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Start Over Coverage 135-142

2. Life cycle of the temporary fish parasite, Gnathia africana (Crustacea: Isopoda: Gnathiidae)

Creator:
Smit, Nico J., Basson, Linda, and Van As, Jo G.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
Isopoda, Gnathiidae, Gnathia africana, life cycle, and fish parasite
Language:
English
Description:
Laboratory work was conducted to elucidate the life cycle of the South African gnathiid isopod, Gnathia africana Barnard, 1914. The natural fish hosts of this temporary parasite, the super klipfish Clinus superciliosus (Linnaeus, 1758), were exposed to gnathiid larvae in the laboratory. It was found that G. africana has three larval stages, consisting of three unfed (zuphea) and three fed (praniza) stages. First-, second- and third-stage zuphea larvae took an average of 2 h 18 min, 2 h 43 min and 10 h 8 min respectively to complete their feeding and the first- and second-stage praniza moulted at 8 and 10 days respectively into the next zuphea stage. Three to six days after its last blood meal, the sex of the third and final praniza stage could be determined by the presence of either a testis or two ovaries in the dorsal pereon. Male larvae moulted into adult males between 8 and 10 days post feeding. Female larvae moulted at approximately 17 days into adult females. Fertilisation of the eggs by the male took place within 24 hours of completion of the female moult. The development of the embryos and subsequent release of the young larvae between 15 and 23 days post fertilisation completed the cycle. This entire cycle took approximately 62 days in water temperatures of 20-25°C.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

3. mesophyll cell defective1, a mutation that disrupts leaf mesophyll differentiation in sunflower

Creator:
Fambrini, M., Degl'Innocenti, E., Cionini, G., Pugliesi, C., and Guidi, L.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
botanika, botany, carotenoids, chlorophyll, chlorophyll fluorescence imaging, Helianthus annuus L., and leaf development
Language:
Multiple languages
Description:
Mutants with altered leaf morphology are useful as markers for the study of genetic systems and for probing the leaf differentiation process. One such mutant with deficient greening and altered development of the leaf mesophyll appeared in an inbred line of sunflower (Helianthus annuus L.). The objectives of the present study were to determine the inheritance of the mutant leaf trait and its morphological characterisation. The mutation, named mesophyll cell defective1 (mcd1), has pleiotropic effects and it is inherited as a monogenic recessive. The structure and tissue organization of mcd1 leaves are disrupted. In mcd1 leaves, the mesophyll has prominent intercellular spaces, and palisade and spongy tissues are not properly shaped. The mutant palisade cells also appear to be more vacuolated and with a reduced number of chloroplasts than the wild type leaves of equivalent developmental stage. The lamina thickness of mcd1 leaves is greatly variable and in some areas no mesophyll cells are present between the adaxial and abaxial epidermis. The leaf area of the mcd1 mutant is extremely reduced as well as the stem height. A deficient accumulation of photosynthetic pigments characterizes both cotyledons and leaves of the mutant. In mcd1 leaves, chlorophyll (Chl) fluorescence imaging evidences a spatial heterogeneity of leaf photosynthetic performance. Little black points, which correspond to photosystem II (PSII) maximum efficiency (Fv/Fm) values close to zero, characterize the mcd1 leaves. Similarly, the lightadapted quantum efficiency (ΦPSII) values show a homogeneous distribution over wild type leaf lamina, while the damaged areas in mcd1 leaves, represented by yellow zones, are prominent. In conclusion, the loss of function of the MCD1 gene in Helianthus annuus is correlated with a variegated leaf phenotype characterized by a localized destruction of mesophyll morphogenesis and defeat of PSII activity. and M. Fambrini ... [et al.].
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

4. On the development and life cycle of Spirocamallanus mysti (Nematoda: Camallanidae)

Creator:
De, N. C.
Format:
print
Type:
model:internalpart and TEXT
Subject:
Spirocamallanus, copepods, life cycle, and Mystus
Language:
English
Description:
The development of Spirocamallanus mysti (Karve, 1952) was studied in the copepod hosts Mesocyclops crassus (Fischer) and M. leuckarti (Claus) and in the fish host Mystus viltatus (Bloch). When eaten by copepods the first-stage larvae burrow through the intestinal wall into the haemocoel and there they moulted twice to become the third, infective stage. The first moulting occurred on day 4 p.i. at 18-2ГС (on day 6 p.i. at 16-20"C) and the second moultingoccurred on day 8 p.i. at 18-19.5"C (on day 11 p.i. at 16-20"C. Further development occurred only after reaching the stomach of the fish definitive host. In the fish stomach two more larval moultings occurred, the third on day 15 p.i. and the fourth (final) on day 37 p.i. in “male” larvae and day 67 p.i. in “female” larvae. The individual developmental stages and the morphological changes occurring during development are described in detail.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

7. Regionalizing time of concentration using landscape structural patterns of catchments

Creator:
Amiri , Bahman Jabbarian, Gao , Junfeng, Fohrer , Nicola, and Adamowski , Jan
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
landscape metrics, time of concentration, hydrologic soil group, and hydrologic response
Language:
Slovak
Description:
There is an emerging challenge within water resources on how, and to what extent, borrowing concepts from landscape ecology might help re-define traditional concepts in hydrology in a more tangible manner. A stepwise regression model was adopted in this study to assess whether the time of concentration of catchments could be explained by five landscape structure-representing metrics for land use/land cover, soil and geological patches, using spatial data from 39 catchments. The models suggested that the times of concentration of the catchments could be predicted using the measures of four landscape structure-representing metrics, which include contiguity index (r2 = 0.46, p ≤0.05), fractal dimension index (r2 = 0.51, p ≤0.05), related circumscribing circle (r2 = 0.52, p ≤0.05), and shape index (r2 = 0.47, p ≤0.05). The models indicated that the regularity or irregularity in land use/land cover patch shape played a key role in affecting catchment hydrological response. Our findings revealed that regularity and irregularity in the shape of a given patch (e.g., urban and semi-urban, rangeland and agricultural patches) can affect patch functions in retarding and/or increasing flow accumulation at the catchment scale, which can, in turn, decrease or increase the times of concentration in the catchments.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

8. Ultrastructure of chloroplasts of poikilohydric plants Haberlea rhodopensis Friv. and Ramonda serbica Panč. during recovery from desiccation

Creator:
Markovska, Y.K., Tutekova, A.A., and Kimenov, G.P.
Format:
print
Type:
model:internalpart and TEXT
Subject:
grana, irradiation, mesophyll cell, starch, stoma, vacuole, and water saturation deficit
Language:
Multiple languages
Description:
In anabiotic statě mesophyll cells of both species were filled with vacuoles, chloroplasts were round and without outer envelope and starch. During an 8-d rewatering period cell water saturation deficit continuously (from 80-85 % to 15- 20 %) declined, eliptic shape of chloroplasts was restored, their outer membrane was recovered, grana stacks grew in size and were ordered, stroma was denser, and starch grains started to be formed. The processes were more rapid in Ramonda serbica than in Haberlea rhodopensis. The course of processes was different in irradiated plants than in those kept in the dark.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public