Microbiological Synthesis of Fat: THE EFFECTS OF VARYING PH, TEMPERATURE, NITROGEN, INCUBATION PERIOD, AND SUGAR CONCENTRATION ON FAT-PRODUCING MOULDS

1. A more detailed study has been made of the influence of thesefactors on fat formation by Aspergillus nidulans, Penicilliumspinulosum, and Penicillium javanicum. 2. The effect of halving the glucose, while keeping the ammoniumnitrate concentration constant, lowered the yield of fat onsugar used in A. nidulans and P. spinulosum but not in P. javanicumcultures. 3. Keeping the same N: C ratio and raising the glucose concentrationfrom ro to 20 per cent. showed that to per cent. glucose wasmore efficiently converted to fat by A. nidulans and P. javanicum. 4. The iodine values of the extracted fats were higher, in general,with increased length of incubation. Low ammonium nitrate concentrations,however, tended to give low iodine values. 5. The results have been applied on a larger scale by growthin Roux bottles, Glaxo flasks, and a flat stainless-steel tank.     

Effects of Temperature and Water Potential on Germination, Radicle Elongation and Emergence of Mungbean

Controlled environment experiments were performed to determinethe effects of temperature and water potential on germination,radicle elongation and emergence of mungbean (Vigna radiata(L.) Wilczek cv. IPB-M79-17-79). The effects of a range of constant temperatures (15–45°C) and water potentials (0 to –2.2 MPa) on germinationand radicle elongation rates were studied using an osmoticumtechnique, in which seeds were held against a semi-permeablemembrane sac containing a polyethylene glycol solution. Linearrelationships were established between median germination time(Gt₅₀) and water potential at different temperatures, and betweenreciprocal Gt₅₀ (germination rate) and temperature at differentwater potentials. Germination occurred at potentials as lowas –2.2 MPa at favourable temperatures (30–40 °C),but was fastest at 40 °C when water was not limiting, withan estimated base temperature (T_b) of about 10 °C. Subsequentradicle elongation, however, was restricted to a slightly narrowertemperature range and was fastest at 35 °C. The conceptof thermal time was used to develop an equation to model thecombined effects of water potential and temperature on germination.Predictions made using this model were compared with the actualgermination obtained in a related series of experiments in columnsof soil. Some differences observed suggested the additionalimportance of the seed/soil/water contact zone in influencingseed germination in soil. Seedling emergence appeared to reflectfurther the radicle elongation results by occurring within anarrower range of temperatures and water potentials than germination.Emergence had an estimated T_b of 12.6 °C and was fastestat 35 °C. A soil matric potential of not less than about–0.5 MPa at sowing was required to obtain 50% or moreseedling emergence. Key words: Germination, temperature, water potential     

Phylogenetic synthesis of morphological and molecular data reveals new insights into the higher‐level classification of Tipuloidea (Diptera)

Tipuloidea, the crane flies, are a diverse lineage of true flies (Insecta: Diptera) whose phylogenetic classification and taxonomy remain a challenge. Here we present the results of a quantitative phylogenetic analysis of Tipuloidea based on combined morphological characters (adult, larvae and pupae) and nuclear gene sequence data (28S rDNA and CAD). Forty‐five species, from 44 genera and subgenera, were sampled, representing the four putative families of Tipuloidea (Cylindrotomidae, Limoniidae, Pediciidae and Tipulidae sensu stricto). Analyses of individual datasets, although differing in overall topology, support the monophyly of several major lineages within Tipuloidea. Parsimony and Bayesian analyses using individual morphological and molecular datasets resulted in incongruent topologies. Increased resolution and tree support was obtained when both datasets (morphology and genes) were combined, in both combined evidence parsimony and Bayesian analyses, than when analysed separately. The recovered consensus phylogeny was not consistent with any previously proposed Tipuloidea classification, with previous importance assigned to character states shown here to represent losses and reversals seen as a major factor influencing erroneous classification. The results provided here, together with evidence from previous analyses, were used to append the Tipuloidea classification to supported evolutionary lineages. Tipuloidea is presented as two families: Pediciidae and Tipulidae. Pediciidae is recovered as the sister group to all remaining Tipuloidea. Our current phylogenetic hypothesis is not consistent with the existing subfamilial classification of the ‘Limoniidae’, which is paraphyletic with respect to a well‐supported Tipulinae + Cylindrotominae clade, whereas the three ‘limoniid’ subfamilies are para‐ or polyphyletic. The recognition of ‘Limoniidae’ as a valid monophyletic family is discouraged and the subfamilies of ‘Limoniidae’ are amended and placed within Tipulidae. A revised phylogenetic classification is proposed for the crane flies based on a synthesis of evidence from multiple genes and morphology.     

Effect of Vanadium Pentoxide on the Incorporation of (2-14C)-Acetate into Fungal Lipids

Mycelia of Glomerella cingulata grown in the presence of vanadium pentoxide (V₂O₅), incorporated many times less (2-¹⁴C)-acetate into their lipids than mycelia of the same organism grown in the absence of V₂O₅. All neutral and polar lipid fractions investigated were affected. These data suggested that V₂O₅ depressed lipid biosynthesis in G. cingulata.     

The activation of diazinon by ganglia of the cockroach Periplaneta americana L. and its action on nerve conduction and cholinesterase activity

When sixth abdominal ganglia of the cockroach Periplaneta americana were irrigated continuously with diazinon solution in situ, its effects on nerve conduction and cholinesterase activity closely resembled those of diazoxon; spontaneous activity and after-discharge increased until conduction was blocked, which happened while some cholinesterase was still uninhibited. The symptoms were only slightly relieved by irrigating ganglia with saline. Though the LD50's of diazinon and diazoxon applied topically to adult male P. americana were similar (2.5 ± 0.33 and 4.5 ± 0.38 μig. per insect), diazoxon was about 300 times more active than diazinon against nerve function and cholinesterase activity in the sixth abdominal ganglion. This is probably because in the nerve preparations contact between the insecticide and the tissues surrounding the nerve cord, which in whole insects convert diazinon, a thionophosphate, into its phosphate analogue diazoxon, a more active anticholinesterase, was minimized. Indeed, taking into account the evidence of workers who previously compared in vitro the anticholinesterase activities of several thionophosphates with those of their phosphate analogues and found the phosphates much more active, the effect of diazinon on cholinesterase activity and nerve function in our experiments was unexpectedly great. By applying diazinon to nerve cords with SKF 525-A, a compound likely to prevent oxidation of diazinon to diazoxon, an attempt was therefore made to decide whether diazinon directly affected nerve conduction or whether the effect resulted either from its conversion to diazoxon within the nerve tissue or from impurities in the diazinon used. Results were inconclusive, for SKF 525-A (p-diethylaminoethyl diphenylpropylacetate hydrochloride) not only failed to prevent the inhibition of cholinesterase, but interfered with the action of both diazinon and diazoxon on nerve conduction, and itself affected nerve conduction when applied alone. The possibility that diazinon is itself a mild anticholinesterase was not excluded. SKF 525-A applied to sixth abdominal ganglia at 2 × 10^-4M blocked conduction from cereal nerves to giant fibres in 50–97 min. and at 4 × 10^-5M decreased the post-synaptic response; applied to giant fibres at 2 × 10^-4M it blocked conduction in 90–208 min. The effects of the larger concentration were not completely reversible. Although SKF 525-A has been widely used to study the metabolism of drugs, its direct effects on conduction in nerve axons seem not to have been noted previously.     

Herbivory by Resident Geese: The Loss and Recovery of Wild Rice Along the Tidal Patuxent River

Abstract: Well known for a fall spectacle of maturing wild rice (Zizania aquatica) and migrant waterbirds, the tidal freshwater marshes of the Patuxent River, Maryland, USA, experienced a major decline in wild rice during the 1990s. We conducted experiments in 1999 and 2000 with fenced exclosures and discovered herbivory by resident Canada geese (Branta canadensis). Grazing by geese eliminated rice outside exclosures, whereas protected plants achieved greater size, density, and produced more panicles than rice occurring in natural stands. The observed loss of rice on the Patuxent River reflects both the sensitivity of this annual plant to herbivory and the destructive nature of an overabundance of resident geese on natural marsh vegetation. Recovery of rice followed 2 management actions: hunting removal of approximately 1,700 geese during a 4-year period and reestablishment of rice through a large-scale fencing and planting program.     

Food consumption and utilization responses to dietary dilution with cellulose and water by velvetbean caterpillars, Anticarsia gemmatalis

Abstract Dilution of an artificial diet with water or cellulose to nutrient levels of 32% (undiluted), 19% and 10% fresh weight (fw) resulted in increased fw and dry weight (dw) food consumption (both absolute amounts and weight-relative rates) by velvetbean caterpillars, Anticarsia gemmatalis Hübner. Despite these increases, the absolute amount and relative rate of nutrient intake by the caterpillars declined with dilution, as did their dw gain and dw (% fw) and lipid (% dw) contents. The proportion of consumed food (dw, including cellulose) that was digested and absorbed declined with increased dietary cellulose; however, the proportion of consumed nutrients (dw, excluding cellulose) that was digested and absorbed was not affected by the presence of cellulose, although it increased slightly (but significantly) with dietary water. The efficiency with which the absorbed nutrients were converted to biomass energy showed a negative relationship with the various measures of food consumption and thus a positive relationship with dietary nutrient level.
The compensatory increases in feeding mitigated the deleterious impact of dietary dilution on growth, which would have declined further without the increased feeding. These data suggest that food consumption is regulated primarily through an evaluation of food nutrient level, and that the metabolic costs associated with the increased consumption and processing of food may be substantial, especially on the most diluted diets. Another hypothesized cost of increased feeding, reduced efficiency of digestion and absorption as food presumably passes more rapidly through the gut, was not detected.     

A Periscope Method for Observing Root Growth and Distribution in Field Soil

This paper describes a technique for observing root growth inthe field using glass tubes and a periscope. Roots of two crops(winter wheat and millet) were studied in situ with the periscopeand the results compared with those obtained from washed soilsamples. Generally, both techniques gave similar patterns ofgrowth and distributions of roots although the periscope measurements,when compared with washed soil samples, tended to underestimateroot density close to the soil surface and overestimate densitieslower in the profile. Both methods allowed differences in theroot systems of irrigated and unirrigated crops to be distinguishedbut the periscope method was considerably faster     

Polysome formation in Pinus resinosa at initiation of seed germination

Ribonucleic acid systems present in dormant embryos of red pine(Pinus resinosa Ait.) were studied. Sucrose gradient centrifugationwas used to isolate ribosomes of dormant embryos and embryosimbibed for various times in the light. In dormant embryos,ribosomes existed as monomers. After imbibition, a gradual decreasein the monomers was observed, with subunits and polymers ofribosomes detected within 4 hr. When poly U was added to homogenatesof dormant embryos, formation of polysomes was observed aftera 15-min incubation at 25°C. However, artificial polysomeformation required some factors from heavy particles in thehomogenates. ¹ Contribution from the Missouri Agricultural Experiment Station,Journal Series No. 7079. ² Present address: Government Forest Experiment Station, Meguro,Tokyo, Japan. (Received April 20, 1971; )