Superficial Cortical Cells Research Articles

Comparative light and scanning electron microscopic studies of the lenses in the insectivorous bat (Pipistrellus kuhlii) and Egyptian fruit bat (Rousettus aegyptiacus).

Bats have the ability to fly without eye application in the darkness. In this study, we aimed to characterize the functional and structural acclimations of the lenses of two common bats with a various lifestyle in the Egyptian environment: the insectivorous bat (IB) (Pipistrellus kuhlii) and Egyptian fruit bat (FB) (Rousettus aegyptiacus). From each species, seven lenses were extracted from adult eyes. The scanning electron microscopic (SEM) and light microscopic examination of the lens were carried out. FB lenses were made up primarily of fiber cells and sheets, which were encapsulated by a thin collagenous capsule and covered by single epithelial layer anteriorly. On the other hand, the IB lens had two poles and was visibly oval shaped. Both lenses had epithelial cells of the same cuboidal form that were subjected to continuous division and differentiation into new fiber cells at the center. SEM revealed that the normal FB lens had regularly organized shells of fiber cells of intact lens fibers which were connected by membrane interdigitations with different shapes mainly ball-and-socket junctions through the superficial cortical fiber cells. The IB lens was composedof parallel, evenly spaced fibers with various types of interdigitations between fibers that can be seen and increased close to the middle region revealing tiny bumps along the scrubby portions and sockets and balls in the center of the wide portions. Near the center of both lenses, there were large interlocking paddles with little and lengthy protrusions along their short sides. In conclusion, our study discovered several ultrastructural and structural variations among the investigated species. The detection of specialized membrane interdigitations with different shapes protruding from the lens fiber sheets is considered the most characteristic of the FB lens. RESEARCH HIGHLIGHTS: FB lens has more organized sheets of fibers parallel to each other than IB lens. Different shapes of interdigitations protruded from the FB lens have been detected. Interlocking paddles, balls, and sockets with tongue-like fiber flabs are characteristic to FB lens.

Laminar organization of neocortical activities during systemic anoxia

The neocortex is highly susceptible to metabolic dysfunction. When exposed to global ischemia or anoxia, it suffers a slowly propagating wave of collective neuronal depolarization that ultimately impairs its structure and function. While the molecular signature of anoxic depolarization (AD) is well documented, little is known about the brain states that precede and follow AD onset. Here, by means of multisite extracellular local field potentials and intracellular recordings from identified pyramidal cells, we investigated the laminar expression of cortical activities induced by transient anoxia in rat primary somatosensory cortex. Soon after the interruption of brain oxygenation, we observed a well-organized sequence of stereotyped activity patterns across all cortical layers. This sequence included an initial period of beta-gamma activity, rapidly replaced by delta-theta oscillations followed by a decline in all spontaneous activites, marking the entry into a sustained period of electrical silence. Intracellular recordings revealed that cortical pyramidal neurons were depolarized and highly active during high-frequency activity, became inactive and devoid of synaptic potentials during the isoelectric state, and showed subthreshold composite synaptic depolarizations during the low-frequency period. Contrasting with the strong temporal coherence of pre-AD activities along the vertical axis of the cortical column, the onset of AD was not uniform across layers. AD initially occurred in layer 5 or 6 and then propagated bidirectionally in the upward and downward direction. Conversely, the post-anoxic waves that indicated the repolarization of cortical neurons upon brain reoxygenation did not exhibit a specific spatio-temporal profile. Pyramidal neurons from AD initiation site had a more depolarized resting potential and higher spontaneous firing rate compared to superficial cortical cells. We also found that the propagation pattern of AD was reliably reproduced by focal injection of an inhibitor of sodium‑potassium ATPases, suggesting that cortical AD dynamics could reflect layer-dependent variations in cellular metabolic regulations.

Interspecific fastening tissue between Hypnea pannosa and Hypnea spinella (Cystocloniaceae, Rhodophyta)

ABSTRACT There have been frequent reports in several macroalgae of fusions between algal structures. However, most of these reports have documented the (intraspecific) adhesion of portions of the same thallus. The different adhesion structures have been termed anastomoses, and include ring-shaped cells, adherent discs, tentacle cells and pseudo-laterals. Hypnea pannosa and H. spinella are seasonally highly persistent and abundant species in the Mexican Tropical Pacific, with a wide distribution in the region. When the species grow together in the rocky intertidal zone, they produce contact points between their thalli, which hold them together. The fusions between the branches and axes of these species result in a fastening tissue that is distinct from all those previously described. Here we describe the anatomical changes that occur at the contact points between the branches and axes of the two species using optical microscopy, scanning electron microscopy and transmission electron microscopy. The adhesion structures resulted in significant morphological and anatomical changes to the superficial cortical cells, with a new type of interspecific fastening tissue growing outside of the contact points. We characterize this new type of interspecific fastening tissue, consider its origin and structural complexity, and compare it to other connecting structures reported. Additionally, we discuss the consequences of this new type of tissue and its possible ecological significance.

Non-invasive assessment of superficial and deep layer circuits in human motor cortex.

Key points The first indirect (I) corticospinal volley from stimulation of the motor cortex consists of two parts: one that originates from infragranular layer 5 and a subsequent part with a delay of 0.6 ms to which supragranular layers contribute.Non‐invasive probing of these two parts was performed in humans using a refined electrophysiological method involving transcranial magnetic stimulation and peripheral nerve stimulation.Activity modulation of these two parts during a sensorimotor discrimination task was consistent with previous results in monkeys obtained with laminar recordings. Circuits in superficial and deep layers play distinct roles in cortical computation, but current methods to study them in humans are limited. Here, we developed a novel approach for non‐invasive assessment of layer‐specific activity in the human motor cortex. We first conducted brain slice and in vivo experiments on monkey motor cortex to investigate the output timing from layer 5 (including corticospinal neurons) following extracellular stimulation. Neuron responses contained cyclical waves. The first wave was composed of two parts: the earliest part originated only from stimulation of layer 5; after 0.6 ms, stimuli to superficial layers 2/3 could also contribute. In healthy humans we then assessed different parts of the first corticospinal volley elicited by transcranial magnetic stimulation (TMS), by interacting TMS with stimulation of the median nerve generating an H‐reflex. By adjusting the delay between stimuli, we could assess the earliest volley evoked by TMS, and the part 0.6 ms later. Measurements were made while subjects performed a visuo‐motor discrimination task, which has been previously shown in monkey to modulate superficial motor cortical cells selectively depending on task difficulty. We showed a similar selective modulation of the later part of the TMS volley, as expected if this part of the volley is sensitive to superficial cortical excitability. We conclude that it is possible to segregate different cortical circuits which may refer to different motor cortex layers in humans, by exploiting small time differences in the corticospinal volleys evoked by non‐invasive stimulation.

Morphology and distribution of Laurencia sp.1 (Ceramiales, Rhodophyta) from Myanmar

The plants of Laurencia sp. 1 were collected from Nyaw Byin (Lat. 13˚40′N, Long. 98˚00′E) to Sittwe (Lat. 20˚08′ N, Long. 92˚54′E) of Myanmar from 1987 to 2019. Laurencia sp.1 was characterized by the absence of corps en cerise within each superficial cortical cell, and lenticular thickenings in the walls of medullary cells, and the presence of secondary pit-connections between cortical cells, four pericentral cells per axial segment and tetrasporangia formed in the apical portion of the lateral axis with a parallel arrangement and cystocarps with one or more ostioles, based on the external and internal morphologies of both the vegetative and reproductive structures. The distribution and some ecological notes along with potential uses of this species were briefly described.

The Changes of 8-OHdG, hOGG1, APE1 and Pol β in Lenses of Patients with Age-Related Cataract

Purpose: To evaluate the changes of oxidative DNA damage (in the form of 8-OHdG) and three key DNA base-excision repair (BER) proteins, human 8-oxoguanine DNA glycosylase 1 (hOGG1), apurinic/apyrimidinic endonuclease 1 (APE1) and DNA polymerase β (Pol β), in lens epithelium cells (LECs), cortex and nucleus of lenses with age-related cataract (ARC) and age-matched controls.Methods: A total of 90 patients with ARC and 21 control subjects were enrolled. The samples included the anterior lens capsules (mainly composed of LECs) and various portions of lens. An ELISA assay was used to assess the 8-OHdG levels of genomic DNA extracted. Immunofluorescence and Western blot were used to analyze the localization and quantification of three BER proteins, respectively.Results: The 8-OHdG levels in lenses with ARC were higher than those of controls, and were not different among ARC subtypes. The 8-OHdG levels were the highest in the nucleus, followed by the LECs and cortex. The repair proteins were predominantly detected in the cellular nuclei of the LECs and superficial cortical cells. In the LECs, the protein levels of the three BER enzymes were higher in ARC than in controls. In the cortex, a downward trend of the levels of three BER enzymes was found with the increasing opaque degrees. In the nucleus, no enzymes were detected.Conclusions: Our findings indicate that the oxidative DNA damage increases in lenses with ARC, and the three BER enzymes compensatively increase in the LECs, while decreasing in the opaque cortex. The results suggest that the oxidative DNA damage may be related ARC and the alteration of DNA repair enzyme levels in ARC is associated with the location and opaque degrees of lens.

Reduced Cognition in Syngap1 Mutants Is Caused by Isolated Damage within Developing Forebrain Excitatory Neurons

Syngap1 haploinsufficiency is a common cause of sporadic intellectual disability. Syngap1 mutations disrupt developing pyramidal neurons, although it remains unclear if this process contributes to cognitive abnormalities. Here, we found that haploinsufficiency restricted to forebrain glutamatergic neurons was sufficient to disrupt cognition and removing mutations from this population prevented cognitive abnormalities. In contrast, manipulating Syngap1 function in GABAergic neurons had no effect on cognition, excitability, or neurotransmission, highlighting the specificity of Syngap1 mutations within forebrain excitatory neurons. Interestingly, cognitive abnormalities were reliably predicted by the emergence of enhanced excitatory synaptic function in mature superficial cortical pyramidal cells, which was a neurophysiological disruption caused by Syngap1 dysfunction in developing, but not adult, forebrain neurons. We conclude that reduced cognition in Syngap1 mutants is caused by isolated damage to developing forebrain glutamatergic neurons. This damage triggers secondary disruptions to synaptic homeostasis in mature cortical pyramidal cells, which perpetuates brain dysfunction into adulthood.

Role of secondary metabolites as defense chemicals against ice-ice disease bacteria in biofouler at carrageenophyte farms

Carrageenophyte farming is an expanding economical activity in North Borneo Island, Malaysia. During routine monitoring of “ice-ice” disease and epiphyte outbreak at commercial farms, it was apparent that culture lines were heavily (60–80%) infested with biofoulers, particularly Acanthophora spp. and Laurencia majuscula. However, only L. majuscula showed dominance and flourished even during “ice-ice” disease outbreak. Presence of chemical defense against seaweed pathogens was investigated in two populations of L. majuscula collected from three major carrageenophyte farms in two districts; (A) Lohok Butun, Selakan Island, and Bum-Bum Island, in Semporna district, and (B) Telutuh, Carrington Reef, and Balambangan Island, in Kudat district. The first population contained elatol (1), and iso-obtusol (2), and, second population contained (Z)-10,15-dibromo-9-hydroxy-chamigra-1,3(15),7(14)-triene (3) and (E)-10-15-dibromo-9-hydroxy-chamigra-1,3(15),7(14)-triene (4), as their antibacterial metabolites. All four metabolites showed highly selective inhibition against “ice-ice” disease bacteria compared to human pathogens at 30 µg disk−1. In addition, seasonal variation of these compounds at two representative farms (Selakan Island [P-1] and Balambangan Island [P-2]) revealed a 120–170% increase in concentration during “ice-ice” disease outbreak. Microscopy of fresh specimens showed the presence of corps en cerise, which is the synthesis and storage site of halogenated metabolites at superficial cortical cells, branch tips, and trichoblasts. This suggests the importance of these metabolites as defense chemicals against “ice-ice” disease bacteria in L. majuscula that grows on seaweed culture lines.

Mitochondrial “Movement” and Lens Optics following Oxidative Stress from UV‐B Irradiation

Mitochondria provide energy generated by oxidative phosphorylation and at the same time play a central role in apoptosis and aging. As a byproduct of respiration, the electron transport chain is known to be the major intracellular site for the generation of reactive oxygen species (ROS). Exposure to solar and occupational ultraviolet (UV) radiation, and thus production of ROS and subsequent cell death, has been implicated in a large spectrum of skin and ocular pathologies, including cataract. Retinal pigment epithelial cell apoptosis generates photoreceptor dysfunction and ultimately visual impairment. The purpose of this article was to characterize in vitro changes following oxidative stress with UV-B radiation in (a) ocular lens optics and cellular function in terms of mitochondrial dynamics of bovine lens epithelium and superficial cortical fiber cells and (b) human retinal pigment epithelial (ARPE-19) cells. Cultured bovine lenses and confluent cultures of ARPE-19 cells were irradiated with broadband UV-B radiation at energy levels of 0.5 and 1.0 J/cm(2). Lens optical function (spherical aberration) was monitored daily up to 14 days using an automated laser scanning system that was developed at the University of Waterloo. This system consists of a single collimated scanning helium-neon laser source that projects a thin (0.05 mm) laser beam onto a plain mirror mounted at 45 degrees on a carriage assembly. This mirror reflects the laser beam directly up through the scanner table surface and through the lens under examination. A digital camera captures the actual position and slope of the laser beam at each step. When all steps have been made, the captured data for each step position is used to calculate the back vertex distance for each position and the difference in that measurement between beams. To investigate mitochondrial movement, the mitochondria-specific fluorescent dye Rhodamine 123 was used. Time series were acquired with a Zeiss 510 (configuration Meta 18) confocal laser scanning microscope equipped with an inverted Axiovert 200 M microscope and 40-x water-immersion C-Apochromat objective (NA 1.2). The optical analysis showed energy level-dependent increases in back vertex distance variability (loss of sharp focus) from 0.39 +/- 0.04 mm (control, n = 11) to 1.63 +/- 0.33 mm (1.0 J/cm(2), n = 10) and 0.63 +/- 0.13 mm (0.5 J/cm(2), n = 9). Confocal laser scanning microscopy analysis of both bovine lenses and ARPE-19 cells showed that following treatment at 0.5 J/cm(2) the mitochondria stopped moving immediately whereas at 1.0 J/cm(2) not only did the mitochondria stop moving, but fragmentation and swelling was seen. Untreated control tissue exhibited up to 15 microm/min of movement of the mitochondria. This could represent normal morphological change, presumably allowing energy transmission across the cell from regions of low to regions of high ATP demand. Lack of mitochondrial movement, fragmentation, and swelling of mitochondria may represent early morphological changes following oxidative stress that may lead to activation of caspase-mediated apoptotic pathways.

New records of three marine red algae from Japan

SUMMARYThree species in the red algal order Ceramiales, Dasya longifila Masuda et Uwai (Dasyaceae), Endosiphonia horrida (C. Agardh) P. Silva (Rhodomelaceae) and Laurencia flexilis Setchell (Rhodomelaceae), are reported from Japan for the first time, and their morphological features are described along with taxonomic comments. Our findings point to the northernmost limit of geographic distribution of these species in the north‐western Pacific. Dasya longifila is characterized by small, sparsely corticated axes, long pseudolaterals in which intercalary cell divisions take place, and a small number of tetrasporangial stichidia and spermatangial branches per fertile pseudolateral. Endosiphonia horrida is characterized by frequently anastomosing branches that form a bush‐like tuft without a percurrent axis, inner cortical cells becoming the same length as the axial and periaxial cells, and luxuriously developed, unbranched trichoblasts. Laurencia flexilis is characterized by numerous cartilaginous rigid axes developing from a basal disc without creeping branches, the production of 4 periaxial cells per vegetative segment and the absence of longitudinally oriented secondary pit‐connections between contiguous superficial cortical cells.

Manganese-Enhanced MRI Reveals Structural and Functional Changes in the Cortex of Bassoon Mutant Mice

Manganese-enhanced magnetic resonance imaging (ME-MRI) was used to analyze the brain architecture in mice lacking the functional presynaptic active zone protein Bassoon. Anatomical characterization revealed a significant increase in the total brain volume in Bassoon mutants as compared with wild-type mice, which is mainly caused by changes in cortex and hippocampus volume. The measured enlargement in cortical volume coincides with an altered Mn2+ distribution within cortical layers as visualized by T1-weighted magnetic resonance imaging. Two days after manganese application, the cortex of Bassoon mutant mice appeared more laminated in ME-MRI, with an enhanced accumulation of manganese in deep, central, and superficial cortical cell layers. Whereas morphologically the cortical lamination is not affected by the absence of a functional Bassoon, an altered basal activation pattern was found in the cortex of the mutant mice both by metabolic labeling with [14C]-2-deoxyglucose and histochemical detection of the potassium analogue thallium uptake. Consequently, the results indicate that the absence of the functional presynaptic protein Bassoon causes disturbance in the formation of normal basal cortical activation patterns and thereby in the functional cortical architecture. Furthermore, this study shows that ME-MRI can become a valuable tool for a structural characterization of genetically modified mice.

Functional Thalamocortical Synapse Reorganization from Subplate to Layer IV during Postnatal Development in theReeler-Like Mutant Rat (Shaking Rat Kawasaki)

Transient synapse formation between thalamic axons and subplate neurons is thought to be important in thalamocortical targeting. Shaking rat Kawasaki (SRK), having reversed cortical layering similarly observed in reeler mouse, provides an interesting model system to test this idea. The spatial and temporal pattern of excitation was investigated using optical recording with voltage-sensitive dyes in thalamocortical slice preparations from SRK. At postnatal day 0 (P0), a strong optical response was elicited within the superplate of the SRK in the cell layer corresponding to subplate in wild-type (WT) rats. By P3, this response rapidly descended into deep cortical layers comprised of layer IV cells, as identified with 5-bromo-2'-deoxyuridine birthdating at embryonic day 17. During the first 3 postnatal days, both the subplate and cortical plate responses were present, but by P7, the subplate response was abolished. Tracing individual axons in SRK revealed that at P0-P3, a large number of thalamocortical axons reach the superplate, and by P7-P10, the ascending axons develop side branches into the lower or middle cortical layers. Synaptic currents were also demonstrated in WT subplate cells and in SRK superficial cortical cells using whole-cell recording. These currents were elicited monosynaptically, because partial AMPA current blockade did not modify the latencies. These results suggest that the general developmental pattern of synapse formation between thalamic axons and subplate (superplate) neurons in WT and SRK is very similar, and individual thalamic arbors in cortex are considerably remodeled during early postnatal development to find layer IV equivalent neurons.

Effect of hyperbaric oxygen on guinea pig lens optical quality and on the refractive state of the eye

The main objective of this study was to investigate the effect of in vivo hyperbaric oxygen (HBO) treatment of albino guinea pigs on ocular refractive state and optical properties of the lens in vitro, as well as on the integrity of the mitochondria of the lens. The animals were treated 30–35 times (2·5–3 months) or 70 times (6 months) with HBO. An increased level of lens nuclear light scattering was evident by slit-lamp at 30 treatments, and this increased at 70 treatments. After 30–35 HBO treatments a myopic shift in refractive state of the eye was seen in two separate studies with two different refractionists. Also, the average back vertex distance of the lens was significantly shorter after 35 HBO treatments while spherical aberration (focal variability) increased after 70 treatments. No difference in refractive state was noted after 70 HBO treatments (a reversal of the initial myopic effect). The mitochondrial distribution and morphology of the lens epithelium and the superficial cortical fibre cells were normal after both 35 and 70 HBO treatments, highlighting that HBO treatment does not affect the superficial cortex of the lens. The results of the in vitro lens optical analysis carried out in this study correlate with the myopia observed after 30–35 HBO in vivo treatments. A similar reversible myopia and increase in lens nuclear light scattering is known to occur in humans treated with HBO for extended periods and the results suggest that the myopia was caused by a change in the refractive index of the lens. The significant loss of sharp focus after 70 HBO treatments can be correlated with previous reports of biochemical and morphological changes associated with HBO-induced loss of lens nuclear transparency in mature guinea pigs. The guinea pig HBO model may be a useful approach for the study of lens development and refractive error.

Optical properties, mitochondria, and sutures of lenses of fishes: a comparative study of nine species

This comparative study of lenses from nine fish species consisted of seven teleosts (oscar, Astronotus ocellatus; smallmouth bass, Micropterus dolomieu; orangespotted sunfish, Lepomis humilus; Arctic char, Salvelinus alpinus; common carp, Cyprinus carpio; rainbow trout, Oncorhynchus mykiss; American eel, Anguilla rostrata) and two species representing more primitive forms (brook lamprey, Lampetra lamotteni; lake sturgeon, Acipenser fulvescens). Lens optical properties were analysed using an automated scanning laser monitor. Lens suture anatomy and the morphology and distribution of mitochondria were analysed using a confocal laser scanning microscope. Lenses of Arctic char exhibited the sharpest focus, whereas American eel lenses exhibited the poorest ability to focus and the highest amount of spherical aberration. Metabolically active mitochondria are found in lens epithelial and superficial cortical fibre cells, as in mammals. The results of the detailed study of the lens sutures show that teleost lenses exhibit "line" sutures, whereas "Y" sutures are seen in lake sturgeon lenses. Line sutures are also seen in lenses of brook lamprey and American eel. These last results contrast with the common report of "point" sutures in fish lenses.

Mechanisms of ocular toxicity using the in vitro bovine lens and sodium dodecyl sulfate as a chemical model.

Previous work using the in vitro bovine lens as a model has shown a correlation between toxicity and lens optical function and showed much higher sensitivity in detecting irritancy of several surfactants at much lower concentrations than the Draize score. In the current study, cultured bovine lenses were used to study the effects of the surfactant sodium dodecyl sulfate (SDS) on lens optical properties and mitochondrial integrity. Bovine lenses were exposed to SDS (0.1 to 0.00625%) for 30 min and cultured for 24 h. Compared to controls (n = 17), loss of sharp focus was evident immediately following exposure to 0.1% SDS (n = 14, p < 0.0001). At 24 h loss of sharp focus became evident in all groups. Loss of lens transparency, significant increase in lens wet weight, and axial length were seen 24 h postexposure in lenses treated with 0.1 to 0.025% SDS. Confocal analysis 24 h postexposure showed SDS concentration-dependent decrease in number and length of the mitochondria in lens epithelial and superficial cortical fiber cells. The results of this study show a correlation between lens optical properties and metabolic function and together provide a sensitive in vitro model of ocular chemical toxicity. Results of confocal analysis suggest that the mitochondrial integrity of the superficial cortical fiber cells is most sensitive to damage caused by SDS. The results further suggest that recovery of lens metabolic function is necessary for the recovery of lens optical properties.

Taxonomic Notes on Marine Algae from Malaysia. XI. Four Species of Rhodophyceae

Hypnea cornuta (Kutzing) J. Agardh var. stellulifera J. Agardh (Hypneaceae, Gigartinales) is distinguished from the type variety by the short, thick, rigid axes that produce thick adventitious branchlets as well as the tetrasporangial sori and spermatangial sori that extend to the parental axis and branches. Var. stellulifera is raised to the rank of species as Hypnea stellulifera (J. Agardh) Yamagishi et Masuda on the basis of these morphological differences and comparative chloroplast-encoded rbcL sequences. Reproductive structures of Heterosiphonia crispella (C. Agardh) Wynne (Dasyaceae, Ceramiales), which is referable to var. laxa (Borgesen) Wynne, are described. Two species of Laurencia (Rhodomelaceae, Ceramiales) are reported from Malaysia for the first time: L. pygmaea Weber-van Bosse and L. majuscula (Harvey) Lucas. Critical features of L. pygmaea include four pericentral cells per segment, the presence of a single (rarely two) corps en cerise per superficial cortical cell, and the production of a single tetrasporangium-bearing pericentral cell on each fertile segment.

Taxonomic Notes on Marine Algae from Malaysia. VIII. Three Species of Laurencia (Rhodophyceae)

Three species of the red algal genus Laurencia (Ceramiales, Rhodomelaceae) are reported from Malaysia for the first time: L. lageniformis Masuda, L. nangii Masuda and L. calliclada Masuda. Some morphological features regarding corps en cerise and spermatangial branches, which have been unknown for these species, are described. The occurrence of plural corps en cerise in individual trichoblast cells of L. nangii is the first report for the species of Laurencia, as some species have been reported to possess two to four (or more) corps en cerise in superficial cortical cells, but such species are known to contain only a single corps en cerise in trichoblast cells. Furthermore, halogenated secondary metabolite contents of these species are reported.

Heat shock proteins of adult and embryonic human ocular lenses

We investigated the presence and distribution of heat shock proteins, HSP-70 [Horwitz, J. 1992. Proc Natl Acad Sci 89:10449-10453], HSP-40, HSc-70, HSP-27, and alphabeta-crystallin in different regions of adult and fetal human lenses and in aging human lens epithelial cells. This study was undertaken because heat shock proteins may play an important role in the maintenance of the supramolecular organization of the lens proteins. Human adult and fetal lenses were dissected to separate the epithelium, superficial cortex, intermediate cortex, and nucleus. The water soluble and insoluble protein fractions were separated by SDS-PAGE, and transferred to nitrocellulose paper. Specific antibodies were used to identify the presence of heat shock proteins in distinct regions of the lens. HSP-70 [Horwitz, 1992], HSP-40, and HSc-70 immunoreactivity was mainly detected in the epithelium and superficial cortical fiber cells of the adult human lens. The small heat shock proteins, HSP-27 and alphabeta-crystallin were found in all regions of the lens. Fetal human lenses showed immunoreactivity to all heat shock proteins. An aging study revealed a decrease in heat shock protein levels, except for HSP-27. The presence of HSP-70 [Horwitz, 1992], HSP-40, and HSc-70 in the epithelium and superficial cortical fiber cells imply a regional cell specific function, whereas the decrease of heat shock protein with age could be responsible for the loss of optimal protein organization, and the eventual appearance of age-related cataract.

Laurencia venusta (Ceramiales, Rhodophyta): a New Record from the Atlantic Ocean

Laurencia venusta Yamada, originally described from the western Pacific Ocean, is recorded for the first time from the Atlantic Ocean. It occurs in Quintana Roo State, Mexico, which is located on the eastern portion of Yucatan Peninsula, Caribbean Sea. The present species belongs to the subgenus Laurencia by nature of possessing four pericentral cells per vegetative axial segment, secondary pit-connections between superficial cortical cells, and parallel-type arrangement of the tetrasporangia. The principal characteristics for species identification are: pale green color, soft and flaccid thalli, verticillate branching, and the presence of lenticular thickenings in the walls of medullary cells.

The distinction between Chondrophycus patentirameus and C. paniculatus (Ceramiales, Rhodophyta)

The red algae Chondrophycus patentirameus (Montagne) Nam (‘patentiramea’) and L. paniculata (C. Agardh) J. Agardh were investigated on the basis of type material and recent collections. Both species show the following features: (i) production of two vegetative pericentral cells from each axial segment; (ii) absence of secondary pit connections between cortical cells; (iii) lack of projecting cortical cells near the apex; (iv) absence of lenticular thickenings in the walls of medullary cells; and (v) perpendicular arrangement of tetrasporangia, each of which is produced from the second pericentral cell in each fertile segment with no additional tetrasporangial pericentral cells. However, C. patentirameus has a stoloniferous holdfast, divaricate branching (with branches arising at angles up to 90°) and non-palisade-like superficial cortical cells, whereas L. paniculata has a discoid holdfast, non-divaricate branching and a palisade-like cortical layer. From this study it is concluded that C. patentirameus (here lectotypified) is distinct from L. paniculata. The latter species is here transferred to the genus Chondrophycus (Tokida & Saito) Garbary & T. Harper as follows: Chondrophycus paniculatus (C. Agardh) G. Furnari.