Plant communication

Plants are constantly in a process of sharing, talking, communicating among them self, in our surroundings.  

Fundamentally they have intelligence. 

Recent researches have shown very supportive proof regarding this 
communication phenomenon 
in 
plants.

Plants: The oxygen provider: Plants are an integral part of our 'respiratory-cycle', a major player in the give and take mechanism of O2 and CO2, which is so much important for the balance, a must for the existence of all aerobic animals...

 

Plants: Reducing carbon to carbohydrate: Green plants are the only major trappers of solar radiation, the primary energy source on earth; and then converting them into chemical form.

So, green plants are the 'Primary Producers', again a major player of 'Food Cycle' and 'Energy Cycle' ..

 

Plant: communication: As LUCA is the same for plants as well as the animals, so the plants are as ancient as we in the our evolutionary journey on this planet. That makes a strong point in the favor of existence of 'some possible communication-skills' among them self and with their neighbors; possibly these plants may be having, which is less explored so far and less understood too.Even some recent studies have indicated so:

#Report 1

Plants do communicate and kin relationship has a bearing: Newly published research in Proceedings of the Royal Society B shows that kin have distinct advantages when it comes to plant communication, just as "the ability of many of many animals to recognize kin has allowed them to evolve diverse cooperative behaviors,"

Ecologist Richard Karban of the UC Davis Department
of Entomology studying kin relationship in sagebrush

says lead researcher and ecologist Richard Karban, a professor in the UC Davis Department of Entomology.

This ability is less well studied for plants until now.

http://phys.org/news/2013-02-communicateand-kin-relationship.html

February 14, 2013

#Report 2

Gabe Popkin

National Geographic News

Published April 15, 2013

Trees Call for Help—And Now Scientists Can Understand Team identifies the sounds made by drought-stressed trees.

A tree stands alone in the drought-stricken
Salmon-Challis National Forest, Idaho,
in an undated picture.

Photograph by Pete Ryan, National Geographic

When drought hits, trees can suffer—a process that makes sounds. Now, scientists may have found the key to understanding these cries for help.

In the lab, a team of French scientists has captured the ultrasonic noise made by bubbles forming inside water-stressed trees. Because trees also make noises that aren't related to drought impacts, scientists hadn't before been able to discern which sounds are most worrisome. (Watch a video: Drought 101.)

"With this experiment we start to understand the origin of acoustic events in trees," said Alexandre Ponomarenko, a physicist at Grenoble University in France, whose team conducted the research.

This discovery could help scientists figure out when trees are parched and need emergency watering, added Ponomarenko, who presented his team's results last month at an American Physical Society meeting in Baltimore, Maryland.

Plant-human transaction: 

In our own lives....we have found much solace with these plants....be it any hour of the day....perhaps due some 'Communication Message' showered on our own senses....

The Bodhi Tree, also known as Bo (from the Sinhalese Bo), was a large and very old Sacred Fig tree (Ficus religiosa) located in Bodh Gaya (about 100 km (62 mi) from Patna in the Indian state of Bihar), under which Siddhartha Gautama, the spiritual teacher later known as Gautama Buddha, is said to have achieved enlightenment, or Bodhi. In religious iconography, the Bodhi tree is recognizable by its heart-shaped leaves, which are usually prominently displayed.

For young as well as old; plantation is a concern of both generations.

In our evenings of life, when shades are long, plant serve as succor, for the day dreaming....

On a hot sunny day, there is a cool and  fragrant invitation from these creatures, we call plants.

Even in night time, tender tendril is there to convey things un-said in the day hours.

 ********

Kingdom Plantae: Alternation of generations

Life scientists have developed several theories to account for the evolution of alternation of generations in plants. One theory has to do with having the “best of both worlds” in terms of variation in a population. In the formation of spores, only one parent contributes the hereditary material. This could be beneficial if that parent exists in a stable environment — it creates offspring with the same characteristics that allowed it to survive and reproduce. 
With sex cells, two parents are involved, and a mixing of hereditary material occurs. 
This results in offspring that vary from both parents and from one another. 
This could be beneficial in a changing environment where some variants are likely to be suited to that environment while others may not be.

All multicellular plants have a life cycle comprising two generations or phases. One is termed the gametophyte, has a single set of chromosomes (denoted 1N), and produces gametes (sperm and eggs). The other is termed the sporophyte, has paired chromosomes (denoted 2N), and produces spores. The gametophyte and sporophyte may appear identical – homomorphy – or may be very different – heteromorphy.

The pattern in plant evolution has been a shift from homomorphy to heteromorphy. The algal ancestors of land plants were almost certainly haplobiontic, being haploid for all their life cycles, with a unicellular zygote providing the 2N stage. All land plants (i.e. embryophytes) are diplobiontic – that is, both the haploid and diploid stages are multicellular. Two trends are apparent: bryophytes (liverworts, mosses and hornworts) have developed the gametophyte, with the sporophyte becoming almost entirely dependent on it; vascular plants have developed the sporophyte, with the gametophyte being particularly reduced in the seed plants.

Moss life cycle diagram

There are two competing theories to explain the appearance of a diplobiontic lifecycle.

The interpolation theory (also known as the antithetic or intercalary theory) holds that the sporophyte phase was a fundamentally new invention, caused by the mitotic division of a freshly germinated zygote, continuing until meiosis produces spores. This theory implies that the first sporophytes bore a very different morphology to the gametophyte they depended on.

Diagram of alternation of generations in ferns

Plant ovules (megagametophytes): Gymnosperm ovule on left, angiosperm ovule (inside ovary) on right

The evolution of syncarps.
a: sporangia borne at tips of leaf
b: Leaf curls up to protect sporangia
c: leaf curls to form enclosed roll
d: grouping of three rolls into a syncarp

Angiosperm life cycle

Double fertilization

This seems to fit well with what is known of the bryophytes, in which a vegetative thalloid gametophyte is parasitised by simple sporophytes, which often comprise no more than a sporangium on a stalk. Increasing complexity of the ancestrally simple sporophyte, including the eventual acquisition of photosynthetic cells, would free it from its dependence on a gametophyte, as seen in some hornworts (Anthoceros), and eventually result in the sporophyte developing organs and vascular tissue, and becoming the dominant phase, as in the tracheophytes (vascular plants). This theory may be supported by observations that smaller Cooksonia individuals must have been supported by a gametophyte generation. The observed appearance of larger axial sizes, with room for photosynthetic tissue and thus self-sustainability, provides a possible route for the development of a self-sufficient sporophyte phase.

The alternative hypothesis is termed the transformation theory (or homologous theory). This posits that the sporophyte appeared suddenly by a delay in the occurrence of meiosis after the zygote germinated. Since the same genetic material would be employed, the haploid and diploid phases would look the same. This explains the behaviour of some algae, which produce alternating phases of identical sporophytes and gametophytes. Subsequent adaption to the desiccating land environment, which makes sexual reproduction difficult, would result in the simplification of the sexually active gametophyte, and elaboration of the sporophyte phase to better disperse the waterproof spores. The tissue of sporophytes and gametophytes preserved in the Rhynie chert is of similar complexity, which is taken to support this hypothesis.

#graphics thankfully shared from wikipedia.org

Genetic base in evolution of Oogamy and origin of male-female differentiation

Japanese researchers found the genetics basis of sex dimorphism (two genders) by investigating two closely related species of green algae that practice different forms of sexual reproduction.

Human egg cell

So, how did sex cells modify to eggs and sperm? It seems that a gene underlying a more primitive system of reproduction was likely co-opted during evolution to participate in sex-specific sperm development. 

The Japanese team found a genetic connection between male sexuality of an oogamous multicellular green algae species, Pleodorina starrii, and one of the mating types of a more primitive isogamous unicellular alga Clamydomonas reinhardtii. In C. reinhardtii, isogamy occurs through "plus" (MT+) and "minus" (MT-) mating types. MT- represents a "dominant sex" due to a particular gene, MID ("minus-dominance"), both necessary and sufficient to cause the cells to differentiate as MT- isogametes. However, no sex-specific genes related to MID had been identified in closely related oogamous species.

Human sperm cell

But now the scientists have successfully identified a version of the MID gene in Pleodorina starrii. This "PlestMID" gene is present only in the male genome, and it encodes a protein abundant in the nuclei of mature sperm. This means that P. starrii maleness evolved from the dominant sex (MT-) of its isogamous ancestor. This breakthrough discovery can answer many questions about the evolution of oogamy and the origins of male-female differentiation.

Origin and evolution of sex in lower plants

Origin of sex, Most primitive algae the cyanophyceae (Myxophyceae) reproduce only the method of asexual and vegetative reproduction. Sexual reproduction is entirely absent in their case. In forms like Nostoc and oscillatoria, it takes place by means of hormogones in which the plant body breaks up into group of few cells. In class xanthophyceae, chrysophyceae, cryptophyceae and dinopphyceae, sexuality is rare and has not much evolved beyond the stage of isogamy.

Spirogyra (Watersilk)

Chlamydomonas

In higher classes of algae reproduction takes place by vegetative, asexual and sexual methods. The commonest method of asexual reproduction is by means of Zoospores. The possibility of gametes from zoospores can evolved from the following description.

In genera like ulothrix, ordogonium, cladophora, zoospores were probably produced before the origin of sexual reproduction. In ulothrix three types of swarm spores are formed.

(i)         Quadriflagellate macro-zoospores: They are produced either singly or in small numbers from a single cell. These swarmers are capable of developing into normal plants.

(ii)        Macro-zoospores: They are either quadriflagellate or biflagellate and are produced in greater number from each cell than macro-zoospores. They give rise to vary weak plants which are smaller in size.

(iii) Gametes: These are always biflagellate, smaller than the micro-zoospores due to more division in the protoplasts of the cell and hence are largest in number. They are unable to develop into any plant individually but if two of these come together they behave as gametes and fuse leading to the formation of a zygote which germinates into a normal plant.

Oedogonium

Thus a gradual loss in vitality of swarmers can be traced, the end product (i.e. gametes) being largest in number but smallest in size and physically in capable of developing into usual plants. It is believed that there was a by chance fusion between these swarmers previously accustomed to reduce vegetatively and then the plants regularly took to the method of fusion or sexual reproduction. It may be concluded that the gametes are ordinary zoospores but reduced in size and unable to germinate without the stimules of sexual fusion. These biciliate gametes unite in pair (isogamy) forming a zygospore which forms a new plant. This proves the derivation of gametes from asexual swarmers.

In the evolution of sex, the trend is same in various classes of algae and the sex in all orders and genera has evolved from asexual bodies. Isogamy is the simplest mode of sexual reproduction where two morphological similar gametes fuse e.g.: chlamydomonas media and ulothrix. Isogamy gives rise to anisogamy where two morphologically dissimilar gametes fuse. Anisogamy may be advanced and primitive depending upon the difference in size and behaviour of the gametes e.g.: Pandoriva, Eudoriva, species of chlamydomonas.

Chlamydomonas reinhardtii

Oogamy is most advanced type of sexuality where the two gametes are so dissimilar in shape, size, structure and function that one of them is known as oogonuim and other as antheridium e.g.: volvox, chlamydomonas and ordogobium. In chlorophyceae evolution of sex may be seen from isogamy to oogamy when we study individual genera like chlamydomonas (C. media iroamous, C. brounii anisogamous, C. Coccifera oogamous) or order volvocales in which pandorina and endorina are anisogamous and volox is oogamous. In order ulotrichales family ulvaceae genus enteromarphs sexually ranges from isogamy to oogamy.

In Rhodophyceae isogamy and anisogamy are found. In Polysiphomia advanced oogamy is present in phacophycal ectocarpus shows isogamy and anisogamy. Anisogamy is also seen in cutariales. Fucus shows primitive type of oogornium. Sargassum shows advanced oogany because only one ovum is produced in oogonium after fertilization takes place.

It may concluded that in the evolution of sex in algae, the differentiation of gametes is associated with the differentiation of sex organ. It also shows that evolution of sex in algae has taken place from simplest type of the highest evolved type. 

*pictures shared from various internet sources, thankfully.

Red Blood Corpuscle enucleation and in vitro synthesis

Riding on the red road: Red blood cells are also known as RBCs, red cells, red blood corpuscles (an archaic term), haematids, erythroid cells or erythrocytes (from Greek erythros for "red" and kytos for "hollow", with cyte translated as "cell" in modern usage).

These cells' cytoplasm is rich in haemoglobin, an iron-containing biomolecule that can bind oxygen and is responsible for the blood's red color.

As red blood cells contain no nucleus, protein biosynthesis is currently assumed to be absent in these cells, although a recent study indicates the presence of all the necessary biomachinery in the cells to do so.

In humans, mature red blood cells are oval and flexible biconcave disks. They lack a cell nucleus and most organelles to accommodate maximum space for haemoglobin. 2.4 million new erythrocytes are produced per second. The cells develop in the bone marrow and circulate for about 100–120 days in the body before their components are recycled by macrophages. Each circulation takes about 20 seconds. Approximately a quarter of the cells in the human body are red blood cells.

Scanning electron micrograph of blood cells.
From left to right: human erythrocyte,
thrombocyte (platelet), leukocyte.

RBCs are specialized bags of hemoglobin Red blood cells are designed to pick up oxygen from the lungs and release it into the tissues of the body.  This is their major function.  The only reason that they can pick up and carry oxygen around is because they contain a protein within them called hemoglobin.

If red blood cells (RBCs, or erythrocytes) have to carry oxygen, yet it is the hemoglobin inside them that carries the oxygen, we might expect that RBCs should be loaded with hemoglobin. And in fact, they are!  They load themselves up so much with hemoglobin to carry oxygen that their nuclei get in the way.  So, RBCs don't have any nuclei!  1/3 of their entire volume is due to hemoglobin!

Production of RBCs: This process is called erythropoiesis.  Hemocytoblasts and RBC precursors have nuclei.  But, as cell division continues toward producing the RBC, a cell called a normoblast is made.   The normoblast continues to manufacture hemoglobin (at this point, it looks like a normal cell, but somewhat red).  Then, the normoblast ejects its nucleus.  The cytoplasm continues to make hemoglobin, even without a nucleus, because the instructions from the nucleus are still in the cytoplasm, even though the nucleus is gone.   Eventually, enough hemoglobin is made and the cell is released into the blood as an RBC.

    The odd-looking shape of the RBC actually allows lots of surface area to exist on this cell. That is another important feature of the RBC because it helps there be more room on the RBC for gas exchange across its membrane. The RBCs are rather small, averaging about 8 mm in diameter; a small size also helps them increase their surface area.

Life of RBC: Red blood cells can't last forever.  They have no nucleus. They have to squeeze through the teeniest of blood vessels all day long!  The odds are against them-- either they will run out of materials they need because they have no nucleus to make more, or they will squeeze through one too many teeny blood vessels and burst.  They can only last so long.

    On average, a red blood cell will survive 120 days (that's about 4 months... which is pretty good, considering their difficulties). Over 120 days, each RBC wll travel through the entire body about 75,000 times!  Wow!

Regulation of RBC production: Some people have a hard time with the change in altitude for a couple of days.  That's because at higher elevations there is less oxygen in the air... so to get enough oxygen, we actually need more RBCs in our body.  

    A drop in oxygen levels in one's body triggers the release of erythropoietin. Erythropoietin is released from the kidneys and liver, and it triggers erythropoiesis to occur.  Within a couple days, new RBCs are in the blood, and a person's RBC level increase.  

    Just like with the other hormones, there is a negative feedback loop to control erythropoiesis.  As oxygen levels return to normal, the kidneys (and liver) stop making erythropoietin.  The extra RBC production declines as long as oxygen levels remain normal.

Why RBCs are enucleated: Because they were descended from ancestors that had evolved red blood cells that had the ability to enucleate themselves as part of the process of red blood cell maturation. That's about it. This is useful because:

1. The enucleated red blood cell has more room for carrying hemoglobin and thus oxygen if it's not carrying around a nucleus

2. The enucleated red blood cell doesn't need an aerobic metabolism to support a nucleus, and therefore isn't itself using up the oxygen that it's carrying

3. The enucleated red blood cell is more bendy than a nucleated one, and can thus fit through narrower capillaries, which is more efficient since more of the body mass can be given over to cells of the body rather than capillary volume.

Enucleation less understood: Prior to entering the blood stream, developing erythroid or red blood cells condense and expel their nucleus. This unusual process occurs millions of times per minute in a healthy adult, and is unique to mammals. However, our understanding of this process is very limited.

Mammalian erythrocytes or red blood cells circulate without a nucleus. During development in the bone marrow, erythroid progenitors expand, mature and condense and expel their nucleus. This is estimated to occur 2 millions/second in a healthy adult human. The processes that regulate this event are extremely poorly defined. Interestingly, enucleation is restricted to mammals. All mammals possess enucleated red blood cells whereas erythrocytes of birds, reptiles, amphibians and fish all possess their nuclei. We are very interested in exploring the processes by which mammalian erythroid cells condense and expel their nuclei and asking why other vertebrates do not.

Enucleation is the hallmark of erythropoiesis in mammals. Previously, we determined that yolk sac–derived primitive erythroblasts mature in the bloodstream and enucleate between embryonic day (E)14.5 and E16.5 of mouse gestation. While definitive erythroblasts enucleate by nuclear extrusion, generating reticulocytes and small, nucleated cells with a thin rim of cytoplasm (“pyrenocytes”), it is unclear by what mechanism primitive erythroblasts enucleate. Immunohistochemical examination of fetal blood revealed primitive pyrenocytes that were confirmed by multispectral imaging flow cytometry to constitute a distinct, transient cell population. The frequency of primitive erythroblasts was higher in the liver than the bloodstream, suggesting that they enucleate in the liver, a possibility supported by their proximity to liver macrophages and the isolation of erythroblast islands containing primitive erythroblasts. Furthermore, primitive erythroblasts can reconstitute erythroblast islands in vitro by attaching to fetal liver–derived macrophages, an association mediated in part by α4 integrin. Late-stage primitive erythroblasts fail to enucleate in vitro unless cocultured with macrophage cells. Our studies indicate that primitive erythroblasts enucleate by nuclear extrusion to generate erythrocytes and pyrenocytes and suggest this occurs in the fetal liver in association with macrophages. Continued studies comparing primitive and definitive erythropoiesis will lead to an improved understanding of terminal erythroid maturation.

Human erythrocytes are produced through a process named erythropoiesis, developing from committed stem cells to mature erythrocytes in about 7 days. When matured, these cells live in blood circulation for about 100 to 120 days (and 80 to 90 days in a full term infant). At the end of their lifespan, they become senescent, and are removed from circulation.

Erythropoiesis is the development process by which new erythrocytes are produced; it lasts about 7 days. Through this process erythrocytes are continuously produced in the red bone marrow of large bones, at a rate of about 2 million per second in a healthy adult. (In the embryo, the liver is the main site of red blood cell production.) The production can be stimulated by the hormone erythropoietin (EPO), synthesised by the kidney. Just before and after leaving the bone marrow, the developing cells are known as reticulocytes; these comprise about 1% of circulating red blood cells.

Blood in a dish: in vitro synthesis of red blood cells

In vitro production of RBCs: the 2-step erythroid culture system

Red blood cells, currently obtained from donors, represent the most common form of cell-based therapy. A better understanding of normal erythropoiesis is leading to improved multi-step protocols for the in vitro generation of fully mature red cells. The extensive in vitro expansion of embryonic erythroblasts and development of erythroid precursors as a potential transfusion product may help to deal with issues of scale and eventually find a place in the treatment of patients with acute and chronic anemias.

# pictures thankfully shared from wikipedia.org and other internet resources.