Defensive potential of components of the larval osmeterial secretion of papilionid butterflies against ants

ABSTRACT. Toxicity and repellency of components of larval osmeterial secretions of the Papilionidae to the ants Lasius niger and Crematogaster matsumurai were evaluated in the laboratory and in the field. The test chemicals comprised five aliphatic acids, five esters, three monoterpene hydrocarbons and four sesquiterpenes.
The majority of aliphatic acids and esters exhibited weak to potent toxicity, but exposure to acetic, isobutyric, 2-methylbutyric and isovaleric acids, ethyl 2-methylbutyrate and methyl 3-hydroxy- n -butyrate proved fatal to both ant species. Monoterpene hydrocarbons also had considerable toxicity, whereas sesquiterpenes were only slightly or not toxic. Of the terpenic compounds tested, α-pinene was found to be the most toxic. L. niger ejected formic acid in response to d -limonene.
Field experiments revealed that all the compounds examined except 3-hydroxy- n -butyric acid were significantly repellent to worker ants of both species. Acetic, isobutyric and 2-methylbutyric acids especially showed pronounced repellency, while the esters were less deterrent.
Among terpenic compounds, the repellency of caryophyllene oxide was noticeable. d -Limonene elicited no particular response, other than rapid evasion, by L. niger.     

Localization of Possible Calcium-Binding Sites in the Cilia of Paramecium caudatum

SYNOPSIS. Electron-dense deposits indicating possible Ca-binding sites were found at the ciliary base of Paramecium caudatum fixed in a glutaraldehyde solution containing 5 mM CaCl₂. The deposits appeared mainly at the inner surface of the ciliary membrane above the "ciliary necklace" region, although they could also occur in the space between the outer and the central microtubules. In some cases a ring of exactly 9 deposits was found in a ciliary cross section of a cilium.     

Prospective Neural Areas and Their Morphogenetic Movements during Neural Plate Formation of Xenopus Embryos. I. Development of Vegetal Half Embryos and Chimera Embryos

Development of animal cap-less Xenopus gastrulae was examined. In vegetal halves from which the animal cap was removed 0.6 mm above the blastopore, an apparently normal array of craniocaudal structures developed. Histological examination showed differentiation of central nervous system (CNS) structures in the cap-less embryos, but differentiation of sensory organs, such as a lens and ear vesicle in only a few embryos. Only the dorsal midline of the embryos was covered with epidermis, and its lateral-ventral areas consisted of bare endoderm and mesoderm. The development of animal cap was also investigated by exchanging the animal cap of X. laevis embryos with that of X. borealis embryos, which can be distinguished by quinacrine fluorescence staining. The central nervous system of chimera embryos consisted mainly of X. laevis cells stained homogeneously with quinacrine but a small number of punctately-stained X. borealis cells was in the anterior tip of the forebrain. Cells of the lens and ear vesicle were punctately stained. More than two-thirds of the epidermal area consisted of punctately-stained cells and only the dorsal midline of the posterior head- and trunk-epidermis consisted of homogeneously-stained cells.
Areas of the prospective central nervous system and their movement during embryogenesis of Xenopus are discussed.     

Prospective Neural Areas and their Morphogenetic Movements during Neural Plate Formation in the Xenopus Embryo. II. Disposition of Transplanted Ectoderm Pieces of X. borealis Animal Cap in Prospective Neural Areas of Albino X. laevis gastrulae.

Small pieces of the animal cap of X. borealis gastrulae were transplanted into various regions of the noninvoluting marginal zone of albino X. laevis gastrulae, and the distribution of the donor cells was analyzed by quinacrine fluorescence staining.
The present study indicated that the prospective central nervous system (CNS) lies as a belt-shaped area in the noninvoluting marginal zone of early gastrulae. This belt-shaped prospective neural area extends as far as 0.7 mm (115° to the vegetal pole) above the blastopore in the dorsal midline and 1.3 mm lateral (130° to the dorsal midline) to the dorsal midline. The ectoderm of the dorsal region extends in the animal-vegetal direction and forms the ventral side of the CNS. The dorsalateral and lateral regions converge toward the dorsal midline and extended in the animal-vegetal direction. The former constitutes the lateral side of the anterior CNS, and the latter the dorso-lateral side of the posterior CNS.
The outer layer of ectoderm which was transplanted onto the inner layer of the host gastrula differentiated into neural tissues.
The prospective areas of the CNS and their morphogenetic movement during Xenopus embryogenesis are also discussed with regard to neural induction.     

Arginine Vasopressin Contents of the Hypothalamus and Pituitary during Fetal and Postnatal Development in the Mouse

The contents of arginine vasopressin (AVP) in the hypothalamus and the pituitary of the mouse during fetal and postnatal development were measured by radioimmunoassay. AVP was first detected in the hypothalamo-pituitary system at the fetal age of 14 days (FA 14). After FA 15, the pituitary levels were higher than the hypothalamic levels except on FA 16. The greater AVP content of the hypothalamus than the pituitary only on FA 16 suggests that AVP synthesis in the perikarya of AVP-producing neurons may significantly increase between FA 15 and FA 16, and that the hormonal transport to the pituitary may be characteristically activated between FA 16 and FA 17. The levels of AVP in both the hypothalamus and the pituitary increased exponentially until the postnatal age of 21 days (PA 21). After PA 30, the content in the pituitary continued to increase, while that in the hypothalamus was kept almost constant. The decrease in AVP content in the pituitary was found between PA 0 and PA 1, and PA 21 and PA 30. These results suggest that AVP might be released from the pituitary in response to significant changes in water metabolism elicited at birth and weaning.     

Involvement of calcium ion in turgor regulation upon hypotonic treatment in Lamprothamnium succinctum

Abstract When internodal cells of Lamprothamnium succinetum were exposed to a hypotonic medium containing more than 1 mol m^?3 Ca²⁺, the elevated turgor pressure decreased and reached a steady state within 30–60 min. The hypotonic treatment caused the membrane potential to depolarize, with a time lag of ca. 1 min. The membrane conductance increased transiently with the same time lag and reached a peak value within 2–3 min. When the external Ca²⁺ concentration was lowered to 0.01 mol m^?3, both turgor regulation and change in the membrane conductance were strongly inhibited, although the membrane depolarization was not affected. When the Ca2+ level was returned to the normal level, the cells recovered their ability for turgor regulation and the membrane conductance attained a peak value after ca. 15–30 s. This response time is definitely shorter than that needed for the conductance change in cells exposed to a hypotonic medium having a normal level of Ca²⁺ from the beginning. We thus conclude that at least two sequential processes are involved in turgor regulation: a Ca²⁺ -independent process, followed by a Ca²⁺-dependent process.     

A bimodal germination response to temperature in cocklebur seeds. II. ATP and adenylate pool

Abstract. The mechanism involved in a bimodal germination-temperature response in pre-soaked cocklebur (Xanthium pennsylvanicum Wallr.) seeds was studied with special reference to adenylate metabolism. Exposure to either low (optimal at 8°C) or high (optimal at 34°C) temperature which was effective in inducing the germination of the seeds brought about the accumulation of ATP in them. The ATP level remained unchanged at temperatures around 23°C. Pretreatment with KCN, stimulating germination even at 23°C, subsequently increased the ATP content, total adenylate pool and energy charge (EC) in the axial tissue prior to germination above those of the untreated controls. The lower the treatment temperature, the greater the inhibitory effect of KCN on ATP formation. An increase in germination following an increasing duration of pre-soaking at 8°C was comparable to increasing both the ATP content and total adenylate pool of axes, but not the EC value. Similarly, changes in germination following an increased exposure duration at 8°C correlated with changes in ATP content rather than EC value in the axes. Unlike the case of chilling, an increase in ATP level in response to 34°C was greater in the early period of water imbibition, during which times its germination-stimulating effect appeared more striking than in the later period, and it occurred without a concomitant rise in EC value because of the increased supply of AMP. Such a supply of AMP was reduced in the presence of benzohydroxamic acid or propyl gallale, inhibitors of an alternative respiratory pathway. It was thus concluded that both low temperature, coupled with warm temperature, and high temperature, by itself, can induce seed germination by increasing the ATP level as well as the total adenylate pool, but not the EC value, in the axial tissue. Further, that increases in both the ATP level and the adenylate pool especially are required for seed germination to proceed, probably depending on the activities of the cytochrome and alternative respiration pathways, respectively.     

Change in Molecular Size of Cellulose during Regeneration of Cell Wall on Carrot Protoplasts

Protoplasts isolated from carrot cells were cultured in a chemically defined medium. The majority of them regenerated cell wall and underwent cell division. Cellulose synthesis started without a noticeable lag but the rate of deposition was very low during the initial stage. The degree of polymerization of cellulose was determined by viscosity measurement of the nitrated product. The cellulose formed in the early stage of the wall regeneration consisted mainly of low molecular weight glucan chains. Change in the average molecular weight of cellulose was found during the growth cycle of carrot cells in normal suspension culture.     

Short-term regulation of cytosolic Ca2+, cytosolic pH and vacuolar pH under NaCl stress in the charophyte alga Nitellopsis obtusa

Isolated characean internodal cells of Nitellopsis obtusa can be stored in artificial pond water for many days, but they cannot survive in 100mol m^?3 NaCl solution unless more than several mol m^?3 Ca²⁺ is added. Short-term effects of NaCl stress on the cytosolic concentration of Ca²⁺ ([Ca²⁺]_c), cytosolic pH (pH_c) and vacuolar pH (pH_v) were studied in relation to the external concentration of Ca²⁺ ([Ca²⁺]_e). Changes in [Ca²⁺]_c were measured with light emission from a Ca²⁺-sensitive photoprotein, semisynthetic fch-aequorin which had been injected into the cytosol. Both pH_c and pH_v were measured with double-barrelled pH-sensitive microelectrodes. When internodal cells were treated with 100 mol m^?3 NaCl (0–1 mol m^?3 NaCl (0.1 mol m^?3 [Ca²⁺]_e), [Ca²⁺]_c increased and then recovered to the original level within 60 min. The time course of the transient change in [Ca²⁺]_c was not influenced by the level of [Ca²⁺]_c (0.1 and 10 mol m^?3). In some cases, the transient increase in [Ca²⁺]_c was induced only by increasing external osmotic pressure with sorbitol. In response to treatment with 100 mol m^?3 NaCl (0.1 mol m^?3 [Ca²⁺]_c), pH_c decreased by 0.1–0.2 units after 10min but recovered after 30–60 min, while pH_v increased by 0.4–0.5 units after 2–50 min and tended to recover after 60 min. The initial changes in both pH_c and pH_v were suppressed when [Ca²⁺]_e was raised from 0.1 to 10mol m^?3. These results show that the charophyte alga Nitellopsis can regulate [Ca²⁺]_c, pH_c and pH_v under NaCl stress in the short term and that the protective effect of Ca²⁺ on salinity stress is apparently unrelated to perturbation of Ca²⁺ and pH homeostasis.