scholarly journals CHROMOSOMAL ALTERNATION OF GENERATIONS IN NEREOCYSTIS LUETKEANA (MERTENS) POSTELS AND RUPRECHT

1961 ◽  
Vol 39 (7) ◽  
pp. 1711-1724 ◽  
Author(s):  
Lindley Kemp ◽  
Kathleen Cole
Keyword(s):  
Life History ◽  
Life Cycle ◽  
Nuclear Division ◽  
Basal Cells ◽  
Cytological Examination ◽  
Male And Female ◽  
Nereocystis Luetkeana ◽  
History Of ◽  
Alternation Of Generations

A cytological examination of the life history of Nereocystis luetkeana has shown that an alternating chromosome number corresponds to the morphological alternation of generations. The first division sequence of the zoosporangial nucleus is meiotic and is followed by three, usually synchronous, mitotic divisions. Thirty-two zoospores are liberated from each sporangium, and their germination gives rise to male and female gametophytes. Genotypic determination of the sexes is believed to take place in Nereocystis. Mitosis in the gametophytes is regular and cytokinesis follows each nuclear division, producing few cells in the female and many cells in the male gametophytes. Thirty-one chromosomes can be counted at the mitotic prophase. Oogamy exists in Nereocystis and fertilization takes place after the egg is extruded from the oogonium. Nuclear division in the sporophyte appears to be preceded by division of the nucleolus. Colorless and non-septate rhizoids develop as elongations of the basal cells of the sporophyte.Temperature is an important factor in the development of various stages of the life cycle of Nereocystis grown in culture, particularly in the gametophytic stage where sexual structures are produced only at temperatures less than 10 °C and vegetative growth is most prolific at 14–18 °C.Some of the unfertilized eggs develop parthenogenetically and give rise to stunted, deformed plants with multinucleate cells.

Life history of Amblyseius fustis (Pritchard and Baker), an indigenous predator of the cassava red mite, Oligonychus gossypii (zacher) in south western Nigeria

1985 ◽  
Vol 6 (2) ◽  
pp. 193-197 ◽  
Author(s):  
T. O. Ezulike ◽  
J. A. Odebiyi
Keyword(s):  
Life History ◽  
Life Cycle ◽  
Relative Humidity ◽  
Developmental Stages ◽  
Developmental Period ◽  
Life Stages ◽  
Male And Female ◽  
Significant Difference ◽  
History Of ◽  
Male To Female

AbstractThe life history of Amblyseius fustis (Pritchard and Baker) was studied in the laboratory at a fluctuating temperature and relative humidity ranging from 24.4 to 28.0°C and 55.5 to 75.6%, respectively. The developmental stages consist of egg, larva, protonymph, deutonymph and adult. The life cycle, from egg to adult of both male and female was about 8 days, while longevity was about 19.2 days. Mated female laid an average of 18.8 eggs. There was no significant difference in the longevity and fecundity of predators fed on different life stages of the host. The proportion of male to female in the progeny of mated females was 1:4.A. fustis has a shorter developmental period and lives longer than its prey, but the latter is more fecund (26.9 eggs/♀) and has a higher proportion of females in its progeny (1:4.8). The shorter developmental period and the longer life span of the predator are likely to offset the higher fecundity of the prey.

Studies on Polystomella Lamarck (Foraminifera)

1942 ◽  
Vol 25 (3) ◽  
pp. 607-666 ◽  
Author(s):  
Margaret W. Jepps
Keyword(s):  
Life History ◽  
Life Cycle ◽  
Canal System ◽  
Experimental Conditions ◽  
Complete Life Cycle ◽  
Laboratory Cultures ◽  
History Of ◽  
Nuclear Changes ◽  
Opening Up

Part I. After a brief statement of the present unsatisfactory position regarding the life history of Polystomella crispa, an account is given of experiments with various fixatives on P. crispa, collected near Drake's Island, Plymouth. A method is described for the cultivation of Polystomella in diatom cultures, especially with Navicula mutica var., with which a flagellate (Bodo sp.) was constantly present. The identification of individual Foraminifera, and determination of growth, were often possible by some irregularity in the shell, or by noting the attachment of one or more stalked egg cocoons of an unknown turbellarian worm. The feeding of Polystomella on diatoms seized by the pseudopodia outside the shell is described; the structures previously taken for ingested algal cells inside the shell are shown to be foraminal plugs (‘bouchons’ of le Calvez) which are discarded from time to time and thrown out of the shell along with the excretory granules (xanthosomes), mostly via the canal system.Part II. Notes are given on the microspheric form and its reproduction, through the spring and summer, by schizogony. The rearing of two broods in laboratory cultures is described, with an account of the formation of a new chamber to the shell. It is concluded that a complete life cycle consisting of one microspheric and one megalospheric phase occupies a period of about two years.Part III. Sporulation of the megalospheric form is described as seen during life; and various factors are discussed which might affect the process. The relatively small size of the reproducing Polystomella with which Lister worked is ascribed to their having lived under less favourable conditions. From a study of stained preparations, certain details are added concerning the opening up of the shell, presumably to facilitate the eventual escape of the flagellate swarm spores; also concerning the accompanying cytoplasmic and nuclear changes. Some account is given of the form and structure of the swarm spores, both alive and in permanent preparations. Experiments are described which constitute an attempt to carry the life cycle beyond the stage of sporulation. They are so far unsuccessful, with one possible exception, under all the various experimental conditions which are briefly discussed in their turn.

Some observations on the life history of Podocarpus falcatus

1960 ◽  
Vol 8 (3) ◽  
pp. 243 ◽  
Author(s):  
TGB Osborn
Keyword(s):  
Life History ◽  
Life Cycle ◽  
Pollen Tube ◽  
Mother Cell ◽  
Nuclear Division ◽  
Embryonic Cells ◽  
Linear Tetrad ◽  
Zygote Nucleus ◽  
Layer Membrane ◽  
History Of

Podocarpus falcatus (R.Br. ex Mirb.) belongs to the 1-year life cycle type of podocarp. Ripe seeds are shed 12–13 months after pollination. There is a single gynospore mother cell in a well-defined tapetum, and the inner spore of a linear tetrad is functional. Pollen tubes make contact with the developing female prothallus before the stage of free nuclear division is complete. They continue to grow downwards between it and the nucellus. There are several superficial archegonia, some of which may be enveloped by a common jacket layer. They are of intermediate length, and develop along the line of contact between the pollen tube and prothallus. The gynospore layer membrane remains thin at this point. Five free mitoses of the zygote nucleus take place, the first two in the mid archegonial area. The proembryonic nuclei become tiered with a low number in the embryonic layer. The embryonic cells have the usual binucleate phase followed by tetrad formation. Simple polyembryony is common, and though fission may occur it is not general.

scholarly journals On Apogamy and the development of Sporangia upon fern prothalli

1898 ◽  
Vol 63 (389-400) ◽  
pp. 56-61
Keyword(s):  
Life History ◽  
Point Of View ◽  
The Other ◽  
Normal Life ◽  
Other Hand ◽  
General Importance ◽  
Two Generations ◽  
History Of ◽  
Alternation Of Generations

The two most important deviations from the normal life-history of ferns, apogamy and apospory, are of interest in themselves, but acquire a more general importance from the possibility that their study may throw light on the nature of alternation of generations in archegoniate plants. They have been considered from this point of view Pringsheim, and by those who, following him, regard the two generations as homologous with one another in the sense that the sporophyte arose by the gradual modification of individuals originally resemblin the sexual plant. Celakovsky and Bower, on the other hand, maintaint the view tha t the sporophyte, as an interpolated stage in the life-history arising by elaboration of the zygote, a few thallophytes.

The reproduction and larval development of Nereis fucata (Savigny)

1959 ◽  
Vol 38 (1) ◽  
pp. 65-80 ◽  
Author(s):  
J. B. Brown-Gilpin
Keyword(s):  
Life History ◽  
Life Cycle ◽  
Experimental Methods ◽  
Point Of View ◽  
Hermit Crabs ◽  
Special Importance ◽  
Reproductive Patterns ◽  
Complete Life Cycle ◽  
History Of ◽  
The Many

The wide variety of reproductive patterns and behaviour in the many species of Nereidae already studied clearly justifies further research. But the life history of Nereis fucata (Savigny) is not only of interest from the comparative point of view. Its commensal habit (it occurs within shells occupied by hermit crabs) immediately gives it a special importance. This alone warrants a detailed study, particularly as no commensal polychaete has yet been reared through to metamorphosis and settlement on its host (Davenport, 1955; Davenport & Hickok, 1957). The numerous interesting problems which arise, and the experimental methods needed to study them, are, however, beyond the range of a paper on nereid development. It is therefore proposed to confine the present account to the reproduction and development up to the time when the larvae settle on the bottom. The complete life cycle, the mechanism of host-adoption, and related topics, will be reported in later papers.

scholarly journals A STUDY OF THE LIFE HISTORY OF TRICHOBILHARZIA CAMERONI SP. NOV. (FAMILY SCHISTOSOMATIDAE)

1953 ◽  
Vol 31 (4) ◽  
pp. 351-373 ◽  
Author(s):  
Liang-Yu Wu
Keyword(s):  
Life History ◽  
Life Cycle ◽  
Room Temperature ◽  
Migratory Birds ◽  
Local Infection ◽  
Domestic Ducks ◽  
Ottawa River ◽  
Daughter Sporocyst ◽  
Physa Gyrina ◽  
History Of

A cause of swimmer's itch in the lower Ottawa River is Trichobilharzia cameroni sp. nov. Its life cycle has been completed experimentally in laboratory-bred snails and in canaries and ducks, and the various stages are described. The eggs are spindle-shaped. The sporocysts are colorless and tubular. Mother sporocysts become mature in about a week. The younger daughter sporocyst is provided with spines on the anterior end and becomes mature in about three weeks. The development in the snail requires from 28 to 35 days. A few cercariae were found to live for up to 14 days at 50 °C., although their life at 16° to 18 °C. was about four days. Cercariae kept at room temperature for 60 to 72 hr. were found infective. The adults become mature in canaries and pass eggs in about 12 to 14 days. Physa gyrina is the species of snail naturally infected. It was found in one case giving off cercariae for five months after being kept in the laboratory. Domestic ducks were found to become infected until they were at least four months old, with the parasites developing to maturity in due course; no experiments were made with older ducks. Furthermore, miracidia were still recovered from the faeces four months after the duck had been experimentally infected, and it is suggested that migratory birds are the source of the local infection.

The life history of Pleurogenoides malampuzhensis sp. nov. (Digenea: Pleurogenidae) from amphibious and aquatic hosts in Kerala, India

2013 ◽  
Vol 88 (2) ◽  
pp. 230-236 ◽  
Author(s):  
R. Brinesh ◽  
K.P. Janardanan
Keyword(s):  
Life History ◽  
Life Cycle ◽  
Related Species ◽  
Growth And Development ◽  
Systematic Position ◽  
Patent Period ◽  
Hoplobatrachus Tigerinus ◽  
Life Cycle Stages ◽  
Muscle Tissues ◽  
History Of

AbstractThe life-cycle stages of Pleurogenoides malampuzhensis sp. nov. infecting the Indian bullfrog Hoplobatrachus tigerinus (Daudin) and the skipper frog Euphlyctiscyanophlyctis (Schneider) occurring in irrigation canals and paddy fields in Malampuzha, which forms part of the district of Palakkad, Kerala, are described. The species is described, its systematic position discussed and compared with the related species, P. gastroporus (Luhe, 1901) and P. orientalis (Srivastava, 1934). The life-cycle stages, from cercaria to egg-producing adult, were successfully established in the laboratory. Virgulate xiphidiocercariae emerged from the snail Digoniostoma pulchella (Benson). Metacercariae are found in muscle tissues of dragonfly nymphs and become infective to the frogs within 22 days. The pre-patent period is 20 days. Growth and development of both metacercariae and adults are described.

Analysis of a Population Sampling Method for the Lodgepole Needle Miner in Canadian Rocky Mountain Parks

1952 ◽  
Vol 84 (10) ◽  
pp. 316-321 ◽  
Author(s):  
R. W. Stark
Keyword(s):  
Life History ◽  
Life Cycle ◽  
Sampling Method ◽  
Rocky Mountain ◽  
Fixed Time ◽  
Forest Stand ◽  
Population Sampling ◽  
Adequate Sampling ◽  
History Of ◽  
External Feeding

General.—The purpose of this paper is to analyse a sampling method devised to assess larval populations in an outbreak of the lodgepole needle miner, Recurvaria milleri Busck (Busck 1914, Hopping 1945).The problem of developing an adequate sampling method is intimately concerned with the life-history of the insect, the region of the outbreak and the nature of the forest stand in which the outbreak occurs. In sampling most defoliator populations the problem is made more difficult by external feeding and wandering habits, hence it is usually done in some relatively inactive stage at a fixed time. de Gryse (1934) describes the problems inherent in sampling these insects. The needle miner, however, is fixed in its location for most of its life-cycle and is therefore readily obtainable for study. The problem here is reduced to a statistical one, that of obtaining an acceptable sample i.e. within suitable error limits with due regard for existing variables.

LIFE HISTORY STUDIES OF THE TOBACCO FLEA BEETLE, EPITRIX HIRTIPENNIS (MELSHEIMER) (COLEOPTERA: CHRYSOMELIDAE)

1987 ◽  
Vol 22 (3) ◽  
pp. 237-244 ◽  
Author(s):  
W. Davis Martin ◽  
G. A. Herzog
Keyword(s):  
Life History ◽  
Larval Stage ◽  
Flea Beetle ◽  
Pupal Stage ◽  
Adult Emergence ◽  
Adult Longevity ◽  
Male And Female ◽  
Controlled Conditions ◽  
History Of ◽  
The Mean

The life history of the tobacco flea beetle, Epitrix hirtipennis (Melsheimer) (= Epitrix parvula Fab.) was studied under the controlled conditions of 27 ± 2.8°C, 80 ± 6% and a 14L:10D photophase. Eggs matured in ca. 4 days, the larval stage, including 3 instars, developed in 13 days, prepupal development took 3 days and the pupal stage lasted approximately 5 days. There was a 24 day interval between oviposition and adult emergence. Females laid 3.1 eggs/day with a 13 day period between adult emergence and first oviposition. The mean number of total eggs/female was 138.6 ± 14.7. Female oviposition continued until a few days before death and adult longevity was approximately 70 days. A visual means of distinguishing between male and female beetles was also developed.

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