomiting, allergic reactions, mucositis, alopecia, erythema, hyperkeratosis, hypopigmentation, skin ulceration, and acute arthritis [Cheson BD. Pharmacology of cancer chemotherapy: miscellaneous chemotherapeutic agents. In De Vita Jr. VT, Hellmann S, Rosenberg AS, editors. Cancer principles and practice of oncology. Lippincott Willians & Wilkins; 2001. p. 452-459; Hay J, Shahzeidi S, Laurent G. Mechanisms of bleomycin-induced lung damage. Arch Toxicol 1991;65:81-94]. Fever is reported in 20-50% of patients and some of them present hyperthermia [Hay J, Shahzeidi S, Laurent G. Mechanisms of bleomycin-induced lung damage. Arch Toxicol 1991;65:81-94].

Dissolved organic carbon and disinfection by-product precursor release from managed peat soils.

A wetland restoration demonstration project examined the effects of a permanently flooded wetland on subsidence of peat soils. The project, started in 1997, was done on Twitchell Island, in the Sacramento-San Joaquin Delta of California. Conversion of agricultural land to a wetland has changed many of the biogeochemical processes controlling dissolved organic carbon (DOC) release from the peat soils, relative to the previous land use. Dissolved organic C in delta waters is a concern because it reacts with chlorine, added as a disinfectant in municipal drinking waters, to form carcinogenic disinfection byproducts (DBPs), including trihalomethanes (THMs) and haloacetic acids (HAAs). This study explores the effects of peat soil biogeochemistry on DOC and DBP release under agricultural and wetland management. Results indicate that organic matter source, extent of soil organic matter decomposition, and decomposition pathways all are factors in THM formation. The results show that historical management practices dominate the release of DOC and THM precursors. However, within-site differences indicate that recent management decisions can contribute to changes in DOC quality and THM precursor formation. Not all aromatic forms of carbon are highly reactive and certain environmental conditions produce the specific carbon structures that form THMs. Both HAA and THM precursors are elevated in the DOC released under wetland conditions. The findings of this study emphasize the need to further investigate the roles of organic matter sources, microbial decomposition pathways, and decomposition status of soil organic matter in the release of DOC and DBP precursors from delta soils under varying land-use practices.

Effects of the polyubiquitin gene Ubi. U4 leader intron and first ubiquitin monomer on reporter gene expression in Nicotiana tabacum.

We have previously shown by RNA gel blot analyses that the tobacco polyubiquitin-encoding gene Ubi.U4 is expressed in a complex pattern during plant development (Genschik et al., 1994). In order to study its tissue-specific expression, we cloned the fragment containing the -263 bp proximal promoter of the gene, the leader intron and the first ubiquitin monomer in front of the reporter GUS gene. Histochemical analyses for GUS activity during tobacco plant development revealed that the gene is expressed at variable amounts in many plant tissues with high levels in metabolically active and/or dividing cells and in the vascular tissues of the plant. We also analysed the expression pattern of constructs in which either the intron or the intron together with the first ubiquitin monomer were deleted. Our results indicate that the ubiquitin leader intron is not only a quantitative determinant of gene expression but may also influence the tissue-specific expression pattern.

Cell cycle -dependent proteolysis in plants. Identification Of the destruction box pathway and metaphase arrest produced by the proteasome inhibitor mg132

It is widely assumed that mitotic cyclins are rapidly degraded during anaphase, leading to the inactivation of the cell cycle-dependent protein kinase Cdc2 and allowing exit from mitosis. The proteolysis of mitotic cyclins is ubiquitin/26S proteasome mediated and requires the presence of the destruction box motif at the N terminus of the proteins. As a first attempt to study cyclin proteolysis during the plant cell cycle, we investigated the stability of fusion proteins in which the N-terminal domains of an A-type and a B-type tobacco mitotic cyclin were fused in frame with the chloramphenicol acetyltransferase (CAT ) reporter gene and constitutively expressed in transformed tobacco BY2 cells. For both cyclin types, the N-terminal domains led the chimeric cyclin-CAT fusion proteins to oscillate in a cell cycle-specific manner. Mutations within the destruction box abolished cell cycle-specific proteolysis. Although both fusion proteins were degraded after metaphase, cyclin A-CAT proteolysis was turned off during S phase, whereas that of cyclin B-CAT was turned off only during the late G2 phase. Thus, we demonstrated that mitotic cyclins in plants are subjected to post-translational control (e.g., proteolysis). Moreover, we showed that the proteasome inhibitor MG132 blocks BY2 cells during metaphase in a reversible way. During this mitotic arrest, both cyclin-CAT fusion proteins remained stable.

Pearls in neurodermatology.

Many diseases present with both neurologic and dermatologic manifestations. Eight such clinical cases are presented, along with clinical photographs of the skin lesions, in the format of a self-evaluation. Each case is followed by a discussion and a brief review of the characteristic cutaneous and neurologic findings. The intent is to demonstrate classic dermatologic manifestations of diseases seen by neurologists.

Chemical Fate of a Metamorphic Inducer in Larvae-like Buds of the Cnidarian Cassiopea andromeda.

Larvae-like vegetative buds of the scyphozoan Cassiopea andromeda metamorphose into polyps in the presence of oligopeptides that have a well-defined primary structure. Buds were incubated with the hexapeptide 14C-dansyl-GPGGPA, a representative inducer. Autoradiography of longitudinal sections of these buds revealed rapid internalization of peptide by the buds. Silver grain density was highest in the pre-pedal disc region (or aboral knob) of metamorphosing buds. Larvae and buds sporadically explore their habitat with this aboral knob, searching for a suitable solid substrate to which irreversible attachment will be made. Buds were incubated for 3, 8, or 16 h with 14C-dansyl-GPGGPA, then homogenized and the supernatants analyzed to determine the chemical fate of the inducer. The signal molecule was shown to be partly degraded to 14C-dansyl-GP, partly to 14C-dansyl-G, and in part still present in its original structure. These cleavage products were also found in the surrounding medium after an incubation time of 8 h with 14C-dansyl-GPGGPA, but did not induce metamorphosis. This study suggests that exposure of metamorphosis-inducing peptides to buds of Cassiopea andromeda results in signal termination.

The 20S proteasome gene family in Arabidopsis thaliana.

The complexity of the proteasome gene family in higher plants was investigated by identification and sequencing cDNA clones from the Arabidopsis thaliana database showing homologies to 20S proteasome subunits. We identified plant counterparts for each of the 14 proteasomal subunit subfamilies. Moreover, several of them were highly related isoforms. Mapping data indicate a random distribution of the proteasome genes over the Arabidopsis genome.