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Phytoplasma strains that belong to group 16SrI (aster yellows phytoplasma group), subgroup A (I-A, North American tomato big bud phytoplasma subgroup) were discovered in diverse plant species in Lithuania. Plants in which the strains were found exhibited symptoms characteristic of infections by phytoplasma. Carrot (Daucus sativus) with carrot proliferation disease exhibited symptoms of proliferation of the crown, chlorosis of young leaves, and reddening of mature leaves. Diseased phlox (Phlox paniculata) exhibited symptoms of virescence and leaf chlorosis. Diseased sea-lavender (Limonium sinuatum) exhibited abnormal proliferation of shoots, chlorosis of young leaves, reddening of mature leaves, and degeneration of flowers. Diseased hyacinth (Hyacinthus orientalis) exhibited chlorosis of leaves and undeveloped flowers. Diseased Aconitum sp. exhibited proliferation of shoots. Phytoplasma-characteristic ribosomal (r) DNA was detected in the plants by use of the polymerase chain reaction (PCR). The rDNA was amplified in PCR primed by primer pair P1/P7 and reamplified in nested PCR primed by primer pair R16F2n/R16R2 (F2n/R2), as previously described (1). The phytoplasmas were classified through restriction fragment length polymorphism (RFLP) analysis of 16S rDNA, amplified in the nested PCR primed by F2n/R2, using single endonuclease enzyme digestion with AluI, MseI, KpnI, HhaI, HaeIII, HpaI, HpaII, RsaI, HinfI, TaqI, and Sau3AI. Collective RFLP patterns indicated that all detected phytoplasma strains were affiliated with subgroup I-A. The 16S rDNA amplified from the phytoplasma (CarrP phytoplasma) in diseased carrot was cloned in Escherichia coli, sequenced, and the sequence deposited in the GenBank data library (GenBank accession no. AF291682). The 16S rDNAs of CarrP and tomato big bud (GenBank acc. no. AF222064) phytoplasmas shared 99.8% nucleotide sequence similarity. Phytoplasmas belonging to group 16SrIII (3), group 16SrV (D. Valiunas, unpublished data), and subgroup I-C in group 16SrI (2,3) occur in Lithuania. This report records the first finding of a subgroup I-A phytoplasma in the Baltic region and expands the known plant host range of this phytoplasma subgroup. References: (1) R. Jomantiene et al. Int. J. Syst. Bacteriol. 48:269, 1998. (2) Jomantiene et al. Phytopathology 90:S39, 2000. (3) Staniulis et al. Plant Dis. 84:1061, 2000.

Symptoms of phyllody of flowers and general plant yellowing indicating possible phytoplasma infection were observed in diseased plants of hairy willow-weed (Epilobium hirsutum L., family Onagraceae) growing in a meadow at Harku Village near Tallin, Estonia. DNA was extracted from diseased E. hirsutum using a Genomic DNA Purification Kit (Fermentas AB, Vilnius, Lithuania) and used as a template in nested polymerase chain reaction (PCR). Ribosomal (r) DNA was initially amplified in PCR primed by phytoplasma universal primer pair P1/P7 (4) and reamplified in PCR primed by nested primer pair 16SF2n/16SR2 (F2n/R2) (1) as previously described (2). Products of 1.8 kbp and 1.2 kbp were obtained in PCR primed P1/P7 and F2n/R2, respectively, from all four symptomatic plants examined. These data indicated that the diseased E. hirsutum plants were infected by a phytoplasma, termed epilobium phyllody (EpPh) phytoplasma. The 16S rDNA amplified in PCR primed by nested primer pair F2n/R2 was subjected to restriction fragment length polymorphism (RFLP) analysis using restriction endonucleases AluI, MseI, HpaI, HpaII, HhaI, RsaI, HinfI, and HaeIII (Fermentas AB). On the basis of the collective RFLP profiles, EpPh phytoplasma was classified in group 16SrI (aster yellows phytoplasma group), subgroup B (aster yellows phytoplasma subgroup), according to the phytoplasma classification scheme of Lee et al. (3). The 1.8-kbp rDNA product of P1/P7-primed PCR, which included 16S rDNA, 16S-23S intergenic spacer region, and the 5′ -end of 23S rDNA, was cloned in Escherichia coli using the TOPO TA Cloning Kit (Invitrogen, Carlsbad, Ca) according to manufacturer's instructions and sequenced. The sequence was deposited in the GenBank database as Accession No. AY101386. This nucleotide sequence shared 99.8% sequence similarity with a comparable rDNA sequence (GenBank Accession No. AF322644) of aster yellows phytoplasma AY1, a known subgroup 16SrI-B strain. The EpPh phytoplasma sequence was highly similar (99.9%) to operons rrnA (GenBank Accession No. AY102274) and rrnB (GenBank Accession No. AY102273) from Valeriana yellows (ValY) phytoplasma infecting Valeriana officinalis plants in Lithuania. ValY phytoplasma was found to exhibit rRNA interoperon sequence heterogeneity (D. Valiunas, unpublished data). To our knowledge, this is the first report to reveal E. hirsutum as a host of phytoplasma and to demonstrate the occurrence of a plant pathogenic mollicute in the northern Baltic region. References: (1) D. E. Gundersen and I.-M. Lee. Phytopathol. Mediterr. 35:144, 1996. (2) R. Jomantiene et al. HortScience 33:1069, 1998. (3) I.-M. Lee et al. Int. J. Syst. Bacteriol. 48:1153, 1998. (4) B. Schneider et al. Phlogenetic classification of plant pathogenic mycoplasma-like organisms or phytoplasmas. Page 369 in: Molecular and Diagnostic Procedures in Mycoplasmology, Vol 1, R. Razin, and J. G. Tully eds. Academic Press, San Diego, 1995.

The nucleocapsid (N) protein of hantaviruses (family Bunyaviridae) is the most abundant component of the virion; it encapsidates genomic RNA segments and participates in viral genome transcription and replication, as well as in virus assembly. During RNA encapsidation, the N protein forms intermediate trimers and then oligomers via ‘head-to-head, tail-to-tail’ interactions. In previous work, using Tula hantavirus (TULV) N protein as a model, it was demonstrated that an intact coiled-coil structure of the N terminus is crucial for the oligomerization capacity of the N protein and that the hydrophobic ‘a’ residues from the second α-helix are especially important. Here, the importance of charged amino acid residues located within the coiled-coil for trimer formation and oligomerization was analysed. To predict the interacting surfaces of the monomers, the previous in silico model of TULV coiled-coils was first upgraded, taking advantage of the recently published crystal structure of the N-terminal coiled-coil of the Sin Nombre virus N protein. The results obtained using a mammalian two-hybrid assay suggested that conserved, charged amino acid residues within the coiled-coil make a substantial contribution to N protein oligomerization. This contribution probably involves (i) the formation of interacting surfaces of the N monomers (residues D35 and D38, located at the tip of the coiled-coil loop, and R63 appear particularly important) and (ii) stabilization of the coiled-coil via intramolecular ionic bridging (with E55 as a key player). It is hypothesized that the tips of the coiled-coils are the first to come into direct contact and thus to initiate tight packing of the three structures.

Hantaviruses, members of the genus Hantavirus in the Bunyaviridae family, are enveloped single-stranded RNA viruses with tri-segmented genome of negative polarity. In humans, hantaviruses cause two diseases, hemorrhagic fever with renal syndrome (HFRS) and hantavirus pulmonary syndrome (HPS), which vary in severity depending on the causative agent. Each hantavirus is carried by a specific rodent host and is transmitted to humans through excreta of infected rodents. The genome of hantaviruses encodes four structural proteins: the nucleocapsid protein (N), the glycoproteins (Gn and Gc), and the polymerase (L) and also the nonstructural protein (NSs). This thesis deals with the functional characterization of hantavirus N protein with regard to its structure. Structural studies of the N protein have progressed slowly and the crystal structure of the whole protein is still not available, therefore biochemical assays coupled with bioinformatical modeling proved essential for studying N protein structure and functions. Presumably, during RNA encapsidation, the N protein first forms intermediate trimers and then oligomers. First, we investigated the role of N-terminal domain in the N protein oligomerization. The results suggested that the N-terminal region of the N protein forms a coiled-coil, in which two antiparallel alpha helices interact via their hydrophobic seams. Hydrophobic residues L4, I11, L18, L25 and V32 in the first helix and L44, V51, L58 and L65 in the second helix were crucial for stabilizing the structure. The results were consistent with the head-to-head, tail-to-tail model for hantavirus N protein trimerization. We demonstrated that an intact coiled-coil structure of the N terminus is crucial for the oligomerization capacity of the N protein. We also added new details to the head-to-head, tail-to-tail model of trimerization by suggesting that the initial step is based on interaction(s) between intact intra-molecular coiled-coils of the monomers. We further analyzed the importance of charged aa residues located within the coiled-coil for the N protein oligomerization. To predict the interacting surfaces of the monomers we used an upgraded in silico model of the coiled-coil domain that was docked into a trimer. Next the predicted target residues were mutated. The results obtained using the mammalian two-hybrid assay suggested that conserved charged aa residues within the coiled-coil make a substantial contribution to the N protein oligomerization. This contribution probably involves the formation of interacting surfaces of the N monomers and also stabilization of the coiled-coil via intramolecular ionic bridging. We proposed that the tips of the coiled-coils are the first to come into direct contact and thus initiate tight packing of the three monomers into a compact structure. This was in agreement with the previous results showing that an increase in ionic strength abolished the interaction between N protein molecules. We also showed that residues having the strongest effect on the N protein oligomerization are not scattered randomly throughout the coiled-coil 3D model structure, but form clusters. Next we found evidence for the hantaviral N protein interaction with the cytoplasmic tail of the glycoprotein Gn. In order to study this interaction we used the GST pull-down assay in combination with mutagenesis technique. The results demonstrated that intact, properly folded zinc fingers of the Gn protein cytoplasmic tail as well as the middle domain of the N protein (that includes aa residues 80 248 and supposedly carries the RNA-binding domain) are essential for the interaction. Since hantaviruses do not have a matrix protein that mediates the packaging of the viral RNA in other negatve stranded viruses (NSRV), hantaviral RNPs should be involved in a direct interaction with the intraviral domains of the envelope-embedded glycoproteins. By showing the N-Gn interaction we provided the evidence for one of the crucial steps in the virus replication at which RNPs are directed to the site of the virus assembly. Finally we started analysis of the N protein RNA-binding region, which is supposedly located in the middle domain of the N protein molecule. We developed a model for the initial step of RNA-binding by the hantaviral N protein. We hypothesized that the hantaviral N protein possesses two secondary structure elements that initiate the RNA encapsidation. The results suggest that amino acid residues (172-176) presumably act as a hook to catch vRNA and that the positively charged interaction surface (aa residues 144-160) enhances the initial N-RNA interacation. In conclusion, we elucidated new functions of hantavirus N protein. Using in silico modeling we predicted the domain structure of the protein and using experimental techniques showed that each domain is responsible for executing certain function(s). We showed that intact N terminal coiled-coil domain is crucial for oligomerization and charged residues located on its surface form a interaction surface for the N monomers. The middle domain is essential for interaction with the cytoplasmic tail of the Gn protein and RNA binding. Hantavirusten nukleokapsidiproteiinin rakenne ja toiminta Hantavirukset kuuluvat Bunyaviridae-perheen Hantavirus-sukuun ja ovat vaipallisia yksisäikeisiä RNA-viruksia, joilla on kolmiosainen polariteetiltaan negatiivinen genomi. Ihmisissä hantavirukset aiheuttavat kahta tautia, munuaisoireista verenvuotokuumetta (hemorrhagic fever with renal syndrome, HFRS) ja hantaviruskeuhko-oireyhtymää (hantavirus pulmonary syndrome, HPS), joiden vaikeusaste vaihtelee aiheuttajaviruksesta riippuen. Nephropathia epidemica (NE), eli myyräkuume on lievä HFRS-tauti ja hyvin yleinen Suomessa. Kullakin hantaviruksella on oma isäntäjyrsijänsä, jonka eritteistä virus tarttuu ihmiseen. Hantavirusten genomi koodittaa neljää rakenneproteiinia: nukleokapsidiproteiinia (N), glykoproteiineja (Gn ja Gc), ja polymeraasia (L) sekä nonstrukturaalista proteiinia (NSs). Tämä väitöskirja selvittää hantavirusten toimintaa suhteessa rakenteeseen. N-proteiinin rakenteen tutkimus on edistynyt hitaasti eikä koko proteiinin kiderakennetta ole vielä selvitetty. Näin ollen biokemialliset analyysit liitettynä bioinformatiikan mallinnukseen ovat olleet olennaisia N-proteiinin rakenteen ja toiminnan tutkimuksessa. Ilmeisesti RNA:n liittyessä viruksen kapsidiin N-proteiini muodostaa ensin trimeerejä ja sitten oligomeerejä. Tutkimme aluksi N-proteiinin aminoterminaalisen jakson osuutta N-proteiinin oligomerisoituessa. Tulokset viittasivat siihen, että N-proteiinin aminoterminaalinen jakso muodostaa kierteinen-kierre-rakenteen (coiled-coil), joka on olennainen N-proteiinin kyvylle oligomerisoitua. Kierteinen kierre syntyy kahden vastakkaissuuntaisen alfa-kierteen sitoutuessa hydrofobisella saumalla. Paikallistimme tätä rakennetta stabiloivat aminohapot. Tulokset sopivat “pää-päähän” ja” häntä-häntään” malliin N-proteiinin trimerisoituessa. Täydensimme tätä trimerisaation mallia siten, että alkuvaiheessa intaktit molekyylien sisäiset kierre-kierre sidokset ovat olennaisia. Määritimme myös kierteinen-kierre–rakenteen varattujen aminohappojen merkityksen N-proteiinin oligomerisaatiossa. Tietokone-avusteisessa in silico mallissa kolmea trimeeriksi liittynyttä kierre-kierre–rakennetta käytettiin ennustamaan sitoutumispinnat, jonka jälkeen mutatoimme näitä ennustettuja aminohappoja. Tulosten mukaan kierre-kierteen konservoidut varatut aminohapot osallistuvat keskeisesti N-proteiinin oligomerisatioon. Ehdotimme, että kierre-kierteen kärjet muodostavat alkukontaktin ja täten laukaisevat kolmen monomeerin pakkautumisen kiinteäksi rakenteeksi. Tämä sopi aiempiin havaintoihin, että ionivahvuuden lisäys poistaa N-proteiinimolekyylien välisen sitotumisen. Osoitimme myös, että aminohapot, joila on suurin vaikutus N-proteiinien oligomerisaatioon eivät ole hajallaan kierre-kierteisessä 3D-mallissa vaan muodostavat rykelmiä. Työssä todistettiin myös N-proteiinin sitoutuvan glykoproteiini Gn:n sytoplasmiseen häntään. Tätä sitoutumista tutkimme käyttäen ns. GST-pull-down-menetelmää mutageneesiin liitettynä. Tulostemme mukaan Gn-proteiinin sytoplasmisen hännän intaktit, oikealla tavalla laskostuneet sinkkisormet (zinc fingers) sekä N-proteiinin keskiosa ovat olennaisia sitoutumiselle. Koska hantaviruksilla ei ole matrix-proteiinia–välittämässä RNA:n pakkautumista kuten muilla negatiivi-säikeisillä RNA-viruksilla – hantavirusten ribonukleoproteiinin täytynee sitoutua suoraan virusvaippaan pedattujen glykoproteiinien viruksen sisäisiin osiin. Osoittaessamme N-Gn sitoutumisen saimme suoraa näyttöä viruksen synteesin keskeisestä vaiheesta ribonukleoproteiinien hakeutuessa viruksen muodostumiskohtiin soluissa. Lopuksi aloimme tutkia N-proteiinin sitoutumista virus-RNA:han, sitoutumisalue löytyy ilmeisesti N-proteiinin keskiosista. Kehitimme mallin tämän sitoutumisen alkuvaiheelle. Hypoteesimme mukaan hantaviruksen N-proteiinissa on kaksi sekundaarirakenteen elementtiä, jotka johtavat RNA:n joutumiseen kapsidirakenteeseen. Toisen niistä oletamme toimivan “koukkuna” kalastamaan virus-RNA ja toinen, positiivisesti varattu, oletettavasti lisää entisestään N-RNA -sitoutumista. Kaiken kaikkiaan, löysimme N-proteiinille uusia toimintoja. Ennustimme tietokonemallinnuksella (in silico) proteiinin domeenirakenteen ja osoitimme kokeellisesti kunkin domeenin osuuden tietyissä toiminnoissa. Osoitimme intaktin N–terminaalisen coiled-coil -domeenin keskeisen roolin oligomerisaatiossa ja että varatut aminohapot sen pinnalla muodostavat N-monomeereille sitoutumispinnan. Keskinen domeeni on olennainen N-proteiinin sitoutuessa Gn-glykoproteiinin sytoplasmiseen häntään ja virus-RNA:han.

Hantaviral N and Gn proteins were shown to interact, thus providing the long-awaited evidence for one of the crucial steps in the virus replication at which RNPs are directed to the site of the virus assembly. Using pull-down assay and point mutagenesis it was demonstrated that intact, properly folded zinc fingers in the Gn protein cytoplasmic tail as well as the middle domain of the N protein (that includes aa residues 80-248) are essential for the interaction.

The P1 cistron encodes the first and most variable part of the polyprotein of potyviruses. A site tolerant to a pentapeptide insertion at the N-terminus of Potato virus A P1 (Genome Res. 12, 584–594) was used to express heterologous proteins (insertions up to 783 nucleotides) with or without flanking new proteolytic sites. Aequorea victoria green fluorescent protein (GFP) accumulated to high levels when proteolytically released from P1 and showed strong fluorescence in leaves systemically infected with vector virus. Deletions in GFP and adjacent viral sequences emerged 2–4 weeks after infection, revealing putative recombination hot spots. The inserts in P1 diminished infectivity host-specifically, reduced virus accumulation in protoplasts and systemically infected leaves, alleviated symptoms and reduced accumulation of mRNA and HCpro in cis in a virus-free system. This heterologous protein expression site is the first within a protein-encoding cistron and the third in the genome of potyviruses.

Two isolates (SL1 and SL6) of Peru tomato virus (PTV, genus Potyvirus) were obtained from cocona plants (Solanum sessiliflorum) growing in Tingo Maria, the jungle of the Amazon basin in Peru. One PTV isolate (TM) was isolated from a tomato plant (Lycopersicon esculentum) growing in Huaral at the Peruvian coast. The three PTV isolates were readily transmissible by Myzus persicae. Isolate SL1, but not SL6, caused chlorotic lesions in inoculated leaves of Chenopodium amaranticolor and C. quinoa. Isolate TM differed from SL1 and SL6 in causing more severe mosaic symptoms in tomato, and vein necrosis in the leaves of cocona. Pepper cv. Avelar (Capsicum annuum) showed resistance to the PTV isolates SL1 and SL6 but not TM. The 5′- and 3′-proximal sequences of the three PTV isolates were cloned, sequenced and compared to the corresponding sequences of four PTV isolates from pepper, the only host from which PTV isolates have been previously characterised at the molecular level. Phylogenetic analyses on the P1 protein and coat protein amino acid sequences indicated, in accordance with the phenotypic data from indicator hosts, that the PTV isolates from cocona represented a distinguishable strain. In contrast, the PTV isolates from tomato and pepper were not grouped according to the host. Inclusion of the sequence data from the three PTV isolates of this study in a phylogenetic analysis with other PTV isolates and other potyviruses strengthen the membership of PTV in the so-called “PVY subgroup” of Potyvirus. This subgroup of closely related potyvirus species was also distinguishable from other potyviruses by their more uniform sizes of the protein-encoding regions within the polyprotein.

Bone marrow (BM)-derived cells are thought to participate in the growth of blood vessels during postnatal vascular regeneration and tumor growth, a process previously attributed to stem and precursor cells differentiating to endothelial cells. We used multichannel laser scanning confocal microscopy of whole-mounted tissues to study angiogenesis in chimeric mice created by reconstituting C57BL mice with genetically marked syngeneic BM. We show that BM-derived endothelial cells do not significantly contribute to tumor- or cytokine-induced neoangiogenesis. Instead, BM-derived periendothelial vascular mural cells were persistently detected at sites of tumor- or vascular endothelial growth factor-induced angiogenesis. Subpopulations of these cells expressed the pericyte-specific NG2 proteoglycan, or the hematopoietic markers CD11b and CD45, but did not detectably express the smooth muscle markers smooth muscle α-actin or desmin. Thus, the major contribution of the BM to angiogenic processes is not endothelial, but may come from progenitors for periendothelial vascular mural and hematopoietic effector cells. (Blood. 2004;104: 2084-2086)

Diseased plants of oat (Avena sativa L.) exhibiting abnormal proliferation of spikelets were observed in the field in Raseniai, Lithuania. The possible association of a phytoplasma with the disease, termed oat proliferation (OatP), was determined using polymerase chain reaction (PCR) for amplification of phytoplasmal ribosomal (r) RNA gene (rDNA) sequences from template DNA extracted from the diseased oats. DNA extractions and nested PCRs were conducted as previously described (2). In the nested PCRs, the first reaction was primed by phytoplasma-universal primer pair P1/P7, and the second (nested) PCR was primed by primer pair R16F2n/R16R2 (F2n/R2). Phytoplasmal rDNA was amplified in the nested PCR, indicating that the plants contained a phytoplasma, designated oat proliferation (OatP) phytoplasma. The OatP phytoplasma was identified and classified according to the system of Lee et al. (2) through restriction fragment length polymorphism (RFLP) analysis of 16S rDNA amplified in the PCR primed by F2n/R2. On the basis of collective RFLP patterns of the 16S rDNA, the OatP phytoplasma was classified as a member of group 16SrI (group I, aster yellows phytoplasma group). The RFLP patterns of the 16S rDNA were indistinguishable from those of 16S rDNA from tomato big bud (BB) phytoplasma and other phytoplasmas classified in group I, subgroup A (subgroup I-A, tomato big bud phytoplasma subgroup). The 1.8-kbp rDNA product of PCR primed by primer pair P1/P7 was cloned, and its nucleotide sequence was determined. The sequence was deposited in GenBank under Accession No. AF453416. Results from putative restriction site analysis of the cloned and sequenced rDNA were in excellent agreement with the results from enzymatic RFLP analysis of uncloned rDNA from OatP-diseased oat plants. Sequence similarity between the 1.8-kbp rDNA of OatP phytoplasma and that of BB phytoplasma (GenBank No. AF222064) was 99.2%; 9 of the 14 base changes were in the 16S-23S rRNA intergenic spacer region. The base differences in rDNA may signal that the OatP and BB phytoplasmas are mutually distinct in their biologies. Phytoplasmas classified in subgroup I-A have previously been reported in a broad range of plant species in North America and Europe, although there are no previous definitive reports of oat as a host of a subgroup I-A phytoplasma (3,4). In 1977, Fedotina (1) reported electron microscopy of a mycoplasma-like organism (phytoplasma) in pseudorosette-diseased oat plants in Siberia, but the identity of that phytoplasma remains unknown. Subgroup I-A phytoplasma strains are geographically widespread and have been found in numerous plant species (3,4). The discovery reported here, of a subgroup I-A phytoplasma in diseased oats in Lithuania, provokes questions concerning possible impacts of this phytoplasma on oat cultivation in central Europe and other regions. References: (1) V. L. Fedotina. Arch. Phytopathol. Pflanzenschutz 13:177, 1977. (2) I.-M. Lee et al. Int. J. Syst. Bacteriol. 48:1153, 1998. (3) C. Marcone et al. Int. J. Syst. Evol. Microbiol. 50:1703, 2000. (4) D. Valiunas et al. Plant Dis. 85:804, 2001.

Alnus glutinosa (alder) is widespread in Europe and is an important component of biological diversity in natural forest ecosystems in the Baltic Region. In 2000, diseased trees of A. glutinosa exhibiting characteristically phytoplasmal disease symptoms of shoot proliferation and leaf yellowing were observed in Aukstaitija National Park, Lithuania. In other parts of Europe, alder is affected by a phytoplasmal disease known as alder yellows, which is characterized by symptoms that include yellowing and reduced leaf size, die-back of branches, and decline of trees (2,3). Proliferation of shoots has not been previously reported with this disease. An association between alder yellows and infection by a phytoplasma has been reported in A. glutinosa in Germany and Italy, and a phytoplasma has been found in A. glutinosa in France and Hungary (2,4). We examined symptomatic alder from Lithuania using nested polymerase chain reaction (PCR) (1), primed by P1/P7 and followed by R16F2n/R16R2 (F2n/R2), for amplification of phytoplasmal ribosomal (r) DNA. The results indicated the presence of a phytoplasma, designated ALY-L, in the diseased alder. We classified the ALY-L phytoplasma through restriction fragment length polymorphism (RFLP) analysis of 16S rDNA. A 1.2-kbp fragment (F2n-R2 segment) of rDNA, amplified in PCR primed by F2n/R2, was analyzed using single endonuclease enzyme digestion with AluI, MseI, KpnI, HhaI, HaeIII, HpaI, HpaII, RsaI, HinfI, TaqI, Sau3AI, BfaI, and ThaI. On the basis of collective RFLP patterns, phytoplasma ALY-L was classified as a member of group 16SrV (group V, elm yellows group), subgroup C. The amplified 16S rDNA was cloned in Escherichia coli and sequenced, and the sequence was deposited in the GenBank data library (Accession No. AY028789). Nucleotide sequence alignment revealed that 16S rDNA from phytoplasma ALY-L shared 100% sequence similarity with 16S rDNA (GenBank Accession No. Y16387) from a phytoplasma associated with alder yellows (ALY) disease in Italy. The results support the conclusion that a strain of ALY phytoplasma is present in Lithuania. Phytoplasmas belonging to groups 16SrI (aster yellows phytoplasma group) and III (X-disease phytoplasma group) have been found in herbaceous plant species in Lithuania. This report records the first finding of a group V phytoplasma, and the first finding of a phytoplasma in a tree species in the eastern Baltic Region. These findings contribute knowledge about the diversity of phytoplasmas in the Baltic Region and the distribution of ALY phytoplasma in Europe. Apparently, A. glutinosa may be infected by the phytoplasma but not develop obvious disease symptoms, as has been reported elsewhere (3). Thus, it is possible that ALY-L phytoplasma is widespread, but as yet undetected, throughout the geographic range of alder in the Baltic Region. This possibility is supported by the finding of the monophagous leafhopper vector (Oncopsis alni) of ALY phytoplasma throughout Europe (cited in Maixner and Reinert [3]). Further research is needed to assess the impact of phytoplasmal infections such as those by ALY-related phytoplasma strains on trends in biological diversity in the natural forest ecosystems of the Baltic Region and elsewhere in Europe. References: (1) R. Jomantiene et al. Int. J. Syst. Bacteriol. 48:269, 1998. (2) W. Lederer and E. Seemüller. Eur. J. For. Pathol. 21:90, 1991. (3) M. Maixner and W. Reinert. Eur. J. Plant Pathol. 105:87, 1999. (4) R. Mäurer et al. Phytopathology 83:971, 1993.