Preferensi dan Pengaruh Jenis Makanan Terhadap Pertumbuhan Larva Croccidolomia binotalis Zell.

Croccidolomia binotalis Zell. merupakan hama tanaman Cruciferace. Ketertarikan hama ini terhadap cruciferace karena rangsangan nutritif maupun non nutritif. Pilihan inang akan menentukan pertumbuhan, perkembangan dan aktifitas normal hama. Penelitian ini menggunakan rancangan acak lengkap (RAL) dengan 3 perlakuan dan 3 ulangan. Perlakuan berupa pemberian jenis makanan daun kubis berkrop, daun kubis bunga dan daun kubis Cina. Data yang diperoleh dianalisis dengan sidik ragam dan uji lanjut dengan DNMRT pada taraf nyatal 5 % . Hasil penelitian menunjukkan bahwa Croccidolomia binotalis Zell. mempunyai preferensi makanan yang lebih tinggi pada daun kubis bunga daripada kubis krop dan kubis Cina. Ketiga daun kubis yang diberikan tidak menghambat pertumbuhan dan aktifitas normal larva C. binotalis Zell. Rata-rata luas daun yang dimakan larva berpengaruh terhadap pertambahan berat rata-rata larva sedangkan rata-rata berat daun yang dikonsumsi tidak berpengaruh terhadap pertambahan berat larva C. binotalis Zell.

Determination and morphogenesis in the sea urchin embryo

The study of the sea urchin embryo has contributed importantly to our ideas about embryogenesis. This essay re-examines some issues where the concerns of classical experimental embryology and cell and molecular biology converge. The sea urchin egg has an inherent animal-vegetal polarity. An egg fragment that contains both animal and vegetal material will produce a fairly normal larva. However, it is not clear to what extent the oral-aboral axis is specified in embryos developing from meridional fragments. Newly available markers of the oral-aboral axis allow this issue to be settled. When equatorial halves, in which animal and vegetal hemispheres are separated, are allowed to develop, the animal half forms a ciliated hollow ball. The vegetal half, however, often forms a complete embryo. This result is not in accord with the double gradient model of animal and vegetal characteristics that has been used to interpret almost all defect, isolation and transplantation experiments using sea urchin embryos. The effects of agents used to animalize and vegetalize embryos are also due for re-examination. The classical animalizing agent, Zn2+, causes developmental arrest, not expression of animal characters. On the other hand, Li+, a vegetalizing agent, probably changes the determination of animal cells. The stability of these early determinative steps may be examined in dissociation-reaggregation experiments, but this technique has not been exploited extensively. The morphogenetic movements of primary mesenchyme are complex and involve a number of interactions. It is curious that primary mesenchyme is dispensable in skeleton formation since in embryos devoid of primary mesenchyme, the secondary mesenchyme cells will form skeletal elements. It is likely that during its differentiation the primary mesenchyme provides some of its own extracellular microenvironment in the form of collagen and proteoglycans. The detailed form of spicules made by primary mesenchyme is determined by cooperation between the epithelial body wall, the extracellular material and the inherent properties of primary mesenchyme cells. Gastrulation in sea urchins is a two-step process. The first invagination is a buckling, the mechanism of which is not understood. The secondary phase in which the archenteron elongates across the blastocoel is probably driven primarily by active cell repacking. The extracellular matrix is important for this repacking to occur, but the basis of the cellular-environmental interaction is not understood.(ABSTRACT TRUNCATED AT 400 WORDS)

The amino acid metabolism of a developing insect cuticle: the larval cuticle and puparium of Calliphora vomitoria . I. Changes in amino acid composition during development

The amino acid composition of the developing larval cuticle and puparium of Calliphora vomitoria has been examined by means of paper chromatography. The most significant changes during development concern the aromatic amino acids. Phenylalanine and para -tyrosine apparently combine with the tanning quinone when the puparium hardens, and ortho -tyrosine is present for a brief period at about 7 days The presence of o -tyrosine, together with evidence resulting from the extraction of larval cuticles with water, gives rise to the suspicion that aromatic amino acids may be metabolized in the cuticle during development and give rise to hydroxylated products. The cuticle of ‘permanent larvae’, which fail to pupate even after the lapse of 2 to 3 weeks owing to the extirpation of Weismann’s ring before the end of the normal feeding period, has also been examined. Its amino acid composition shows none of the changes seen in the normal larva.

The Respiration of Insects Through the Skin

1. When blowfly larvae are paralysed by ligaturing behind the ganglion the resultant respiration of the hind parts represents the basal metabolism of the animal. 2. When the hind spiracles are also ligatured off, all respiration takes place by diffusion through the skin and is about one-quarter of the basal value. The R.Q. of the twice-ligatured larvae is 1.34. This indicates that part of the metabolic processes are maintained by anaerobic respiration. 3. The O2 tension inside the larvae has been measured and is about 15% inside the normal larvae and 2.4% inside the double-ligatured larvae. 4. Therefore a much larger amount of oxygen diffuses through the skin in the double-ligatured than in the normal larvae, and it has been found by calculation for the normal larva to be one-tenth of the basal value. 5. When insects are submerged in water their spiracles are not able to function and all respiration takes place by diffusion through the skin. 6. In the normal blowfly respiration is independent of the O2 tension from 100% O2 down to about 7.5%, whereas in the double-ligatured larvae it is entirely dependent on the oxygen tension. 7. Experiments with other insects, Chaerocampa elpenor larvae (spiracles blocked with grease), Tenebrio molitor larvae and Culex sp. larvae (submerged in water), gave results similar to those obtained with the blowfly larvae.

The Origin of Competence for Lens Formation in the Amphibia

1. Presumptive ectoderm of Triton alpestris was removed from the young gastrula and cultivated in Holtfreter solution at 25° C. until control embryos had developed open neural plates. 2. Presumptive eye material from neural plate embryos, with some attached archenteron roof, was then implanted into the isolated fragments of ectoderm. 3. The grafted tissue formed single complete eyes, and bilaterally symmetrical portions of the brain, although the implant contained asymmetrical portions of the neural plate. 4. In some of the explants the competence for neural differentiation was retained even to this late stage, and neural tubes were induced. In other specimens the inner layer of ectoderm consists of long, cylindrical, regularly arranged cells, like those of the sensory inner layer of ectoderm in the mouth region of a normal larva. Still other specimens formed thin-walled vesicles with no sensorisation, and others again differentiated into the compact masses of tissue normally formed by isolated gastrula ectoderm. 5. Lenses were induced in all types of explant mentioned above except the last. 6. It is concluded that the formation of lens competence is not dependent on the presence of non-axial mesoderm or on the previous occurrence of a process of neural induction, but is dependent on the differentiation of the ectoderm into a thin layer, which differentiation may be brought about in various ways, and perhaps purely mechanically. The formation of a thin layer of ectoderm is probably a sufficient as well as a necessary condition for the origin of lens competence.

Memoirs: The Occurrence of Situs inversus among artificially-reared Echinoid Larvae

1. Under artificial conditions more than 10 per cent. of tho larvae of Echinus miliaris exhibited the situs inversus. 2. So far as I could examine, the internal as well as external structures of such abnormal larvae were mirror-images of those of the normal larva. 3. The young sea-urchins metamorphosed from such inverse larvae showed no abnormal features externally. 4. The manner in which such abnormal larvae departed from the normal development seems to be analogous to that in the case of ‘compensatory hypertypy’ in the claws of Alpheus. 5. In an early stage of the normally-developing happens sometimes that the left dorsal pore becomes obliterated. This seems to be associated with the shifting of the pore towards the mid-dorsal line. The hydrocoele, thus deprived of its communication with the exterior, ceases to develop and then degeneration of the whole water-vascular system sets in. 6. The right anterior coelom, on the other hand, is now evoked to realize its latent potentiality of producing a hydrocoele (homoeosis). The degenerating left hydrocoele gives place to a newly-appearing right hydrocoele. 7. The right hydrocoele stimulates its adjoining tissues to give rise together to an echinus-rudiment. 8. The external factor or factors which cause the obliteration of the dorsal pore could not be found. This probably is connected with the presence of too much diatom-food and other micro-organisms in the culture jar. 9. If a new dorsal pore is formed on the left side before the degeneration of the left hydrocoele sets in, the developing power of the latter will thereby be revived. If sufficiently fed a double-hydrocoele larva will result under such a condition. 10. If, while the left hydrocoele is arrested in its development and then degenerates, the right anterior coelom fails to develop a new hydrocoele presumably from want of sufficient food, a larva devoid of hydrocoele will result.

Reversal of asymmetry in the plutei of Echinus miliaris

While engaged in artifical rearing of Echinus miliaris under the guidance of Prof. MacBride, I have come across a number of abnormal plutei which had the hydrocœle developed on the right side instead of in its normal position on the left side. Such reversed larvæ were first found on May 31, 1920, when they were eleven days old (text-fig. 1). The “larval” body was quite normal both in size and shape, but the hydrocœle, stone-canal, axial sinus, madreporic vesicle, and amniotic invagination were all situated on the right side, so that the larva became a perfect mirror-image of the normal larva. Such larvæ developed further with exactly the same rate of growth as the normal ones, an echinus-rudiment being well developed on the right side, until at last, when a month old, some few of them passed metamorphosis. The young urchins (text-fig. 2) showed no features visible externally which differed from those of urchins metamorphosed from normal larvæ. A similar case has previously been described only by Runnström in two individuals found among artifically reared larvæ of Strongylocentrotus lividus ((9), pp. 2–3, 7–10; (12), pp. 419–24, Plate 14, figs. 12–16). In other classes of Echinoderms, auriculariæ with the hydrocœle on the right side were noticed by Müller many years ago ((7), pp. 101, 109; Plate 5, fig. 1), and a similar state of affairs in two plutei of Ophionotus hexactis has recently been discovered by Mortensen. In both these case the abnormal larvæ were found in nature, not reared under artificial conditions. The purpose of our experiments was to repeat Prof. MacBride’s method of artifical production of the double hydrocœle (6). Having been unable to get an uninterrupted supply of enough food, which consisted of Nitzchia , and from other causes unknown to us at present, we could not arrive at any satisfactory conclusion so far as the effect of the increased salinity is concerned. From both lots of cultures, treated with the “hypertonic” sea water as well as untreated, more than 10 per cent. of the larvæ exhibited the situs inversus, and much less number, 2 per cent. at most, developed the double hydrocœle.

Studies in heredity. I.―The effects of crossing the sea-urchins echinus esculentus and echinocardium cordatum

The manner in which parental characters are transmitted to the offspring when different species of Echinoderms are crossed has been the subject of much experimental enquiry and quite contradictory conclusions have been arrived at by different investigators. Thus Vernon (13), who carried out a most extensive series of experiments with the species of the genera Arbacia, Echinus, Strongylocentrotus, Sphærechinus, and Echinocardium which are available at Naples, came to the conclusion that the condition of the genital glands of the parents (whether imperfectly ripe, fully ripe, or stale) determines in many cases whether or not a hybrid will be formed, and further that though in the majority of cases the hybrid exhibits purely maternal characters, yet it sometimes exhibits paternal characters also, and that this result is also due to the condition of ripeness of the genital glands of its parents. Herbst (5), who also worked at Naples and who used the genera Echinus, Strongylocentrotus, and Sphærechinus for his experiments, found also that the hybrids in many cases showed the paternal influence, but that the extent to which this influence was exhibited varied with the temperature. Doncaster (1), who likewise worked at Naples, also arrived at the conclusion that the greater or less development of paternal characters in the hybrid was due to the temperature. On the other hand, Loeb (7, 8) and his pupil Hagedoorn (4) came to the conclusion that the hybrid exhibited purely maternal characters, and Fischel (2) arrived at the same conclusion on the whole. This conclusion is the more remarkable because Hagedoorn in his experiments used two species of the same genus. Tennent (12) crossed species of the American genera Toxopneustes and Hipponoe and found that the characters of Hipponoe were dominant in the hybrid whichever way the cross was made, but that if the alkalinity of the sea-water were reduced by the addition of dilute acid the influence of Toxopneustes became increased. Lastly Loeb, Redman King, and Moore in a joint paper published quite recently (9), in which they record the results of experiments with the same two species which Hagedoorn used, arrive at the conclusion that the exhibition of paternal and maternal characters in the hybrid is governed by the principle of Mendelian dominance, since, as they assert, the same characters appear in the hybrid whichever way the cross is made, whether, that is to say, in any particular case the character in question is inherited from the male or from the female parent. During a study of the whole subject which I recently made with the object of summarising the present state of our knowledge of this question of the inheritance of paternal and maternal characters in the hybrid, I was struck with the necessity of a preliminary thorough investigation of the characters of the normal larvæ of the species used in hybridisation experiments. The amount of general acquaintance with Echinoderm larvæ displayed by several of the investigators who have attacked the subject is, to say the least, somewhat defective. Thus Herbst (5), who studied chiefly the cross between Sphærechinus and Strongylocentrotus, attaches great importance to the extent to which lattice-work appears in the skeleton of the arms of the hybrid. In the normal larva of Strongylocentrotus, it is true, all four arms are supported by unbranched calcareous rods, whilst in the normal larva of Sphærechinus, each of the two posterior arms is supported by parallel rods connected by cross-pieces like the steps of a ladder, an arrangement which is termed “lattice-work.” But Herbst fails to take into account the fact that in the normal larva of Strongylocentrotus a lattice-work skeleton can appear as a variation, and hence an attempt such as he makes to estimate quantitatively the influence of one parent by the amount of lattice-work which appears in the hybrid rests upon an insecure foundation.