Two new species of the diatom genusChaetoceros (Bacillariophyta)

Two new planktonic diatom species of the genusChaetoceros are described herein:Ch. octagonus andCh. rectus, from material of Baja California coasts and the Gulf of California, respectively;Ch. rectus was also found in a sample from Australian waters.Ch. octagonus is a robust species, with a characteristic pyramidal valve shape, heavily silicified valves and setae, and one central rimoportula on every valve in the chain; it is compared with related species, which show a similar morphology, especially by electron microscopy. It belongs into subg.Chaetoceros, sect.Borealia. Ch. rectus is placed in subg.Hyalochaete, and provisionally within sect.Anastomosantia. Its major characters are: chains, cells, and setae are delicate and fragile, cells are joined in the chain by a bridge which connects sibling intercalary setae, valves and setae are weakly silicified, and one rimoportula is present on terminal valves only. Comparison is made with another species of the same section.Ch. rectus shows a different manner of chain-forming within the genus than previously described in the literature.     

DNA base composition within the genusScenedesmus (Chlorophyta)

The DNA base compositions of 60 strains ofScenedesmus were determined and found to be a valuable indicator for the differentiation within this genus (except for the very closely related species of the subsect.Desmodesmus). The range for allScenedesmus species was 49.9–69.3 mol% GC for nuclear DNA and 36.8–39.9 mol% GC for chloroplast DNA. The separation of the genusTetradesmus cannot be verified by GC values, becauseS. obliquus andS. (Tetradesmus)wisconsinensis have a similar GC content.S. (Chlorella)ultrasquamata, S. costato-granulatus (sect.Costato-granulati) andS. lunatus are separated clearly from all other species of the genus because of their high GC content.     

Phytotoxic activity of selected water-soluble metabolites of Fusarium against Lemna minor L. (Duckweed)

Phytotoxicity and inhibitory effects of the fusarial toxins fumonisin B₁ (FB₁) [m.p. 103–105 °C], fusaric acid [m.p. 106–107 °C], butenolide (4-acetamido-4-hydroxy-2-butenoic acid lactone) [116–117 °C], 9, 10-dihydroxyfusaric acid [m.p. 150–155 ° C], and moniliformin on chlorophyll synthesis in the aquatic macrophyte Lemna minor (duckweed) were examined. FB₁ proved to be most active, reducing the growth of L. minor fronds and their ability to synthesize chlorophyll by 53% and 59%, respectively, at 0.7 g/ml. The growth rate of L. minor was reduced 59% by 6.7 g/ml fusaric acid, 62% by 66.7 g/ml butenolide, and 22% by 66.7 g/ml 9,10-dihydroxyfusaric acid. Moniliformin was the least phytotoxic to L. minor, with only a 16% suppression of growth rate and a 54% reduction in chlorophyll at 66.7 g/ml.The mention of firm names or trade products does not imply that they are endorsed or recommended by the US Department of Agriculture over other firms or similar products not mentioned.     

Studies in the embryology of the diandrous orchidCypripedium cordigerum (Cypripedieae,Orchidaceae)

The anther wall layers ofCypripedium cordigerum are six to eight. The glandular tapetum is 2- or 3-layered and its cells are uninucleate. Simultaneous cytokinesis results in decussate, isobilateral and tetrahedral pollen tetrads. Ripe pollen grains are 2-celled. The mature ovules are anatropous, bitegmic and tenuinucellate. Both the integuments are dermal in origin and 2-layered. The inner integument alone forms the micropyle. The female gametophyte is 6-nucleate and bisporic. The reduction of nuclei is due to the strike phenomenon. Double fertilization occurs. The primary endosperm nucleus divides to form two free endosperm nuclei. The mature embryo is undifferentiated. The cells ca, m and n contribute to the embryo. The suspensor is single-celled. The seed coat is formed entirely by the outer layer of the outer integument. There are three sterile and three fertile valves in the ovary. In the prefertilization stages these valves consist of parenchymatous cells with starch and raphides. After fertilization, the sterile valves develop sclerotic cells whereas the fertile valves remain parenchymatous. The pericarp structure and embryological features support the retention of tribeCypripedieae within theOrchidaceae.     

Cell multiplication and ultrastructure ofMicrasterias denticulata (Desmidiaceae) grown under salt stress

Cells ofMicrasterias denticulata Bréb. were kept in nutrient solution of high osmolality (salt stress) for four weeks. In a special cell multiplication test it was established that cell division is gradually inhibited at increasing salt concentrations and totally arrested at the highest concentration (26 mosm/kg). Recovery studies proved that even cells from the highest concentration range start dividing immediately after being placed in aqua bidest. thus indicating the full reversibility of the inhibiting effect. — Cells of the highest concentration range show marked ultrastructural changes. Besides an enormous accumulation of starch and oil bodies and a condensed appearance of the ground plasma, a reduction of mitochondria, ER and the Golgi-system is found. The most striking effect occurs on the vacuolar system which appears extremely reduced and condensed. The cell wall is thickened by the formation of an additional cell wall layer with a spongy electron microscopical appearance. Through the cell wall many droplets of a probably fat-like substance are excreted. — In summary, salt stress induces growth-inhibited akinete cells in the sense ofFritsch; these can be reactivated by decreasing the salt concentration. The salt-induced akinete state seems to be an ecological adaption to unfavourable conditions rather than a degeneration of the cells.Dedicated to Prof. DrLothar Geitler on the occasion of his 90th birthday.23. 12. 1988     

The spermatozoon of Oikopleura dioica Fol (Larvacea,Tunicata)

Summary The spermatozoon of Oikopleura dioica is about 30 m long, with a spherical head, about 1 m wide, a 3 m long and 1 m wide midpiece, and a 25 m long tail with a tapered end piece. The head contains a nucleus with the chromatin volume limited to about 0.1 m³. A small acrosome is found in an anterior inpocketing, and a flagellar basal body in a posterior inpocketing of the nucleus. The midpiece contains a single mitochondrion with the flagellar axoneme embedded in a groove along its medial surface. The flagellar axoneme has the typical 9 + 2 substructure, and the basal body the typical 9+0 substructure. A second centriole and special anchoring fibres are absent.     

SEXUAL REPRODUCTION IN STEPHANODISCUS NIAGARAE (BACILLARIOPHYTA)1

We observed sexual reproduction in a clonal culture of Stephanodiscus niagarae Ehrenb. and used light and scanning electron microscopy to absent flagellated male cells, auxospore growth, initial valve structure and production, and subsequent daughter cell division. Free auxospores were spherical and nonsiliceous throughout growth, producing hemispherical initial valves devoid of spines and with nonfasciculate striae. Pregametangial cells averaged 43% of the diameter of the daughter cell population and were 1/9 the biovolume of initial, cells. This paper is the first confirmed report of sexual reproduction in S. niagarae, although it appears that specimens of Actinocyclus niagarae H. L. Smith, described from Lake Erie in 1878, are actually initial valves of S. niagarae.     

Haustoria inUrocystis (Tilletiales)

Haustoria of severalUrocystis spp. have been investigated by transmission electron microscopy. The haustoria are botryose and have an extrahaustorial matrix with vesiclelike bodies. The extrahaustorial membrane shows high ATPase activity in contrast to the haustorial plasmalemma. In walled off haustoria the haustorial plasmalemma stains more intensely than the extrahaustorial membrane. The vesicle-like bodies are ATPase negative. The role of the vesicle-like bodies is discussed.Dedicated to Prof. DrLothar Geitler on the occasion of the 90th anniversary of his birthday. Part 55 of a series Studies inHeterobasidiomycetes.     

Quantitative resistance to barley leaf stripe (Pyrenophora graminea) is dominated by one major locus

A major gene underlying quantitative resistance of barley against Pyrenophora graminea, a seedborne pathogen causing leaf stripe, was mapped with molecular markers in a barley doubled haploid (DH) population derived from the cross Proctor x Nudinka. This quantitative trait locus (QTL) accounts for r ²= 58.5% and was mapped on barley chromosome 1, tightly linked to the naked gene. A second resistance QTL accounting for 29.3% of the variation in the trait was identified on the P arm of barley chromosome 2. Another two minor QTLs were detected by further analysis. None of the QTLs was found in the barley chromosome 2 Vada region studied by Giese et al. (1993).     

Cytogenetic studies of the intergeneric hybrids between Secale cereale and Elymus caninus,E. brevipes,and E. tsukushiensis (Triticeae: Poaceae)

Summary Integeneric hybridizations were carried out between Secale cereale L. (2n = 14, RR) and three Elymus species, namely, E. caninus (L.) L. (2n = 28, SSHH), E. brevipes (Keng) Löve (2n = 28, SSYY) and E. tsukushiensis Honda (2n = 42, SSHHYY). Chromosome pairing was studied at metaphase I in the parental species and the hybrids. Meiotic configurations of the hybrids were 20.74 1+0.14 II for E. caninus x S. cereale (SHR), 16.35 I+2.17 II+0.09 III for E. brevipes x S. cereale (SYR) and 25.84 I+1.10 II+0.02 III for E. tsukushiensis x S. cereale (SHYR), in addition to some secondary associations in the different hybrids. It is concluded from the study that (1) a certain, different homoeologous relationship exists among S, H and Y genomes in the investigated Elymus species; (2) low homoeology is present between genomes of Elymus (S or H or Y) and rye (R); (3) the Secale genome affects homoeologous chromosome pairing between different genomes in E. brevipes and E. tsukushiensis.     

Nuclear Overhauser effect investigation on GM1 ganglioside containingN-glycolyl-neuraminic acid (II3Neu5GcGgOse4Cer)

The conformational properties of the oligosaccharide chain of GM1 ganglioside containingN-glycolyl-neuraminic acid, -Gal-(1-3)--GalNAc-(1-4)-[-Neu5Gc-(2-3)]--Gal-(1-4)--Glc-(1-1)-Cer, were studied through NMR nuclear Overhauser effect investigations on the monomeric ganglioside in dimethylsulfoxide, and on mixed micelles of ganglioside and dodecylphosphocholine in water. Several interresidual contacts for the trisaccharide core--GalNAc-(1-4)-[-Neu5Gc-(2-3)]--Gal-were found to fix the relative orientitation of the three saccharides, while the glycosidic linkage of the terminal -Gal-was found to be quite mobile as the -Gal-(1-3)--GalNAc-disaccharide exists in different conformations. These results are similar to those found for two GM1 gangliosides containingN-acetyl-neuraminic acid and neuraminic acid [1].Abbreviations Ganglioside nomenclature is in accordance with Svennerholm [23] and the IUPAC-IUB Recommendations [24] GM3(Neu5Ac) II³Neu5AcLacCer, -Neu5Ac-(2-3)--Gal-(1-4)--Glc-(1-1)-Cer - GM3(Neu5Gc) II³Neu5GcLacCer, -Neu5Gc-(2-3)--Gal-(1-4)--Glc-(1-1)-Cer - GM1(Neu5Ac) II³Neu5AcGgOse₄Cer, -Gal-(1-3)--GalNAc-(1-4)-[-Neu5Ac-(2-3)]--Gal-(1-4)--Glc-(1-1)-Cer - GM1(Neu5Gc) II³Neu5GcGgOse₄Cer, -Gal-(1-3)--GalNAc-(1-4)-[-Neu5Gc-(2-3)]--Gal-(1-4)--Glc-(1-1)-Cer - GM1(Neu) II³NeuGgOse₄Cer, -Gal-(1-3)--GalNAc-(1-4)-[-Neu-(2-3)]--Glc-(1-1)-Cer - GD1a IV³Neu5AcII³Neu5AcGgOse₄Cer, -Neu5Ac-(2-3)--Gal-(1-3)--GalNAc-(1-4)-[-Neu5Ac-(2-3)]--Gal-(1-4)--Glc-(1-1)-Cer - GalNAc-GD1a IV⁴GalNAcIV³Neu5AcII³Neu5AcGgOse₄Cer, -GalNAc-(1-4)-[-Neu5Ac-(2-3)]--Gal-(1-3)--GalNAc-(1-4)-[-Neu5Ac-(2-3)]--Gal-(1-4)--Glc-(1-1)-Cer - Neu neuraminic acid - Neu5Ac N-acetyl-neuraminic acid - Neu5Gc N-glycolyl-neuraminic acid - Cer ceramide     

Seed oil fatty acid patterns of theAconitum-Delphinium-Helleborus complex (Ranunculaceae)

Many members ofRanunculaceae contain unusual fatty acids in their seed oils. This leads to rather typical genus-specific fatty acid patterns or fingerprints in these seed oils. The members of theDelphinioideae and/orHelleboroideae, however, do not contain highly unusual fatty acids. Nevertheless, their seed oil fatty acid fingerprints are also fairly typical and genus-specific, and the patterns found are rather consistent throughout several species of one genus. It was found that species ofAconitum do not contain fatty acids with 20 carbon atoms.Delphinium, Consolida, Helleborus, Nigella and others do contain C₂₀ fatty acids. In allHelleborus species, for example, there was a consistent C₂₀ fatty acid pattern of 20:020:120:2>20:3. Species ofNigella andGaridella contain high levels,Helleborus low levels, of 20:2n-6 in their seed oils.Delphinium andAconitum both contain low levels of 18:3n-3, whereasHelleborus spp. consistently show high levels of this fatty acid. The genus-specific fatty acid patterns found are discussed, and a correlation with the subfamily and tribe affiliation of the genera investigated here is attempted.     

Effects of individual Bacillus thuringiensis insecticidal crystal proteins on adult Heliothis virescens (F.) and Spodoptera exigua (Hubner) (Lepidoptera: Noctuidae)

Bacillus thuringiensis (Bt) is a grampositive, spore forming bacterium, which is principally distinguishedfrom other bacilli by the production of large, insecticidal,protein crystals (Insecticidal Crystal Proteins, or ICPs). Theseproteins are usually thought to act only on the actively feedinglarvae of susceptible species by a mechanism which involvesconsumption and proteolytic processing of the protein followed bybinding to, and lysis of, midgut epithelial cells. However, few authorshave reported Bt toxicity to adult insects. In the followingpaper, we expand on previous reports of toxicity to adult insects andpresent data which demonstrate that: (1) proteolytically activated ICPssignificantly reduce the lifespans of adult Heliothis virescensand Spodoptera exigua at concentrations of 500 g/ml, butnot 167 or 25 g/ml, (2) individual activated ICPs are differentiallytoxic to adult H. virescens and S. exigua, and (3)adult S. exigua are sensitive to Cry1C protoxin at aconcentration of 1 mg/ml.Deceased     

Raiding behavior of the dulotic antChalepoxenus muellerianus (Finzi) in the field (Hymenoptera: Formicidae,Myrmicinae)

Summary Little information is available regarding the raiding behavior in nature of dulotic ants belonging to the tribeLeptothoracini. Between July 17 and 24, 1991, several raids ofChalepoxenus muellerianus (Finzi) were observed in nature near Tignale/Lago di Garda, Italy. Apparently, this species raids frequently during its summer raiding season (5 raids were observed during 7 days spent observing 8 colonies). A singleChalepoxenus colony sometimes raids more than one host colony more or less simultaneously. Observations during which oneChalepoxenus colony raided another and captured slavemaker brood indicate that intraspecific raids can occur either accidentally, or as a result of competition or territoriality when there is a sufficient dense slavemaker population.     

Abscisic acid in shoots and roots of Scots pine (Pinus sylvestris L.) seedlings grown in controlled long-day and short-day environments

Scots pine (Pinus sylvestris L.) seedlings grown in nutrient solution in controlled-environment chambers were used. The effects of a shortday (SD, early autumn) treatment on growth and the content of free and alkaline hydrolysable abscisic acid (ABA) in shoots and roots were investigated. The weekly relative growth rates of seedlings grown continuously under long-day (LD, summer) conditions were stable at approx. 0.08 g g^–1 d^–1 between weeks four and eight from germination. Weekly relative growth rates of seedlings transferred to SD conditions decreased rapidly to a then stable level of approx. 0.04 g g^–1 d⁰¹. Shoot elongation ceased within two weeks of SD treatment. The content of both free and alkaline hydrolysable ABA was approx. 40–50% higher in shoots of seedlings grown for five weeks in LD plus one week in SD than in shoots of seedlings grown for five or six weeks in LD. Two additional weeks of SD did not change the free ABA content. Three weeks in simulated late autumn (SD but decreased temperatures) and three weeks in simulated winter (lower light intensity and temperature) further increased the content of free ABA in the shoots. A transfer back to LD conditions reduced the ABA content to a level equal to the level found during the first LD period. The recovery of radioactive ABA at certain times after application ofr[³H] ABA was the same in shoots and roots of LD-grown and SD-treated seedlings.Abbreviations ABA abscisic acid - LD long day(s) - RGR₇ weekly relative growth rates - SD short day(s)     

Infloreszenz- und Blütenentwicklung bei der KugeldistelEchinops exaltatus (Asteraceae)

InEchinops the flowers are surrounded by several scales and initiated in an acropetal and spiral succession on a cone-like inflorescence axis (Figs. 1–6). The floral organs originate in the following sequence: petals—stamens—carpels—pappus. The petals arise from a meristematic rim and therefore are already interconnected when they arise as primordia. This sympetalous zone remains rather inconspicuous for a long period, but eventually, the elongated corolla tube is formed through intercalary growth in a ring zone. Thereby, the stamens are moved upwards and form ledges on the corolla tube (Fig. 34). In the inferior ovary the usual zones of the typical angiospermous gynoecium can be distinguished, namely a synascidiate, symplicate and hemisymplicate zone. The ovule is borne on carpellary tissue.

     

Silicon amelioration of aluminium toxicity in teosinte (Zea mays L. ssp. mexicana)

The influence of different Al concentrations, (0, 60 and 120 M Al) on growth and internal concentrations of Al, Si and selected organic acids was analysed in plants of teosinte (Zea mays L. ssp. mexicana), a wild form of maize from acid soils from Mexico. The plants were grown in nutrient solutions (pH 4.0) with or without 4 M silicon. Analysis with the GEOCHEM speciation program did not reveal differences between free activities of Al³⁺ in solutions with and without 4 M Si, but solutions with Si yielded lower concentrations of monomeric Al species, [Al]_mono, when analysed by a modified aluminon method. Plants grown on solutions with similar [Al]_mono, but differing in silicon, showed highly significant differences in growth and tissue concentrations of Al and organic acids. Silicon prevented growth inhibition at [Al]_mono concentrations as high as 35 M, while plants grown without Si suffered severe growth reductions with 33 M [Al]_mono. In solutions with similar [Al]_mono concentrations plants with Si had lower tissue Al concentrations and higher concentrations of malic acid than plants without Si. In view of both the significant influence of Si on the response of plants to Al toxicity and the fact that some soluble Si is always present in soil solutions, the addition of low Si concentrations to nutrient solutions used for Al-tolerance screening is recommended.     

Effects of G-protein probes on interactions between auxin efflux carriers and phytotropin receptors in zucchini (Cucurbita pepo L.) microsomal membranes

Microsomal vesicles prepared from etiolated hypocotyl tissue of zucchini (Cucurbita pepo L. cv. All Green Bush) exhibited saturable N-1-naphthylphthalamic acid ([³H]NPA) binding, NPA-stimulated association of indol-3yl-acetic acid ([³H]IAA), and saturable binding of guanosine 5-O-[3-thiotriphosphate] (GTP--[³⁵S]). These vesicles were used to test the possibility that NPA receptors might interact with IAA-anion efflux carriers by coupling through a GTP-binding protein (G-protein). Unlabelled GTP--S or guanosine 5-O-[2-thiodiphosphate] (GDP--S) had no effect on saturable NPA binding or on the NPA-stimulated association of IAA with microsomes. NPA did not affect saturable binding of GTP--[³⁵S] to microsomes, either in the presence or absence of saturating concentrations of unlabelled GTP--S or GDP. It is concluded that the occupancy of phytotropin receptors is not transduced to auxin efflux carriers by a GTP-binding protein.     

Nuclear DNA and heterochromatin contents in theScilla hohenackeri group,S. persica,andPuschkinia scilloides (Liliaceae)

DNA contents (presented as 1C-values) have been determined cytophotometrically in 7 species of theScilla hohenackeri group (10.18 to 22.71 pg), and in the systematically more isolated taxaS. persica (21.02 pg) andPuschkinia scilloides (6.80 pg). The heterochromatin amount is not correlated with the nuclear DNA content. Euchromatin, therefore, is not a particularly conservative part of the genome. However, high C-values and large but few terminal heterochromatin bands, and lower C-values and numerous but smaller heterochromatin bands are found to be linked in theS. hohenackeri group. Obviously, numerous chromosomal changes have accompanied speciation in this group. DNA contents, and C-banded karyotypes are consistent with systematic affinities based on morphological similarities.Evolution ofScilla and Related Genera, III.     

Cytotaxonomy and karyotype evolution inPhleum sect.Phleum (Poaceae) in Poland

Three taxa are distinguished in the sectionPhleum Griseb. in Poland:P. nodosum (2n = 14),P. pratense (2n = 42), and the third one unformally named hereP. commutatum (2n = 14). It corresponds morphologically toP. commutatum Gaud. reported as a tetraploid taxon (2n = 28) from other geographic regions. Giemsa C-banded karyotypes of these three taxa help clarify the taxonomic status ofP. commutatum and the origin of the hexaploidP. pratense. It is suggested that changes in the amount of telomeric heterochromatin played an important role in the evolution ofPhleum karyotypes.