Thalassiosira bulbosa Syvertsen,sp. nov., an arctic marine diatom

Summary Thalassiosira bulbosa Syvertsen is described from one clonal culture and natural marine, arctic material collected from brown spots on the ice and from seawater close to the ice border. The new taxon belongs to the group of Thalassiosira species with a single central strutted process and one marginal ring of strutted processes. Specific features are the conspicuous bulbshaped outer part of the marginal strutted processes and a strutted tube surrounded by two oblong, bean-shaped satellite pores. T. bulbosa forms resting cells differing from the vegetative cells mainly in the degree of silicification and by having fewer openings through the frustule. The species may obtain its maximal cell size by a purely vegetative auxospore formation.     

BRACKISH WATER AND FRESHWATER SPECIES OF THE DIATOM GENUS SKELETONEMA. II. SKELETONEMA POTAMOS COMB. NOV.1

Electron microscope investigations of the siliceous frustule show that the diatom described by Hustedt as Stephanodiscus subsalsus (A. Cleve) Hust. is not Skeletonema subsalsum (A. Cleve) Bethge (Melosira subsalsa A. Cleve) but is Microsiphona potamos Weber. This species is so similar to Skeletonema costatum (Grev.) Cleve and Skeletonema subsalsum that the combination Skeletonema potamos (Weber) Hasle is suggested. Present records classify Skeletonema potamos as a freshwater species of lakes and rivers. In Sandusky Bay, Lake Erie (U.S.A.) and in River Wümme, a tributary of the River Weser (Germany) it grows with Skeletonema subsalsum. In nature, and when grown in cultures at a salinity of 0%, the processes are extremely short; when grown at salinities of 2% or more, the processes are much longer.     

Multiple paternity in Ixodes ricinus (Acari: Ixodidae), assessed by microsatellite markers

This investigation examines multiple paternity in Ixodes ricinus (Acari: Ixodidae). Previous studies have shown that multiple mating occurs in this tick, but this is the first evaluation of multiple paternity. Three family groups were examined by a panel of polymorphic microsatellite loci; all ticks were bred from wild-collected engorged females with a copulating male attached. For most larvae, the attached males could be excluded as possible sire, and in the 3 tested families, at least 2 of 3 females mated successfully with more than 1 male. This finding suggests that multiple paternity is a common reproductive strategy in I. ricinus, which may have consequences for the ticks' dispersal success by increasing the genetic diversity in broods from single females colonizing new sites.     

THE MARINE,PLANKTONIC DIATOMS THALASSIOSIRA OCEANICA SP. NOV. AND T. PARTHENEIA1

The diatom clone 13–1 isolated from the Sargasso Sea by Dr. R. R. L. Guillard as Cyclotella nana Hust. or Thalassiosira pseudonana Hasle and Heimdal is described as a separate species, Thalassiosira oceanica sp. nov. An amplified diagnosis of Thalassiosira partheneia Schrader is given, and a comparison of the two species is made based on light and electron microscopy. Similarities are present in the apparent distribution pattern, cell size, and girdle structure. Differences are present in the shape of the areolae of the valvocopula and the copula, in the structure of the vela of these bands, in the texture of the external valve surface, in the morphology of the strutted processes, in the location of the labiate process, in the distance between the marginal strutted processes, and by the presence of a marginal ridge in T. oceanica. Fifteen nanoplanktonic (maximum diameter = 20 UmUm) Thalassiosira species are listed, among them T. oceanica and T. partheneia.     

Some Nitzschia and related diatom species from fast ice samples in the Arctic and Antarctic

Summary Some Nitzschia and closely related species have been examined in the light and electron microscopes from fast ice samples in the Arctic and Antarctic. Nitzschia neofrigida, forming arborescent colonies, and Nitzschia promare, forming loose ribbon colonies, are described as new species, both probably included in the distribution of other similar species. A new combination, Auricula compacta, represents the first report of this genus from ice samples. Colony formation is reported for the first time in Nitzschia arctica and Nitzschia taeniiformis. No biopolar species were found and several reports of Arctic species in Antarctic ice samples have been refuted.     

Nationwide germline whole genome sequencing of 198 consecutive pediatric cancer patients reveals a high incidence of cancer prone syndromes

PURPOSE: Historically, cancer predisposition syndromes (CPSs) were rarely established for children with cancer. This nationwide, population-based study investigated how frequently children with cancer had or were likely to have a CPS. METHODS: Children (0–17 years) in Denmark with newly diagnosed cancer were invited to participate in whole-genome sequencing of germline DNA. Suspicion of CPS was assessed according to Jongmans’/McGill Interactive Pediatric OncoGenetic Guidelines (MIPOGG) criteria and familial cancer diagnoses were verified using population-based registries. RESULTS: 198 of 235 (84.3%) eligible patients participated, of whom 94/198 (47.5%) carried pathogenic variants (PVs) in a CPS gene or had clinical features indicating CPS. Twenty-nine of 198 (14.6%) patients harbored a CPS, of whom 21/198 (10.6%) harbored a childhood-onset and 9/198 (4.5%) an adult-onset CPS. In addition, 23/198 (11.6%) patients carried a PV associated with biallelic CPS. Seven of the 54 (12.9%) patients carried two or more variants in different CPS genes. Seventy of 198 (35.4%) patients fulfilled the Jongmans’ and/or MIPOGG criteria indicating an underlying CPS, including two of the 9 (22.2%) patients with an adult-onset CPS versus 18 of the 21 (85.7%) patients with a childhood-onset CPS (p = 0.0022), eight of the additional 23 (34.8%) patients with a heterozygous PV associated with biallelic CPS, and 42 patients without PVs. Children with a central nervous system (CNS) tumor had family members with CNS tumors more frequently than patients with other cancers (11/44, p = 0.04), but 42 of 44 (95.5%) cases did not have a PV in a CPS gene. CONCLUSION: These results demonstrate the value of systematically screening pediatric cancer patients for CPSs and indicate that a higher proportion of childhood cancers may be linked to predisposing germline variants than previously supposed.     

PSEUDO-NITZSCHIA PUNGENS AND P. MULTISERIES (BACILLARIOPHYCEAE): NOMENCLATURAL HISTORY,MORPHOLOGY, AND DISTRIBUTION1

Pseudo-nitzschia pungens f: multiseries is raised in rank from form to species based on morphological, physiological, and genetic features. Distinctive details of the valve face striae, the valve mantle, and the girdle of P. pungens and P. multiseries are outlined. The nomenclatural history and the distribution of the two species and their relationship to other species of the genus are discussed.