The determination of organic nitrogen in biological materials

Fleck, A.; Munro, Hamish N.

doi:10.1016/0009-8981(65)90083-5

Cited by 167 publications

(41 citation statements)

References 69 publications

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“…Oviposition behavior and performance aspects of Ascia monuste ground and the total organic nitrogen content was determined by the Kjeldhal method (FLECK & MUNRO 1965;BREMNER & MULVANEY 1982apud QUIRING 1992.…”

Section: -X100mentioning

confidence: 99%

Oviposition behavior and performance aspects of Ascia monuste (Godart, 1919) (Lepidoptera, Pieridae) on kale (Brassica oleracea var. acephala)

Catta-Preta¹,

Zucoloto²

2003

Rev. Bras. entomol.

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ABSTRACT. Host part selection by ovipositing females of Ascia monuste (Godart, 1919) (Lepidoptera, Pieridae) on kale (Brassica oleracea var. acephala) was determined in greenhouse and field. Performance of offspring (larval period, efficiency of food utilization, number of eggs/female and others) was investigated under laboratory conditions. In the field, the number of A. monuste egg clutches on the apical and medium parts of kale leaves was greater than on the basal part. In greenhouse, A. monuste exhibited a strong preference for the apical part of kale leaves for ovipositing. The best results on food utilization indices, pupal mass and female wing size were obtained with the leaf apical part. This part of kale leaves exhibited the highest nitrogen and protein concentration and the smallest water content, when compared to the other leaf parts. However, the apical part of the leaves seems not to provide ovipositing females with enough protection against birds, making them easy preys in the field. We suggest that good relationship between oviposition preference and performance of offspring was hindered by predation in field conditions.

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Section: -X100mentioning

confidence: 99%

Oviposition behavior and performance aspects of Ascia monuste (Godart, 1919) (Lepidoptera, Pieridae) on kale (Brassica oleracea var. acephala)

Catta-Preta¹,

Zucoloto²

2003

Rev. Bras. entomol.

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“…The homogenate was then centrifuged in a refrigerated ultracentrifuge initially at 600g for 15 min and then at 25,000 g for 60 min, as previously described (Griffiths et al, 1974), to produce a supernatant (soluble/cytoplasmic) fraction; the supernatant fraction was dialyzed overnight against double-distilled water at 4 °C. The non-diffusible nitrogen content (in micrograms N, as a measurement of the protein content) was determined by a micro-Kjeldahl technique (Fleck and Munro, 1965).…”

Section: Preparation O F the Hypothalamic Fractionmentioning

confidence: 99%

Inactivation of Two Hyperactive LH-RH Analogues by Rat Hypothalamic Peptidases

Griffiths¹,

Hopkinson²

1979

Horm Res

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Hyperactive analogues of luteinizing hormone-releasing hormone (LH-RH) are believed to derive their properties from either increased binding affinity to anterior pituitary receptor sites or through decreased susceptibility to enzymic degradation. To investigate the latter suggestion and to examine the possible sites of action of hypothalamic peptidases inactivating LH-RH, D-Ser(TBU)⁶-EA¹⁰-LH-RH and D-Leu⁶-EA¹⁰-LH-RH, which are known to have considerably greater activity than LH-RH, were incubated with a hypothalamic supernatant fraction containing active peptidases degrading LH-RH, and their gonadotrophin-releasing ability after incubation with the enzymes was tested in normal, adult male rats; LH-RH was also tested in the same way. From a comparison of the relative losses of biological activity, both the LH-RH analogues treated proved to be more resistant to the hypothalamic peptidases than LH-RH itself: the D-Leu⁶-EA¹⁰-LH-RH retained its gonadotrophin-releasing activity longer than the D-Ser(TBU)⁶-EA¹⁰-LH-RH. These findings indicate that increased activity of the analogues may, in part, be due to increased resistance to enzymic inactivation and suggest initial sites of cleavage at the Gly-Leu and Pro-Gly NH₂bonds in the LH-RH decapeptide by the hypothalamic enzymes. Studies on the action of peptidases on LH-RH and its analogues may yield useful information in the design of peptides with increased biological activity.

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“…The partic ulate fraction was resuspended in about 0.8 ml distilled water; both this and the supernatant fraction from each brain area were dialyzed overnight against distilled water at 4 °C. The non-diffusible nitrogen content of the fractions was determined by a micro-Kjeldahl method (Fleck and Munro, 1965).…”

Section: Preparation O F the Brain Areasmentioning

confidence: 99%

Effect of Neonatal Androgen on the Activity of Peptidases in the Rat Brain Inactivating Luteinizing Hormone-Releasing Hormone

Griffiths¹,

Hooper²,

Jeffcoate³

et al. 1976

Horm Res

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The activity of peptidase enzymes in different brain areas inactivating luteinizing hormone-releasing hormone (LH-RH) was investigated in normal male and female rats and female rats treated neonatally with androgen. Of the two fractions containing peptidase activity, changes were found only in the supernatant (soluble/cytoplasmic) fraction and were restricted to the hypothalamus and cortex. In both these brain areas, peptidase activity was considerably higher in androgen-treated than in normal female rats; there was no significant difference between activity in male rats and the androgen-treated female rats. These findings indicate that neonatal androgen produces masculinization of the mechanisms responsible for LH-RH inactivation in the hypothalamus which may reflect changes observed elsewhere in gonadotropin secretion in androgen-treated female rats. The changes in peptidase activity in the cortex may infer that sexual differentiation of the brain under the influence of androgen is not limited to the hypothalamus and can be manifested at extrahypothalamic sites within the central nervous system.

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The determination of organic nitrogen in biological materials

Cited by 167 publications

References 69 publications

Oviposition behavior and performance aspects of Ascia monuste (Godart, 1919) (Lepidoptera, Pieridae) on kale (Brassica oleracea var. acephala)

Oviposition behavior and performance aspects of Ascia monuste (Godart, 1919) (Lepidoptera, Pieridae) on kale (Brassica oleracea var. acephala)

Inactivation of Two Hyperactive LH-RH Analogues by Rat Hypothalamic Peptidases

Effect of Neonatal Androgen on the Activity of Peptidases in the Rat Brain Inactivating Luteinizing Hormone-Releasing Hormone

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