THE FINE STRUCTURE OF DIFFERENTIATING SPERMATOZOA AND SERTOLI CELLS IN THE GONAD OF THE POND SNAIL, LYMNAEA STAGNALIS

The fine structure has been examined, of spermatogonia, spermatocytes,early spermatids, late spermatids and early spermatozoa nestlingagainst Sertoli cells in the gonad of Lymnaea stagnalis. Changes in the Sertoli cells are linked with the phases of spermdifferentiation. Details on differentiation particularly ofthe head of the sperm, are presented. (Received 14 March 1981;     

Parsnip (Pastinaca sativa) seed production: effects of seed crop plant density, seed position on the mother plant, harvest date and method, and seed grading on embryo and seed size and seedling performance

Parsnip seeds from four years of seed production (1980–83) were used to examine the effects of position of the seed on the parent plant and several cultural factors on seed and embryo growth and seedling performance. Maximum seed dry weight was reached c. 50 days after flowering (DAF) but embryos continued to grow for a further 7–15 days. The coefficient of variation (C.V.) of seed weight fell from c. 35–40% at 40 DAF, to about 20–25% at maturity. The corresponding figures for C.V. of embryo length were 25–35% at the early harvest and 12–15% at maturity. The effects of seed position, plant density, harvest method, seed grading after harvest on seedling emergence and weight characters were small. Harvesting seeds c. 60 DAF gave, on average, 3.3 days earlier emergence, c. 3.6 days lower ‘spread’ of emergence time and c. 9% higher seedling emergence than harvesting 2 wk earlier. Late harvesting of the seed crop reduced the C.V. of seedling weight from 53 to 46%, on average, but there were variations in response from year to year. Seedling emergence and seedling weight characters were more closely related to embryo length than to seed weight characters.     

Synthesis of two distinct α-glucosidase activities in Bacillus licheniformis

When grown with maltose or starch as carbon source at 37°C, Bacillus licheniformis synthesized two α-glucosidases which could be resolved by polyacrylamide gel electrophoresis. One of these enzymes preferentially hydrolysed p -nitrophenyl-α-D-glucoside ( p NPG) and the other was inactive on p NPG but hydrolysed maltose (maltase). Only the maltase could be detected in induced cells grown at 50°C.     

Electronic nose evaluation of onion headspace volatiles and bulb quality as affected by nitrogen, sulphur and soil type

Edaphic factors affect the quality of onions (Allium cepa). Two experiments were carried out in the field and glasshouse to investigate the effects of N (field: 0,120 kg ha⁻¹; glasshouse: 0,108 kg ha⁻¹), S (field: 0, 20 kg ha⁻¹; glasshouse: 0, 4.35 kg ha⁻¹) and soil type (clay, sandy loam) on onion quality. A conducting polymer sensor electronic nose (E-nose) was used to classify onion headspace volatiles. Relative changes in the E-nose sensor resistance ratio (%dR/R) were reduced following N and S fertilisation. A 2D Principal Component Analysis (PCA) of the E-nose data sets accounted for c. 100% of the variations in onion headspace volatiles in both experiments. For the field experiment, E-nose data set clusters for headspace volatiles for no N-added onions overlapped (D²= 1.0) irrespective of S treatment. Headspace volatiles of N-fertilised onions for the glasshouse sandy loam also overlapped (D²=1.1) irrespective of S treatment as compared with distinct separations among clusters for the clay soil. N fertilisation significantly (P < 0.01) reduced onion bulb pyruvic acid concentration (flavour) in both experiments. S fertilisation increased pyruvic acid concentration significantly (P < 0.01) in the glasshouse experiment, especially for the clay soil, but had no effect on pyruvic acid concentration in the field. N and S fertilisation significantly (P < 0.01) increased lachrymatory potency (pungency), but reduced total soluble solids (TSS) content in the field experiment. In the glasshouse experiment, N and S had no effect on TSS. TSS content was increased on the clay by 1.2-fold as compared with the sandy loam. Onion tissue N: water-soluble SO₄²⁻ ratios of between five and eight were associated with greater %dR/R and pyruvic acid concentration values. N did not affect inner bulb tissue microbial load. In contrast, S fertilisation reduced inner bulb tissue microbial load by 80% in the field experiment and between 27% (sandy loam) and 92% (clay) in the glasshouse experiment. Overall, onion bulb quality discriminated by the E-nose responded to N, S and soil type treatments, and reflected their interactions. However, the conventional analytical and sensory measures of onion quality did not correlate with %dR/R.     

THE PRODUCTION OF ANTIBIOTICS IN SOIL V. BREAKDOWN OF GRISEOFULVIN IN SOIL

When griseofulvin (I; R = Cl, R '= OCH₃), a chlorine-containing antibiotic produced by Penicillium nigricans , was added to fresh garden loam, after an initial lag it disappeared rapidly. When further griseofulvin was added it was inactivated from the start and at rates which increased with each successive addition, suggesting that it was degraded biologically. The numbers of one organism, a Pseudomonas sp., increased in the soil steadily after adding griseofulvin.
When a little soil was added to a solution (pH 7·0) containing inorganic salts and griseofulvin as the sole carbon source, bioassays showed that the griseofulvin disappeared within 5 days. An organism isolated from the broth was identified as the Pseudomonas sp. thought to break down griseofulvin in soil. Griseofulvin also disappeared from a broth at pH 5·0 inoculated with soil, but at this lower pH value a dematiaceous fungus was responsible for its breakdown.
The Pseudomonas sp. also degraded two derivatives of griseofulvin, dechlorogriseofulvin (I; R = H, R'= OCH₃) and the amine (I; R = Cl, R '= NH₂). Cl^– was detected in the solutions after breakdown of griseofulvin by the Pseudomonas ; the amount present agreed well with that calculated on the assumption that all the chlorine in the griseofulvin supplied was liberated as Cl^–. Spectrophotometric examination of the solutions showed no metabolites with the aromatic ring intact, and confirmed the complete breakdown of griseofulvin suggested by the liberation of Cl-.     

Effects of Boron Deficiency on the Chemical Composition of a Marine Diatom

Cells of Cylindrotheca fusiformis, a marine pennate diatom,multiplied in complete nutrient medium (containing 0?5 mg l^–1B) with a generation time of 11 h; in a boron-deficient culturemedium (0?02 mg l^–1 B), the generation time was 90 h.The chemical composition of logarithmically growing cells harvestedfrom each of the two culture conditions was compared in orderto assess the effects of boron deficiency on the various chemicalfractions. Under conditions of boron deficiency, the concentrationof protein, carbohydrate, and RNA was depressed below that ofcontrol cells; DNA showed no change, while lipids, phenoliccompounds, and unaccounted-for organic fractions were all increasedin concentration. The greatest effect was on the phenolic fraction.These results are discussed and related to the published literatureon effects of boron deficiency on higher plants.     

A neglected lineage of North American turtles fills a major gap in the fossil record

Abstract: The fossil record of the two primary subclades of softshell turtles (Trionychidae) is exceedingly asymmetric, as a result of a ghost range of total clade Cyclanorbinae that is estimated at 80 Ma. Herein, we present the first phylogenetic analysis of Trionychidae that includes a representative of the poorly studied taxon Plastomenidae, which is known from the Campanian to Eocene of North America. The analysis reveals that plastomenids are stem cyclanorbines, thus significantly reducing the apparent ghost range of total group Cyclanorbinae to approximately 30 Ma. Plastomenids are either an early branching clade of stem Cyclanorbinae, or they represent a paraphyletic grade that gave rise to modern cyclanorbines. Although abundant, the fossil record is still too poorly understood to distinguish between these two primary hypotheses. The previously persistent extremely long ghost range of total clade Cyclanorbinae appears to have been the result of a research bias.     

Declaration of Taking Twice: The Fazendeville Community of the Lower Ninth Ward

The Fazendeville Village was a residential community founded during the Reconstruction era in 1867 on the land where the Battle of New Orleans (1815) was fought during the War of 1812 in what is now Chalmette, LA. The entire community was displaced and their homes were razed in 1964 to provide more land for the National Historical Park to commemorate the battle. Most of the residents moved to the Lower Ninth Ward in New Orleans and now, 42 years later, they are displaced again and their homes (those that are still standing) will be razed because of the devastation of Hurricanes Katrina and Rita and the floods. Previous research has proven that vernacular networks affect the exodus, return, recovery, and rebuilding of certain communities after traumatic situations. In this study, I suggest that in the Fazendeville community during past trauma, the maintenance of cultural livelihood was caused by communality, spirituality, and traditionality. In addition, I propose that these are also the vernacular networks that are catalyst for community renewal and empowerment—after hurricanes, floods, and historic displacement by the federal government. My ultimate goal is to transform ethnographies into a praxis capable of making the community present and not marginalized or excluded from history and the strategic plan for rebuilding New Orleans.     

Self- and open-pollination as factors influencing seed quality in leek (Allium porrum)

The effect of self-pollination compared with open-pollination on leek seed weight, and subsequent seedling emergence and growth were observed for two years of seed production. Open-pollination gave higher mean seed weights and lower seedling losses during plant establishment than self-pollination. Depending upon the year, the individual plant and pollination method, between 2. 4 and 56.6% of the variation in seedling weight c. 4–5 wk after sowing under controlled conditions was accounted for by differences in seed weight and time of seedling emergence. In 1984 but not 1983, a greater proportion of the variation in seedling weight was accounted for by seed weight and time of seedling emergence in open than self-pollinated seeds.