Changes in foliage distribution with relative irradiance and tree size: Differences between the saplings ofAcer platanoides andQuercus robur

Dependencies of foliage arrangement and structure on relative irradiance and total height (TH) were studied in saplings ofAcer platanoides andQuercus robur. The distribution of relative foliar area and dry weight (leaf area and weight in a crown layer per total tree leaf area and weight, respectively) were examined with respect to relative height (RH, height in the crown per TH) and characterized by the Weibull function. The distributions of relative area and weight were nearly identical, and the differences between them were attributable to a systematic decline in leaf dry weight per area with increasing crown depth. Foliage distribution was similarly altered by tree size in both species; RH at foliage maximum was lower and relative canopy size (RCS, length of live crown per TH) greater in taller trees. However, the distribution was more uniform inA. platanoides than inQ. robur. Apart from the size effects, relative irradiance also influenced canopy structure; RCS increased inQ. platanoides and decreased inQ. robur with increasing irradiance. As crown architecture was modified by irradiance, foliage distribution was shifted upwards with decreasing irradiance inA. platanoides, but it was independent of irradiance inQ. robur. Higher foliage maximum at lower irradiance in more shade-tolerantA. platanoides is likely to contribute towards more efficient foliar display for light interception and increase the competitive ability of this species in light-limited environments. Consequently, these differences in crown architecture and foliage distribution may partly explain the superior behavior ofA. platanoides in understory.     

MORPHOLOGICAL DESCRIPTION OF THE LARVAE OF CERATOPHYLLUS FARRENICHAOI AND THEIR COMPARISON WITH THE LARVAE OF CERATOPHYLLUS CALLINAE TRIBULIS

Abstract This paper deals with the morphology of the larvae of Cerutophyllus farreni chaoi Smit and Allen, 1955 and a comparison is made with the larvae of C. gallinue tribulis Jordan, 1926.
The diagnostic characters of the larvae of the two subspecies are the shape of egg burster, number of mandibular teeth, the relative positions of the sense organs and setae on the tergites of the thorax and abdomen and number of the setae of anal comb and the strut setae.     

Taxonomy of Pyramimonas obovata and other observations on the subgenus Vestigifera of Pyramimonas (Prasinophyceae, Chlorophyta)

A vestigiferan species commonly referred to as Pyramimonas obovata N. Carter has been redescribed as P. melkonianii sp, nov. Characters of this species and a further six (P. disomata Butcher ex McFadden, Hill et Wetherbee, P. mantoniae Moestrup et Hill, P. mitra Moestrup et Hill. P. moestrupii McFadden, P. aff. nephroidea McFadden, P. orientalis Butcher ex McFadden, Hill et Wetherbee) isolated from South African waters are used to define further the subgenus Vestigifera McFadden. This includes a unique chloroplast shape and basal hyaline region with stellate or cruciform vacuoles, a transitional plate-like structure in the flagellum, and a different microtubular root system. The proximal set of basal body connectives were found to be remarkably symmetrical and like those of the subgenus Trichocystis McFadden, and a duct fibre was found associated with the Id root in all currently investigated species. The validity of the larger body (box and crown) scales as taxonomic markers at a fine level is also questioned.     

Morphology and life history of Halopteris filicina (Sphacelariales, Phaeophyceae) from Korea

The vegetative morphology and life history of Halopteris filicina (Grateloup) Kutzing, collected from Korea, were examined in laboratory culture. Field plants attaining 3–5 cm in height were epilithic, tufted, yellowish-brown, and produced numerous erect axes with alternately distichous branches from compact basal discs. They were cultured under a 12:12 h LD photoperiod at 10°-C, 15°C and 20°C to observe the influence of temperature on reproduction. At 10°C plants grew only vegetatively, whereas at 15°C and 20°C they produced unilocular sporangia. Unispores released from sporangia developed into monoecious, anisogamous gametophytes that formed plurilocular female and male gametangia on the same lateral branches. The zygotes, by fusion of female macrogametes and male microgametes, developed into sporophytes bearing unilocular sporangia, whereas the unfused female gametes germinated parthenogenetically. This species was confirmed to have an isomorphic life history, basically similar to the other species of Sphacelariales.     

Mesocyclops thermocyclopoides species-group: redefinition and content

Within the genus Mesocyclops the thermocyclopoides species-group is defined on the basis of the presence of spiniform armature on the maxillar coxa. Examination of nineteen, mainly Palaeotropical species of Mesocyclops and nine representatives of the closely related genus Thermocyclops revealed, that the coxal part of the maxillar syncoxa of the species recently unified in the thermocyclopoides group is adorned with distinct rows of big spinules on its frontal surface. This character, with only one known exception in South Indian M. cf. papuensis, is absent in other species of Mesocyclops and all the Thermocyclops studied here. These species have no spinules on the maxillar coxa at all or very tiny scattered ones.     

Effects of substratum morphology on cell physiology

Among the host of substratum properties that affect animal cell behavior, surface morphology has received relatively little attention. The earliest effect of surface morphology on animal cells was discovered almost a century ago when it was found that cells became oriented in response to the underlying topography. This phenomenon is now commonly known as contact guidance. From then until very recentrly, little progress has been made in understanding the role of surface morphology on cell behavior, primarily due to a lack of defined surfaces with uniform morphologies. This problem has been solved recently with the development of photolithographic techniques to prepare substrata with well defined and uniform surface morphologies. Availability of such surfaces has facilitated systematic in vitro experiments to study influence of surface morphology on diverse cell physiological aspects such as adhesion, growth, and function. For example, these studies have shown that surfaces with uniform multipls parallel grooves can enhance cell adhesion by confining cells in grooves and by mechanically interlocking them. Several independent studies have demosterated that cell shape is a major determinant of cell growth and function. Because surface morphology has been shown to modulate the extent of cell spreading and cell shape, its effects on cell growth and function appear to be mediated via this biological coupling between cell shape and function. New evidence in the cell biology literature is emerging to suggest that surface morphology could affect other cell behavioral properties such as post-translational modifications. Further elucidation of such effects will enable better designs for implant and cell culture substrata.     

Neosteinernema longicurvicauda n. gen., n. sp. (Rhabditida: Steinernematidae), a Parasite of the Termite Reticuldermes flavipes (Koller)

A nematode isolated from the termite Reticulitermes flavipes (Koller) was identified and described as a new genus and species, Neosteinernema longicurvicauda. Primary distinguishing characters, by contrast to members of the genus Steinernema, were females having prominent phasmids, a curved tail longer than the body width at the anus, a spiral shape in juvenile-bearing females, and juveniles becoming infective-stage juveniles before emerging from the female; males having prominent phasmids, a digitate tail tip, a characteristic shape of the spicules (foot-shaped with a hump on the dorsal side), and 13-14 pairs of genital papillae, with eight pairs preanal; and infective juveniles having prominent phasmids and a filiform curved tail as long as the esophagus. Adult nematodes are found outside the termite cadaver. Diagnosis of the family Steinernematidae was emended to accommodate the new species.     

Descriptions of Two New Species of Chronogaster Cobb, 1913 from India

Two new species of Chronogaster in India were described and illustrated, based on light and scanning electron microscopy. Chronogaster neotypica n. sp. collected from a sewage slurry was characterized by a medium-sized body, a ventral tail mucro without additional spines, absence of longitudinal incisures in lateral fields, and by the presence of crystalloids in the body. Diagnostic for C. spinicauda n. sp. collected from soil around roots of mango were a medium-sized body, a tail mucro with 10 spines, and absence of lateral lines and crystalloids. Males were not found.     

Factors affecting variability in anther culture and in conversion of androgenic embryos ofSolanum phureja

The variation for embryo production in anther ofSolanum phureja was examined as a function of maximum greenhouse temperature prior to bud harvest and innate responsiveness among anthers within a bud. Four clones ofS. phuyreja were grown in a greenhouse under a 16-h photoperiod. The temperature was monitored continuously. Buds (60 per day on 10 days) were collected and the anthers cultured in two groups of five flasks (30 anthers per flask). In the first group, each flask contained the 30 anthers from six buds; in the second group, each flask contained one anther from each of 30 buds. Significantly smaller coefficients of variation were observed for the second group, suggesting that variation for embryogenic capcity among buds was greater than that among anthers within a bud. Variation in embryo yield as a function of greenhouse temperature was examined by stepwise regression analysis. Embryogenic capacity of one clone was adversely affected by high temperatures (31–37°C) that occurred two and seven days before bud harvest. However, similarly high temperatures appeared to enhance the androgenic response of another clone. Conversion of anther-derived embryos over three subcultures to fresh regeneration medium was examined as a function of anther donor or clone, cold pretreatment of embryos, and morphological classification of embryos. Only clonal origin significantly affected conversion rate which ranged from 12.5% to 46.0%. Conversion rate declined on each serial subculture.Abbreviations BA N⁶-benzyladenine - GA₃ gibberellic acid, IAA-indole-3-acetic acid