Structure and organization of the peridinin-chlorophyll a-binding protein gene in Gonyaulax polyedra.

We have identified a major 32-kDa protein in the dinoflagellate Gonyaulax polyedra as a peridinin-chlorophyll a-binding protein (PCP), based on micro-sequence data and immunological cross-reaction with antibodies raised against PCP from another dinoflagellate species. A cDNA for this protein, identified by a PCR-based cloning strategy, encoded all 68 of the amino acids microsequenced, thus confirming the identity of the clone. The PCP gene is highly expressed at both the mRNA and protein levels, and only PCP transcripts corresponding in size to the cDNA sequence were detected. Slot blot analyses show that there are roughly 5000 copies of the PCP gene in Gonyaulax, making this gene one of the most highly repeated protein-coding genes ever reported, yet the sequence of the different gene copies in the genome appears extraordinarily well conserved as judged by Southern blot analyses. The gene, as indicated by Southern blot and PCR data, is suggested to be present in 5000 intronless copies arranged head to tail in the genome, separated by conserved 1-kb spacers. Based on the conserved sequence of the spacer region, its presence next to each of the PCP coding sequences, and the uniform size of the PCP transcript, we propose that this region represents a dinoflagellate transcriptional promoter. This putative promoter region contains none of the sequence elements for DNA-binding proteins involved in transcriptional initiation reported in other organisms.

Isolation of membrane bound light-harvesting-complexes from the dinoflagellates Heterocapsa pygmaea and Prorocentrum minimum.

We have isolated Chl a-Chl c-carotenoid binding proteins from the dinoflagellates Prorocentrum minimum and Heterocapsa pygmaea grown under high (500 µmol m(-2) s(-1), HL) and low (35 µmol m(-2) s(-1), LL) light conditions. We compared various isolation procedures of membrane bound light harvesting complexes (LHCs) and assayed the functionality of the solubilized proteins by determining the energy transfer efficiency from the accessory pigments to Chl a by means of fluorescence excitation spectra. The identity of the newly isolated protein-complexes were confirmed by immunological cross-reactions with antibodies raised against the previously described membrane bound Chl a-c proteins (Boczar et al. (1980) FEBS Lett 120: 243-247). Spectroscopic analysis demonstrated the relatedness of these proteins with the recently described Chl-a-c 2-peridinin (ACP) binding protein (Hiller et al. (1993) Photochem Photobiol 57: 125-131; Iglesias Prieto et al. (1993) Phil Trans R Soc London B 338: 381-392). The water-soluble peridinin-Chl a binding-protein (PCP) was not detectable in P. minimum. Two functional forms of ACP with different pigmentation were isolated. A variant of ACP which was isolated from high-light grown cells, that specifically binds increased amounts of diadinoxanthin was compared to the previously described ACPs that bind proportionately more peridinin.

High abundance of Archaea in Antarctic marine picoplankton.

Archaea (archaebacteria) constitute one of the three major evolutionary lineages of life on Earth. Previously these prokaryotes were thought to predominate in only a few unusual and disparate niches, characterized by hypersaline, extremely hot, or strictly anoxic conditions. Recently, novel (uncultivated) phylotypes of Archaea have been detected in coastal and subsurface marine waters, but their abundance, distribution, physiology and ecology remain largely undescribed. Here we report exceptionally high archaeal abundance in frigid marine surface waters of Antarctica. Pelagic Archaea constituted up to 34% of the prokaryotic biomass in coastal Antarctic surface waters, and they were also abundant in a variety of other cold, pelagic marine environments. Because they can make up a significant fraction of picoplankton biomass in the vast habitats encompassed by cold and deep marine waters, these pelagic Archaea represent an unexpectedly abundant component of the Earth's biota.

Characterization of two full-length cDNA sequences encoding for apoproteins of peridinin-chlorophyll a-protein (PCP) complexes.

Characterizations are presented for RNA, 2 cDNA libraries, and 2 full-length cDNA sequences encoding for photosynthetic light-harvesting peridinin-chlorophyll a-protein (PCP) in the dinoflagellate Heterocapsa pygmaea. Subsequent analyses of the PCP system also indicate that (1) it is represented by multiple nuclear encoded genes, (2) a subset of mRNAs encoding for PCP apoproteins are regulated by growth irradiance, (3) PCP preproteins are larger than the mature apoproteins, and (4) PCP cDNA clones sequenced thus far contain a conserved region but are not identical. Results are discussed in the context of photoadaptation in dinoflagellates.

[Characterization of the convoluted seminiferous tubule wall. II. Ultrastructural alteration after testis retention in the abdominal cavity]. / Caratterizzazione della parete del tubulo seminifero contorto. II) Modificazioni ultrastrutturali dopo ritenzione del testicolo in cavita' addominale.

An ultrastructural analysis has been carried out on the seminiferous tubules after different periods of stay of the rat testis in the abdominal cavity. With respect to control rats, no changes are detectable after 5 days, while after 15 and 30 days considerable modifications take place. A number of cellular features are modified, such as the nuclear shape and the perinuclear vesicles, while the cytoplasmic filaments show a less ordered appearance. In addition, the extracellular amorphous matrix undergoes a large increase, due either to an enhanced production or to a reduced turnover related with a lowered cell activity.

Interactions among DNA, metallic ions, and lipids.

Interactions amond DNA, phospholipids, and Cu2+ ions have been investigated by means of thermal denaturation technique. The results indicate that phosphatidylserine and sphingomyelin interact with Cu2+ ions, which are able to prevent the chance of binding of the phospholipids to the double helix. This interaction is strictly dependent upon the concentration of the divalent cation and reduces the capability of the employed phospholipids to modify the thermal stability of DNA.

[Cytogenetics in bone marrow transplantations. I. Bone marrow aplasia]. / Citogenetica in trapianti midollari. I) Aplasia midollare.

A bone marrow transplantation has been carried out in a patient with bone marrow aplasia. Besides the cytochemical and haematological tests, the cytogenetic analysis has been performed to check whether the transplantation was successful. In this case the donor was the patient's sister, so that the presence of the chimere has been used as a criteria for judging the conditions of the transplantation. the cytogenetic analysis, furthermore, is suitable to detect other chromosome abnormalities, which can represent a condition of instability of the transplanted cells and are probably an early expression of the transplanted bone marrow.

[Rubella seroepidemiology. proposal of a predictive mathmatical model (author's transl)]. / Sieroepidemiologia della rosolia. Proposta di un modello matematico predittivo.

This paper deals with time dependent epidermic behaviour of rubella. The hypothesis that ten classes of immuno-response (Stewart test) can be reduced to three is assumed (= low, intermediate and high level). Upon these conditions a mathematical model is developed and tested using experimental data measured during six years over 1288 subjects. Initial conditions, time-constants and transition probability for the model are also estimated from experimental data.

A conversational program for hierarchic and non-hierarchic cluster analysis.

The theoretical basis and the features of some cluster analysis programs are described in this paper. These programs use as input data an N x M matrix. For the N' less than or equal to N set of individuals, the cross-correlation matrix, R = (rij), is then calculated. The dissimilarity matrix, D = (dhk), and the distribution histogram of the distances between each pair is worked out. Hierarchic and non-hierarchic clustering techniques are allowed. Using the non-hierarchic strategy, the non-overlapping clusters are then separated into different groups. The distances between these groups are calculated and statistical tests of significance are performed. In the hierarchic case, a dendrogram is drawn using an agglomerative algorithm. As an example the programs (written in FORTRAN, batch or TSS version) were used to classify human mitotic chromosomes.

[A mathematical model for the study of the kinetics of serum alkaline phosphatase inhibition by sodium diethyldithiocarbamate (NaDDTC)]. / Modello matematico per lo studio della cinetica di inibizione della fosfatasi alcalina sierica ad opera del dietilditiocarbammato di sodio (NaDDTC).

A mathematical model for the kinetic of the serum alkaline phosphatase inhibition by NaDDTC is described in this paper. The model is tested over an experimental data set consisting on measured % residual activity of enzyme in human serum, after inhibition. The Bessey method is used. The solution of the differential equations for the model is found to be the best fitting for the observed time-dependent phenomena. The rate constant, K, for the inhibition reaction is then computed.

Effect of phosphatidylcholine vesicles on the activity of DNA polymerase-alpha.

Phosphatidylcholine vesicles stimulate the activity of the DNA polymerase-alpha from calf thymus. This effect is dependent upon the way of addition to the Mg ions, and the extent of the 3H-dTTP incorporation is closely related to the concentration of the vesicles. A role of phospholipids on the activity of the DNA-related enzymes is suggested.

[Effects of ionizing radiations on the ultrastructure of bursa of Fabricius]. / Effetti delle radiazioni ionizzanti sulla ultrastruttura della borsa di Fabrizio.

The alterations induced in the lymphoid and epitelial cells of the Bursa of Fabricius in chicks exposed at different doses of gamma rays mainly occur during the interfase. The extent of these alterations appears reduced in comparison with that observed in the chick thymus treated in the same way.

[Mathematical models in epidemiology: Study on viral hepatitis in Italy (author's transl)]. / Modelli matematici in epidemiologia: studio dell'epatite virale in Italia.

In this paper a mathematical approach to the epidemics is proposed. The method is based upon a model able to describe any time-depending phenomena using the following elements: "class", "transition" and "related probability". The solution of the differential equations describing the model are obtained: first, by numerical techniques; second, by a Montecarlo simulation method. Deterministic and stochastic solutions which have been obtained, by applying the model to the study of viral hepatitis in Italy during 1960--1970, have been compared each other, to improve the model itself.