Morphological colour change: Stage independent, optically induced ommochrome synthesis in larvae of the stick insect,Carausius morosus Br.

Summary The eyes of 4th, 5th, and 6th instar larvae of the stick insect,Carausius morosus, were partially covered with black varnish, and the ommochrome content of treated and untreated animals was determined throughout the instar. In untreated animals kept at 20°C in 16:8 LD the ommochrome content of the integument remains at the level found in newly hatched larvae (10 g/animal), up to the third moult, and increases only slightly (to 30 g) until the adult moult. Darkening the dorsal halves of the eyes does not influence the ommochrome content. Darkening the ventral halves, thus imitating the visual situation of an animal in light on a dark ground, causes after a lag of 3–4 days, a continuous increase of ommochrome content by about 5 g per day. The increase is equal at the beginning and during the second half of the 4th instar, and is also equal in the three instars investigated. Ommine and xanthommatine equally contribute to the increase.     

Regional and subcellular distribution of taurine-synthesizing enzymes in the rat central nervous system

The distribution of cysteine oxidase (CO) and cysteine sulfinate decarboxylase (CSD) was examined in 12 regions of the rat central nervous system (CNS). The distribution of CO activity, expressed as mol of cysteine sulfinate formed per h per g, was the following: hypothalamus, superior and inferior colliculi, 94–99 mol/h/g; olfactory bulbs, cerebral cortex, striatum, and hippocampus, 44–51 mol/h/g; cerebellum, 71 mol/h/g; pons-medula and spinal cord, 94 and 60 mol/h/g, respectively. The distribution of CSD activity expressed as mol of cysteine sulfinate decarboxylated per h per g was the following: hypothalamus and colliculi, 14–21 mol/h/g; olfactory bulbs, cerebral cortex, striatum, hippocampus, and cerebellum, 8–13 mol/h/g; pons-medulla, 7.3; and spinal cord, 3.6 mol/h/g. No CSD activity was detected in sciatic nerve. The subcellular distribution of CO and CSD activities was studied in hypothalamus, colliculi, and cerebral cortex. CO activity was localized in synaptosomes, mitochondria, and microsomes. CSD was primarily confined to the crude mitochondrial fraction and after subfraction, recovered mainly in the synaptosomal fraction.     

Morphological colour change (2): The effects of total and partial blinding on epidermal ommochrome content in the stick insect,Carausius morosus Br.

Summary Fourth instar larvae of the stick insect,Carausius morosus, kept at 20°C in 16:8 LD, contained about 10 g/animal of epidermal ommochrome. Surgical removal of the ventral half of each eye caused an increase to 110 g/animal. A similar response (90 g/animal) is produced by masking the ventral eye-halves with black varnish. Masking or surgically removing the dorsal half of each eye only caused a slight increase (20 g/animal).The effect of total blinding, either by surgical removal of the eyes or optic lobes, or by electro-coagulation of the eyes, was similar to that of total darkness (40–60 g/animal). The effects of blinding were not enhanced by keeping the insects in total darkness. Eyes that had been destroyed or removed did not regenerate but were replaced by plain cuticle at subsequent moults. Consequently the blinding persisted through the following instars, and the fresh adults contained 300–600 g/animal as compared to 23 g in untreated animals.The results indicate that the effects of illumination on ommochrome pigmentation are mediated entirely through the compound eyes. Removal, destruction or disconnection of eyes or parts of them produced the same response as did lack of light stimulation in the same eyes or parts of eyes when left intact.First communication: J. Comp. Physiol.115, 185–193 (1977)Dedicated to Professor Peter Karlson on the occasion of his 50th birthday     

Ultrastructural changes in the mitochondria of brown adipose cells during the hibernation cycle of Citellus lateralis

Summary The mitochondrial structure in the brown adipose cells of the golden mantled squirrel, Citellus lateralis, was examined throughout the year in biopsy samples. The mitochondria showed remarkable and apparently reversible changes in size and internal structure related to the physiologic activity of the animal. In the active animal the size of the largest mitochondria was 2.4 m × 1.5 m; during hibernation it increased to 7 m × 2.5 m; and during arousal it reached 11.2m × 5.3 m. The cristae of the mitochondria in the brown adipose cells of the animals in hibernation phase formed loops, whorls and mesh-like interconnections. During the arousal phase they underwent further configurational changes. The most remarkable structure was associated with mitochondria of most unusual proportions which by dissolution gave rise to a new generation. This was a common finding during arousal but did not occur in any other phase of the hibernation cycle. The new mitochondria were virtually indistinguishable from those of brown adipose cells of any active animal.Supported by a grant from the Medical Research Council of CanadaThe author is grateful to colleagues, Dr. G. Dempster and Dr. W.A. Spencer, for many valuable suggestions in the course of the work     

Oocysts of Isospora ernsti n. sp. and Isospora blagburni n. sp. (Apicomplexa: Eimeriidae) from the black-capped bulbul,Pycnonotus xanthopygos

Oocysts of Isospora ernsti n. sp. and Isospora blagburni n. sp. are described from the black-capped bulbul Pycnonotus xanthopygos from Lincoln Park Zoo, Chicago, Illinois. The bird came from southwestern Africa seven years earlier. I. ernsti oocysts are ellipsoidal to bluntly ovoid, 28–38 × 23–31m (mean 34 × 28 m) and have a single-layered oocyst wall. Micropyle, oocyst residuum and polar granules are absent. Sporocysts are elongate ovoid, 24–30 × 11–16 m (mean 27×13 m). Stieda and substiedal bodies and sporocyst residuum are present. I. blagburni oocysts are spherical to subspherical. 21–28 × 19–26 m (mean 25 × 23 m) and have a single oocyst wall. Sporocysts are ovoid and 17–23 × 10–13 m (mean 20 × 12 m). Stieda and substiedal bodies and sporocyst residuum are present.     

The contribution of size-fractionated plankton to biomass and primary production of phytoplankton in saline–alkaline ponds

Primary productivity, biomass and chlorophyll-a of size fractionated phytoplankton (<0.22 m, <3 m, <8 m, <10 m, <40 m, <64 m, <112 m and <200 m) were estimated in 6 ponds and 5 experimental enclosures. The results showed that the planktonic algae less than 10 m are important in the biomass and production of phytoplankton in saline–alkaline ponds. The production of size fractionated phytoplankton corresponding to <112 m, <10 m and <3 m in saline–alkaline ponds were 10.5 ± 6.6 , 8.6 ± 5.4 and 0.33 ± 0.1 mgC l^–1 d^–1, respectively. Mean community respiration rate was 1.80 ± 0.73, 1.69 ± 0.90 and 1.38 ± 1.12 mgC l^–1 d^–1, respectively. The average production of phytoplankton corresponding to micro- (10–112 m), nano- (3–10 m) and pico- (<3 m) were 1.61, 8.30 and 0.33 mgC l^–1 d^–1, respectively. The ratio of those to the total phytoplankton production was 15%, 79% and 3%, respectively. The mean respiration rate of the different size groups was 0.11, 0.31 and 1.38 mgC l^–1 d^–1; the ratio of those to total respiration of phytoplankton was 6%, 17% and 77%, respectively. The production of size-fractionated phytoplankton corresponding to <200 m, <10 m and <3 m in enclosures was 2.19 ± 1.63, 2.08 ± 1.75 and 0.22 ± 0.08 mgC l^–1 d^-1, respectively. Mean community respiration rates were 1.25 ± 1.55, 1.17 ± 1.42 and 0.47 ± 0.32 mgC l^–1 d^–1, respectively. The average production of phytoplankton corresponding to micro- (10–200 m), nano- (3–10 m) and pico- (<3 m) plankton was 0.11, 1.86 and 0.22 mgC l^–1 d^–1, respectively. The ratio of those to the total production of phytoplankton was 5%, 85% and 10%, respectively. The mean respiration rate of different size groups were 0.08, 0.72 and 0.46 mgC l^–1 d^–1, the ratio of those to total respiration of phytoplankton was 6%, 57% and 37%, respectively. The concentrations of chlorophyll-a of the phytoplankton in the corresponding size of micro- (10–112 m), nano- (3–10 m) and pico- (<3 m) plankton in the experimental ponds were 19.3, 98.2 and 11. 9 g l^–1, respectively. The ratio of those to the total chlorophyll-a was 15%, 76% and 9%, respectively. The concentrations of chlorophyll-a of phytoplankton micro- (10–200 m), nano- (3–10 m) and pico- (<3 m) plankton in enclosures were 1.7, 34.3 and 3.0 g l^–1, respectively. The ratio of those to the total chlorophyll-a was 4%, 88% and 8%, respectively.     

Plant regeneration via somatic embryogenesis in Styrian pumpkin: cytological and biochemical investigations

Somatic embryo formation was induced from cotyledon explants of Styrian pumpkin (Cucurbita pepo L. subsp. pepo var. styriaca Greb.) by using a solid MS medium supplemented with 16.11M NAA and 4.44M BA or 26.85M NAA and 13.32M BA. The callus proliferation was more efficient on medium supplemented with 26.85M NAA and 13.32M BA. In contrast, the embryogenic response was higher on medium with lower concentrations of growth regulators (16.11M NAA and 4.44M BA). The time needed for embryo induction did not depend on medium composition. Embryos in globular stage were transferred to three different maturation media, containing 2.89M GA₃ in combination with 0.54M NAA, 11.42M IAA and growth regulator-free medium. The germination rate was the highest when embryos were cultured on medium with 11.42M IAA. Plantlets grown on this medium achieved maturity suitable for transplantation into soil within 9 to 10weeks. The regenerated plants were successfully transferred into field and developed fertile flowers and set fruits. Biochemical analysis showed significant lower total glutathione levels among in vitro grown plantlets compared to seedlings grown in soil. When the plantlets were transferred into soil, they reached a normal size within a month and the glutathione concentration was comparable to seed-derived plants at the same developmental stage. Transmission electron microscopy was used to investigate possible differences in the ultrastructure of cells from callus cultures, and leaf cells of regenerated and seed-derived plants. Differences in the ultrastructure were found within chloroplasts which contained only single thylakoids, large starch grains and small plastoglobuli in callus cells in comparison to leaf cells, which possessed a well developed thylakoid system, small starch grains and large plastoglobuli.     

Clonal propagation of Callistemon by tissue culture techniques

Callus development in Callistemon viminalis was readily achieved when axillary buds derived from nodal tissue were placed in a medium containing macro- and micro-nutrients, sucrose (0.06 M), inositol (300 M), nicotinic acid (20 M), pyridoxine hydrochloride (3 M), thiamine hydrochloride (2 M), riboflavin (10 M), cytokinins (5 M) and auxins (0.1 M). The presence of benzylaminopurine (5 M) and p-chlorophenoxyacetic acid (0.1 M) promoted the most vigorous callus development and sprout formation. Rooting of nodal material was rare but occurred readily following the transference of sprouts developed on callus to a basal medium containing sucrose and salts. Root initiation was stimulated, however, by the presence of auxins. Chlorophenoxyacetic acid while stimulating root initiation repressed root growth. Indole butyric acid stimulated both root initiation and shoot growth at concentrations of 0.005 to 0.1 M. The treatment of choice for rooting and shoot growth was the addition of indole butyric acid at a concentration of 0.01 M.     

The spermatozoon of Oikopleura dioica Fol (Larvacea,Tunicata)

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

Stimulation of ethylene production by catecholamines and phenylethylamine in potato cell suspension cultures

The catecholamines (50 M dopamine, 50 M norepinephrine and 100 M epinephrine) and phenylethylamine (200 M) were found to stimulate ethylene production in potato suspension cultures. When 100 M amino-oxyacetic acid was added together with epinephrine, ethylene release returned to control levels. The endogenous 1-aminocyclopropane-1-carboxylic acid levels were increased in parallel with the release of ethylene, suggesting that the observed effect probably occurs via regulation of aCC synthase. Our results suggest that there is a link between these naturally occurring monoamines and ethylene in plants.Abbreviations AOA amino-oxyacetic acid - ACC 1-aminocyclopropane-1-carboxylic acid - DA dopamine - NE norepinephrine - E epinephrine - CA catecholamines - PEA phenylethylamine