RESUMO
Microbial processes are critical to the function of freshwater ecosystems, yet we still do not fully understand the factors that shape freshwater microbial communities. Furthermore, freshwater ecosystems are particularly susceptible to effects of environmental change, including influx of exogenous nutrients such as nitrogen and phosphorus. To evaluate the impact of nitrogen loading on the microbial community structure of shallow freshwater lakes, water samples collected from Lake Shenandoah (Virginia, USA) were incubated with two concentrations of either ammonium, nitrate, or urea as a nitrogen source. The potential impact of these nitrogen compounds on the bacterial community structure was assessed via 16S rRNA amplicon sequencing. At the phylum level, the dominant taxa in Lake Shenandoah were comprised of Actinobacteria and Proteobacteria, which were not affected by exposure to the various nitrogen treatments. Overall, there was not a significant shift in the diversity of the bacterial community of Lake Shenandoah with the addition of nitrogen sources, indicating this shallow system may be constrained by other environmental factors.
Assuntos
Lagos , Nitrogênio , Bactérias , Proteobactérias , RNA Ribossômico 16SRESUMO
External cervical resorption (ECR) is a sequela of dentoalveolar trauma that may cause functional, esthetic, and psychologic alterations. The aim of this study was to report a successful multidisciplinary treatment approach performed in a 12-year-old patient who presented with posttraumatic ECR associated with extensive opened cavity, pulp necrosis, and periapical lesion of tooth number 9, with an initial unfavorable prognosis. Crown lengthening was done to enable restoration of vestibular surface with resin composite, forming a barrier that allowed endodontic treatment. Afterwards, a prefabricated fiberglass post was cemented and esthetic restoration was performed using the adhesive technique and direct composite veneer. Reconstructive periodontal surgery was performed to correct irregular gingival contour. After treatment and successive follow-up sessions, it was concluded that although the tooth had been indicated for extraction, low invasive direct techniques were effective to recover function and esthetics and to maintain the tooth in the oral cavity.
Assuntos
Incisivo/lesões , Equipe de Assistência ao Paciente , Reabsorção da Raiz/terapia , Criança , Resinas Compostas/química , Aumento da Coroa Clínica/métodos , Cárie Dentária/complicações , Materiais Dentários/química , Necrose da Polpa Dentária/complicações , Restauração Dentária Permanente/métodos , Facetas Dentárias , Estética Dentária , Feminino , Seguimentos , Gengivoplastia/métodos , Vidro/química , Humanos , Planejamento de Assistência ao Paciente , Doenças Periapicais/complicações , Técnica para Retentor Intrarradicular/instrumentação , Tratamento do Canal Radicular/métodos , Fraturas dos Dentes/complicações , Resultado do TratamentoRESUMO
In eukaryotic cells, the enclosure of the genetic information in the nucleus allows the spatial and temporal separation of DNA replication and transcription from cytoplasmic protein synthesis. This compartmentalization not only permits a high level of regulation of these processes but at the same time necessitates a system of selective macromolecular transport between the nucleus and the cytoplasm. Transfer of macromolecules between both compartments is mediated by soluble receptors that interact with components of nuclear pore complexes (NPCs) to move their specific cargos. Transport occurs by way of a great variety of different pathways defined by individual receptors and accessory factors. Often, processes in substrate biogenesis that precede transport concurrently recruit transport factors to substrates, thus making transport responsive to correct and orderly synthesis of substrates. Some current challenges are to understand how transport factor-substrate interactions are controlled and integrated with sequential steps in substrate biogenesis, how large macromolecular complexes are restructured to fit through the NPC channel and to understand how transport factor-NPC interactions lead to actual translocation through the NPC.
Assuntos
Transporte Ativo do Núcleo Celular , Receptores Citoplasmáticos e Nucleares , Sequência de Aminoácidos , Animais , Compartimento Celular , Proteínas Ativadoras de GTPase/metabolismo , Humanos , Carioferinas/metabolismo , Modelos Biológicos , Chaperonas Moleculares , Dados de Sequência Molecular , Poro Nuclear/metabolismo , Complexo de Proteínas Formadoras de Poros Nucleares/metabolismo , Proteínas Nucleares/metabolismo , Sinais Direcionadores de Proteínas/genética , RNA Mensageiro/metabolismo , RNA de Transferência/metabolismo , Ribossomos/metabolismo , Transdução de Sinais , Proteína ran de Ligação ao GTP/metabolismo , Proteína Exportina 1RESUMO
An inexpensive headholder for mice ranging from 3-week-old animals to adults was designed to provide reliable long-term head fixation. Its shape allows the direct access to the dorsal and ventral sides of the head which makes the headholder ideal for the use with both an upright and an inverted microscope. Because the headholder does not use a nose clamp, the apparatus allows surgery, stimulation of the olfactory system and concomitant optical recording of neuronal activity.
Assuntos
Mapeamento Encefálico/instrumentação , Restrição Física/instrumentação , Animais , Desenho de Equipamento , Camundongos , Bulbo Olfatório/fisiologia , Fotomicrografia/instrumentação , Olfato/fisiologiaRESUMO
The signal recognition particle (SRP) is a cytoplasmic RNA-protein complex that targets proteins to the rough endoplasmic reticulum. Although SRP functions in the cytoplasm, RNA microinjection and cDNA transfection experiments in animal cells, as well as genetic analyses in yeast, have indicated that SRP assembles in the nucleus. Nonetheless, the mechanisms responsible for nuclear-cytoplasmic transport of SRP RNA and SRP proteins are largely unknown. Here we show that the 19 kDa protein subunit of mammalian SRP, SRP19, was efficiently imported into the nucleus in vitro by two members of the importin beta superfamily of transport receptors, importin 8 and transportin; SRP19 was also imported less efficiently by several other members of the importin beta family. Although transportin is known to import a variety of proteins, SRP19 import is the first function assigned to importin 8. Furthermore, we show that a significant pool of endogenous SRP19 is located in the nucleus, as well as the nucleolus. Our results show that at least one mammalian SRP protein is specifically imported into the nucleus, by members of the importin beta family of transport receptors, and the findings add additional evidence for nuclear assembly of SRP.
Assuntos
Núcleo Celular/metabolismo , Carioferinas/metabolismo , Proteínas Nucleares/metabolismo , Partícula de Reconhecimento de Sinal/metabolismo , Proteína ran de Ligação ao GTP/metabolismo , Transporte Ativo do Núcleo Celular/fisiologia , Núcleo Celular/química , Células HeLa , Humanos , Carioferinas/análise , Proteínas Nucleares/análise , Receptores Citoplasmáticos e Nucleares , Partícula de Reconhecimento de Sinal/análise , beta Carioferinas/análise , beta Carioferinas/metabolismo , Proteína ran de Ligação ao GTP/análiseRESUMO
To study the effects of posture and meal structure on gastric emptying and satiety, nine women ingested tomato soup and then immediately or 20 min later an egg sandwich, when seated and when supine. The lag time was not different, but the half-emptying time of the sandwich was 32% longer (P < 0.01) and the emptying rate after the lag phase was 39% slower (P < 0.01) when the subjects were supine than when they were seated. The half-emptying time of the soup was 50% longer (P < 0.01) when the subjects were supine and ingested the soup immediately before the sandwich than in the other three conditions. Postprandial hunger ratings recovered more slowly (P < 0.01) when the subjects ingested the soup 20 min before the sandwich than when they ingested the soup immediately before the sandwich. These results suggest that posture did not affect the intragastric distribution of the sandwich but affected propulsion of the meal into the intestine and that postprandial satiety was enhanced by the cumulative effect over time of a 20-min "head start" in stimulation of intestinal receptors by emptying of the soup.
Assuntos
Ingestão de Alimentos/fisiologia , Esvaziamento Gástrico/fisiologia , Postura/fisiologia , Resposta de Saciedade/fisiologia , Adulto , Artefatos , Metabolismo Energético , Feminino , Humanos , Fome/fisiologia , Intestino Delgado/fisiologiaRESUMO
Two parallel preload studies were conducted to determine the relative contributions of inhibitory feedback from the stomach and intestine to satiation (meal termination) and postprandial satiety. In the Gastric Emptying Study, five normal-weight women each ingested an egg sandwich (307 kcal) (1) immediately after a tomato soup preload (120 kcal), (2) 20 min after a tomato soup preload, and (3) with no preload. There was 125 g more of soup in the stomach when subjects began ingesting the sandwich immediately compared to 20 min after the soup, and the emptying of the sandwich was delayed when it was ingested immediately but not 20 min after the soup. The lag times for emptying of the sandwich were 76.5 (69.1-82.4), 47.2 (20.1-67.7), and 42.4 (17.8-65.1) min for the three conditions, respectively, p < 0.05. In the Food Intake Study, 16 normal-weight women ate significantly less (p < 0.01) in test meals offered immediately (978+/-246 kcal) and 20 min (1027+/-298 kcal) after the soup preload than in a test meal with no preload (1151+/-279 kcal). Despite the different amounts of soup in the stomach, subjects' test-meal intake in the two preload conditions was not significantly different. Subjects' fullness ratings following the preloads and the test meals were not different among the treatment conditions. The results suggest that feedback from neither the gastric nor the postgastric compartment is primary in determining meal size and postprandial satiety. Instead, signals from gastric and postgastric sources are combined to determine meal size and postprandial satiety.
Assuntos
Retroalimentação/fisiologia , Esvaziamento Gástrico/fisiologia , Intestinos/inervação , Saciação/fisiologia , Resposta de Saciedade/fisiologia , Estômago/inervação , Adolescente , Adulto , Ingestão de Energia/fisiologia , Feminino , Humanos , Fome/fisiologia , Mecanorreceptores/fisiologia , Inibição Neural/fisiologia , Valores de ReferênciaRESUMO
The signal recognition particle (SRP) is a ribonucleoprotein complex that mediates translocation of proteins into the endoplasmic reticulum. Protein SRP19 is an essential structural component of SRP and is believed to promote assembly of the particle. In order to have a convenient source for the purification of milligram amounts of SRP19, we expressed in Escherichia coli a human SRP19 cDNA with an amino-terminal addition of six histidine residues. Expression at 25 degrees C eliminated formation of insoluble SRP19 and resulted in accumulation of soluble hexahistidine-SRP19 to 68% of total cell protein after 24 h. Metal chelation chromatography yielded 40 mg of hexahistidine-SRP19 per liter of culture, with a purity slightly greater than 97%. To examine protein function, the RNA-binding properties of the purified protein were determined by RNA electromobility shift assays. The histidine-tagged SRP19 bound specifically to a 150-nucleotide RNA derived from SRP RNA, with an apparent Kd of 1 nM, and bound, with greatly reduced affinity, to a mutagenized form of the SRP RNA derivative that contained an altered helix 6 tetranucleotide loop. The purified protein was also photochemically crosslinked to the 150-nucleotide SRP RNA fragment, providing the means to potentially identify portions of hexahistidine-SRP19 which are in close proximity to the RNA molecule.
Assuntos
Histidina , Proteínas de Ligação a RNA/metabolismo , Partícula de Reconhecimento de Sinal/metabolismo , Sequência de Aminoácidos , Ligação Competitiva , Reagentes de Ligações Cruzadas , Escherichia coli/genética , Humanos , Dados de Sequência Molecular , Oligopeptídeos/genética , Peptídeos/genética , Ligação Proteica , Proteínas de Ligação a RNA/genética , Proteínas de Ligação a RNA/isolamento & purificação , Proteínas Recombinantes de Fusão/isolamento & purificação , Proteínas Recombinantes de Fusão/metabolismo , Partícula de Reconhecimento de Sinal/genética , Partícula de Reconhecimento de Sinal/isolamento & purificação , Raios UltravioletaAssuntos
Bancos de Sangue/organização & administração , Departamentos Hospitalares/organização & administração , Qualidade da Assistência à Saúde , Serviço Hospitalar de Anestesia/economia , Serviço Hospitalar de Anestesia/organização & administração , Serviço Hospitalar de Anestesia/normas , Bancos de Sangue/economia , Bancos de Sangue/normas , Controle de Custos , Cuidados Críticos/economia , Cuidados Críticos/organização & administração , Cuidados Críticos/normas , Custos Hospitalares , Departamentos Hospitalares/economia , Departamentos Hospitalares/normas , Reestruturação Hospitalar , HumanosRESUMO
Established alternative methods of visualisation of intracranial vessels--MR-angiography and angio-CT--give only two dimensional views similar to angiography. It is a subjective matter of the neurosurgeon's imagination to produce three dimensional views on the basis of these methods. Three dimensional processing of dynamic sequence or helical axial computed tomograms give any number you like of stereo-scopic views of the Willisi circulus. Comparing the usefulness of DSA and 3D-CT in 34 aneurysms, the latter often gives supplementary information concerning the direction, neck and adjacent arteries, helpful in planning surgery treatment. It is difficult or sometimes impossible to separate basal aneurysms (a.c.i.) from sinus cavernosus and skull base by this method, but especially in aneurysms located in the area of a.com.a. and c.m.a. the 3D-CT is sufficient for diagnosis and planning surgical treatment without DSA.
Assuntos
Processamento de Imagem Assistida por Computador , Aneurisma Intracraniano/diagnóstico por imagem , Tomografia Computadorizada por Raios X , Angiografia Digital , Angiografia Cerebral , Círculo Arterial do Cérebro/diagnóstico por imagem , Círculo Arterial do Cérebro/cirurgia , Gráficos por Computador , Humanos , Aneurisma Intracraniano/cirurgiaRESUMO
The signal recognition particle is a cytoplasmic RNA-protein complex that mediates translocation of secretory polypeptides into the endoplasmic reticulum. We have used a Xenopus oocyte microinjection assay to determine how signal recognition particle (SRP) RNA is exported from the nucleus. Following nuclear injection, SRP RNA accumulated in the cytoplasm while cytoplasmically injected SRP RNA did not enter the nucleus. Cytoplasmic accumulation of SRP RNA was an apparently facilitated process dependent on limiting trans-acting factors, since nuclear export exhibited saturation kinetics and was completely blocked either at low temperature or by wheat germ agglutinin, a known inhibitor of nuclear pore-mediated transport. At least one target for trans-acting factors that promote nuclear export of SRP RNA appears to be the Alu element of the molecule, since a transcript consisting of only the Alu sequence was exported from the nucleus in a temperature-dependent manner and the Alu transcript competed in the nucleus for transport with intact SRP RNA. Although the identities of trans-acting factors responsible for SRP RNA transport are at present unknown, we suggest that proteins contained within the cytoplasmic form of SRP are candidates. Consistent with this idea were the effects of a mutation in SRP RNA that prevented binding of two known SRP proteins to the Alu sequence.
Assuntos
Núcleo Celular/metabolismo , RNA Nuclear Pequeno/metabolismo , Sequências Repetitivas de Ácido Nucleico , Partícula de Reconhecimento de Sinal/metabolismo , Animais , Sequência de Bases , Transporte Biológico , Citoplasma/metabolismo , Microinjeções , Dados de Sequência Molecular , Membrana Nuclear/metabolismo , Conformação de Ácido Nucleico , Oócitos , Sinais Direcionadores de Proteínas/metabolismo , RNA/administração & dosagem , RNA/metabolismo , RNA Nuclear Pequeno/química , Proteínas de Ligação a RNA/metabolismo , Temperatura , Xenopus laevisRESUMO
Three dimensional processing of cranial dynamic sequence computertomograms enables in cases of tumour enhancement the simultaneous imaging of vessels, bone structures and tumour in their relations. In our opinion, especially in tumours of the frontotemporal basal region, the method may frequently substitute angiography and gives serious information in planning operative treatment.
Assuntos
Neoplasias Encefálicas/diagnóstico por imagem , Interpretação de Imagem Radiográfica Assistida por Computador , Tomografia Computadorizada por Raios X , Mapeamento Encefálico , Neoplasias Encefálicas/irrigação sanguínea , Neoplasias Encefálicas/cirurgia , Seio Cavernoso/diagnóstico por imagem , Seio Cavernoso/cirurgia , Córtex Cerebral/irrigação sanguínea , Córtex Cerebral/diagnóstico por imagem , Córtex Cerebral/cirurgia , Círculo Arterial do Cérebro/diagnóstico por imagem , Círculo Arterial do Cérebro/cirurgia , Humanos , SoftwareRESUMO
To study the biochemistry of ribonucleoprotein export from the nucleus, we characterized an in vivo assay in which the cytoplasmic appearance of radiolabeled ribosomal subunits was monitored after their microinjection into Xenopus oocyte nuclei. Denaturing gel electrophoresis and sucrose density gradient sedimentation demonstrated that injected subunits were transported intact. Consistent with the usual subcellular distribution of ribosomes, transport was unidirectional, as subunits injected into the cytoplasm did not enter the nucleus. Transport displayed properties characteristic of a facilitated, energy-dependent process; the rate of export was saturable and transport was completely inhibited either by lowering the temperature or by depleting nuclei of ATP; the effect of lowered temperature was completely reversible. Transport of injected subunits was likely a process associated with the nuclear pore complex, since export was also inhibited by prior or simultaneous injection of wheat germ agglutinin, a lectin known to inhibit active nuclear transport by binding to N-acetyl glucosamine-containing glycoproteins present in the NPC (Hart, G. W., R. S. Haltiwanger, G. D. Holt, and W. G. Kelly. 1989. Annu. Rev. Biochem. 58:841-874). Although GlcNAc modified proteins exist on both the nuclear and cytoplasmic sides of the nuclear pore complex, ribosomal subunit export was inhibited only when wheat germ agglutinin was injected into the nucleus. Finally, we found that ribosomal subunits from yeast and Escherichia coli were efficiently exported from Xenopus oocyte nuclei, suggesting that export of some RNP complexes may be directed by a collective biochemical property rather than by specific macromolecular primary sequences or structures.
Assuntos
Núcleo Celular/metabolismo , Oócitos/metabolismo , Ribossomos/metabolismo , Trifosfato de Adenosina/fisiologia , Animais , Transporte Biológico/efeitos dos fármacos , Transporte Biológico/fisiologia , Centrifugação Zonal , Eletroforese em Gel de Poliacrilamida , Escherichia coli , Feminino , Cinética , Substâncias Macromoleculares , Microinjeções , Membrana Nuclear/fisiologia , Saccharomyces cerevisiae , Temperatura , Aglutininas do Germe de Trigo/farmacologia , Xenopus laevisRESUMO
Two particular seven-amino-acid segments from yeast ribosomal protein L29 caused a non-nuclear reporter protein to associate almost exclusively with the yeast nucleus. The two L29-derived nuclear localizing sequences were identical in five of the seven residues, many of which were basic amino acids. Generally, localization of the reporter protein was most impaired by replacement of the basic residues. A particular Arg residue was unique; substitution by any amino acid including Lys diminished nuclear localization of the reporter protein. In L29 the corresponding Arg 25----Lys substitution within the nuclear localizing sequence distal to the N-terminus was without effect, as evidence by normal rates of ribosome assembly and cell growth. However, the analogous Arg 8----Lys substitution within the localizing sequence proximal to the N-terminus led to greatly reduced rates of ribosome assembly and cell growth. Finally, when both localizing sequences contained the Arg----Lys substitution a still greater decrease in ribosome assembly and cell growth was observed. These results were as expected if the two short peptide sequences functioned in nuclear localization and/or assembly of yeast ribosomal protein L29.
Assuntos
Núcleo Celular/metabolismo , Proteínas Ribossômicas/metabolismo , Saccharomyces cerevisiae/análise , Sequência de Aminoácidos , Clonagem Molecular , Imunofluorescência , Dados de Sequência Molecular , Mutação , Plasmídeos , Precursores de RNA/metabolismo , RNA Ribossômico/metabolismo , Proteínas Recombinantes de Fusão , Proteínas Ribossômicas/genética , Ribossomos/metabolismo , Saccharomyces cerevisiae/ultraestrutura , Relação Estrutura-Atividade , beta-Galactosidase/genéticaRESUMO
It is reported about the results in malignant gliomas, which were operated on and than followed by an irradiation therapy. This group is compared with patients, which have been irradiated exclusively. The improvement rate in the latter was 58%, in the first group 74%. The average survival time was 8.5 months in patients only irradiated, while it was 23 months in the group operated upon and followed by irradiation. Conclusions are drawn from these results.
Assuntos
Neoplasias Encefálicas/cirurgia , Complicações Pós-Operatórias/mortalidade , Astrocitoma/mortalidade , Astrocitoma/radioterapia , Astrocitoma/cirurgia , Neoplasias Encefálicas/mortalidade , Neoplasias Encefálicas/radioterapia , Terapia Combinada , Feminino , Seguimentos , Glioblastoma/mortalidade , Glioblastoma/radioterapia , Glioblastoma/cirurgia , Humanos , Masculino , Exame Neurológico , Oligodendroglioma/mortalidade , Oligodendroglioma/radioterapia , Oligodendroglioma/cirurgia , Qualidade de Vida , Taxa de SobrevidaRESUMO
A cDNA clone of mouse ribosomal protein L27' was shown previously to be 62% identical in amino acid residues to yeast ribosomal protein L29. The L27' cDNA was expressed in yeast to determine the ability of the mouse protein to substitute for yeast L29 in assembling a functional ribosome. In a yeast strain resistant to cycloheximide by virtue of a recessive mutation in the L29 protein, the murine cDNA did not produce a sensitive phenotype, indicating failure of the mouse L27' protein to assemble into yeast ribosomes. However, when the mouse L27' gene was expressed in cells devoid of L29 and otherwise inviable, the murine protein supported normal growth, demonstrating that mouse ribosomal protein L27' indeed was interchangeable with yeast L29. We conclude that mouse ribosomal protein L27' is assembled into ribosomes in yeast, but yeast L29 is assembled preferentially when both L29 and L27' are present in the same cell.
Assuntos
Proteínas Ribossômicas/genética , Ribossomos/metabolismo , Saccharomyces cerevisiae/genética , Animais , Cicloeximida/farmacologia , Resistência Microbiana a Medicamentos , Genes , Genes Fúngicos , Teste de Complementação Genética , Camundongos , Hibridização de Ácido Nucleico , Plasmídeos , Biossíntese de Proteínas , RNA Mensageiro/genética , Saccharomyces cerevisiae/efeitos dos fármacosRESUMO
A report is given on the diagnosis of spontaneous intracerebral haemorrhages, which points art that because of possibly occurring surgical consequences every acute occurrence of cerebral symptoms should be cleared up as soon as possible. In this diagnosis the computer tomography is well to the fore, which enables not only the recognition of the haematoma itself and its extent, but in particular also positional relations to important cerebral structures. In a number of cases, however, a representation of the cerebral vessels is nevertheless necessary. As an exclusive diagnostic measure in case of an intracerebral haematoma the angiography does not reach the value of information of computer tomography.
Assuntos
Hemorragia Cerebral/diagnóstico , Neoplasias Encefálicas/diagnóstico , Angiografia Cerebral , Hemangioma/diagnóstico , Humanos , Aneurisma Intracraniano/diagnóstico , Tomografia Computadorizada por Raios XRESUMO
A report is given on the indication for the operation, the surgical procedure, and the results of the operation in 36 spontaneous intracerebral haematomas. The method of choice for the treatment was the osteoplastic trepanation with a removal of the haematoma. In two thirds of the cases a complete or essential retrogression of the preoperative neurological symptoms was achieved. On this basis, some fundamental statements for the therapy of spontaneous intracerebral haematomas are made.
Assuntos
Hemorragia Cerebral/cirurgia , Complicações Pós-Operatórias/etiologia , Adolescente , Adulto , Dano Encefálico Crônico/etiologia , Criança , Seguimentos , Hematoma Subdural/cirurgia , Humanos , TrepanaçãoRESUMO
The DNA sequence UAST (TCGTTTTGTACGTTTTTCA) was found to mediate transcription of yeast ribosomal protein gene TCM1. UAST was defined as a transcriptional activator on the basis of loss of transcription accompanying deletions of all or part of UAST, orientation-independent restoration of transcription promoted by a synthetic UAST oligomer inserted either into TCM1 or into the yeast CYC1 gene lacking its transcriptional activation region, and diminished transcription following nucleotide alterations in UAST. UAST bound in vitro to a protein denoted TAF (TCM1 activation factor); TAF was concluded to be a transcriptional activator protein because nucleotide alterations in UAST that diminished transcription in vivo also diminished TAF binding in vitro. The sequence of UAST bore no obvious resemblance to UASrpg, the principal cis-acting element common to most yeast ribosomal protein genes. Likewise, TAF was distinguished from the UASrpg-binding protein TUF, since (i) TAF and TUF were chromatographically separable, (ii) binding of either TAF or TUF to its corresponding UAS was unaffected by an excess of UASrpg or UAST DNA, respectively, and (iii) photochemical cross-linking experiments showed that TAF was a protein of 147 kilodaltons (kDa), while TUF was detected as an approximately 120-kDa polypeptide, consistent with its known size. Cross-linking experiments also revealed that both UAST and UASrpg bound a second heretofore unobserved 82-kDa protein; binding of this additional protein appeared to require binding of TAF or TUF. On the basis of the biochemical characterization of TAF and a lack of sequence similarity between UAST and UASrpg, we suggest that transcription of TCM1 is mediated by a cis-acting sequence and at least one trans-acting factor different from the elements which promote transcription of most other ribosomal protein genes. A second trans-acting factor may be shared by TCM1 and other ribosomal protein genes; this factor could mediate coordinate regulation of these genes.