Structure of reproductive apparatus of Gracilaria/ Gracilariopsis lemaneiformis (Gracilariaceae, Rhodophyta)

Reproductive apparatus of Gracilaria/Gracilariopsis lemaneiformis collected from Qingdao city were studied with a light and a transmission electron microscope. The special superficial arrangement of spermatangium for this species was clearly observed, and the ultrastructure of spermatangial development revealed the similar cytodynamic pattern followed by all the Gracilariaceae members developed from spermatangial mother cells to spermatangium. The female reproductive apparatus before fertilization was also observed and trichogyne was found protruding above the cortex, contrary to the earlier reports. Tetrasporangium was formed by an outer cortical cell and the tetraspores became spherical and expended after being released. Supported by the National Natural Sciences Foundation of China (Grant No. 40606034) and the National High-Tech Research and Development Program of China (Grant No. 2006AA10A413)     

Structure of reproductive apparatus of Gracilaria/Gracilariopsis lemaneiformis (Gracilariaceae,Rhodophyta)

Reproductive apparatus of Gracilaria/Gracilariopsis lemaneiformis collected from Qingdao city were studied with a light and a transmission electron microscope. The special superficial arrangement of spermatangium for this species was clearly observed, and the ultrastructure of spermatangial devel-opment revealed the similar cytodynamic pattern followed by all the Gracilariaceae members devel-oped from spermatangial mother cells to spermatangium. The female reproductive apparatus before fertilization was also observed and trichogyne was found protruding above the cortex, contrary to the earlier reports. Tetrasporangium was formed by an outer cortical cell and the tetraspores became spherical and expended after being released.     

Optimization of the yield and quality of agar from Gracilariopsis lemaneiformis (Gracilariales) from the Gulf of California using an alkaline treatment

The effect of several alkali treatments on the yield, gel strength, rheology, and chemical characteristics (quality) of the agar obtained from Gracilariopsis lemaneiformis from the Gulf of California was analyzed using different alkali concentrations, temperatures and treatment times. In the first stage of the experiment, all treatments lasted 60 min and the NaOH concentrations (2.5, 3.0, 4.0, 5.0, 6.0%) and temperature (80, 90, 100°C) varied. At constant time, temperature played the predominant role, promoting an increase in agar gel strength. Based on the best treatment conditions found (4% and 5% NaOH, and 90°C and 100°C temperature), in the second stage different treatment times (15, 30, 60, 90, 120 min) were used. Since agar yields were not significantly different among temperatures and times, the optimal conditions to obtain best quality agar were those providing the highest gel strength. Treatment time played an important role in increasing gel strength. Maximum gel strength (Nikan, 954 g cm⁻²) was obtained with 5% NaOH at 100°C after 90 min of treatment, though these conditions resulted in an agar yield reduction of 25.5% relative to native agar. This treatment proved to efficiently yield G. lemaneiformis agar that will meet the commercial quality requirements regarding gel strength, 3,6 anhydrogalactose and sulfate content, as well as rheology and hysteresis. Enrique Hernández-Garibay holds a CONACyT scholarship.     

Observations on Flattened Species of Gracilaria (Gracilariaceae, Rhodophyta) from Taiwan

Four flattened Gracilaria species have been reported from Taiwan: G. spinulosa, G. vieillardii, G. textorii and G. punctata, identified based on branching pattern, the presence or absence of spines, and characters that often vary seasonally. Gracilaria spinulosa was originally described from the type locality, Tainan. Species with toothed margins are usually referred to G. “vieillardii”; those with smooth margins to G. “textorii”, and those with smooth margins and dark spots scattered over the blade to G. “punctata”. Molecular analyses show that specimens with marginal teeth cluster in three different groups: a G. “vieillardii” clade, a G. spinulosa clade, and a clade sister to G. spinulosa. An undescribed species comprises the third clade, which is distinguished by its relatively large gonimoblast cells and weakly developed tubular nutritive cells. The three clades can be separated by the character of the tubular nutritive cells, the size of gonimoblast cells and certain vegetative features. Plants with entire margins form a single clade characterized by cystocarps with basal tubular nutritive cells and their absence in the cystocarp cavity. They are nested in the Hydropuntia complex and are referred to as Gracilaria “punctata” here. The records of G. textorii and G. punctata from Taiwan require reinvestigation in comparison with the Japanese species.     

Photosynthetic and respiratory responses of Gracilaria vermiculophylla (Ohmi) Papenfuss collected from Kumamoto, Shizuoka and Iwate, Japan

The photosynthetic and respiratory responses to irradiance, salinity and temperature of the red alga, Gracilaria vermiculophylla, collected from Kumamoto, Shizuoka and Iwate in Japan were studied using an electronic Dissolved Oxygen sensor. The parameters derived from the photosynthesis versus irradiance relationship indicated the potential to acclimate to broad irradiance variations in all of the populations of G. vermiculophylla collected from these three sites. In addition, the light-saturated photosynthesis rate (P _max) and the dark respiration rate of all populations increased with increasing temperature up to 20–30°C, while the P _max decreased at 35°C. All populations also showed a broad variation of photosynthetic responses to salinity changes in the range from 10 to 30 psu. On the other hand, the population from Iwate showed high photosynthetic efficiency, especially in the temperature range of 5–10°C, and showed low values of saturation irradiance compared to the populations from Shizuoka and Kumamoto. These results suggest that there is greater potential to acclimate to low irradiance and low temperature in the population from Iwate compared to those from the Shizuoka and Kumamoto populations. However, the P _max of the populations from Iwate and Shizuoka was reached at 20°C and 25°C, respectively, while the Kumamoto population reached P _max at 30°C. This implies that the latter population has greater potential to tolerate higher temperatures than the former. Such characteristics in photosynthesis and respiration of G. vermiculophylla collected from the three locations probably indicate an acclimation to prevailing environmental conditions in their respective habitats.     

Evidence of gonochorism in a grouper, <Emphasis Type="Italic">Mycteroperca rosacea</Emphasis>, from the Gulf of California,Mexico

The sexual pattern and sexual development of the leopard grouper, Mycteroperca rosacea, were investigated from 483 specimens collected from the Gulf of California, Mexico. Histological and population data indicated a gonochoric sexual pattern. Some juveniles passed through an immature bisexual phase of gonadal development, but no evidence of post-maturational sex change was found. The immature bisexual phase is believed to be associated only with male development. The size distribution and size at sexual maturity were similar for both males and females. In accordance with predictions of the size-advantage model, the gonochoric sexual pattern of M. rosacea is likely influenced by its group-spawning mating system.

Structure and properties of agar from two unexploited agarophytes from Venezuela

The red seaweeds Gelidiella acerosa and Gracilaria mammillaris growing along the coast of Venezuela were investigated as potential economic sources of agar. Agar extracted from Gracilaria mammillaris accounted for 27% of the algal dry weight but had quite a poor gelling ability because of the presence of alkali-stable sulphate groups on the D-galactose residue. However, the gel strength of its aqueous solutions was considerably enhanced by the addition of potassium, sodium and calcium ions (up to 1N). On the contrary, the galactan from Gelidiella acerosa (yield of about 20% w/w) exhibited quite good properties. In particular, the gel strength was comparable to that of commercial agaroses. Sulphate esters were not detectable by chemical methods and NMR spectroscopy revealed an agarose backbone with a high degree of methylation on both D and L-galactose residues.     

Comparison of three gracilarioids: growth rate, agar content and quality

Three gracilarioid species, Gracilariopsis bailiniae and Gracilaria tenuistipitata from Vietnam and Gracilaria gracilis from Russia, were studied in order to determine whether Gracilaria gracilis might be a superior species for cultivation in brackish-water ponds for agar production compared with the Vietnamese species. The effects of different salinity levels on the growth rate and agar production as well as agar properties of three gracilarioid species were compared in controlled laboratory experiments. Gracilaria tenuistipitata and G. gracilis were tolerant to low salinity (∼10‰), whereas Gp. bailiniae died under these conditions. G. tenuistipitata showed superior growth among the three species examined. Gracilaria gracilis had the highest agar content [36.8–46.6% dry weight (dw)]. Agar yield from Vietnamese gracilarioids did not exceed 30% dw. Gel strength of native agar from Gracilaria gracilis was two-fold higher that from Vietnamese species (278 g cm⁻² vs 130 g cm⁻²). Alkali pretreatment increased gel strength significantly for Gracilaria gracilis (1.4-fold), and G. tenuistipitata and Gp. bailiniae (2.3-fold) compared with native agar. The results suggest that Gracilaria gracilis may be a suitable species for production of reasonably good quality agar.     

Antifungal properties of selected plants from the Yucatan peninsula,Mexico

A total of 20 plants belonging to different genera (Acalypha, Ageratum, Ambrosia, Bidens, Blechum, Caesalpinia, Calea, Carlowrightia, Croton, Eugenia (2), Furcraea, Stenandrium, Tephrosia, Trichilia (2), Randia (3), and Vitex) were selected from native flora of the Yucatan peninsula. All plants selected were collected and separated in to leaves, stems and roots. These were then extracted with ethanol and their crude extracts (54) were evaluated against Alternaria tagetica, Colletotrichum gloeosporioides, Fusarium oxysporum and Rhizopus sp. using the filter paper disc diffusion assay. Results lead to the selection of 33 crude extracts active against at least one of the target strains, which were assessed to determine their ability to inhibit the mycelial growth of the pathogenic fungi in a second antifungal assay. The results of this assay indicated that extracts from the roots of Croton chichenensis were the most promising, with a wide activity spectrum against all pathogens tested in both assays with inhibition percentages of greater than 60%. Furthermore, extracts from leaves of Ambrosia hispida, Trichilia minutiflora, and roots of Acalypha gaumeri were able to cause growth inhibition against two or three pathogen strains (≥50%). Studies of these active extracts should be continued at different levels. In general, results revealed a good bioactive potential of the flora from the Yucatan peninsula to produce metabolites with potential applications as botanical pesticides in the near future.     

Samuraia tabularasa gen. nov., sp. nov. (Cnidaria,Hydrozoa, Hydrocorynidae), an intertidal hydroid from the Gulf of California,Mexico

Samuraia tabularasa, the samurai hydroid, a previously unreported genus and species of athecate hydrozoan, family Hydrocorynidae, is described, based upon field and laboratory observations. Colonies live attached to rocky substrates in the middle of the intertidal zone in the northern and central Gulf of California, Mexico. The principal characters that allow this species to be referred to a new genus are associated with its mode of sexual reproduction by eumedusoids that can remain attached to the colony, or be released as ephemeral, rudimentary structures. This is in contrast to the feeding, free medusae produced by the two species of the other genus, Hydrocoryne, in the family Hydrocorynidae.     

Endocrinological investigation into the reproductive cycles of two sympatric skate species, Malacoraja senta and Amblyraja radiata, in the western Gulf of Maine

The smooth skate, Malacoraja senta, and thorny skate, Amblyraja radiata, are two commercially exploited batoids found within the Gulf of Maine. During the past five years, we conducted a large study to accurately describe important biological life history parameters previously lacking for these species. As part of that project, the current study reports our findings on the hormonal profiles associated with the reproductive cycles of M. senta and A. radiata. Blood samples were obtained from mature M. senta and A. radiata of both sexes from all months of the year, and plasma testosterone (T), estradiol (E₂) and progesterone (P₄) concentrations were determined using radioimmunoassay (RIA). In female M. senta and A. radiata, monthly T concentrations ranged from 4,522 pg ml⁻¹ to 1,373 pg ml⁻¹ and 31,940 pg ml⁻¹ to 14,428 pg ml⁻¹, E₂ concentrations from 831 pg ml⁻¹ to 60 pg ml⁻¹ and 8,515 pg ml⁻¹ to 2,902 pg ml⁻¹, and P₄ concentrations from 3,027 pg ml⁻¹ to 20 pg ml⁻¹ and 3,264 pg ml⁻¹ to 331 pg ml⁻¹, respectively. No statistical differences were detected between any months for any hormone. Estradiol concentrations were not correlated with ovary weight, shell gland weight, or diameter of the largest follicles in either species. Monthly T concentrations in male M. senta and A. radiata ranged from 23,146 to 12,660 pg ml⁻¹ and from 57,500pg ml⁻¹ to 24,737 pg ml⁻¹, while E₂ concentrations ranged from 7.5 pg ml⁻¹ to undetectable and 103 to 30 pg ml⁻¹, respectively. No statistical differences were observed between months for either steroid. Testosterone concentrations were weakly correlated with testes weight and percent of stage VI spermatocysts in A. radiata, however, no correlation was detected between T and stage VI spermatocysts in M. senta. Collectively, these data support the previous conclusion that M. senta and A. radiata of both sexes are capable of reproducing year round in the western Gulf of Maine.     

Calliandra dolichopoda and C. cualensis (Leguminosae, Mimosoideae), two new species from Mexico

Calliandra dolichopoda and C. cualensis, two species endemic to Guerrero and Jalisco, Mexico, respectively, are described and illustrated. Both species appear to be closely related to C. hirsuta.

---

Resumen  Se describen e ilustran Calliandra dolichopoda y C. cualensis, dos especies endémicas de Guerrero y Jalisco, México, respectivamente. Ambas especies parecen estar relacionadas con C. hirsuta.

     

Pinus georginae (Pinaceae), a new species from western Jalisco, Mexico

Pinus georginae is described and illustrated as a new endemic species from the valleys in the southern basin of Río Ameca, Jalisco, western Mexico. It is closely related to Pinus praetermissa; however, after studying the cones and anatomy of the leaves in detail, characteristics were revealed that identify P. georginae as a distinct species.

---

Resumen  Se describe e ilustra Pinus georginae como una especie nueva, endémica de algunos valles intermontanos al sur del Río Ameca, Jalisco, en el Occidente de México. Los árboles se parecen a Pinus praetermissa; sin embargo, al estudiar con detalle los conos y la anatomía de las acículas lo ubican a Pinus georginae como una entidad biológica con categoría específica independiente.

     

Ecological effects of seaweed harvesting in the Gulf of California and Pacific Ocean off Baja California and California

The ecological effects of harvesting were investigated for two species, the giant kelp Macrocystis pyrifera and Eucheuma uncinatum, by using harvest records and aerial surveys that show yield changes and by using studies of recruitment, survivorship and community interactions. There were no ecological effects found for M. pyrifera harvested with contemporary methods, and there are no recommendations for changing current management practices for this species. It is recommended that E. uncinatum, which on occasion produces commercially significant standing crops, not be harvested unless special precautions are taken to leave some plants for regeneration of the harvested populations.     

Effects of season on the yield and quality of agar from Gracilaria species (Gracilariaceae, Rhodophyta)

The effect of season on yield and physical properties of agars extracted from Gracia gracilis and G. bursa-pastoris were determined. The agar yield from G. gracilis was maximum during spring (30%) and minimum during autumn (19%). In G. bursa-pastoris, the agar yield was greatest in summer (36%) and lowest in winter (23%). Agar yield from G. bursa-pastoris was positively correlated with temperature (r=0.94; P<0.01) and salinity (r=0.97; P<0.01) and negatively with nitrogen content (r=−0.93; P<0.01). Agar gel strengths fluctuated from 229 to 828 g cm⁻² and 23 to 168 g cm⁻² for G. gracilis and G. bursa-pastoris, respectively. The gelling temperature showed significant seasonal variation for both species. Chemical analysis of agar from the two seaweeds indicated variation in 3,6-anhydrogalactose and sulfate content (P<0.01). Furthermore, there was an inverse correlation between the two chemical variables. In general, agar extracted from G. gracilis possessed better qualities than agar extracted from G. bursa-pastoris and can be considered a candidate for industrial use.     

Three new species of ferns (Woodsiaceae and Polypodiaceae) from Mexico

Three new species of ferns are described from Mexico:Athyrium tripinnatum, Cystopteris millefolia, andPolypodium praetermissum.     

Seasonal accumulation of metals by red alga Gracilaria verrucosa (Huds.) Papens. from Thermaikos Gulf, Greece

Concentrations of Fe, Pb, Cu, Zn and Cd were determined during one season in the red alga Gracilaria verrucosa, sediment and seawater from the Thermaikos Gulf, Greece. This region has been subject to change due to increases in industrial and domestic activities. The relative abundance of metals in G. verrucosa and seawater decreased in the order: Fe>Zn>Pb>Cu>Cd and in the sediment: Pb>Fe>Zn>Cu>Cd. Cadmium concentration in the alga correlated positively with that in seawater. There was positive correlation between Fe concentrations in the alga and those of the Zn and Cu. The concentrations of metals in the alga showed no significant differences between the stations. Lead, Zn and Cu concentrations in the alga were slightly higher at Biamyl, whereas Cd was higher at Perea and Fe at Nea Krini. Seasonal variation of metal concentrations in the alga was significant for Cd and Fe. Copper and Fe increased from winter to summer, whereas Cd was the opposite. Zinc concentrations were minimum and Pb concentrations were maximum during spring. These variations are discussed in relation to tissue age, life cycle, ambient concentrations of metals and other environmental conditions. Cd and Pb concentrations inG. verrucosa in the Thermaikos Gulf were higher and those of Cu and Zn were lower than in other species of the genus. This revised version was published online in August 2006 with corrections to the Cover Date.     

Loureirophonte psammophila,a new species of Laophontidae T. Scott, 1904 (Copepoda: Harpacticoida) from Baja California,Mexico

Loureirophonte psammophila n. sp. was collected from coarse sediments of a beach near La Paz, Baja California, Mexico. The species belongs to the subterranea-group as defined by Fiers (1993). It differs from the other representative of the group, L. subterranea (Lang, 1965) in the presence of an outer dentiform process on 2nd segment of the antennula, the chaetotaxy of P.2–P.5 and the 1-segmented male endopodite P.4. A map with the distribution of the eleven species known so far is provided.     

Thirteen new species and two new combinations of Stevia (Asteraceae: Eupatorieae) from Mexico

Thirteen new species of the genusStevia are described and illustrated from Mexico:S. chilapensis, S. coahuilensis, S. crassifolia, S. ecatepecana, S. filodecaballoana, S. mascotensis, S. mexicana, S. oaxacana, S. oligophylla, S. potosina, S. rotundifolia, S. scabrelloides, andS. viejoana. In addition, two varieties,Stevia aschenborniana Sch. Bip. ex Klotzsch var.occidentalis Grashoff andS. palmeri A. Gray var.constricta Grashoff are herein redefined as being distinct species,S. occidentalis andS. constricta stat. nov.Stevia mexicana resemblesStevia trifida Lagasca but differs in the habit.