ALBERT

Notes: Polysaccharides have been isolated from Eimeria bovis and E. stiedai by the use of alkali. The purified polysaccharides stain purple with iodine and have been shown by chemical and enzymic means to be amylopectin. The storage amylopectins of these coccidia differ slightly from typical plant amylopectins in their fine structure.

Notes: Cultures of Tetrahymena pyriformis strain ST were exposed to 300 μg chloramphenicol/ml or 15 μg ethidium bromide/ml for 48 hr. Qualitative assessments of electron micrographs reveal that the abundance of mitochondrial cristae decreases greatly. By equating the spatial characteristics of the organism with those of a prolate spheroid, the distribution and abundance of mitochondria were quantified. Such characterizations reveal that the size of individual mitochondria decreases by 35–60% and that the number of mitochondria/cell increases ∼8 fold. The observations are discussed in terms of coordinated mitochondrial and nuclear genetic activities.

Notes: The life cycle of I. canis Nemeséri, 1959 was studied in experimentally infected dogs. Freshly sporulated oocysts were ovoid and 34–40 × 28–32 μm. The endogenous stages were found directly beneath the epithelium of the distal portion of the small intestinal villi. Most of the endogenous stages were in the lower 1/3 of the small intestine, but occasionally they were found in other portions of the small intestine. Three asexual generations were present. First-generation schizonts were 16–38 × 11–23 μm and contained 4–24 merozoites; mature 1st-generation merozoites were 8–11 × 3–5 μm. First-generation schizogony lasted up to 7 days after inoculation. Second-generation schizonts were 12–18 × 8–13 μm and contained up to 12 merozoites which were 11–13 × 3–5 μm. Second-generation schizogony was present on postinoculation days 6 and 7. Third-generation schizonts were formed by nuclear division of 2nd-generation merozoites. Most 2nd-generation merozoites underwent nuclear division without leaving the parasitophorous vacuole of the 2nd-generation schizont. Mature 3rd-generation schizonts were 13–38 × 8–24 μm and contained 6–72 merozoites. Third-generation merozoites were 8–13 × 1–3 μm. Third-generation schizogony was present on days 6–8 after inoculation. Mature macrogametes were 22–29 × 14–23 μm. Mature microgametocytes were 20–38 × 14–26 μm. Gametes were present on postinoculation days 7–10. Oocysts were present in tissue sections on postinoculation days 8–10 and 12. The prepatent period was 9–11 days.

Notes: Book reviewed in this article:Cheng, T. C., ed. 1973. Current Topics in Comparative Pathobiology.

Notes: Gregarine Selenidium fauchaldi sp. n. is described from the intestinal lumen of the polychaete Phragmatopoma californica (Fewkes, 1889) in the intertidal zone of the Pacific Ocean on Santa Catalina Island, California. In addition, the new combination Selenidium telepsavi (Stuart, 1871) comb. nov. is introduced for the gregarine originally described as Monocystis telepsavi from the polychaete Telepsavus castarum in the Black Sea.

Notes: Two of 15 road-killed opossums examined for coccidia were found to be infected with a hitherto undescribed species of Eimeria, herein named Eimeria indianensis. The oocysts were spherical (63%) or slightly subspherical (37%) with a double-layered wall. The outer layer was ∼1.5 μm thick, yellowish, striated, and appeared rough and pitted on the surface. A micropyle was absent. The spherical oocysts were 16.3 (13–18) μm in diameter; the subspherical ones, 17.6 (15–18) × 16.4 (14–17) μm. The sporocysts measured 9.1 (8–10) × 6.2 (6–7) μm and contained a granular residuum. The sporozoites were elongate, measuring 13.4 (13–15) × 1.8 (1.6-2.0) μm; no refractile globules were seen. The prepatent period was 10 days and the patent period ranged from 9–15 days.A few oocysts of an Isospora sp. were present in one opossum. It was not possible to confirm whether they were specifically of the opossum or of spurious origin.

Notes: Khawkinea quartana, a naturally occurring colorless homologue of Euglena, was examined with the electron microscope. The organism is biflagellate though only one of the 2 flagella emerges from the anterior reservoir. The pellicular strips covering the body of the organism are supported by microtubules which are continuous in part with microtubules bordering the reservoir. Additional rows of microtubules are found associated with the kinetosomes. An eyespot is located in the wall of the reservoir and, adjacent to it, the contractile vacuole.The nucleus, mitochondria, and Golgi complexes are similar to those described in other euglenoid flagellates. The food reserve is paramylon.The study supports the phylogenetic origin of Khawkinea from pigmented Euglena through the loss of chloroplasts.

Notes: Le cortex de la face dorsale (non ciliée) ne contient pas de cinétosomes; sous des alvéoles bien développés se trouve un épiplasme épais, puis une couche irrégulière de microtubules longitudinaux; de nombreux pores cylindriques traversent le cortex. La région ventrale, limitée aux faces internes des 2 lèvres apicales, porte la ciliature somatique répartie en 2 champs inégaux (droit 〉 gauche). Chaque cinétie somatique comporte une seule rangée de cinétosomes qui, tous, possèdent des formations fibrillaires associées: (a) dérivés classiques: fibres transverses, fibres postciliaires, fibre cinétodesmale; (b) une lame transverse gauche, dense, accompagnant les fibres transverses; (c) une couche de microtubules sous-cinétiens s'étendant vers l'avant de la cinétie.L'existence d'une ciliature buccale spécialisée est démontrée; elle consiste en une cinétie “circumorale” don l'infraciliature est faite de paires de cinétosomes (1 cilifère, l'autre non), que ne sont pas des dyades; de ce fait, cette infraciliature n'est pas l'equivalent de celle d'une membrane ondulante ou d'une parorale de Cilié des Ordres supérieurs. De plus, sa polarité antéro-postérieure est inversée par rapport à celle des cinéties somatiques, donc par rapport à celle du Cilié; elle est accompagnée sur sa droite par quelques cinéties somatiques (3 au maximum) qui sont également inversées; il est probable que ces inversions résultent de mouvements morphogénétiques identiques à ceux qui se produisent lors de la stomatogénese chez les Chlamydodontidae et les Dysteriidae. Aucune armature de némadesmes n'entoure le cytopharynx; ce dernier est soutenu par des rideaux de microtubules qui lui donnent un aspect feuilleté trèe particulier, et le phagoplasme qui l'accompagne renferme des tubules complexes (vermicelles).L'organisation du cortex dorsal est comparée à celle d'autres Ciliés de divers groupes. Les formations fibrillaires associées aux cinétosomes somatiques sont identiques à celles décrites chez des Chlamydodontidae, des Dysteriidae, certains Rhynchodina et les bourgeons ciliés de certains Acinétiens.La disposition et la constitution de l'infraciliature somatique, la présence et les caractéristiques d'une différenciation infraciliaire périorale (“circumorale”), l'aspect feuilleté de la paroi cytopharyngienne, la présence de tubules complexes (vermicelles) dans le phagoplasme, l'origine de l'appareil fixateur, l'héteromérie du macronoyau, sont autant de caractères communs avec les families Chlamydodontidae et Dysteriidae. Aussi, une révision systématique est envisagée, avec l'établissement de 2 sous-ordres, proches l'un de l'autre, et appartenant à l'ordre des Hypostomatida: S/O Chonotrichina et S/O Cyrtophorina (ce dernier limité aux seules families Chlamydodontidae et Dysteriidae).〈section xml:id="abs1-2"〉〈title type="main"〉SYNOPSISThe non-ciliated dorsal cortex is devoid of kinetosomes, but perforated with numerous pores; it contains large alveoli, an important epiplasm and an irregular sheet of longitudinal microtubules. The ventral side is confined to the internal faces of the 2 apical lips which bear 2 unequal fields of somatic ciliature (right 〉 left). A somatic kinety has only one line of kinetosomes, the associated fibers of which are: (a) classical derivatives: transverse, postciliary and kinetodesmal fibers; (b) a dense transverse spur, running along the transverse fibers; (c) a sheet of subkinetal microtubules extending forward along the kinety.The special buccal ciliature is a “circumoral kinety,” the infraciliature of which is composed of pairs of kinetosomes (1 ciliated, 1 nonciliated), which are different from dyades; so, this circumoral kinety is not homologous to the UM of ciliates included in superior orders. Furthermore, its anteroposterior polarity is inverse with regard to that of the somatic kineties and that of the cell; the circumoral kinety is accompanied by some inverse somatic kineties (maximum 3); all these inversions are probably the result of morphogenetic movements analogous to these which are described in the stomatogenesis of Chlamydodontidae and Dysteriidae. The wall of the cytopharynx is composed of overlapping sheets of microtubules. “Vermicelles” form the phagoplasm. Nemadesmata are absent.The dorsal cortical organization is compared with that of other ciliates. The fibers associated with somatic kinetosomes are identical to those of Chlamydodontidae, Dysteriidae, rhynchodine Ancistrocomidae, and ciliated buds of some Acineta.All the characteristics (somatic infraciliature and its derivates, cytopharyngeal wall, vermicelles, origin of the fixative apparatus, heteromerous macronucleus) are common for Chilodochona and the 2 families Chlamydodontidae and Dysteriidae. A revision of the systematics is envisaged, with the establishment of 2 new close suborders, belonging to the order Hypostomatida: S/O Chonotrichina and S/O Cyrtophorina (the last one with only the 2 familes: Chlamydodontidae, Dysteriidae).

Notes: The fate of labeled DNA in macronuclear fragments of starving Paramecium aurelia exconjugants was studied by quantitative autoradiography. Labeled material originally contained in DNA of macronuclear fragments is incorporated into macronuclear anlagen. During the starvation period the mean number of macronuclear fragments per cell decreased exponentially while there was an approximately exponential increase in the volume of macronuclear anlagen. Fragments appeared to be selectively and individually autolyzed. Labeled material originally contained in fragments was largely if not completely conserved through 108 hr of starvation during which more than 90% of the fragments were lost. Soluble labeled material was detectable after autolysis of fragments began, but finally almost all labeled material was incorporated into macronuclear anlagen.

Notes: SYNOPSIS. The recent literature on the physical, chemical and biological characterization of antigens from the African trypanosomes is reviewed. The antigens are divided into three major groups: a) variant-specific antigens, b) common antigens, and c) host-like antigens. The variant-specific antigen(s) are relatively small molecular weight proteins located on the surface of the trypanosome, and are involved in protection and agglutination. It is suggested that there is more than a single variant-specific antigen on the cell surface. In contrast, the common antigens are internal or somatic antigens which are believed to have structural or enzymatic functions but are not involved in either protection or agglutination. In addition, evidence is also presented which suggests that there are host-like antigens within the surface coat and/or membranes of the trypanosomes. The importance of these three groups of antigens, and the mechanis(s) of antigenic variation are discussed in relationship to the immune response of the host to the African trypanosomes. Several possible approaches for future investigations are described.

Notes: Book reviewed in this article:Olsen, O. Wilford. 1974. Animal Parasites. Their Life Cycles and Ecology.

Notes: SYNOPSIS. Diplodinium flabellum, previously described on the basis of its occurrence in rumen contents from 3 hosts of Bos indicus, has been observed in domestic sheep. Numbers of this species were quite high, constituting up to 18.8% of the total fauna in one instance. Diurnal changes in numbers for sheep fed once daily were similar to the cycles reported for other Ophryoscolecids. No obvious relationship was found between the occurrence and numbers of D. flabellum and other genera of rumen ciliates. Two new morphologically distinct forms of this species were observed, one without any spines on the posterior left side and one with a single spine. This is in contrast to the original species description in which 2 spines occur on the posterior left side. Intermediate forms were observed which connected the 3 morphological types, indicating their conspecific relationship. It is proposed that the species description for Diplodinium flabellum be emended to include a total of 3 subspecies: Diplodinium flabellum Kofoid and MacLennan, 1932 flabellum subsp. n.; Diplodinium flabellum aspinatum subsp. n.; and Diplodinium flabellum monospinatum subsp. n. Considerable variation in the shape and length of the caudal fan was observed in specimens of the subspecies aspinatum. In three of the four sheep studied, the subspecies aspinatum predominated, while the species monospinatum was highest in the fourth animal. D. flabellum flabellum occurred in very low numbers, ranging from 0 to 2.5% of the total species number.

Notes: SYNOPSIS. Electron microscope and time lapse, phase contrast cinematography studies on Babesia equi organisms within equine red blood cells revealed that this hemoprotozoon has two organelles possibly involved with ingestion of nutrients: a cytostome that takes in hemoglobin from the host cell and a tubule that extends from the main body of the parasite through the erythrocyte to the blood plasma and appears to ingest plasma during periods of rapid growth and development.

Notes: Book reviewed in this article:Prescott, D. M., ed. 1973. Methods in Cell Biology. Vol. VI.

Notes: SYNOPSIS. Relatively high concentrations (10–100 μM) of chromate, selenate, and vanadate ions accelerated growth of Leishmania tarentolae in a chemically defined medium containing taurine as the sole sulfur source. These ions also enhanced the incorporation of [35S]taurine label in whole cell, 10% trichloroacetic acid insoluble, and 10% trichloroacetic acid soluble cell fractions.

Notes: SYNOPSIS. Application of the triple stain of Grosso (methyl green-pyronin-orange G) to the exconjugants of different species of ciliates produces a differential coloration of their nuclei. Both the old macronucleus or its remnants and the micronuclei bind methyl green whereas the newly developing macronucleus (macronuclear anlage) has a selective affinity for the orange G present in the mixture. This finding holds true not only for hypotrichous ciliates, whose macronuclear anlagen are involved in the formation of polytene chromosomes, but also for other ciliates not included in the order Hypotrichida. Such a reaction of the new macronuclei apparently results from the presence of non-histone (acidic) proteins associated with the nucleic acids.The staining method is fully described to provide a more general application.

Notes: SYNOPSIS. Mating type analysis of new isolates of Polysphondylium violaceum supports the subdivision of this morphological species into two reproductively isolated breeding groups or syngens. Representatives of both syngens have been identified in soil samples taken from widely separated geographical locations. Intersyngenic cross reactions have been observed in some stocks.

Notes: SYNOPSIS. A new carotenoid, manixanthin, was isolated from a bleached, autolysed culture of the marine cryptomonad Chroomonas salina grown on glycerol in light, after the culture showed disappearance of the chlorophylls and carotenoids normally produced. Manixanthin lacked carbonyl, ester, and epoxy groups in chemical tests, whilst its spectroscopic properties indicated a conjugated nonaene chromophore. In its chromatographic mobility, manixanthin closely resembled alloxanthin, the major normal xanthophyll of the cryptomonad. The iodine-catalysed photostereomutation of manixanthin produced the same equilibrium mixture of cis-isomers as that given by similar treatment of alloxanthin. This mixture of isomers completely lacked the all-trans alloxanthin and contained ∼60% manixanthin. It was concluded that manixanthin is an unusually stable cis-isomer of alloxanthin, and is presumably produced in the culture medium by the action of light on alloxanthin released by autolysed cells of the cryptomonad. The unusual stability of manixanthin relative to alloxanthin was investigated by effecting partial stereoisomerizations under conditions using either of heat, light, or iodine, and evidence was obtained for a series of at least 10 isomers with a trend of stability increase from alloxanthin to manixanthin. It was inferred that manixanthin may be 9,9′-dicis-alloxanthin.

Notes: Die Hemmung der mitochondrialen DNS-Snythese von Acanthamoeba castellanii der logarithmischen Wachstumsphase durch Äthidiumbromid induziert die stationäre Wachstumsphase, in deren Verlauf Cysten gebildet werden. Diese Cystenbildung ist, im Gegensatz zu der durch Sauerstoff oder Nahrungsmangel hervorgerufenen, nicht von einer in DNS-RNS-Hybridisierungen nachweisbaren Synthese qualitativ neuer RNS-Arten begleitet.Wahrend der durch Äthidiumbromid, Sauerstoff- und Nahrungsmangel induzierten stationären Wachstumsphase und Encystierung findet eine starke Reduktion des [3H]Uridin-Einbaus in die RNS statt; davon ist die ribosomale stärker als die niedermolekulare RNS betroffen.In der durch Äthidiumbromid induzierten stationären Wachstumsphase und in der späten 1WP sind in der RNS weniger DNS-ähnliche RNS-Arten vorhanden als in der frühen logarithmischen Wachstumsphase.

Notes: Book reviewed in this article:Bauer, O. N., Musselius, V. A. and Strelkov, Yu. A. 1969. Bolezni prudovykh ryb. [Diseases of pond fishes.] Transl. from Russian by A. Mercado. Edited by O. Theodor. 1973.

Notes: A species of Stenior isolated from freshwater ponds and tanks in and around Bangalore, India, showed striking differences from those that have been described so far. The ciliate is red in color and has 2 spherical macronuclei and 2 small micronuclei. On the basis of the nuclear apparatus and pigmentation of the body, it is believed to be a new species, named in honor of Professor Vance Tartar as Stentor tartari. n. sp.

Notes: Crithidia deanei from the reduviid hemipteron, Zelus leucogrammus, unlike most lower trypanosomatids cultivated in defined medium, required only 2 amino acids, methionine and tyrosine; only 4 vitamins, folic acid, thiamine, biotin, and nicotinamide; and neither hemin nor a purine source. Electron microscopy reveals an endosymbiont, probably bacterial, which presumably provides the other basic trypanosomatid essential nutrients.

Notes: Micronuclear changes of variety 1 of Tetrahymena pyriformis during meiotic prophase have been observed by the light microscope. Morphologic changes in the micronucleus are divided into 6 stages. In stage I, chromatin begins to polarize; in stage II, the micronucleus becomes spindle shaped; and in stage III, one end of the micronucleus protrudes to form a “neck.” In stage IV, where the micronucleus elongates to maximal length, the whole micronucleus consists of 2 chromatin threads pairing longitudinally. One thread probably contains one genome. In stage V, the elongated thread becomes shorter and thicker. Finally, in stage VI, separate chromosomes appear and enter into metaphase.To discover the role of the elongation of the micronucleus, called crescent formation, autoradiographic analysis of RNA and DNA synthesis were undertaken using [3H]uridine and [3H]thymidine. Pulse label and chase experiments show that the crescent in stages II and III is actively synthesizing RNA. Though no remarkable DNA synthesis was observed during meiosis, a small amount of DNA synthesis occurred during the 1st and 2nd prezygotic divisions.

Notes: Promastigotes of Leishmania donovani, 3S strain, were cultured from homogenized infected hamster spleen incubated at 25 C in a particle-free modification of Tanabe's (1923) medium, and were subcultured in this medium from 1 to 4 times. Promastigotes were inoculated intracardially to golden hamsters (Mesocricetus auratus).Promastigotes that were subcultured frequently by transfer from log phase of growth retained their infectivity for hamsters, as assayed by numbers of amastigotes in the liver at 16 days post infection. Promastigotes that were subcultured infrequently by transfer from stationary phase declined in infectivity. The extent of the decline was roughly proportional to the length of the incubation periods of the primary culture plus 1st subculture.Promastigotes harvested from log phase of growth were significantly less infective for hamsters than those harvested from stationary phase of growth, in that numbers of amastigotes found in the liver after 16 days were lower, and times to death longer, when log phase organisms were used to infect hamsters.The age of the hamster at the time of inoculation was found to affect the apparent infectivity of promastigotes from a 1st or 2nd subculture. When weanling (age 4 weeks), juvenile (age 8 weeks) and adult (age 24 to 32 weeks) hamsters received the same numbers of promastigotes, the weanlings had the highest numbers of liver amastigotes at 16 days, and shortest times to death, of the 3 groups; juveniles were intermediate between weanlings and adults; and adults had the lowest numbers of parasites and longest times to death of the host. Differences were statistically significant only between weanlings and adults. Responses of weanling and adult hamsters to infection with promastigotes could be rendered indistinguishable if the promastigotes were inoculated on the basis of 105 promastigotes per g of host body weight.

Notes: Trypanosoma cruzi epimastigotes from cultures were separated into nuclear, mitochondrial, lysosomal, microsomal, and cell-sap fractions. Enzymic and ultrastructutal controls served to determine the cleanness of separation. The bulk of the DNA was in the nuclear (78%) and mitochondrial (12%) fractions. RNA was found in microsomal (74%) and cell-sap (14%) fractions. Marker enzyme distribution (succinic dehydrogenase, acid phosphatase, and glucose-6-phosphatase) was compared with their distribution in mammalian tissues. Subcellular localization of antigens by Ouchterlony tests revealed 2 specific precipitin lines in cell sap and 1 in the microsomal fraction. These antigens may prove diagnostically and immunoprotectively valuable.

Notes: Tryptophan enhanced the growth of Ochromonas malhamensis at concentrations up to 0.4 mg/ml; higher concentrations inhibited, the growth inhibition being reversible by tyrosine and adenine. The presence of a tryptophan synthetase system in vitro was demonstrated. Tyrosine and phenylalanine stimulated the activity of this enzyme. The uptake of exogenous tryptophan was accompanied by an increase in the free tryptophan pool which in turn suppressed the tryptophan synthetase system, thus pointing to a controlled mechanism. Incorporation of tryptophan in the growth medium enhanced the biosynthesis of folate-active compounds. An elucidation of the mode of action of tryptophan is attempted on the basis of known metabolic pathways.

Notes: Book reviewed in this article:Elliott, A. M. ed. 1973. The Biology of Tetrahymena.

Notes: Book reviewed in this article:Grell, K. G. 1973. Protozoology.

Notes: Considerable sectioning was required to demonstrate the mitochondrial cristae of pre-erythrocytic Plasmodium berghei in rat liver. The cristae vary from thin, budding tubules to dilated cisternae and most are obliquely and tangentially sectioned. These factors give the impression of an unusually small number of cristae. Numerous variations of fixation protocols failed to alter significantly the appearance of pre-erythrocytic parasite membranes. The data confirm previous suppositions that certain cytoplasmic bodies noted in pre-erythrocytic mammalian malarial parasites are indeed mitochondria. The term “acristate mitochondria” should be used with great caution in that it raises a serious semantic problem.

Notes: The fine structure of the sporogonic stages of Haemoproteus metchnikovi has been investigated by electron microscopy. Young oocysts are found beneath the basement membrane of midgut epithelial cells. These eventually protrude outward into the haemocoel space and are surrounded by a distinct oocyst capsule. Sporozoite formation begins with a subcapsular vacuolation. Evagination of the oocyst cytoplasm occurs in regions of membrane thickenings and 100–200 sporozoites are formed about a single sporoblastoid body. Remnants of the ookinete pellicle can be observed in maturing oocysts and always are found in the residual body. The fine structure of the mature sporozoite is essentially similar to that which has been described for other haemosporidia and a spherical body is described in association with the mitochondrion of the sporozoite. The sporogonic stages of H. metchnikovi have features common to the sporogonic stages of Plasmodium and Leucocytozoon that are not held in common by the latter 2 genera, including pattern of sporozoite formation and number of sporozoites formed, the presence of a cytostome and of “crystalloid” in the sporozoite.

Notes: Structure, function, and development of mastigonemes (flagellar hairs) of 2 chrysophycean flagellates were examined with light and electron microscopy in whole mount and sectioned preparations. Mastigonemes of both organisms are identical, consisting of a tapered base 0.25–0.3 μm long, maximum width of 0.03 μm; a hollow shaft 0.85 μm × 23 nm; and 2 types of laterally projecting filaments. Two rows of mastigonemes are attached to the long flagellum, one on each side in the same plane as the central pair of microtubules. One row is composed of single mastigonemes while the other bears them in “tufts.” The primary mastigonemal attachment is on the flagellar membrane. Developmental sequences as supported by electron micrographs and kinetic studies demonstrate the intracellular location of promastigonemes during reflagellation, colchicine-inhibited reflagellation, and release from inhibition. The promastigonemes first appear in the peri-nuclear space in association with the outer nuclear membrane and several dozen may accumulate there. These may pinch off as bundles and move into the cytoplasm, or if mastigonemes are being utilized rapidly by the cell, the promastigonemes are channeled a few at a time from the perinuclear space into the Golgi apparatus where some structural modifications are made. The mastigonemes are then transported in Golgi-derived secretory-type vesicles to the cell surface near the base of the growing flagellum where the vesicle membrane fuses with the plasma membrane and the mastigonemes become extracellular, although the membrane association is retained. The origin of the asymmetric arrangement of mastigonemes on the flagellum is discussed.

Notes: Drug sensitivities of a lower trypanosomatid, Leptomonas sp. from the hemipteran Dysdercus, to antitrypanosomatid agents were estimated by growth inhibition and inhibition of polarographically measured O2 uptake of cells and particulate fractions. Several standard trypanocides, antimalarials, and electron-transport inhibitors were used. Acriflavine, quinacrine, primaquine, pentamidine, and ethidium, each at ∼1 mM, inhibited cellular O2 uptake by 50% after 3-hr incubation. Suramin and melarsen were inactive. Crude particulate fractions oxidized L-α-glycerophosphate at 80% the rate of succinate oxidation and L-proline at 55% the succinate rate, leading to choice of succinate as standard respiratory substrate. Concentrations for 50% inhibition of growth were (μg/ml): ethidium bromide 0.009, acriflavine HCl 0.12, Antrycide 0.83, pentamidine diisethionate 1.5, and stilbamidine isethionate 1.1. Possible use of this trypanosomatid as model organism for screening antitrypanosomatid agents, and use of ethidium and acriflavine as initial model compounds are discussed.

Notes: Paramecium aurelia cells were exposed to N-methyl-N-nitroso-N′-nitroguanidine for periods of 15–30 min. The lethality in homozygous clones derived from treated cells depends on the time of treatment within the cell cycle. Exposures at interfission ages 0.04, 0.40, and 0.80 were tested yielding lethalities of 12.5, 44 and 2%, respectively. These results correlate with the period of DNA synthesis in the micronuclei. A temperature sensitive mutant has been found which cannot live at 31 C but divides at ∼1 fission per day at 19 and 25 C. The rise in temperature from 19–25 C does not significantly change the fission rate whereas in normal cells it would be doubled. Genetic analysis shows that this mutation is caused by a single recessive gene.

Notes: Attempts at continuous labeling of Crithidia fasciculata DNA with [3H]thymidine led to a pulse-chase situation due to a cell-mediated conversion of thymidine to thymine in the medium. The uptake of thymine was slow compared to that of thymidine. Neither the addition of deoxyadenosine nor the sequential addition of several aliquots of [3H]thymidine had an effect on the pattern of labeling.

Notes: A primitive trichomonad, Monocercomonas sp. (strain NS-1:PRR) from Natrix sipedon, was grown axenically in Diamond's medium. Activity of NADH oxidase, malate dehydrogenase, malate dehydrogenase (decarboxylating) and of the anaerobic enzymes, pyruvate synthase and hydrogenase as well as of several hydrolases was demonstrated in homogenates. The subcellular distribution of these activities was studied by means of analytical differential and isopycnic centrifugation of homogenates prepared in 0.25 M sucrose. NADH oxidase and malate dehydrogenase are in the nonsedimentable part of the cytoplasm. Malate dehydrogenase (decarboxylating), pyruvate synthase, and hydrogenase are associated with a large particle which equilibrates at density 1.22. In its properties, this particle corresponds to the microbody-like hydrogenosomes of Tritrichomonas foetus. The 5 hydrolases studied are associated with at least 2 different particle populations: a large particle population equilibrating at densities from 1.10 to 1.16 is the exclusive location of 3 enzymes (β-galactosidase, protease and β-N-acetylglucosaminidase), 2 of which have a pH optimum close to neutrality. These particles contain part of the acid phosphatase and β-glucuronidase. Another part of these 2 enzymes is associated with a separate population of smaller granules with equilibrium densities of 1.16 to 1.18. The 2 types of hydrolase-carrying particles are also biochemically very similar to their counterparts in T. foetus.

Notes: Dihydrofolate reductase activity in duckling erythrocytes was found to be low, while activity in erythrocytes heavily infected with small uninucleate trophozoites was like that of uninfected erythrocytes. Activity of the enzyme in erythrocytes infected with large multinucleate parasites, however, was greatly increased. This activity was 5 times higher in erythrocyte-free large trophozoites than in small ones. The dihydrofolate reductase of P. lophurae differed from the host enzyme in: greater molecular weight; higher sensitivity to pyrimethamine inhibition; pH optimum; substrate and cofactor specificity; and stimulation by salts. The parasite enzyme was partially purified by ammonium sulfate precipitation.

Notes: Book reviewed in this article:Taylor, A. E. R. & Muller, R., eds. 1973. Chemotherapeutic Agents in the Study of Parasites.

Notes: Kudoa cerebralis sp. n. is described from connective tissue of the nervous system in the striped bass, Morone saxatilis (Walbaum), from the southern Chesapeake Bay area. This is the first time the genus Kudoa has been found in association with the nervous system. The polar view mean diameter of the spores was 7.0 μm and the polar capsule mean length was 3.7 μm.

Notes: In a survey of microsporidian parasites of trematode larvae of Malaysian fresh-water snails, species of Nose-matidae were found 7 times in rediae from 425 Lymnaea rubiginosa, 6 times in rediae from 97 Indoplanorbis exustus and not at all in other snails. There were 3 species of Microsporida in all: one, found in Echinoparyphium dunni, Echinostoma hystricosum and Echinostoma malayanum was identified as Nosema eurytremae Canning; another, which was found in E. dunni and Echinostoma audyi, had paired nuclei (diplokaryon form) in sporogony only and was named a new species, Nosema vasicola sp.n.; the 3rd, from E. hystricosum, lacked diplokaryon nuclei throughout development, was considered to belong to a new genus and was named Unikaryon piriformis gen.n., sp.n. Nosema eurytremae was transmitted experimentally to Fasciola hepatica rediae in Lymnaea truncatula.

Notes: A model of the feeding apparatus of Peranema trichophorum Ehrenberg has been constructed from electronmicrographs. A common opening leads via a short anterior canal to the reservoir and cytostome. The cytostome lies close to the internal opening of the canal, and can be moved forward during feeding, closing the passage to the reservoir, and displacing the flagella. The cytostome is supported by the rodorgan in its floor and a double serrated marginal lamella arching over its upper rim from dense bodies lying lateral to the cytostome. A working hypothesis for the movement of the feeding apparatus is proposed. The elaborate system of articulating lamellae operates through these dense bodies which may act as “hinge joints.” The rodorgan is pulled forward by contraction of longitudinal lamellae attached near the bases of the rods. Cytoplasmic pressure may also be involved. It is suggested that the pull is transmitted through the dense bodies and 2 anchoring lamellae to crescentic canal thickenings on either side of the canal opening. The cytostome, rodorgan and double serrated marginal lamella move forward to fill the external opening of the canal, now enlarged by sideways pull from the anchoring lamellae. Withdrawal of these structures sucks food into the cytostomal sac to be packed down by contraction of the double serrated lamella. It is postulated that the rodorgan operates through adhesion and cytolysis and is not adapted for piercing. A conspicuous striated fibril and associated groups of microtubules in the left wall of the reservoir are cytoskeletal structures.

Notes: La structure fine du trophozoïte d'Enterocystis fungoides est voisine de celle décrite chez d'autres Grégarines (Gregarinidae, Stylocephalidae): l'épicyte, la structure fibrillaire de l'ectocyte, les organites cellulaires et les enclaves (amylopectine, mucopolysaccharides) leur sont comparables.Les caractères plus spécifiques sont: (A) l'involution de l'épicyte entre les trophozoïtes associés, due, semble-t-il, à l'appariement très précoce de ces trophozoïtes. (B) les évaginations de l'enveloppe nucléaire. Ce bourgeonnement nucléaire semble en rapport avec l'anabolisme de la jeune Grégarine, cellule en croissance semblable à l'ovocyte par maints caractères: augmentation considérable des dimensions du noyau et du nucléole, accumulation de ribosomes et de substances de réserve dans le cytoplasme.〈section xml:id="abs1-2"〉〈title type="main"〉SYNOPSISThe fine structure of the trophont of Enterocystis fungoides does not differ widely from the ultrastructural organization described in other Gregarines (Gregarinidae, Stylocephalidae). The epicyte, the fibrillar structure of the ectocyte, the cell organelles and inclusions (paraglycogen = amylopectin, mucopolysaccharides) are similar.Its specific peculiar features are the following: (A) The involution of the epicyte between the biassociative trophonts, due to their early pairing. (B) The evaginations of the nuclear envelope. It seems advisable to connect this nuclear budding with the anabolic activity of the young gregarine, a developing cell similar in many features to an ovocyte: increasing of the size of nucleus and nucleolus, accumulation of ribosomes and reserve substances in the cytoplasm.

Notes: Application of direct electric potentials across immobilized Volvox globator colonies produced patterns in the ambient solution that were observable by dark field microscopy by the use of polystyrene spheres in the medium. Two large elliptical swirls occurred immediately adjacent to the colony nearest the anode. A clear area developed outwards from the cathodal side of the colony. Since similar patterns were obtained with live, dead, and deflagellated colonies, it was assumed that the phenomena were purely physical. The electric potential induced an electroosmosis in the glass stimulation chamber. Live or dead colonies, immobilized by being secured with a glass coverslip, experienced an anodal movement of water and associated polystyrene spheres. The electroosmosis gave rise to solution patterns which were shown not to be the result of hydrostatic pressure (turbulence) or thermal convection currents. When anion-exchange beads were substituted for colonies in the stimulation chamber, application of the electric potential produced a smooth laminar flow around the positively charged beads. Cation-exchange beads, on the other hand, produced 2 large anodal swirl patterns. Clearly, the colony surface behaved like a weakly charged cation exchanger. Other investigators have determined that the cell walls of pond water plants and algae are negatively charged and have ion-exchange abilities. The negatively charged Volvox cell wall caused an electroosmosis in the colony, in the cathodal direction. Previous explanations for the galvanotaxis of Volvox are not adequate because they do not take into account the negatively charged cell wall.

Notes: Positive phototaxis was demonstrated in specimens of Amphistegina radiata within the range of photonic fluxes of 1011 to 1015 photons × cm-2× sec-1. No response was found at lower intensities. Amphistegina radiata has a Dartnall nomogram-shaped action spectrum with a peak at ∼500 nm. In addition, A. radiata and A. madagascariensis, which had been maintained at 18 C, moved toward higher temperatures in a horizontal temperature gradient in total darkness. Amphistegina radiata and A. madagascariensis did not move at temperatures ≤ 12 C and ≤ 16 C respectively. An equal number of specimens moved toward the higher and lower temperatures in the gradient when A. radiata was placed at ∼29 C and A. madagascariensis at ∼22 C. The roles of light and temperature in the distribution of the genus Amphistegina in nature are discussed.

Notes: Cultures of Tetrahymena pyriformis in a non-nutrient buffer degrade RNA and excrete hypoxanthine, uracil and orthophosphate. Glucose addition leads to the retention of a portion of the purine, pyrimidine, and orthophosphate by the cells; however, the hexose has little influence on the RNA level. Acetate supplementation has no effect on RNA degradation or on the distribution of the catabolic products between the cells and the environment.Interruption of oxidative phosphorylation by 2,4-dinitrophenol results in an increase in RNA degradation. This action is annulled by the glycolytic substrate, glucose, but not by acetate. A combination of iodoacetic acid and glucose blocks glycolysis and increases cellular RNA loss which can be reversed by the addition of the citric acid cycle substrate, acetate. These findings suggest that the available cellular energy supply in starved cells is sufficient to regulate the rate of RNA degradation. Disruption of ATP generation by the appropriate inhibitors, however, allows the demonstration of the importance of energy-yielding reactions in the determination of the amount of nucleic acid loss. It appears that glycolysis and oxidative phosphorylation are equally efficient in sustaining the regulatory process.RNA synthesis during starvation conditions is a discontinuous process with a sharp rate change after 30 min of incubation. 2,4-Dinitrophenol inhibits [2-14C] uracil incorporation into the nucleic acid. Glucose does not annul the inhibition of synthesis in contrast to the influence of the hexose on RNA degradation. This observation demonstrates that the synthetic and degradative processes are not directly coupled.Glycogen synthesis and RNA degradation appear to compete for the available energy supply and respond in a similar fashion to the metabolic inhibitors and carbon sources.

Notes: The life history, feeding relations and production of the stonefly Stenoperla prasina were studied for 16 months in the Selwyn River, South Island, New Zealand. Larval life is about 1 year with growth occurring in all months. Although emergence of adults was observed only from November to February, egg hatching probably occurred over an extended period as small larvae were present in most months. Larvae were mainly carnivorous except in early instars when most guts contained detritus. Larvae of a mayfly, Deleatidium sp. and a chironomid, Orthocladiinae sp. were the most important prey items. In April of two successive years the guts of most stoneflies examined were filled with diatoms (Gomphonema sp.) and filamentous algae which were abundant in the river only at these times. Algal feeding was not found in other months.Larvae of the main prey species, Deleatidium, were present in all months, being most abundant in summer and declining in numbers during winter. Maximum emergence occurred in March and April. The annual cycle of Deleatidium was diflicuit to interpret as larvae of all sizes were present in all months. Two generations probably occurred in a year, a fast-growing summer generation and a slower-growing and less synchronized winter generation.Mean annual standing biomass, annual production and turnover ratios (P/B) were calculated for both species. The latter were within the range of values given by Waters (1969) but may be subject to error from several sources. Shortcomings in the method used to estimate production are discussed.

Notes: As a result of studies in certain lakes in northern Minnesota it has been found that the spatial distribution of desmids in them depends especially on the following factors: the constitution, abundance and distribution of the lakes' submerged aquatic flora and the morphometry and consequent patterns of their water circulation. The study has also shown a positive relationship between the size of desmid cells present in the plankton and the extent of water circulation. The latter factor may determine the composition and hence the diversity of lake phytoplankton.

Notes: Samples of dace were taken from the Afon Llynfi and the River Lugg each month for 13 consecutive months. Male dace grew faster than females and rates were comparable with those described for several other populations. Variations in year-class strengths were observed and these differed between the populations although 1959 was strongly represented in both. The sex ratio varied throughout life and disturbances in the expected ratio were attributed to the attainment of sexual maturity at the end of the fourth year of life (3+). Observation of the seasonal gonad cycles indicated that spawning occurred in March or April. Fecundity was estimated at about forty eggs per gram of total weight.A seasonal cycle of feeding activity was established with highest food consumption during summer. There was evidence of a fast during the spawning period. No correlation between temperature and feeding activity could be established. Dace were omnivorous, but aquatic insects and algae were the main components of the diet. Seasonal variations generally followed availability. The importance of aerial insects declined with age. Many differences in feeding habits were detected between the populations.

Notes: The age of perch. Perca fluviatilis L. was determined from the annual bands laid down on the opercular bone. Year class monthly mean lengths were based on this ageing. The opercular bones have also been used for back-calculating growth. It was found that back-calculated mean lengths per age were similar to those calculated by direct measurement. There was little difference in growth between the sexes for the first 2 or 3 years of life. The investigation was too short for a correlation to be found between growth increments and degree days above 14°C although Slapton Ley was found to be warm in comparison to other British waters and the perch grew fast. Ford-Walford plots gave L∞= 22.0 cm for males and L∞= 25.0 cm for females. In length-weight relationships, fry and immature females were homogeneous between their monthly subgroups, and fry obeyed the cube law throughout. Mature males and females were heterogeneous between monthly subgroups. Growth has been expressed in weight form and instantaneous growth rates are given. These rates are higher for fry than older fish. Condition was closely related to gonad development in mature fish. Condition fell sharply after spawning and then rose rapidly in May and June. A sudden drop in condition was noted in males during August which cannot be fully explained.

Notes: The population dynamics and production of Daphnia hyaiina^ the dominant cladoceran i n Eglwys Nynydd, a shallow eutrophic reservoir in South Wales, were studied for 2 years against a background of limnological measurements. The appearance and development of successive generations from egg to adult could be followed from changing numbers in arbitrarily defined size classes. Seasonal variations in mean length, mean brood-size and proportion of gravid adults were recorded and mean brood-size was related to changing food and temperature conditions. Egg-development times for D. hyaiina were determined in culture and the population parameters finite birth (S), instantaneous birth (b′), instantaneous population change (r′), instantaneous death (d′) and finite death rates (D) were estimated from field data. Turnover and production estimates were calculated from finite death rates and biomass. The calculated potential rate of increase (b′) was nearly always greater than the observed rate of increase (r′): seasonal changes in death rate (d′) generally parallel changes in birth rate (b′) but remain somewhat out of phase. Population oscillations are probably due t o a delay in the expression of the effects of population density upon birth and death rates.The mean biomass of Daphnia in 1970 was 0-57 mg dry wt/l (0-88 g C/m2) and in 1971 0-32 mg dry wt/l (0.49 g C/m2). Annual production for Daphnia was 11-8 mg dry wt/l (18-2 g C/m2) in 1970 and 8-30 mg dry wt/l (12 8 g C/m2) in 1971. Information available on primary production in the reservoir suggests that the production of Daphnia accounts for less than 2% of gross primary production. However, the pattern of population growth of Daphnia in Eglwys Nynydd almost certainly reflects a food limited system. In summer, blue-green algae may be abundant but serve as a poor food source: throughout the blue-green bloom egg production remains low, at times remaining below 0-5 eggs/adult.

Notes: The development and use of an improved automatic system for the accurate measurement of dissolved organic carbon (D.O.C.) in fresh waters is described. The method, which covers the range 0-25 mgl−1 D.O.C., is based on the oxidation of organic carbon to carbon dioxide by U.V. radiation. The carbon dioxide produced is measured by a non dispersive infra-red gas analyser (I.R.G.A.). The I.R.G.A. is also used in the semi-automatic measurement of particulate organic carbon (P.O.C.) by a combustion method which allows very low concentrations to be measured using samples of 200 ml or less.Results of surveys of two river systems indicate that D.O.C. concentrations of less than 2.0 mg l−1 are typical in unpolluted chalk streams. D.O.C. concentrations of streams draining acid heathland were found to be significantly higher (3-5.5 mg l−1).D.O.C. concentration was found to increase rapidly during a spate, in a river draining areas of mixed underlying geology. The throughput of D.O.C. during the twenty-five to fifty spates which occur annually in the river could amount to 20-30% of the annual flux of D.O.C.P.O.C. concentration in chalk spring waters (0.03–0.04 mg l−1) were found to be higher than expected from preliminary estimates using membrane filtration techniques.The relevance of the measurement of D.O.C. and P.O.C. flux to estimates of the energy budgets of stream ecosystems is discussed and published methods for the automatic measurement of D.O.C. are reviewed.

Notes: (1) Chaoborus anomalus and Chaoborus ceratopogones were found together throughout the year in Lake George, Uganda, the larvae forming 65-85% by number of the macro-benthos of the central lake area.(2) First and second instar larvae were wholly planktonic and third and fourth instar larvae mainly benthic during the day, migrating into the water column at night. A proportion of the third and fourth instar larvae were found in the water column during the day in the centre of the lake where light attenuation was greatest. C. anomalus showed a greater tendency to be benthic than C. ceratopogones.(3) Planktonic larvae were distributed in dense patches thought to be cohorts resulting from oviposition by swarms of adult females. The maximum density of planktonic larvae recorded was 31.7 × 102/m2 column. Third and fourth instar larvae were more evenly distributed in the benthos of the central lake area, the maximum density recorded was 79.9×102/m2.(4) First and second instar larvae occurred mainly in the inshore regions, very few were found in the centre of the lake. Oviposition is likely to take place inshore. The patches of planktonic larvae were not stationary. Dispersal of larvae away from the shore may be active or may result from complex oscillations of the water mass produced by storms. In C. ceratopogones the floating egg batches could he carried away from the north shore by currents produced by inflows and prevailing winds.(5) Adults of C. ceratopogones were more numerous during the rainy seasons than during the dry seasons. A similar, though less marked seasonality was found in the occurrence of C. anomalus adults. The biomass of benthic larvae of C. ceratopo-gones was estimated at 387.0 mg C/m2 in the dry season, June 1970, and 130 0 mg C/m2 in the rainy season, October 1970. That of C. anomalus was constant at 241.7 and 254.3 mg C/m2 in June and October, 1970 respectively.(6) No difference was found in the horizontal distribution of the larvae, or in the size and weight attained by the various stages.(7) Interspecific differences were found in the mean number of eggs per adult female (309, C. anomalus and 224, C. ceratopogones); in the nature ofthe egg batches; n i the morphology of the larval mouthparts and pharyngeal sphincters, as well as i n the vertical distribution of the larvae and seasonal occurrence of the adults. On the basis of these differences the co-existing species are thought not to be competing for the same resources.

Notes: Forty-three species of Plecoptera were collected from emergence traps in an Oregon woodland stream. Adults occurred during every month of the year, but the largest numbers and most species emerged from April to June. Temporal separation of con-generic species occurred within the suborder of Filipalpia, but not in Setipalpia. Some species of Nemoura had split emergence periods.The onset of emergence for a species from year to year generally varied by less than 2 weeks. Peak emergence occurred at least 1-2 weeks after the start ofthe emergence period.

Notes: In 1967 a programme was initiated by the Freshwater Biological Association to study fish populations within the proposed Cow Green reservoir basin and in the Tees downstream of the dam, before and after impoundment. This paper describes the result of a supporting study on aquatic invertebrates covering the pre-impoundment period 1967–70.The benthic faunas of six streams in the reservoir basin, the Tees below Cauldron Snout and Maize Beck, a tributary ofthe Tees below the dam, were studied. Species list are presented for each habitat and changes in seasonal and annual abundance are discussed.All areas sampled lie at altitudes between 440 and 550 m O.D. and are situated amongst moorland and limestone grassland. Conditions in the streams ranged from slow-flowing peaty reaches to small streams with moss-covered bottoms and larger stony rivers and streams with relatively unstable bottoms.Samples were taken in riffles and pools using the ‘kick’ method wherever possible. An attempt was made to quantify kick-sample catches by comparing them with shovel-sample catches which cover a known area of stream bottom. It was found that 10 5 kicks gave a catch equivalent to the populations of 1 m2, giving a population density of about 1200 animals/m for the reservoir-basin riffles.Over 120 taxa were recorded, 100 of which were at the species level. In the reservoir-basin streams, 116 taxa were found with seventy-one in Maize Beck and fifty-six in the Tees below Cauldron Snout. Ephemeroptera were the most abundant group in the reservoir basin and Maize Beck faunas with Rhithrogena semicohrata, Heptagenia lateralis and Baetidae being the most abundant forms, although Ecdyonurus spp. especially E. dispar were much more common in Maize Beck. In other groups Leuctra spp. and Gammarus pulex were very common. In the Tees below Cauldron Snout Limnaea peregra, Chironomidae and Baetidae formed the bulk of the fauna and Plecoptera were uncommon. Amongst the reservoir basin streams Weelhead Sike supported the largest number of species and species groups (eighty-one), and all the streams had forty-nine or more taxa represented.Information on seasonal changes in the numbers of those species or species groups composing 90% or more of the total fauna is presented. Faunal density was high in May with Ephemeroptera, particularly Ecdyonuridae, and the plecopteran Leuctra inermis being the most abundant forms. In August, the numbers of animals appeared t o fall and common members of the community were Baetidae, Diptera, Leuctra fusca and Ecdyonuridae. In October, Ecdyonuridae particularly R. semicolorata, were most abundant.A comparison ofthe bottom fauna of riffles and pools was made and more animals were found in riffles than in pools.The effect of gravel extraction on the bottom fauna of the Tees was examined. A severe drop in the numbers of animals was observed after extraction. Diptera were the first group to return to their pre-disturbance density. Elminthidae and Annelida were worst affected and slowest to recover.The fauna of the area is discussed and possible reasons for its relative species richness are put forward. Habitat diversity and chemical richness appear to be the most likely reasons for the relatively large number of species found.

Notes: Water samples collected weekly from the rivers Yare, Tud, Wensum and Tas in Norfolk, England, displayed marked depletions in the spring and summer of the concentration of dissolved silicon. These were unconnected with any hydrological event and were assumed to be due to the assimilation of silicon by diatoms. Equilibrium concentrations were maintained in the Yare and Tud during the weeks prior to and following the spring bloom. It was estimated that 35 Mg (51%) of the predicted load were removed from the Yare during the 11 weeks of this depletion and 6-0 Mg (45%) from the Tud. The lowest observed concentration (0-4 mg/l) occurred during the first week in May when over 90% of the silicon had been removed. However, the maximum amount of removal and hence maximum diatom productivity occurred earlier at a time of higher water discharge. A similar pattern was observed in the Yare during the spring of 1971. Two small blooms occurred later in the summer of 1970 in the Yare and Tud. It was estimated that 15% ofthe Yare's dissolved silicon load of 263 Mg was in the assimilated form and 12-5%of the Tud's output of 56-6 Mg. The weathering of silicate minerals was probably the source of almost all the silicon and the outputs represented a silicon erosion rate of 1-15 Mg/km2/year for the Yare and 0-77 Mg/kmVyear for the Tud.

Notes: Calorific values of thirty-three species of aquatic invertebrates, representing various life stages, from small prairie wetlands are given. The values for twenty-seven species are new to the literature. Percentage crude protein for fifteen species and the amino acid composition for eleven taxa are presented. The majority of the species dealt with are eaten by waterfowl.

Notes: In this paper the effect of a fulvic acid fraction on the growth of a Pseudomonas sp. from fresh water is reported. The presence of fulvic acid in the culture medium caused an increase in the cell yield and in the cell yield per μl O2 taken up by the Pseudomonas. The observed stimulating effect has been explained in terms of co-metabolism of fulvic acid by the Pseudomonas.

Notes: A buoyant net for catching young fish quantitatively is described, together with some results based on samples taken with this net.

Notes: Phytoplankton counts and chemical/physical analyses were carried out twice weekly for 2^ years on samples taken from Plover Cove Reservoir, and a description of the variations in species composition and abundance is followed by an analysis of the effects of these environmental factors on algal growth, and their correlation with phytoplankton abundance. In addition, 24-h surveys were carried out over a 1-year period in an attempt to evaluate the seasonal, diurnal and vertical distribution patterns ofthe more abundant phytoplankters.Blue-green algal blooms were greatest in winter 1967/68 and in autumn 1969; shoreline-attached diatoms were prevalent in winter 1968/69 and winter 1969/70. The blue-green algal blooms have been attributed to a high rate of phosphorus and nitrogen supply, and the occurrence of diatoms at such specific times to an increase in light penetration due to the paucity of phytoplankton at these times. Various well-marked distribution patterns were seen, and the seasonal pattern in the case of Microcystis aeruginosa was shown to be closely correlated with fluctuations in certain chemical parameters, namely. ammonia-N, nitrate-N and phosphate concentrations. Predictions have been made concerning future trends in the algal community of the reservoir.

Notes: Two species of Stenostomum, viz. S. glanduloswn Kepner and Carter and S. anops Nuttycombe and Waters, are recorded for the first time from Poland. Descriptions of the Polish material are given, and these are compared with published information on the structure of the species. A new sub-species, viz. S. Corderoi Marcus s. sp. poznanensis s. sp. nov. is recorded from Poland, and fully described. Fealures which separate the new sub-species from S. corderoi corderoi Marcus are listed.

Notes: A new species of Stenostomum, viz. S. beryii sp. nov. is described from Kenya. It was recorded from a pool near Nairobi, in April and May. The new species resembles S. hemisphericum Nasonov.

Notes: Stenostomum arevaloi Gieysztor, S. glandulosum Kepner and Carter, S. leucops (Duges), S. pseudoacetabtihtm Nuttycombe and Waters, and S. unicolor Schmidt are reported from E. Africa. The various localities in which each of the species were found are listed. All the species are new records for this region except S. Leucops which was recorded by Bohmig (1897) from Lake Victoria at Bukoba, Uganda. Descriptions of the species, based on the E. African material, are given.

Notes: The seasonal variation in abundance of the phytopiankton groups in the river Oshun before and immediately after the closure of the Asejire dam is described.The river was dominated by the Bacillariophyceae throughout the period before impoundment but soon after, the Volcocaceae and the Dinophyceae became preponderant at the lake although the diatoms remained dominant at the source. Also, the period of maximum abundance of the diatoms occurred 8 weeks before the other phytoplankton groups attained their maxima in the river.Correlation coefficient values enumerated by computer revealed the controlling effect of the discharge, transparency and nitrate nitrogen on phytoplankton development in the Oshun.

Notes: Behaviour of Brachycentrus americanus was observed in a simulated stream in the laboratory every 2 h for 7 days in January, and in Lawrence Creek, Wisconsin, every half hour for 2 days in May. In the field, animals, algae, and detritus in the drift were sampled every half hour with an 800-μm and a 60-μm mesh net.The primary mutually-exclusive behavioural units were filtering, case building, and withdrawn when the larvae had their cases attached to the substrate, and crawling and holding when cases were not attached. Diel changes in behaviour were similar i n the laboratory and field. Almost 100% of the animals were filtering at night, whereas only about 60% were during day. Withdrawn, case building and unattached activities occurred more frequently during the day. While only 0-5% of the laboratory animals were unattached during the day, in Lawrence Creek 10-20% were unattached at that time and many moved across the substrate and grazed. Drifting, which was acyclic, did not correlate closely with the diurnal increase in unattached activity.Available drifting food in both nets increased markedly following rain. In the absence of rain, dry weight of detritus from the 800-μm net increased at night. Changes i n timing and method of feeding are discussed relative to gut contents, morphological adaptations, and energy expenditure of B. americanus, and to food availability.

Notes: Books Reviewed in this Article: Clark, R. B. and Wootton, R. J. (1972) (Eds.). Essays in Hydrobiology presented to Leslie Harvey.

Notes: Larvae of three species of the genus Hydropsyche with distribution patterns indicating they are associated with increasing ranges of flow rate and temperature in the sequence H. instahilis, H. pelhicidula, H. angustipennis, were selected for study. Experiments on frequency of ventilatory movements indicated that the larvae were increasingly tolerant to dissolved oxygen concentration, flow rate and temperature in the same sequence of species. Experiments on net-spinning indicated a corresponding order of preference for higher temperatures and a general preference for higher flow rates. During experiments on net-spinning the number of larval casualties, ascribed to encounters between individuals, showed marked contrasts between species. The significance ofthe behaviour ofthe larvae under experimental conditions is discussed with reference to their distribution in the field.

Notes: The relationship of total body length to formalin dry weight for individuals of Thermo-cyclops hyalinus and Mesocyclops leuckarti, from the tropical Lake George, Uganda, is given and shows that previous estimates of individual biomass and, therefore, of zooplankton standing crop and production based on them, were too high. The annual mean standing crop of total Crustacea, in 1969–70 was 828 mg (dw) m−2 and for T. hyalinus, the dominant species, 559 mg (dw) m−2 Biomass tended to be higher in the mid-lake area than inshore. The annual mean production of T. hyalinus is now estimated to be 44 mg (dw) m−2 day.

Notes: Perch, Percafluviatilis L. were studied in Slapton Ley which is a eutrophic freshwater lagoon in south Devon, England. The perch were caught in traps from February 1970 to June 1971. The traps selected males during the spawning season. The water temperature did not affect the numbers of trapped fish directly, but the sight of perch in the traps appeared to attract others. Sex ratios were found to be equal in the first 2 years of life but older year classes were predominantly female. The population consisted of young individuals. Males were found to mature in their first year and most females matured in their second. The fecundity varied from an average of 1000 eggs in perch n i the 9.75 cm length group to 30,500 eggs in fish in the 27.75 cm group. A few shoals of perch moved throughout the Ley although the majority of fish stayed in the same area. Population estimates showed a range from 10,000 to 95,000 for fish 9.75 cm and above. The large variations in population estimates and survival rates were attributed to the necessity of using traps which had variable catches and to the harmful effects of handling the perch. Chironomids were important in the diet of perch of all sizes. Plankton and Asellus were other important foods, the latter especially during the winter months. Perch 11.5 cm to 13.9 cm selected the widest range of food organisms. Only perch 14.0 cm and above ate fish.

Notes: Toxicity experiments indicated that changes in the fauna following the use of paraquat for weed control were likely to be indirect effects caused by the death and destruction of angiosperms. Generally, invertebrates living amongst the emergent vegetation in the margins of the reservoir and on the sediments were unaffected though the density of the benthic ostracod Cypridopsis vidua increased rapidly after the death of angiosperms. Of the planktonic invertebrates, those which were generally closely associated with the macrophytes were eliminated or survived at lower densities. Many of the invertebrates intimately associated with the angiosperms (e.g. Lepidoptera, Tricho-ptera. Gastropoda) were lost completely or colonized the replacement growth of Chara globularis at reduced densities: these effects were extended to the year after treatment. A few species colonizing Chara were able to establish densities comparable with those found on the angiosperms in the pre-herbicide period but in some cases the time of peak density was delayed.Data from fish gut analyses indicated that there was a change in the diet of the eel following the death of the angiosperms and that this was largely a reflection of the loss, or reduction in density, of many invertebrates associated with the angiosperms.

Notes: A study has been made of the feeding of Chironomus costatus in a temporary fresh-water pond in South India. It was found that, irrespective of the size of the larvae, the food composition was the same. The larvae were non-selective feeders in that the organisms enumerated in the water were also found in the gut.

Notes: The development of chromatophores and the formation of colour patterns in Tilapia mossambica are described. A number of colour patterns are associated with certain aspects of behaviour. Four different melanophore systems are involved in the colour pattern formation. There appear to be 14 patterns which, in various combinations, produce a series of colour patterns. Each of these may convey a different message to different species of Tilapia.

Notes: Some observations on the biology of Mastacembelus armatus (Lacepède) from Muzaffarnagar (U.P., India) have been made during the period July 1966 to June 1969. At a particular stage of maturity of the fish there is a close relationship between the gonad weight and the body weight which helps in determining the breeding period of the fish. Both male and female fishes mature simultaneously. The gonad weight influences the relative condition, while the visceral weight does not exert any significant effect on it. The development of the female gonads greatly affect the curve of relative condition, more than the development of male gonads, though the curve for male fish also shows a steady rise and fall in the seasonal variations of the relative condition. Seasonal fluctuations in relative condition correspond to its spawning season. In M. armatus, the presence of two peaks in the curve confirm two breeding seasons. The present studies have also elucidated to a certain extent the important aspect of the maturation and spawning habits of M. armatus in North India. The fish has two breeding seasons of short duration during June and July and again in November. The mature ovaries of each season contain slight maturing ova of next season along with mature ova of the present season. The entire stock of ova measuring 0.16 mm and above are shed during spawning.

Notes: A cell-free system prepared from spleen cells of DBA/2 mice was stimulated by P815 tumour cells as antigen. The response of the cell-free system to this stimulation was a synthesis of i-RNA in the cell free system. The i-RNA was isolated by a combined phenol-Na-dodecyl-sulphate extraction method and purified by gradient centrifugation. This i-RNA was injected to DBA/2 mice to which P815 tumour cells were implanted at different time intervals before the i-RNA application. It could be demonstrated that the i-RNA inhibits the development of tumour. Theoretical and practical implications of the experiments are discussed.

Notes: A mouse alloantiserum, raised by immunizing B10.D2/n mice with B10.M spleen, has been found to retain cytotoxic activity against a proportion of lymph node cells even after exhaustive absorption with B10.M red blood cells. Titration and absorption with a number of strains showed that the absorbed serum retained antibodies against two new specificities. The absorbed serum gave significant enhancement of B10.M skin grafts on B10.D2 and reacted mainly with B cells.

Notes: Forty-eight leucocytotoxic antisera obtained from parous ewes and from the recipients of osteoarticular and skin allografts were tested with a panel of leucocytes from unrelated sheep. Computer analysis of the serological data and limited adsorption studies have enabled the tentative identification of twenty-one sheep leucocyte antigens. By adsorption erythrocytes have been shown to lack these antigens. It is postulated that the antigens belong to one or possibly more system(s) for which the term ShL-A is proposed.

Notes: Immunoglobulins A, G and M have been measured in three groups of patients with sex chromosome abnormalities, 47,XXY, 47,XYY and 47,XXX. The most significant finding is a greatly elevated IgG level in 47,XXY males and 47.XYY males. In the case of 47,XXY males it was possible to show that the increase in level was almost confined to those who were patients in mental subnormality and maximum security hospitals. Only a few abnormally high IgG values were found in patients referred to endocrine clinics. Low IgA levels were found in institutionalized patients whether or not chromosome abnormalities were present. In 47,XXY males IgM levels were significantly higher than in 46,XY males and the same as those in 46.XX females.Although serious illnesses were recorded in a high proportion of males with a 47,XXY karyotype, the level of IgG was not closely related to a history of disease.Possible reasons for the findings are discussed.

Notes: This communication describes the investigation of serum from parous ewes for the presence of cytotoxic antileucocyte antibodies. Sera from 195 sheep were tested using a fluorochromatic cytotoxic test: 119 from parous ewes, fifty-nine from lambs and seventeen from rams. Only sera from ewes were cytotoxic and 52.1% possessed antibody. This is considered as prima facie evidence for the foetus being responsible for the antibody response. The results are compared with similar studies in man and the sheep and would suggest that maternal immunization is more frequent in this species than previously appreciated.

Notes: The genetic control of the antibody response to poly(Glu52Lys33Tyr15) was studied in twenty-five strains of inbred rats representing a wide variety of major histocompatibility groups. Direct linkage studies, and three subsidiary lines of evidence, demonstrated that the control was linked to the major histocompatibility locus. All of the low responders (Ag-B1, 3 and 6) made less than 65 μg of antibody/ml. In contrast, there were quantitatively significant differences among responders: the Ag-B2 group was a moderate responder (200–500 μg antibody/ml) and the Ag-B4 and Ag-B5 groups were high responders (700–1400 μg/ml). The ability to form antibody segregated with the major histocompatibility allele in the F2 and back-cross generations. Genetic factors other than those controlling the ability to respond influence the quantity of antibody formed: animals of the same genotype can make significantly different amounts of antibody, depending upon the crosses by which they acquire the major histocompatibility alleles.

Notes: A rabbit anti-human serum allowed the identification of a new human polymorphism of the α2-macroglobulin. This polymorphism is represented by three variants: A, having a fast electrophoretic mobility; B, intermediate mobility; and C having a slower migration and the three combinations: AB, AC and BC. Preliminary genetic studies suggest that inheritance is of Mendelian autosomal co-dominant type.

Notes: Comparative aminoacid sequence studies were done on chymotryptic peptides from the Fc fragments of IgG1, IgG2, IgG4a and IgG4b human myeloma proteins. Eleven peptides were positioned within the Fc fragments of IgG4 proteins. While leucine was present at position 309 of the Fc fragment of the IgG4a protein, it was absent from the Fc fragment of the IgG4b protein.

Notes: HL-A antigens in fifty-four coeliac children and in parents and healthy siblings of forty-seven of these patients have been determined, thus allowing deduction of haplotypes and segregation analysis. HL-A8 frequency was found highly significantly increased (χ2= 37.92; P≪ 0.001) in coeliac children compared with a control group of 240 unrelated individuals; the increase of HL-A1 frequency is attributed to linkage disequilibrium between the genes involved. The haplotype HL-A1-8 frequency was also found significantly increased in coeliac children (χ2= 55.13; P≪ 0.001) with frequency elevation in the healthy siblings (χ2= 31.45; P≪ 0.001) in comparison with the controls.In segregation analysis a significant deviation from the expected distribution of HL-A8 (χ2= 15.38) and to a somewhat lesser degree of HL-A1 (χ2= 12.45 could be shown in coeliac children while there was no significant deviation in the distribution of these antigens detectable in their healthy siblings. Only a few haplotypes were frequent enough to be included in segregation analysis of haplotypes. Again in coeliac children a positive correlation with haplotype HL-A1-8 was found differing significantly from the expected distribution (χ2= 8.05), whereas this haplotype appeared almost evenly distributed in the healthy siblings of the patients.

Notes: Histocompatibility antigens have been studied by skin grafting in three successive generations of the Urodele Pleurodeles waltlii Michah. Starting from a brother-sister pair of animals (F1) mutually tolerant, the descendence obtained in F2 is composed of three types of animals called A/A, A/B, B/B according to their mutual capacity for tolerance or rejection. The three types are numerically divided according to the mendelian proportions of monohybridism, that is 25 % of A/A, 50% of A/B and 25% of B/B. All the descendants (F3) born of homozygote parents A/A or B/B are homozygote. The descendants (F3) born of heterozygote parents A/B are composed of type A/A, A/B and B/B animals in mendelian proportions of mono-hybridism. The presence of histocompatibility antigens A and B would be determined by a pair of dominant alleles which are on a locus carried by the same pair of chromosomes.

Notes: The‘tolerogenicity’of neonatal skin grafts, as reflected in their higher survival rate as well as in their capacity to confer this tendency upon simultaneous adult grafts, has been believed to be based on an immunologically specific feature of the neonatal alloantigens.The data presented in this study demonstrate in two weak histocompatibility systems (H-9 and that presented by the male-specific antigen, MSA) that there is also an important non-specific component in the tolerogenic mechanism of neonatal skin allografts. The survival of adult skin allografts was followed in double-grafted animals in which the neonatal graft was either a specific or non-specific allograft or a syngeneic graft. Although the maximum increase in the survival rate of the adult grafts (in comparison to single-grafted controls) was induced by antigenically specific neonatal grafts, significant effects were also induced by antigenically neutral (syngeneic) or antigenically non-specific neonatal grafts. The immunologically nonspecific component in the effect of neonatal skin grafts could be traced back to their primarily high contents of proteoglycans and to their long-lasting production of the latter; consequently, the neonatal graft which is protected by these substances against the concomitant round cell infiltration can secondarily provide some protection also to the adult allograft. This non-specific protection may favour a stepwise establishment of a specific tolerance.

Notes: An alloantiserum has been obtained in the mouse which differentiates specifically between lymph node cells and a sub-population of peritoneal cells. The antigen is associated with chromosome 7 (linkage group I).

Notes: A family study on Gm determinants is reported starting from the pair: mother Gm(a - x - f + b +)/child Gm(a + x - f - b -). The genotypes derived from the results show the probable influence of the inactive allele Gm- described earlier. The importance of this and similar findings for our knowledge of the Gm system and for its use in practical medico legal work is stressed.

Notes: A lymphocytotoxic antibody whose reactions are associated with the blood group A and the ABH secretor status is described.

Notes: Variation in the ability of the host to respond to disease has been recognized but the mechanisms have not been defined. Recent studies suggest a genetic control of the immune response and of the susceptibility or resistance to oncogenic viruses linked to the major histocompatibility locus. Thus histocompatibility-linked genetic control of the immune response might play an important role in determining resistance or susceptibility in disease states. The known gene products of the major histocompatibility autosomal region in humans can be detected by serological and by functional assays.In this prospective study of 115 patients with Hodgkin's disease we have related the serologically detectable gene products, the HL-A antigens, to the course of the disease. The antigens A3 and A11 were decreased in the seventy-nine patients in whom the disease had been present for less than 1 year. The antigen A8 occurred in normal frequency in the patients with recent onset of the disease but was significantly increased in the thirty-six patients who had survived with the disease for longer than 5 years. Both observations are compatible with an ability to resist the disease; that is, either resistance to the onset of the disease or improved survival once the disease has developed.